US Supreme Court Briefs

No. 99-1257

In the Supreme Court of the United States




Solicitor General
Counsel of Record
Assistant Attorney General
Deputy Solicitor General
Assistant to the Solicitor
Department of Justice
Washington, D.C. 20530-0001
(202) 514-2217

General Counsel
Deputy General Counsel
Environmental Protection
Washington, D.C. 20460


Appendix A (court of appeals' opinion, dated May 14, 1999)

Appendix B:

(court of appeals' opinion on rehearing, dated October 29, 1999)

(court of appeals' dissenting statements on rehearing en banc, dated October 29, 1999)

Appendix C (regulatory provisions, 40 C.F.R. 50.7)

Appendix D (regulatory provisions, 40 C.F.R. 50.10)

Appendix E (statutory provisions, 42 U.S.C. 7407, 7408, 7409, 7502, 7511, 7607)



No. 97-1440


Consolidated with

Nos. 97-1546, 97-1548, 97-1551, 97-1552, 97-1553,
97-1555, 97-1559, 97-1561, 97-1562, 97-1565, 97-1567,
97-1571, 97-1573, 97-1574, 97-1576, 97-1578, 97-1579,
97-1582, 97-1585, 97-1586, 97-1587, 97-1588, 97-1592,
97-1594, 97-1596, 97-1597, 97-1598



Consolidated with
Nos. 97-1502, 97-1505, 97-1508, 97-1509, 97-1510,
97-1512, 97-1513, 97-1514, 97-1518, 97-1519, 97-1526,
97-1531, 97-1539, 97-1566, 97-1568, 97-1570, 97-1572,
97-1575, 97-1584, 97-1589, 97-1591, 97-1595, 97-1619

[Decided May 14, 1999]
[Argued December 17, 1998]

On Petitions for Review of an Order of the
Environmental Protection Agency


Opinion for the Court filed PER CURIAM.*

Separate opinion dissenting from Part I filed by Circuit Judge Tatel.



The Clean Air Act requires EPA to promulgate and periodically revise nationalambient air quality standards ("NAAQS") for each air pollutantidentified by the agency as meeting certain statutory criteria. See CleanAir Act §§ 108-09, 42 U.S.C. §§ 7408-09. For each pollutant,EPA sets a "primary standard"-a concentration level "requisiteto protect the public health" with an "adequate margin of safety"-anda "secondary standard"-a level "requisite to protect thepublic welfare." Id. § 7409(b).

In July 1997 EPA issued final rules revising the primary and secondary NAAQSfor particulate matter ("PM") and ozone. See National AmbientAir Quality Standards for Particulate Matter, 62 Fed. Reg. 38,652 (1997)("PM Final Rule"); National Ambient Air Quality Standards forOzone, 62 Fed. Reg. 38,856 (1997) ("Ozone Final Rule"). Numerouspetitions for review have been filed for each rule.

In Part I we find that the construction of the Clean Air Act on which EPArelied in promulgating the NAAQS at issue here effects an unconstitutionaldelegation of legislative power. See U.S. Const. art. I, § 1 ("Alllegislative powers herein granted shall be vested in a Congress of the UnitedStates."). We remand the cases for EPA to develop a construction ofthe act that satisfies this constitutional requirement.

In Part II we reject the following claims: that § 109(d) of the Actallows EPA to consider costs; that EPA should have considered the environmentaldamage likely to result from the NAAQS' financial impact on the AbandonedMine Reclamation Fund; that the NAAQS revisions violated the National EnvironmentalPolicy Act ("NEPA"), Unfunded Mandates Reform Act ("UMRA"),and Regulatory Flexibility Act ("RFA").

In Part III we decide two ozone-specific statutory issues, holding thatthe 1990 revisions to the Clean Air Act limit EPA's ability to enforce newozone NAAQS and that EPA cannot ignore the possible health benefits of ozone.

Finally, in Part IV we resolve various challenges to the PM NAAQS. We agreewith petitioners that EPA's choice of PM10 as the indicator for coarse particulatematter was arbitrary and capricious; we reject petitioners' claims thatEPA must treat PM2.5 as a "new pollutant," that EPA must identifya biological mechanism explaining PM's harmful effects, and that the CleanAir Act requires secondary NAAQS to be set at levels that eliminate alladverse visibility effects.

The remaining issues cannot be resolved until such time as EPA may developa constitutional construction of the act (and, if appropriate, modify thedisputed NAAQS in accordance with that construction).

I. Delegation

Certain "Small Business Petitioners" argue in each case that EPAhas construed §§ 108 & 109 of the Clean Air Act so looselyas to render them unconstitutional delegations of legislative power. Weagree. Although the factors EPA uses in determining the degree of publichealth concern associated with different levels of ozone and PM are reasonable,EPA appears to have articulated no "intelligible principle" tochannel its application of these factors; nor is one apparent from the statute.The nondelegation doctrine requires such a principle. See J.W. Hampton,Jr. & Co. v. United States, 276 U.S. 394, 409 (1928). Here it is asthough Congress commanded EPA to select "big guys," and EPA announcedthat it would evaluate candidates based on height and weight, but revealedno cut-off point. The announcement, though sensible in what it does say,is fatally incomplete. The reasonable person responds, "How tall? Howheavy?"

EPA regards ozone definitely, and PM likely, as non- threshold pollutants,i.e., ones that have some possibility of some adverse health impact (howeverslight) at any exposure level above zero. See Ozone Final Rule, 62 Fed.Reg. at 38,863/3 ("Nor does it seem possible, in the Administrator'sjudgment, to identify [an ozone concentration] level at which it can beconcluded with confidence that no 'adverse' effects are likely to occur.");National Ambient Air Quality Standards for Ozone and Particulate Matter,61 Fed. Reg. 65,637, 65,651/3 (1996) (proposed rule) ("[T]he singlemost important factor influencing the uncertainty associated with the riskestimates is whether or not a threshold concentration exists below whichPM-associated health risks are not likely to occur."). For convenience,we refer to both as non-threshold pollutants; the indeterminacy of PM'sstatus does not affect EPA's analysis, or ours.

Thus the only concentration for ozone and PM that is utterly risk-free,in the sense of direct health impacts, is zero. Section 109(b)(1) says thatEPA must set each standard at the level "requisite to protect the publichealth" with an "adequate margin of safety." 42 U.S.C. §7409(b)(1). These are also the criteria by which EPA must determine whethera revision to existing NAAQS is appropriate. See 42 U.S.C. § 7409(d)(1)(EPA shall "promulgate such new standards as may be appropriate inaccordance with . . . [§ 7409(b)]"); see also infra Part II.A.For EPA to pick any non-zero level it must explain the degree of imperfectionpermitted. The factors that EPA has elected to examine for this purposein themselves pose no inherent nondelegation problem. But what EPA lacksis any determinate criterion for drawing lines. It has failed to state intelligiblyhow much is too much.

We begin with the criteria EPA has announced for assessing health effectsin setting the NAAQS for non-threshold pollutants.1 They are "the natureand severity of the health effects involved, the size of the sensitive population(s)at risk, the types of health information available, and the kind and degreeof uncertainties that must be addressed." Ozone Final Rule, 62 Fed.Reg. at 38,883/2; EPA, "Review of the National Ambient Air QualityStandards for Particulate Matter: Policy Assessment of Scientific and TechnicalInformation: OAQPS Staff Paper," at II-2 (July 1996) ("PM StaffPaper") (listing same factors). Although these criteria, so stated,are a bit vague, they do focus the inquiry on pollution's effects on publichealth. And most of the vagueness in the abstract formulation melts awayas EPA applies the criteria: EPA basically considers severity of effect,certainty of effect, and size of population affected. These criteria, longago approved by the judiciary, see Lead Industries Ass'n v. EPA, 647 F.2d1130, 1161 (D.C. Cir. 1980) ("Lead Industries"), do not themselvesspeak to the issue of degree.

Read in light of these factors, EPA's explanations for its decisions amountto assertions that a less stringent standard would allow the relevant pollutantto inflict a greater quantum of harm on public health, and that a more stringentstandard would result in less harm. Such arguments only support the intuitiveproposition that more pollution will not benefit public health, not thatkeeping pollution at or below any particular level is "requisite"or not requisite to "protect the public health" with an "adequatemargin of safety," the formula set out by § 109(b)(1).

Consider EPA's defense of the 0.08 ppm level of the ozone NAAQS. EPA explainsthat its choice is superior to retaining the existing level, 0.09 ppm, becausemore people are exposed to more serious effects at 0.09 than at 0.08. SeeOzone Final Rule, 62 Fed. Reg. at 38,868/1. In defending the decision notto go down to 0.07, EPA never contradicts the intuitive proposition, confirmedby data in its Staff Paper, that reducing the standard to that level wouldbring about comparable changes. See EPA, "Review of National AmbientAir Quality Standards for Ozone: Assessment of Scientific and TechnicalInformation: OAQPS Staff Paper," at 156 (June 1996) ("Ozone StaffPaper"). Instead, it gives three other reasons. The principal substantiveone is based on the criteria just discussed:

The most certain O3-related effects, while judged to be adverse, are transientand reversible (particularly at O3 exposures below 0.08 ppm), and the moreserious effects with greater immediate and potential long-term impacts onhealth are less certain, both as to the percentage of individuals exposedto various concentrations who are likely to experience such effects andas to the long-term medical significance of these effects.

Ozone Final Rule, 62 Fed. Reg. at 38,868/2.

In other words, effects are less certain and less severe at lower levelsof exposure. This seems to be nothing more than a statement that lower exposurelevels are associated with lower risk to public health. The dissent arguesthat in setting the standard at 0.08, EPA relied on evidence that healtheffects occurring below that level are "transient and reversible,"Dissent at 5, evidently assuming that those at higher levels are not. Butthe EPA language quoted above does not make the categorical distinctionthe dissent says it does, and it is far from apparent that any health effectsexisting above the level are permanent or irreversible.

In addition to the assertion quoted above, EPA cited the consensus of theClean Air Scientific Advisory Committee ("CASAC") that the standardshould not be set below 0.08. That body gave no specific reasons for itsrecommendations, so the appeal to its authority, also made in defense ofother standards in the PM Final Rule, see PM Final Rule, 62 Fed. Reg. at38,677/2 (daily fine PM standard); id. at 38,678/3 (annual coarse PM standard);id. at 38,679/1 (daily coarse PM standard), adds no enlightenment. The dissentstresses the undisputed eminence of CASAC's members, Dissent at 4, but thequestion whether EPA acted pursuant to lawfully delegated authority is nota scientific one. Nothing in what CASAC says helps us discern an intelligibleprinciple derived by EPA from the Clean Air Act.

Finally, EPA argued that a 0.07 standard would be "closer to peak backgroundlevels that infrequently occur in some areas due to nonanthropogenic sourcesof O3 precursors, and thus more likely to be inappropriately targeted insome areas on such sources." Ozone Final Rule, 62 Fed. Reg. at 38,868/3.But a 0.08 level, of course, is also closer to these peak levels than 0.09.The dissent notes that a single background observation fell between 0.07and 0.08, and says that EPA's decision "ensured that if a region surpassesthe ozone standard, it will do so because of controllable human activity,not uncontrollable natural levels of ozone." Dissent at 6. EPA's language,coupled with the data on background ozone levels, may add up to a backhandedway of saying that, given the national character of the NAAQS, it is inappropriateto set a standard below a level that can be achieved throughout the countrywithout action affirmatively extracting chemicals from nature. That maywell be a sound reading of the statute, but EPA has not explicitly adoptedit.

EPA frequently defends a decision not to set a standard at a lower levelon the basis that there is greater uncertainty that health effects existat lower levels than the level of the standard. See Ozone Final Rule, 62Fed. Reg. at 38,868/2; PM Final Rule, 62 Fed. Reg. at 38,676/3 (annual finePM standard); id. at 38,677/2 (daily fine PM standard). And such an argumentis likely implicit in its defense of the coarse PM standards. See PM FinalRule, 62 Fed. Reg. at 38,678/3-79/1. The dissent's defense of the fine particulatematter standard cites exactly such a justification. See Dissent at 6 ("TheAgency explained that 'there is generally greatest statistical confidencein observed associations . . . for levels at and above the mean concentration[in certain studies]'") (emphasis added in dissent). But the increasing-uncertaintyargument is helpful only if some principle reveals how much uncertaintyis too much. None does.

The arguments EPA offers here show only that EPA is applying the statedfactors and that larger public health harms (including increased probabilityof such harms) are, as expected, associated with higher pollutant concentrations.The principle EPA invokes for each increment in stringency (such as foradopting the annual coarse particulate matter standard that it chose here)-thatit is "possible, but not certain" that health effects exist atthat level, see PM Final Rule, 62 Fed. Reg. at 38,678/32-could as easily,for any non-threshold pollutant, justify a standard of zero. The same indeterminacyprevails in EPA's decisions not to pick a still more stringent level. Forexample, EPA's reasons for not lowering the ozone standard from 0.08 to0.07 ppm-that "the more serious effects . . . are less certain"at the lower levels and that the lower levels are "closer to peak backgroundlevels," see Ozone Final Rule, 62 Fed. Reg. at 38,868/2-could alsobe employed to justify a refusal to reduce levels below those associatedwith London's "Killer Fog" of 1952. In that calamity, very highPM levels (up to 2,500 µg/m3) are believed to have led to 4,000 excessdeaths in a week.3 Thus, the agency rightly recognizes that the questionis one of degree, but offers no intelligible principle by which to identifya stopping point.

The latitude EPA claims here seems even broader than that OSHA assertedin International Union, UAW v. OSHA ("Lockout/Tagout I"), 938F.2d 1310, 1317 (D.C. Cir. 1991), which was to set a standard that wouldreduce a substantial risk and that was not infeasible. In that case, OSHAthought itself free either to "do nothing at all" or to "requireprecautions that take the industry to the brink of ruin," with "allpositions in between . . . evidently equally valid." Id. Here, EPA'sfreedom of movement between the poles is equally unconstrained, but thepoles are even farther apart-the maximum stringency would send industrynot just to the brink of ruin but hurtling over it, while the minimum stringencymay be close to doing nothing at all.

In Lockout/Tagout I certain special conditions that have justified an exceptionallyrelaxed application of the nondelegation doctrine were absent, id. at 1317-18,and they are equally absent here. The standards in question affect the wholeeconomy, requiring a "more precise" delegation than would otherwisebe the case, see A.L.A. Schechter Poultry Corp. v. United States, 295 U.S.495, 553 (1935). No "special theories" justifying vague delegationsuch as the war powers of the President or the sovereign attributes of thedelegatee have been or could be asserted. Nor is there some inherent characteristicof the field that bars development of a far more determinate basis for decision.(This is not to deny that there are difficulties; we consider some below.)

EPA cites prior decisions of this Court holding that when there is uncertaintyabout the health effects of concentrations of a particular pollutant withina particular range, EPA may use its discretion to make the "policyjudgment" to set the standards at one point within the relevant rangerather than another. NRDC v. EPA, 902 F.2d 962, 969 (D.C. Cir. 1990); AmericanPetroleum Inst. v. Costle, 665 F.2d 1176, 1185 (D.C. Cir. 1981); Lead Industries,647 F.2d at 1161 (D.C. Cir. 1980). We agree. But none of those panels addressedthe claim of undue delegation that we face here, and accordingly had nooccasion to ask EPA for coherence (for a "principle," to use theclassic term) in making its "policy judgment." The latter phraseis not, after all, a self-sufficient justification for every refusal todefine limits.

It was suggested at oral argument that EPA's vision of its discretion inapplication of § 109(b)(1) is no broader than that asserted by OSHAafter a remand by this court and upheld by this court in International Union,UAW v. OSHA ("Lock-out/Tagout II"), 37 F.3d 665 (D.C. Cir. 1994).But there, in fact, OSHA allowed itself to set only standards falling somewherebetween maximum feasible stringency and some "moderate" departurefrom that level. Id. at 669. As our prior discussion should have indicated,here EPA's formulation of its policy judgment leaves it free to pick anypoint between zero and a hair below the concentrations yielding London'sKiller Fog.

The dissent argues that a nondelegation challenge similar to this one wasrejected in South Terminal Corp. v. EPA, 504 F.2d 646 (1st Cir. 1974), andcites that case's language that "the rationality of the means can betested against goals capable of fairly precise definition in the languageof science," id. at 677. See Dissent at 2. But the action challengedin South Terminal was EPA's adoption of a plan for ending or preventingviolations in Boston of already-established NAAQS, not its promulgationof the NAAQS themselves. Thus, it seems likely that the "means"were the plan's provisions-e.g., a prohibition on most new parking in thecity, see 504 F.2d at 671, and the "fairly precise[ly] defin[ed]"goals were the NAAQS themselves.

Where (as here) statutory language and an existing agency interpretationinvolve an unconstitutional delegation of power, but an interpretation withoutthe constitutional weakness is or may be available, our response is notto strike down the statute but to give the agency an opportunity to extracta determinate standard on its own. Lockout/Tagout I, 938 F.2d at 1313. Doingso serves at least two of three basic rationales for the nondelegation doctrine.If the agency develops determinate, binding standards for itself, it isless likely to exercise the delegated authority arbitrarily. See AmalgamatedMeat Cutters v. Connally, 337 F. Supp. 737, 758-59 (D.D.C. 1971) (Leventhal,J., for three-judge panel). And such standards enhance the likelihood thatmeaningful judicial review will prove feasible. See id. at 759. A remandof this sort of course does not serve the third key function of non-delegationdoctrine, to "ensure[ ] to the extent consistent with orderly governmentaladministration that important choices of social policy are made by Congress,the branch of our Government most responsive to the popular will,"Industrial Union Dep't, AFL-CIO v. American Petroleum Inst., 448 U.S. 607,685 (1980) ("Benzene") (Rehnquist, J., concurring). The agencywill make the fundamental policy choices. But the remand does ensure thatthe courts not hold unconstitutional a statute that an agency, with theapplication of its special expertise, could salvage. In any event, we donot read current Supreme Court cases as applying the strong form of thenondelegation doctrine voiced in Justice Rehnquist's concurrence. See Mistrettav. United States, 488 U.S. 361, 377-79 (1989).

What sorts of "intelligible principles" might EPA adopt? Cost-benefitanalysis, mentioned as a possibility in Lock-out/Tagout I, 938 F.2d at 1319-21,is not available under decisions of this court. Our cases read § 109(b)(1)as barring EPA from considering any factor other than "health effectsrelating to pollutants in the air." NRDC, 902 F.2d at 973; see alsoLead Industries, 647 F.2d at 1148; American Lung Ass'n v. EPA, 134 F.3d388, 389 (D.C. Cir. 1998); American Petroleum Inst., 665 F.2d at 1185 (echoingthe same themes).

In theory, EPA could make its criterion the eradication of any hint of directhealth risk. This approach is certainly determinate enough, but it appearsthat it would require the agency to set the permissible levels of both pollutantshere at zero. No party here appears to advocate this solution, and EPA appearsto show no inclination to adopt it.4

EPA's past behavior suggests some readiness to adopt standards that leavenon-zero residual risk. For example, it has employed commonly used clinicalcriteria to determine what qualifies as an adverse health effect. See OzoneStaff Paper at 59-60 (using American Thoracic Society standards to determinethreshold for "adverse health effect" from ozone). On the issueof likelihood, for some purposes it might be appropriate to use standardsdrawn from other areas of the law, such as the familiar "more probablethan not" criterion.

Of course a one-size-fits-all criterion of probability would make littlesense. There is no reason why the same probability should govern assessmentsof a risk of thousands of deaths as against risks of a handful of peoplesuffering momentary shortness of breath. More generally, all the relevantvariables seem to range continuously from high to low: the possible effectsof pollutants vary from death to trivialities, and the size of the affectedpopulation, the probability of an effect, and the associated uncertaintyrange from "large" numbers of persons with point estimates ofhigh probability, to small numbers and vague ranges of probability. Thisdoes not seem insurmountable. Everyday life compels us all to make decisionsbalancing remote but severe harms against a probability distribution ofbenefits; people decide whether to proceed with an operation that carriesa 1/1000 possibility of death, and (simplifying) a 90% chance of cure anda 10% chance of no effect, and a certainty of some short-term pain and nuisance.To be sure, all that requires is a go/no-go decision, while a serious effortat coherence under § 109(b)(1) would need to be more comprehensive.For example, a range of ailments short of death might need to be assignedweights. Nonetheless, an agency wielding the power over American life possessedby EPA should be capable of developing the rough equivalent of a genericunit of harm that takes into account population affected, severity and probability.Possible building blocks for such a principled structure might be foundin the approach Oregon used in devising its health plan for the poor. Indetermining what conditions would be eligible for treatment under its versionof Medicaid, Oregon ranked treatments by the amount of improvement in "Quality-AdjustedLife Years" provided by each treatment, divided by the cost of thetreatment.5 Here, of course, EPA may not consider cost, and indeed may wellfind a completely different method for securing reasonable coherence. Alternatively,if EPA concludes that there is no principle available, it can so reportto the Congress, along with such rationales as it has for the levels itchose, and seek legislation ratifying its choice.

We have discussed only the primary standards. Because the secondary standardsare at least in part based on those, see Ozone Final Rule, 62 Fed. 38,875/3-76/1; PM Final Rule, 62 Fed. Reg. at 38,680/3, we also remandthe cases to the agency with regard to the secondary standards as well,for further consideration in light of this opinion.

II. Other General Claims

The petitioners and amici contend that the EPA erroneously failed to considera host of factors in revising the PM and ozone NAAQS. We reject each ofthese claims in turn.

A. Consideration of Cost in Revising Standards

As this court long ago made clear, in setting NAAQS under § 109(b)of the Clean Air Act, the EPA is not permitted to consider the cost of implementingthose standards. See Lead Industries, 647 F.2d at 1148 (D.C. Cir. 1980);see also NRDC, 902 F.2d at 973 (following Lead Industries in reviewing particulatematter NAAQS); American Petroleum Inst., 665 F.2d at 1185 (same, in reviewingozone NAAQS). The petitioners make four unsuccessful attempts to distinguishLead Industries and its progeny.

First, the petitioners claim that in Lead Industries we held only that theClean Air Act does not compel the EPA to consider the costs of implementationin setting a NAAQS; on the contrary, we held that the Act precludes theEPA from doing so. See Lead Industries, 647 F.2d at 1148 ("the statuteand its legislative history make clear that economic considerations playno part in the promulgation of [NAAQS]").

Second, that we decided Lead Industries prior to the Supreme Court's decisionin Chevron U.S.A. Inc. v. NRDC, 467 U.S. 837 (1984) does not, as the petitionerssuggest, require us to revisit the earlier case. The Lead Industries decisionwas made in Chevron step one terms, see id., as the post-Chevron progenyof Lead Industries have made clear. See NRDC, 902 F.2d at 973 ("Considerationof costs . . . would be flatly inconsistent with the statute, legislativehistory and case law on this point"); NRDC v. EPA, 824 F.2d 1146, 1158-59(D.C. Cir. 1987) (in banc) ("Vinyl Chloride") ("[S]tatuteon its face does not allow consideration of technological or economic feasibility.. . . Congress considered the alternatives and chose to close down sourcesor even industries rather than to allow risks to health").

Third, though the petitioners are correct that in Lead Industries we interpreted§ 109(b), which governs the setting of NAAQS, and not § 109(d),which governs the revising of NAAQS, we can discern no legally relevantdifference in the two sections that would make Lead Industries inapplicableto § 109(d). Section 109(d)(1) directs the EPA to:

complete a thorough review of the criteria published under section 7408of this title and the [NAAQS] promulgated under this section and [to] makesuch revisions in such criteria and standards and promulgate such new standardsas may be appropriate in accordance with section 7408 of this title andsubsection (b) of this section.

42 U.S.C. § 7409(d)(1). The petitioners contend that considerationof costs is one pertinent factor in determining whether revision of a NAAQSis "appropriate," but this argument ignores the clause immediatelyfollowing "appropriate," which incorporates § 109(b) andthereby affirmatively precludes consideration of costs in revising NAAQS.Section 108(b), 42 U.S.C. § 7408(b), does require the EPA to providethe States with information on the cost of implementing NAAQS, but the referenceto § 108 does not permit consideration of costs in setting NAAQS becauseit clearly relates back to the requirement that the EPA "make . . .revisions in ["the criteria published under section 7408"] . .. as may be appropriate." And insofar as the air quality criteria doapply to the setting of NAAQS, they do so through § 109(b), which (again)precludes the consideration of costs and which is explicitly incorporatedinto § 109(d)(1). See id. § 7409(b)(1) (primary NAAQS to be "basedon [the air quality] criteria" issued under § 108).

Fourth, the petitioners point to § 109(d)(2), which creates the CASACand requires it to advise the EPA about, among other things, "any adversepublic health, welfare, social, economic, or energy effects which may resultfrom various strategies for attainment and maintenance of such [NAAQS]."Id. § 7409(d)(2)(C)(iv). Why, ask the petitioners, would the CASACbe required to advise the EPA about these matters if the EPA were not thensupposed to consider its advice in the course of revising the NAAQS? Asabove, however, the petitioners overlook that § 109(d)(1) directs theEPA to review and to revise, as appropriate, the air quality standards issuedunder § 108 as well as the NAAQS promulgated under § 109(b). Theadvice required in § 109(d)(2)(C)(iv) is pertinent only to the EPA'sduty under § 108 to provide the States with control strategy information.

B. Environmental Consequences of Implementing NAAQS

The State Petitioners argue that the EPA erred in failing "to considerthe environmental consequences resulting from the financial impact of the[revised PM2.5 and ozone NAAQS] on the federal Abandoned Mine ReclamationFund Act." This argument is squarely foreclosed by our decision inNRDC. In reviewing the EPA's previous revision of the PM NAAQS, we rejectedthe argument that the EPA "erred in refusing to consider the healthconsequences of unemployment in determining the primary [NAAQS] for particulatematter" and held that "[i]t is only health effects relating topollutants in the air that EPA may consider." 902 F.2d at 972-73 (emphasisin original). Unlike the positive health benefits of ozone that we hold(in Part III.B, below) the EPA must consider, any detrimental health effectsresulting from the financial impact upon the mine fund, like the healthconsequences of unemployment, are traceable to the cost of complying withthe revised PM2.5 and ozone NAAQS and not to the presence of those pollutantsin the air.

C. The National Environmental Policy Act

In challenging both the revised PM2.5 and ozone NAAQS, the State Petitionersalso argue that the EPA failed to comply with certain requirements of theNEPA. The petitioners recognize that the Congress has exempted all actionsunder the Clean Air Act, including the setting of NAAQS, from the centralrequirement of the NEPA, namely, the preparation of an Environmental ImpactStatement. Compare 42 U.S.C. § 4332(2)(C)-(D) (agency must prepareEIS in all "major Federal actions significantly affecting the qualityof the human environment"), with 15 U.S.C. § 793(c)(1) ("Noaction taken under the Clean Air Act shall be deemed a major Federal actionsignificantly affecting the quality of the human environment within themeaning of the [NEPA]"). Nonetheless, they suggest that the EPA isrequired to complete the functional equivalent of an EIS and also to complywith other requirements in the NEPA, see 42 U.S.C. § 4332(2)(B), (E),(G). State Petitioners' PM Brief at 20; State Petitioners' Ozone Brief at19. We reject each of these suggestions.

First, the State Petitioners contend that this court has "recognizedthat the '[CAA], properly construed, requires the functional equivalentof a NEPA impact statement,'" id. (quoting Portland Cement Ass'n v.Ruckelshaus, 486 F.2d 375, 384 (1973)). Our decision in Portland Cement,however, actually construed only "section 111 of the Clean Air Act."By replacing these words with "[CAA]" in their briefs, the petitionersmisrepresent our interpretation of a single section of the Clean Air Act,dealing with emission standards for stationary sources, as an interpretationof the entire Act. Even if the petitioners were correct, however, PortlandCement predated, and is now superseded by, the statutory exemption in 15U.S.C. § 793(c)(1), which the Congress added in 1974.

Second, the State Petitioners contend that a provision of the NEPA "requiresthat EPA weigh 'economic considerations.'" The section to which thepetitioners refer reads as follows: "all agencies of the Federal Governmentshall . . . identify and develop methods and procedures . . . which willinsure that presently unquantified environmental amenities and values maybe given appropriate consideration in decisionmaking along with economicand technical considerations." 42 U.S.C. § 4332(2)(B). Even ifthis section is properly read generally to require an agency to considerimplementation costs, § 109(d)(1) specifically prohibits the EPA fromdoing so. And the NEPA provides that it shall not "in any way affectthe specific statutory obligations of any Federal agency . . . to complywith criteria or standards of environmental quality." 42 U.S.C. §4334(1). Therefore, § 4332(2)(B) cannot require the EPA to disregardthe prohibition in § 109(d)(1) upon the consideration of costs in settingNAAQS.

The State Petitioners' remaining arguments-that the EPA failed to complywith two other sections of the NEPA-fare little better. Section 4332(2)(E)requires federal agencies to "study, develop, and describe appropriatealternatives to recommended courses of action in any proposal which involvesunresolved conflicts concerning alternative uses of available resources."As with § 4332(2)(B), insofar as § 4332(2)(E) can be read to requirethe EPA to consider the costs of implementing NAAQS when revising thosestandards, contrary to the prohibition in § 109(d)(1), § 4334(1)prevents it from having any effect.

If, on the other hand, § 4332(2)(E) is understood in the context ofthe Clean Air Act to require the EPA merely to discuss implementation alternatives,then it, like the similar § 4332(2)(G) with which the petitioners alsoclaim the EPA failed to comply, is the functional equivalent of § 108(b)(1).That section requires the EPA to provide the States with, among other things,"such data as are available on available technology and alternativemethods of prevention and control of air pollution." As we recognizewith regard to the requirement that the agency prepare an EIS, "[c]ompliancewith NEPA's . . . requirement[s] has not been considered necessary whenthe agency's organic legislation mandates procedures for considering theenvironment that are 'functional equivalents' of the [NEPA's] process."Izaak Walton League of Am. v. Marsh, 655 F.2d 346, 367 n.51 (1981). Therationale for the functional equivalence doctrine is the well-establishedprinciple that a "general statutory rule usually does not govern unlessthere is no more specific rule." Green v. Bock Laundry Mach. Co., 490U.S. 504, 524 (1989); see also Alabama ex rel. Siegelman v. EPA, 911 F.2d499, 504-05 (11th Cir. 1990) (citing cases). The NEPA is the general statuterequiring agencies to consider environmental harms, whereas the Clean AirAct is the more specific and its equivalent provisions apply in place ofthose in the NEPA. See Portland Cement, 486 F.2d at 386 (finding functionalequivalence when more specific statute strikes "workable balance betweensome of the advantages and disadvantages of full application of NEPA").

Our analysis of the petitioners' contentions leads us to conclude that nothingin the NEPA requires the EPA in setting NAAQS to consider or to discussmatters that the Clean Air Act does not already permit or require.

D. The Unfunded Mandates Reform Act

The State Petitioners in the particulate matter case and Congressman Blileyin the ozone case both contend that the EPA is required by the UnfundedMandates Reform Act, 2 U.S.C. § 1501 et seq., to prepare a RegulatoryImpact Statement (RIS) when setting a NAAQS, see id. § 1532, and tochoose the least burdensome from a range of alternative permissible NAAQS,see id. § 1535. Even if the petitioners and the amicus are correctregarding the interaction of the UMRA and the CAA-a point the EPA stronglycontests-we can provide them with no relief. See id. § 1571(a)(3) ("[T]heinadequacy or failure to prepare [a RIS] . . . shall not be used as a basisfor staying, enjoining, invalidating or otherwise affecting [an] agencyrule"); id. § 1571(b) ("Except as provided in [§ 1571(a),which does not mention § 1535,] . . . any compliance or noncompliancewith the provisions of this chapter . . . shall not be subject to judicialreview; and no provision of this chapter shall be construed to [be] . .. enforceable by any person in any . . . judicial action").

The State Petitioners, recognizing the limitations upon judicial reviewin § 1571, contend that the EPA's failure to prepare a RIS can nonethelessrender the NAAQS arbitrary and capricious, see 42 U.S.C. § 7607(d)(9),relying upon Thompson v. Clark, 741 F.2d 401 (D.C. Cir. 1984). In that case,we interpreted a statute that, like the UMRA, both specified that the RISbe included in the record for judicial review and precluded judicial reviewof an agency's compliance with the RIS requirement. We held that a "reviewingcourt will consider the contents of the [RIS], along with the rest of therecord, in assessing not the agency's compliance with the [requirement toprepare the RIS], but the validity of the rule under other provisions oflaw." Id. at 405. No information in a RIS, however, could lead us toconclude that the EPA improperly set the PM and ozone NAAQS; the only informationsuch a statement would add to the rulemaking record for a NAAQS would pertainto the costs of implementation, see 2 U.S.C. § 1532(a), and the EPAis precluded from considering those costs in setting a NAAQS. Accordingly,the failure to prepare a RIS does not render the NAAQS arbitrary and capricious.

E. The Regulatory Flexibility Act

In both the ozone and particulate matter cases, the Small Business Petitionersargue that the EPA improperly certified that the revised NAAQS would nothave a significant impact upon a substantial number of small entities. TheRegulatory Flexibility Act, 5 U.S.C. 601 et seq., as amended in 1996 bythe Small Business Regulatory Enforcement Fairness Act, Pub. L. No. 104-121,tit. II, 110 Stat. 857-74 ("SBREFA"), requires an agency, whenengaging in notice and comment rulemaking, to "prepare and make availablefor public comment an initial regulatory flexibility analysis. . . . [that]describe[s] the impact of the proposed rule on small entities," 5 U.S.C.§ 603(a), including small businesses, small organizations, and smallgovernmental jurisdictions, see id. § 601(6). When promulgating a finalrule, an agency must describe "the steps . . . taken to minimize thesignificant economic impact on small entities." Id. § 604(a)(5).According to the petitioners, if the EPA had complied with the RFA, it wouldlikely have promulgated less stringent PM and ozone NAAQS than those actuallychosen, which would have reduced the burden upon small entities.

A regulatory flexibility analysis is not required, however, if the agency"certifies that the rule will not, if promulgated, have a significanteconomic impact on a substantial number of small entities." Id. §605(b). Further, the SBREFA made no change in the requirement that a regulatoryflexibility analysis conducted pursuant to the RFA include estimates of"the number of small entities to which the proposed rule will apply"and of "the classes of small entities which will be subject to therequirement." 5 U.S.C. § 603(b)(3)-(4). We have consistently interpretedthe RFA, based upon these sections, to impose no obligation upon an agency"to conduct a small entity impact analysis of effects on entities whichit does not regulate." Motor & Equip. Mfrs. Ass'n v. Nichols, 142F.3d 449, 467 & n.18 (1998).

The EPA certified that its revised NAAQS will "not have a significanteconomic impact on small entities within the meaning of the RFA." PMFinal Rule, 62 Fed. Reg. at 38,702/2; Ozone Final Rule, 62 Fed. Reg. at38,887/2-3. According to the EPA, the NAAQS themselves impose no regulationsupon small entities. Instead, the several States regulate small entitiesthrough the state implementation plans (SIPs) that they are required bythe Clean Air Act to develop. See 42 U.S.C. § 7410. Because the NAAQStherefore regulate small entities only indirectly-that is, insofar as theyaffect the planning decisions of the States-the EPA concluded that smallentities are not "subject to the proposed regulation." See Mid-TexElec. Coop., Inc. v. FERC, 773 F.2d 327, 342 (D.C. Cir. 1985); see alsoid. at 343 ("Congress did not intend to require that every agency considerevery indirect effect that any regulation might have on small businessesin any stratum of the national economy.").

The EPA's description of the relationship between NAAQS, SIPs, and smallentities strikes us as incontestable. The States have broad discretion indetermining the manner in which they will achieve compliance with the NAAQS.The EPA "is required to approve a state plan which provides for thetimely attainment and subsequent maintenance of ambient air standards"and cannot reject a SIP based upon its view of "the wisdom of a State'schoices of emission limitations," Train v. NRDC, 421 U.S. 60, 79 (1975)(emphasis in original), or of the technological infeasibility of the plan.See Union Elec. Co. v. EPA, 427 U.S. 246, 265 (1976). Therefore, a Statemay, if it chooses, avoid imposing upon small entities any of the burdensof complying with a revised NAAQS. Only if a State does not submit a SIPthat complies with § 110, 42 U.S.C. § 7410, must the EPA adoptan implementation plan of its own, which would require the EPA to decidewhat burdens small entities should bear. The agency has stated, however,that it will do a regulatory flexibility analysis before adopting an implementationplan of its own, as it did in 1994 when proposing such a plan for Los Angeles.See Ozone Final Rule, 62 Fed. Reg. at 38,891/1; PM Final Rule, 62 Fed. 38,705/3.

The responses of the Small Business Petitioners do not persuade us to rejectthe EPA's argument or to deviate from our holdings in Mid-Tex and its progeny.First, the Small Business Petitioners contend that we must defer to theSmall Business Administration's interpretation of the Act, as expressedin a letter to the EPA from the SBA's Chief Counsel for Advocacy, that theNAAQS do impose requirements upon small entities. The SBA, however, neitheradministers nor has any policymaking role under the RFA; at most its roleis advisory. See, e.g., 5 U.S.C. §§ 601(3), 602(b), 603(a), 605(b),609(b)(1), 612. Therefore, we do not defer to the SBA's interpretation ofthe RFA. See Scheduled Airlines Traffic Offices, Inc. v. Department of Defense,87 F.3d 1356, 1361 (D.C. Cir. 1996) (no Chevron deference owed to agencyinterpretation of statute it does not administer). Nor do we defer to theEPA's interpretation of the RFA, for it does not administer the Act either.We do, however, find the EPA's interpretation of the statute persuasive.

Second, the Small Business Petitioners argue that the EPA cannot claim boththat the NAAQS will have no effect upon small entities and that it willhave positive health effects. Clearly, however, the EPA can maintain thatthe NAAQS will have health effects because the Clean Air Act empowers theagency to ensure that such benefits accrue; and it can maintain that theNAAQS will not directly affect small entities because it has no authority(short of imposing its own implementation plan upon a non-complying state)to impose any burdens upon such entities.

The Small Business Petitioners attempt to distinguish the possible effectsupon small entities in this case from the indirect effects that, as we foundin Mid-Tex, are not within the contemplation of the RFA. But Mid-Tex isnot so easily distinguished. The petitioners in that case argued that theRFA required the FERC to consider economic effects not only upon regulatedindustries but also upon the small entities that are their wholesale customers,even though the customers were not directly regulated by the FERC. We rejectedthat argument, finding a "clear indication" in the language of§ 603 that the RFA is "limited to small entities subject to theproposed regulation." Mid-Tex, 773 F.2d at 342; see also Motor &Equip. Mfrs. Ass'n, 142 F.3d at 467 n.18 ("The RFA itself distinguishesbetween small entities subject to an agency rule, to which its requirementsapply, and those not subject to the rule, to which the requirements do notapply."); United Distribution Cos. v. FERC, 88 F.3d 1105, 1170 (1996)(regulatory flexibility analysis provision applies only to "small entitiesthat are subject to the requirements of the rule") (emphasis in original).That the Clean Air Act requires the States to submit SIPs that will achievecompliance with the NAAQS does not, in view of the States' nearly completediscretion to determine which entities will bear the burdens of a revisedNAAQS, make such small entities as the SIPs may regulate any more subjectto the EPA's regulation than were the wholesalers in Mid-Tex subject toregulation by the FERC.

Finally, the Small Business Petitioners suggest that the Congress in enactingthe SBREFA overruled our prior interpretation of the RFA in Mid-Tex andits progeny. The SBREFA made a number of changes in the RFA, but it didnot change anything in § 603 upon which we relied in Mid-Tex. And althoughthe Congress made a slight modification in § 605(b), we do not understandit to alter our analysis in Mid-Tex. Prior to 1996, § 605(b) requiredan agency to provide "a succinct statement explaining the reasons"for its certification that the promulgated rule would not have a significanteconomic impact upon small entities. That section now requires "a statementproviding the factual basis for such certification." Our decision inMid-Tex contemplates that an agency may justify its certification underthe RFA upon the "factual basis" that the rule does not directlyregulate any small entities. Nothing in the change to § 605(b) suggeststhat basis for certification is no longer permissible. (Indeed, the sectionof the statute amending § 605(b) is labeled "Technical and ConformingAmendments," see SBREFA § 243, 110 Stat. at 866.) We thereforeconclude that the EPA properly certified that its NAAQS would not have asignificant impact upon a substantial number of small entities.

III. Ozone

A. Subpart 2 and the Revised Ozone Standard

In 1990 the Congress substantially revised the Clean Air Act by, among otherthings, adding specific enforcement provisions for carbon monoxide, particulatematter, sulfur oxides, nitrogen dioxide, lead, and as pertinent here, ozone.Previously, the Act required that all areas of the country not attainingthe primary ozone standard, no matter how far from attainment, come intocompliance "as expeditiously as practicable but not later than December31, 1987." 42 U.S.C. § 7502 (1988). Many areas had not attainedthe primary ozone NAAQS by that date; some were still a long way from doingso. The Congress responded to the continued ozone problem by enacting anew enforcement scheme, which it codified as Subpart 2 of Part D of theClean Air Act, 42 U.S.C. §§ 7511-7511f, redesignating the originalprovisions as Subpart 1.

Subpart 2 requires the EPA to classify nonattainment areas based upon theirdesign value, which is a rough measure of whether an area complies withthe 0.12 ppm, 1-hour primary ozone standard.6 A table in Subpart 2, set out here in the margin,7 establishes classifications rangingfrom marginal to extreme, and provides an attainment date for each class.See id. § 7511(a)(1)-(2). Subpart 2 also specifies, for each classof nonattainment areas, both measures that the States must take to reduceemissions of the chemicals that are precursors of ozone and informationthat the States must report to the EPA. See id. § 7511a. In short,Subpart 2 is the Congress's comprehensive plan for reducing ozone levelsthroughout the country.

The State and Non-State Petitioners, along with Congressman Bliley appearingas an amicus curiae, argue that Subpart 2 precludes the EPA from revisingthe primary and secondary ozone NAAQS. We reject this argument (in PartIII.A.1) insofar as it pertains to the EPA's continued ability to promulgatea revised ozone NAAQS or to designate areas as not in attainment with arevised NAAQS. We agree (in Part III.A.2) with those petitioners, however,insofar as they maintain, based upon the text and structure of Subparts1 and 2, that the EPA is precluded from enforcing a revised primary ozoneNAAQS other than in accordance with the classifications, attainment dates,and control measures set out in Subpart 2. Further, we conclude (in PartIII.A.3) that the EPA may not require a State to comply with a revised secondaryozone NAAQS in any area that has yet to attain the 0.12 ppm primary standard.

1. The EPA's Power to Revise the Ozone NAAQS and Designate Areas as Nonattainment

The 1990 amendments did not alter the section of the Clean Air Act thatprovides for setting and revising primary and secondary NAAQS. See 42 U.S.C.§ 7409. The Administrator, therefore, still must "at five-yearintervals [from December 31, 1980] . . . complete a thorough review of .. . the [NAAQS] promulgated under this section and . . . make such revisionsin such . . . standards . . . as may be appropriate." Id. § 7409(d)(1).The Second Circuit held that this section continues to "set[ ] fortha bright-line rule for agency action," American Lung Ass'n v. Reilly,962 F.2d 258, 263 (1992), and we agree. Nothing in the Act modifies this"bright-line rule" or otherwise makes it inapplicable to revisionof the ozone NAAQS.

To the extent that the 1990 amendments shed any light upon this question,they suggest that the EPA retains its authority to revise the ozone NAAQS.For example, if the EPA relaxes a NAAQS after enactment of the 1990 amendments,then "the Administrator shall . . . promulgate requirements applicableto all areas which have not attained that [relaxed] standard as of the dateof such relaxation. . . . [which] shall provide for controls . . . not lessstringent than the controls applicable to areas designated nonattainmentbefore such relaxation." 42 U.S.C. § 7502(e). Although two othersubsections of § 172 are expressly made inapplicable to the ozone regulationsin Subpart 2, see id. § 7502(a)(1)(C), (a)(2)(D), this so-called anti-backslidingprovision contains no such exemption. Accordingly, as the EPA notes, thissection specifically contemplates that the agency may relax its ozone NAAQSand, therefore, necessarily implies that it retains the authority to revisethat NAAQS. Tellingly, neither the petitioners nor the amicus reply to thispoint.

The petitioners and amicus raise two other arguments to support their positionthat the EPA cannot alter the ozone NAAQS without the approval of the Congress.We reject both in short order.

First, the Non-State Petitioners contend that Subpart 2 renders revisionof the ozone NAAQS "inappropriate" within the meaning of §109(d)(1), which provides the EPA shall "make such revisions in such. . . standards . . . as may be appropriate." 42 U.S.C. § 7409(d)(1).This argument, however, pointedly ignores the text immediately followingthe word "appropriate," which specifies that appropriateness isto be determined "in accordance with section 7408 . . . and [§7409(b)]" (and which, as we read it, means exclusively in accord withthose sections). See, e.g., American Methyl Corp. v. EPA, 749 F.2d 826,835-36 (D.C. Cir. 1984). Because Subpart 2 is neither listed in § 109(d)(1)nor incorporated by reference in either § 108, id. § 7408, or§109(b), it cannot render revision of the ozone NAAQS inappropriate.

Second, the State Petitioners and Congressman Bliley argue, based upon theclassification table in § 181(a)(1), id. § 7511(a)(1), that Subpart2 codified the 0.12 ppm ozone NAAQS and, therefore, only the Congress canpromulgate a revised NAAQS. Yet not all areas designated nonattainment forozone will have design values of 0.121 ppm or higher. In fact, this wastrue of areas designated nonattainment for ozone as a result of the 1990amendments, see Ozone Final Rule, 62 Fed. Reg. at 38,884/3, at least inpart because of the stringent criteria in the Clean Air Act for changingthe designation of an area to attainment from nonattainment. See 42 U.S.C.§ 7407(d)(3)(E)(iii) (redesignation permissible only if area's attainmentof NAAQS "is due to permanent and enforceable reductions in emissions").In short, although the numbers in the classification table are based uponthe 0.12 ppm ozone NAAQS, they are neither equivalent to nor a codificationof the NAAQS.

Not only does the EPA, as we conclude above, retain authority to promulgatea revised ozone NAAQS; the agency is still required, "in no case laterthan 2 years from the date of promulgation" of a revised NAAQS, todesignate areas as attainment, nonattainment, or unclassifiable under thatNAAQS. Id. § 7407(d)(1)(B). Although the 1990 amendments extended byroughly 18 months the maximum time between promulgation of a revised NAAQSand designation of nonattainment areas under that NAAQS, see 42 U.S.C. §7407(d)(1)-(2) (1988), they made no substantive change in the EPA's authorityto designate areas as nonattainment under a revised NAAQS. Therefore, wehold that the EPA retains the power to designate areas as nonattainmentunder a revised ozone NAAQS.

2. The EPA's Power to Enforce the Revised Ozone Standard

That the enactment of Subpart 2 does not alter the EPA's authority to revisethe ozone NAAQS or to designate areas as nonattainment for ozone does not,however, compel the conclusion that Subpart 2 has no effect upon the EPA'sauthority to enforce a revised primary ozone NAAQS (We consider the enforcementof secondary ozone NAAQS in Part III.A.3, below.) In fact, the text andstructure of Subparts 1 and 2 suggest precisely the opposite conclusion.After designating an area as nonattainment under a NAAQS, the EPA normallylooks to Subpart 1 for authority to "classify the area for the purposeof applying an attainment date." 42 U.S.C. § 7502(a)(1)-(2). Thecited provisions, however, do not apply "with respect to nonattainmentareas for which classifications [and attainment dates] are specificallyprovided under other provisions of [Part D of Subchapter 1 of the CleanAir Act]." Id. § 7502(a)(1)(C), (a)(2)(D).

The EPA argues that Subpart 2 specifically provides classifications andattainment dates only for nonattainment designations under the 0.12 ppmozone NAAQS.

The State and Non-State Petitioners counter that Subpart 2 specificallyprovides classifications and dates for all areas designated nonattainmentunder any ozone NAAQS. We agree with the petitioners.

The pertinent provision of Subpart 2 reads as follows:

(a) Classification and attainment dates for 1989 nonattainment areas. -(1) Each area designated non-attainment for ozone pursuant to section 7407(d)of this title shall be classified at the time of such designation, undertable 1, by operation of law, as a Marginal Area, a Moderate Area, a SeriousArea, a Severe Area, or an Extreme Area. . . .

Id. § 7511(a)(1). As the petitioners note, § 107(d), 42 U.S.C.§ 7407(d), specifies three different times at which an area can bedesignated "nonattainment for ozone": immediately following enactmentof the 1990 amendments, id. § 7407(d)(4); after the EPA revises theozone NAAQS, id. § 7407(d)(1); and when an area that was in attainment,either when the Congress enacted the 1990 amendments or when the EPA promulgateda revised ozone NAAQS, later ceases to comply, id. § 7407(d)(3). Thepetitioners conclude from the general reference to § 107(d) that theclassifications and attainment dates in Subpart 2 apply to areas designatedunder §§ 107(d)(1), (3), and (4). The EPA gamely responds thatthe reference to § 107(d) includes only subsection (4), but we do notdefer to the agency's interpretation because we find that the Congress hasspoken on the "precise question at issue" and we "must giveeffect to the unambiguously expressed intent of Congress." ChevronU.S.A. Inc., 467 U.S. 837, 842-43 & n.9 (1984). We canvass the two reasonsthat lead us to this conclusion before returning to the EPA's argument.

First, the reference to § 107(d) in § 181(a)(1) appears to havebeen purposeful and not the drafting error that the EPA's interpretationimplies. The Congress considered but did not adopt bills that clearly wouldhave limited the reach of Subpart 2 to nonattainment designations made immediatelyfollowing enactment of the 1990 amendments. The Senate bill contained aversion of Subpart 2 that classified only those areas designated nonattainmentfor ozone under its equivalent of § 107(d)(4). See S. 1630, 101st Cong.§§ 101, 107, reprinted in III Legislative History of the CleanAir Act Amendments of 1990, at 4124-25, 4195 [hereinafter 1990 LegislativeHistory]. The version of Subpart 2 in the House bill, as originally introduced,similarly referred only to designations made under its equivalent of §107(d)(4). See H.R. 3030, 101st Cong. §§ 101(a), 103, reprintedin II 1990 Legislative History, at 3748-49, 3795-96 The House committee,however, replaced the specific reference to what is now § 107(d)(4)with a general reference to § 107(d). See H.R. Rep. No. 101-490, at3-6, 17 (1990), reprinted in II 1990 Legislative History, at 3027-30, 3041.The Conference committee then reported the text of the House bill ratherthan that of the Senate. See H.R. Rep. No. 101-952, at 335 (1990), reprintedin I 1990 Legislative History, at 1785.

Second, our conclusion that the Congress intentionally referred to §107(d) as a whole is supported by a comparison of Subparts 1 and 2. TheCongress enacted Subpart 2 because of the failure of the controls in Subpart1 to bring areas into attainment with the 0.12 ppm standard in the allottedtime. See H.R. Rep. No. 101-490, at 145-50, reprinted in II 1990 LegislativeHistory, at 3169-74. Rather than continue treating all ozone nonattainmentareas alike, the Congress allowed the various areas between 3 and 20 yearsto attain the ozone NAAQS, depending upon the extent of the area's ozoneproblem. See id. at 146-47 ("In 1977, Congress tried to waive [sic]a 'magic wand' and command that all nonattainment areas [for ozone] willmeet the applicable [NAAQS]. . . . by December 31, 1987. . . . [That] date[] ha[s] come and gone and it is clear that ... we had no 'magic' solutions."),reprinted in II 1990 Legislative History, at 3170-71. As the petitionersargue, because the 1990 amendments extended the time for nonattainment areasto comply with the 0.12 ppm ozone NAAQS, they must preclude the EPA fromrequiring areas to comply either more quickly or with a more stringent ozoneNAAQS.

Subpart 1 requires compliance with a primary NAAQS "as expeditiouslyas practicable, but no later than 5 years from the date such area was designatednonattainment." 42 U.S.C. § 7502(a)(2)(A). All nonattainment areaswould have until 2012 to comply with the revised ozone NAAQS if the EPAand the States were to take the full time authorized in Subpart 1 for makingattainment designations and the EPA were to approve every possible extensionfor each area. See id. §§ 7407(d)(1)(A)-(B), 7502(a)(2)(A), (C).Such wide discretion is inconsistent, however, with Subpart 2, in whichthe Congress stripped the EPA of discretion to decide which ozone nonattainmentareas should receive more time to reach attainment (with two limited exceptionsnot relevant here, see id. § 7511(a)(4), (5)). Moreover, under §181(a) of Subpart 2, Los Angeles, the nation's only Extreme Area, has until2010 to attain the 0.12 ppm ozone NAAQS, and the possibility of extendingthat deadline until 2012. That Los Angeles should also have to attain amore stringent ozone standard by that same year, if not earlier, clearlyruns counter to the comprehensive enforcement scheme enacted in Subpart2.

The EPA offers two arguments against this interpretation of Subparts 1 and2. First, the EPA contends that a recent statute confirms its power to designatenonattainment areas under the revised ozone standard. See Pub. L. No. 105-178,§ 6103(a), 112 Stat. 465 (1998) (extending time to two years from oneyear for governor to submit proposed designation under 0.08 ppm ozone NAAQS).That statute also specifically states, however, that "[n]othing insection[ ] . . . 6103 shall be construed by the Administrator of EnvironmentalProtection Agency or any court . . . to affect any pending litigation orto be a ratification of the ozone . . . standard[ ]." Id. § 6104.Further, even if the EPA were correct that § 6103 confirms the agency'spower to designate areas under a revised ozone NAAQS, that power was neverin doubt, as we concluded above. Indeed, § 6104 simply does not bearupon the question we address here: whether Subpart 1 or Subpart 2 providesthe applicable enforcement mechanisms for an area designated nonattainmentunder a revised ozone NAAQS.

Second, the EPA argues that read in context the reference to § 107(d)in § 181(a)(1) relates only to designations made under § 107(d)(4).Because the table in § 181(a)(1) classifies areas based upon a designvalue that roughly measures attainment of the 0.12 ppm ozone NAAQS, theEPA contends that the nonattainment designations referenced in § 181(a)(1)are only those designations made under the 0.12 ppm ozone NAAQS. This explanation,however, does not square with either the Congress's decision not to referto § 107(d)(4) specifically or the long-term nature of the attainmentscheme enacted in Subpart 2; on the EPA's interpretation, that scheme wouldhave been stillborn had the EPA revised the ozone NAAQS immediately afterthe Congress enacted the 1990 amendments.

The EPA points next to § 181(b)(1), which specifies the attainmentdates for areas that met the 0.12 ppm standard when the Congress enactedthe 1990 amendments but that later cease to comply. That section, however,applies only to areas designated under § 107(d)(3) that previouslywere "designated attainment or unclassifiable for ozone under section[107(d)(4)]." That § 181(b)(1) provides special rules for suchareas, but not for areas designated under § 107(d)(3) that had previouslybeen designated attainment for ozone or unclassifiable under § 107(d)(1),does not support the EPA's argument that the phrase in § 181(a)(1)"designated nonattainment for ozone pursuant to section 107(d)"denotes only those designations made under § 107(d)(4). If anything,the specification of § 107(d)(4) in § 181(b)(1) makes its absencefrom § 181(a)(1) all the more striking.

The final bit of context to which the EPA points is the title of §181(a): "Classification and attainment dates for 1989 nonattainmentareas." Because the title specifies "1989 nonattainment areas,"we are told, § 181(a) must refer only to nonattainment designationsmade immediately after enactment of the 1990 amendments, that is, designationsmade under § 107(d)(4). Although "the title of a statute or sectioncan aid in resolving an ambiguity in the legislation's text," INS v.National Ctr. for Immigrants' Rights, Inc., 502 U.S. 183, 189 (1991), atitle cannot be allowed to create an ambiguity in the first place. See Maguirev. Commissioner of Internal Revenue, 313 U.S. 1, 9 (1941) ("[T]he titleof an act will not limit the plain meaning of the text."). The textof § 181(a) clearly encompasses nonattainment designations made underall subsections of § 107(d). There simply is no ambiguity in need ofresolution by reference to the title of the section.

In sum, § 181(a) "specifically provide[s]" for classificationsand attainment dates for areas designated nonattainment for ozone pursuantto § 107(d)(1). Accordingly, Subpart 2, not Subpart 1, provides theclassifications and attainment dates for any areas designated nonattainmentunder a revised primary ozone NAAQS, see 42 U.S.C. § 7502(a)(1)(C),(a)(2)(D), and the EPA must enforce any revised primary ozone NAAQS underSubpart 2.

3. The Secondary Ozone NAAQS

The Non-State Petitioners briefly contend that our conclusion that Subpart2 provides the classifications and attainment dates for areas designatednonattainment under a revised primary ozone NAAQS is equally applicableto the enforcement of a revised secondary ozone NAAQS. We find it impossibleto conclude, however, that Subpart 2 "specifically provide[s]"for classifications and attainment dates for areas designated nonattainmentwith a revised secondary ozone NAAQS; § 181(a)(1) expressly refersonly to primary NAAQS and Subpart 2 not once mentions secondary NAAQS. Further,attainment dates in Subpart 1 for secondary standards are less stringentthan for primary standards, making comparison with the more lenient datesin Subpart 2 less troubling. Compare id. § 7502(a)(2)(B) (attainmentof secondary NAAQS "shall be . . . achieved as expeditiously as practicableafter the date such area was designated nonattainment"), with id. §7502(a)(2)(A) (attainment of primary NAAQS "shall be . . . achievedas expeditiously as practicable, but no later than 5 years from the datesuch area was designated nonattainment"). Nonetheless, we understandSubpart 2 to codify the Congress's judgment as to what is "as expeditiouslyas practicable" in reducing an area's level of ozone. Consequently,the EPA is precluded from requiring any steps toward compliance with a revisedsecondary ozone NAAQS prior to an area's attainment of the 0.12 ppm standard.In areas that meet the 0.12 ppm standard, however, Subpart 2 erects no barto the EPA's requiring compliance with a revised secondary ozone NAAQS "asexpeditiously as practicable."

B. Ozone's Health Benefits

Petitioners presented evidence that according to them shows the health benefitsof tropospheric ozone as a shield from the harmful effects of the sun'sultraviolet rays-including cataracts and both melanoma and nonmelanoma skincancers. In estimating the effects of ozone concentrations, EPA explicitlydisregarded these alleged benefits.

EPA explained its decision first as a matter of statutory interpretation.Under the Clean Air Act, EPA's ambient standards for any pollutant are tobe "based on [the] criteria" that EPA has published for that pollutant.42 U.S.C. § 7409(b)(1) & (2). The "criteria," in turn,are to "reflect the latest scientific knowledge useful in indicatingthe kind and extent of all identifiable effects on public health or welfarewhich may be expected from the presence of such pollutant in the ambientair, in varying quantities." Id. § 7408(a)(2). The reference to"all identifiable effects" would seem on its face to include beneficenteffects.

EPA attempts to avoid this straightforward reading in several ways. First,it points to the term "such pollutant," arguing that the statuterequires it to focus exclusively on the characteristics that make the substancea "pollutant." But the phrase "pollutant" is simplya label used to identify a substance to be listed and controlled by thestatute. While it is perfectly true that a substance known to be utterlywithout adverse effects could not make it onto the list, this fact of nomenclaturedoes not visibly manifest a congressional intent to banish considerationof whole classes of "identifiable effects."

EPA also relies on the fact that two of the three specified considerationsunder § 108(a)(2)'s general mandate refer to "adverse effect[s]":

The criteria for an air pollutant, to the extent practicable, shall includeinformation on-

(A) those variable factors (including atmospheric conditions) which of themselvesor in combination with other factors may alter the effects on public healthor welfare of such air pollutant;

(B) the types of air pollutants which, when present in the atmosphere, mayinteract with such pollutant to produce an adverse effect on public healthor welfare; and

(C) any known or anticipated adverse effects on welfare.

Id. § 7408(a)(2) (emphasis added). EPA's argument would be of uncertainforce even if all three types of effects specifically required to be consideredwere spoken of as "adverse effects"; there is no reason to read"adverse" back into the "all identifiable effects" of§ 108(a)(2). But as one of the three specified classes refers to "effects"unmodified, id. § 7408(a)(2)(A), we can reject EPA's argument withouteven reaching that issue. That Congress qualified "effects" inclauses (B) and (C) with "adverse" seems only to strengthen thesupposition that in (A)-and in the general mandate-it intended to coverall health or welfare effects. Therefore if petitioners' contentions areright, clause (A) applies to ozone: the presence of ultraviolet radiationat various levels "alter[s] the effects [of ozone] on public healthor welfare" by making them on the whole less malign-perhaps even beneficial.

EPA next argues that Title VI of the Clean Air Act, id. §§ 7671-7671q,which mandates certain measures to preserve stratospheric ozone, representsa complete consideration of ozone's beneficial role as a UV shield. Petitioners'claim, however, is that ground-level (tropospheric) ozone-the subject ofthis rule-has a UV-screening function independent of the ozone higher inthe atmosphere. EPA points to nothing in the statute that purports to addresstropospheric ozone.

Finally, EPA directs us towards legislative history from the 1970 and 1990Clean Air Act Amendments. The "all identifiable effects" language,however, dates to the 1967 Amendments. Legislative history from the 1970and 1990 Congresses cannot be "an authoritative interpretation of whatthe [1967] statute meant," because it is "the function of thecourts and not the Legislature, much less a Committee of one House of theLegislature, to say what an enacted statute means." Pierce v. Underwood,487 U.S. 552, 566 (1988).

Under Chevron, we defer to an agency's interpretation of a statute if "thestatute is silent or ambiguous with respect to the specific issue"and "the agency's answer is based on a permissible construction ofthe statute." 467 U.S. at 843. We find no such ambiguity in this case.Further, EPA's interpretation fails even the reasonableness standard ofChevron's second part: it seems bizarre that a statute intended to improvehuman health would, as EPA claimed at argument, lock the agency into lookingat only one half of a substance's health effects in determining the maximumlevel for that substance. At oral argument even EPA counsel seemed reluctantto claim that the statute justified disregard of the beneficent effectsof a pollutant bearing directly on the health symptoms that accounted forits being thought a pollutant at all (suppose, for example, a chemical thatboth impedes and enhances breathing, depending on the person or circumstances);he also seemed unable to distinguish that case from the one here-where thechemical evidently impedes breathing but provides defense against variouscancers.

Legally, then, EPA must consider positive identifiable effects of a pollutant'spresence in the ambient air in formulating air quality criteria under §108 and NAAQS under § 109. EPA's other arguments are technical, andare of two sorts: those that allegedly show petitioners' studies to be fatallyflawed and those that allegedly show specific inflation of results in thesestudies. We need only consider the first sort, for EPA chose to give thestudies no weight at all.

Petitioners rely primarily on studies by Lutter and Cupitt. EPA found thatthese could be ignored because the marginal benefits are difficult, if notimpossible, to quantify reliably and because there is "no convincingbasis for concluding that any such effects . . . would be significant."But these are not the criteria by which EPA assesses adverse health effects.It does not rigorously or uniformly demand either quantifiability, see,e.g., Ozone Final Rule, 62 Fed. Reg. at 38,860/3 (admitting that "quantitativerisk estimates could not be developed" for certain adverse effectsof ozone on which EPA regulated); EPA Ozone Brief at 48 (defending considerationof various effects that "played an important role in the Administrator'sfinal decision" despite absence of quantification: "EPA did notestimate the risk for such effects because 'information [was] too limitedto develop quantitative estimates,'-not because there is doubt the effectsoccur.") (alteration and emphasis in original) (citation omitted),or any specific level of significance. As we can see no reason for imposinga higher information threshold for beneficent effects than for maleficentones, we have no basis for affirming EPA's decision to disregard the studies.

As we said above, we are remanding to EPA to formulate adequate decisioncriteria for its ordinary object of analysis-ill effects. We leave it tothe agency on remand to determine whether, using the same approach as itdoes for those, tropospheric ozone has a beneficent effect, and if so, thento assess ozone's net adverse health effect by whatever criteria it adopts.

IV. Particulate Matter

A. PM10 as Coarse Particle Indicator

We now turn to petitioners' challenges to the Agency's regulation of coarseparticulate pollution. Both the 1987 NAAQS and the proposed standards regulateall particles with diameters under 10 micrometers, signified by the indicatorPM10. The PM10 spectrum includes both coarse and fine particles. While themain distinction between coarse and fine particles is the process by whichthey are produced, EPA and epidemiologists who study the health effectsof particulate pollution identify coarse and fine particles through roughapproximations of those particles' diameters. Coarse particles, which becomeairborne usually from the crushing and grinding of solids, generally havediameters between 2.5 and 10 micrometers and can thus be identified by theindicator PM10-2.5. Fine particles, indicated in these new NAAQS by PM2.5,come mainly from combustion or gases and generally have diameters of 2.5micrometers or less.

Despite EPA's conclusion that coarse and fine particles pose independentand distinct threats to public health, the Agency chose not to adopt anindicator, such as PM10-2.5, that would measure only the coarse fractionof PM10. Petitioners make two arguments: that there is no scientific basisfor regulating coarse particles at all, and that even if there were, retentionof the PM10 indicator simultaneously with the establishment of the new fineparticle indicator is unsupported by evidence in the record and arbitraryand capricious. We agree with this latter argument.

Beginning with petitioners' first challenge, we think the record containssufficient evidence to justify the Agency's decision to regulate coarseparticulate pollution. While the relationship between PM10 pollution andadverse health effects justifying the 1987 NAAQS was well-established, seeNRDC v. EPA, 902 F.2d 962, 967-68 (D.C. Cir. 1990), two studies containedin the record of these proceedings concentrated specifically on the healtheffects caused by the coarse fraction of PM10 pollution. See Mary EllenGordian et al., "Particulate Air Pollution and Respiratory Diseasein Anchorage, Alaska," 104 Envtl. Health Persp. 290 (1996) (studyingvolcanic ash); Brockton J. Hefflin et al., "Surveillance for Dust Stormsand Respiratory Diseases in Washington State, 1991," 49 Archives ofEnvtl. Health 170 (1994) (studying fugitive dust). In addition, the recordcontains at least nine multivariate analyses finding statistically significantrelationships with health effects for both PM2.5 and PM10, suggesting thatthe portion of PM10 pollution unaccounted for by PM2.5 (i.e., coarse particles)explains some of the observed adverse health effects. In other words, becauseregression analysis holds the PM2.5 component constant, the PM10 effectrecognized in these equations actually evidences results from coarse particulatepollution. To be sure, petitioners have pointed to some evidence to thecontrary. But given that our review is limited to "ascertaining thatthe choices made by the Administrator were reasonable and supported by therecord," and does not include "judg[ing] the merits of competingexpert views," Lead Industries, 647 F.2d at 1160, we find ample supportfor EPA's decision to regulate coarse particulate pollution above the 1987levels.

Having found independent health consequences from coarse particulate pollution,EPA nevertheless decided to regulate the coarse fraction of PM10 indirectly,using PM10 (which includes both coarse and fine PM) as a "surrogatefor coarse fraction particles." PM Final Rule, 62 Fed. Reg. at 38,668/2.While recognizing that PM10-2.5 would have served as a satisfactory coarseparticle indicator, EPA offers three justifications for its decision touse PM10 instead: (1) Both the Gordian and Hefflin studies used PM10, notPM10-2.5, as the variable in their models, (2) the PM10 standards will workin conjunction with the PM2.5 standards by regulating the portion of particulatepollution not regulated by the PM2.5 standards, and (3) a nationwide monitoringprogram for PM10 already exists. We find none of these explanations persuasive.

As to the first argument, while acknowledging that the indicator used inthe studies captures both coarse and fine particles, EPA nevertheless maintainsthat PM10 is an effective indicator for the regulation of coarse particulatepollution. "Adopting the indicator used in the studies," the Agencysays, "increases the likelihood that the level selected will resultin the health protections predicted." But as EPA's own staff papersuggests, PM10 is "inherently confounded" by the presence of PM2.5particles, meaning that any regulation of PM10 pollution will include bothcoarse and fine particles. See PM Staff Paper at V-59. Using PM10 as thecoarse particle indicator, instead of PM10-2.5, will thus regulate morethan just the coarse fraction of PM10, and the amount of coarse particulatepollution permitted will depend (quite arbitrarily) on the amount of PM2.5pollution in the air. For example, assuming the 50 microgram annual PM10level adopted by the Agency and a region with an annual PM2.5 pollutionlevel of 15 micrograms, the PM10 indicator would prohibit coarse particulate(PM10-2.5) pollution from exceeding 35 micrograms. But in an area with only5 micrograms of PM2.5 pollution, the NAAQS would permit coarse particulatepollution to reach as high as 45 micrograms.

EPA's second argument-that the PM10 standard will work in conjunction withthe PM2.5 standard-suffers from the same deficiency. Accepting EPA's findingof "profound physicochemical differences" between coarse and finePM, PM Staff Paper at V-59, such that each requires independent regulation,we cannot discern exactly how a PM10 standard, instead of a PM10-2.5 standard,will work alongside a PM2.5 standard to regulate only the coarse fractionof PM10. EPA provides no explanation to aid us in understanding its decision.In fact, as the example above indicates, it is the very presence of a separatePM2.5 standard that makes retention of the PM10 indicator arbitrary andcapricious. Far from working in conjunction to regulate coarse particles,PM10 and PM2.5 indicators, when used together, lead to "double regulation"of the PM2.5 component of PM10 and potential underregulation of the PM10-2.5component since the amount of PM10-2.5 permitted will always depend on theamount of PM2.5 in the air.

EPA's final argument is pragmatic. It maintains that PM10 is a better indicatorthan PM10-2.5 for coarse particulate pollution because a nationwide monitoringprogram for PM10 already exists. But as EPA acknowledges elsewhere in itsbrief, NRDC bars EPA from considering factors unrelated to public healthin setting air quality standards. Echoing our decision in Vinyl Chloride,NRDC held that "the Administrator may not consider cost and technologicalfeasibility in determining what is 'safe'; such a determination 'must bebased solely upon the risk to health.'" NRDC, 902 F.2d at 973 (quotingVinyl Chloride, 824 F.2d 1146, 1166 (D.C. Cir. 1990) (in banc)); see alsoAmerican Petroleum Inst. v. Costle, 665 F.2d 1176, 1185 (D.C. Cir. 1981);Lead Industries, 647 F.2d at 1148-55. The administrative convenience ofusing PM10 cannot justify choosing an indicator poorly matched to the relevantpollution agent.

In view of our conclusion that PM10 amounts to an arbitrary indicator forcoarse particle pollution, we need not address petitioners' separate challengeto the PM10 levels or secondary standards. We note, however, that whateverlevels the Agency ultimately selects for coarse particle pollution willneed to comply with the requirements set forth in Part I of this opinion.

B. Fine Particles as "New Pollutant"

The Attorneys General of Ohio, Michigan, and West Virginia ("statepetitioners") argue that EPA is regulating PM2.5 for the first time.Because they consider PM2.5 to be a "new pollutant," they arguethat § 108 of the Clean Air Act requires EPA to conduct further researchon PM2.5's health effects before listing it as a pollutant, to issue anair quality criteria document reflecting the latest science on the healtheffects of the pollutant, and to assist states by developing "datarelating to the cost of installation and operation, energy requirements,emission reduction benefits, and environmental impact of the emission controltechnology." 42 U.S.C. § 7408(b)(1).

Although EPA never responds to this argument, five northeastern states (asrespondent intervenors and amici) do. Pointing out that previous NAAQS havealways included PM2.5, these attorneys general support the EPA's decisionnot to list PM2.5 separately as a new pollutant. We agree.

The state petitioners cannot escape the fact that the original standardsfor particulate pollution using Total Suspended Particulates (TSP) as indicator,as well as the 1987 NAAQS that used PM10, included by definition every particle2.5 micrometers and smaller. Moreover, in some areas fine particles oftendominate PM10 pollution. See PM Staff Paper at V-63. By refining the NAAQSto focus on smaller particles that EPA found posed distinct threats to publichealth, EPA has done with these regulations exactly what we held it coulddo in 1987 when it made the change from Total Suspended Particulates toPM10. See NRDC, 902 F.2d at 965-66. EPA's decision to update the NAAQS tofocus on PM2.5 merely continues a trend based on evolving science. It doesnot violate the provisions of § 108 of the Clean Air Act.

C. Failure to Identify a Biological Mechanism for Particulate Pollution'sRelationship to Adverse Health Effects

Also challenging the establishment of a fine particle standard, non-statepetitioners argue that EPA failed to explain the biological mechanism throughwhich particulate pollution causes adverse health effects. Even if epidemiologicalstudies show robust statistical relationships between pollution and healtheffects, they say, the absence of proof of causation-i.e., how particlesactually interact with cells and organs to cause sickness and death-is fatalto the standard. We disagree.

To begin with, the statute itself requires no such proof. The Administratormay regulate air pollutants "emissions of which, in his judgment, causeor contribute to air pollution which may reasonably be anticipated to endangerpublic health or welfare." 42 U.S.C. § 7408(a)(1)(A) (1994) (emphasisadded). Moreover, this court has never required the type of explanationpetitioners seek from EPA. In fact, we have expressly held that EPA's decisionto adopt and set air quality standards need only be based on "reasonableextrapolations from some reliable evidence." NRDC v. Thomas, 805 F.2d410, 432 (D.C. Cir. 1986). Indeed, were we to accept petitioners' view,EPA (or any agency for that matter) would be powerless to act whenever itfirst recognizes clear trends of mortality or morbidity in areas dominatedby a particular pathogen.

The numerous epidemiological studies appearing in this record, some of whichEPA also used to support the 1987 NAAQS, easily satisfy the standard articulatedin the statute and emphasized repeatedly in decisions of this court. Coveringdiverse geographic locations with widely varying mixes of air pollution,the studies found statistically significant relationships between air-borneparticulates signified by a variety of indicators and adverse health effects.Given EPA's statutory mandate to establish standards based on "thelatest scientific knowledge," 42 U.S.C. §§ 7408(a)(2), 7409(d),the growing empirical evidence demonstrating a relationship between fineparticle pollution and adverse health effects amply justifies establishmentof new fine particle standards.

D. Visibility Effects

The Environmental Petitioners challenge the EPA's decision to set the secondaryPM2.5 NAAQS at levels equivalent to the primary NAAQS. According to thepetitioners, the EPA's failure to set the secondary NAAQS at more stringentlevels will result in "adverse visibility impacts" in parts ofthe country. In view of our conclusion in Part I, above, that the EPA hasnot adequately explained the principles upon which it relied in settingthe levels in the NAAQS for PM, we need not reach the main thrust of thepetitioners' challenge to the secondary NAAQS. On the other hand, the EnvironmentalPetitioners have also raised a question of statutory interpretation, theresolution of which should assist the EPA if it revisits its decision toset the secondary PM2.5 NAAQS.

In the PM Final Rule, the EPA decided "to address the welfare effectsof PM on visibility by setting secondary standards identical to the suiteof PM2.5 primary standards, in conjunction with the establishment of a regionalhaze program under § 169A of the Act." PM Final Rule, 62 Fed.Reg. at 38,679/3. Section 169A "declares as a national goal the prevention. . . and the remedying of any . . . impairment of visibility in mandatoryclass I Federal areas . . . result[ing] from manmade air pollution."42 U.S.C. § 7491. Mandatory class I areas include all internationalparks, and national parks and wilderness areas of a certain size. See 42U.S.C. § 7472(a). The EPA concluded that reduction of PM2.5 levelsin class I areas would benefit the surrounding areas as well because "thesame haze that degrades visibility within or looking out from a nationalpark also degrades visibility outside it." PM Final Rule, 62 Fed. 38,682/1.

The Environmental Petitioners argue that § 109(b)(2), 42 U.S.C. §7409(b)(2), requires the EPA to set secondary NAAQS at a level sufficientto eliminate all adverse visibility effects and that it leaves the EPA nodiscretion to decide that some visibility impairment is better remediedthrough another program. This argument must be wrong. For, as the EPA argues,the Congress required the EPA to implement a regional haze program specificallyin order to address adverse visibility effects that persist in class I areasafter attainment of the secondary NAAQS. See 42 U.S.C. § 7470(1) (purposeof this part of Clean Air Act is "to protect public . . . welfare fromany actual or potential adverse effect which . . . may reasonably be anticipate[d]to occur . . . notwithstanding attainment and maintenance of all [NAAQS]").Accordingly, we conclude that the Congress did not intend the secondaryNAAQS to eliminate all adverse visibility effects and, therefore, that theEPA acted within the scope of its authority in deciding to rely upon theregional haze program to mitigate some of the adverse visibility effectscaused by PM2.5.


We remand the cases to EPA for further consideration of all standards atissue. We do not vacate the new ozone standards because the standard isunlikely to engender costly compliance activities in light of our determinationthat it cannot be enforced by virtue of Clean Air Act § 181(a), 42U.S.C. § 7511(a). We vacate the challenged coarse particulate matterstandards because EPA will have to develop different standards when it correctsthe arbitrarily chosen PM10 indicator. As to the fine particulate matterstandards, we invite briefing on the question of remedy: possibilities includebut are not limited to vacatur, non-vacatur subject to application to vacate,and non-vacatur.8 An order giving the briefing particulars will follow.

Because of the substantial investment of time this matter has required andthe many unresolved issues bearing on application of whatever standardsmay emerge, this panel will in the interest of judicial economy retain jurisdictionover the cases following remand. See Sierra Club v. Gorsuch, 715 F.2d 653,661 (D.C. Cir. 1983).

* Judge Williams wrote Parts I and III.B; JudgeGinsburg wrote Parts II, III.A, and IV.D; Judge Tatel wrote Parts IV.A-C.

1 Technically, EPA describes the criteria as used only for setting the "adequatemargin of safety." There might be thought to be a separate step inwhich EPA determines what standard would protect public health without anymargin of safety, and that step might be governed by different criteria.But EPA did not use such a process, and it need not. See NRDC v. EPA, 902F.2d 963, 973 (D.C. Cir. 1990). Thus, the criteria mentioned in the textgovern the whole standard-setting process.

2 EPA did cite qualitative evidence for further support for its annual standard,and argued that the evidence "does not provide evidence of effectsbelow the range of 40-50 µg/m3," the standard level. PM FinalRule, 62 Fed. Reg. at 38,678/3. The referenced document, however, bearsno indication that the qualitative evidence demonstrates effects at thelevel of the standard, either. See EPA, "Air Quality Criteria for ParticulateMatter," at 13-79 (April 1996).

3 See W.P.D. Logan, "Mortality in the London Fog Incident, 1952,"The Lancet, Feb. 4, 1953, at 336-38.

4 A zero-risk policy might seem to imply de-industrialization, but in facteven that seems inadequate to the task (and even if the calculus is confinedto direct risks from pollutants, as opposed to risks from the concomitantpoverty). First, PM (at least) results from almost all combustion, so onlytotal prohibition of fire or universal application of some heretofore unknowncontrol technology would reduce manmade emissions to zero. See PM StaffPaper at IV-1. Second, the combustion associated with pastoral life appearsto be rather deadly. See World Bank, World Development Report 1992: Developmentand the Environment 52 (1992) (noting that "biomass" fuels (i.e.,wood, straw, or dung) are often the only fuels that "poor households,mostly in rural areas" can obtain or afford, and that indoor smokefrom biomass burning "contributes to acute respiratory infections thatcause an estimated 4 million deaths annually among infants and children.").

5 The "quality" of various health states was determined by poll,and medical professionals determined the probabilities and durations ofvarious health states with and without the treatment in question.

Oregon was twice forced to revise its system because the United States Departmentof Health & Human Services detemined that the original proposal anda revision violated the Americans with Disabilities Act, 42 U.S.C. §§12101-12213. The reason given for this determination was that both versionsundervalued the lives of persons with disabilities: The original plan measuredquality of life according to the attitudes of the general population ratherthan the attitudes of persons with disabilities. See HHS, "AnalysisUnder the Americans with Disabilities Act ('ADA') of the Oregon Reform Demonstration"(Aug. 3, 1992), reprinted in 9 Issues in L. & Med. 397, 410, 410 (1994).The revised plan ranked treatments leaving the patient in a "symptomatic"state lower than those leaving the patient asymptomatic, and certain disablingconditions were considered "symptoms." See Letter from TimothyB. Flanagan, Assistant Attorney General, to Susan K. Zagame, Acting GeneralCounsel, HHS (Jan. 19, 1993), reprinted in 9 Issues in L. & Med. 397,418, 421 (1994). The Department's determination was extensively criticizedwhen issued. See Maxwell J. Mehlman et al., "When Do Health Care DecisionsDiscriminate Against Persons with Disabilities?" 22 J. Of Health Politics,Policy & L. 1385, 1390 (1997) (HHS's "decision provoked a stormof disbelief and denunciation").

We take no position on whether HHS's view was correct, or if the underlyingnorm also governs EPA's decisions under § 109(b)(1). An affirmativeanswer, however, would not seem to preclude use of some of Oregon's approach.The first step would be giving appropriate weight to the views of personswith disabilities. The second might be measuring the seriousness of a pollution-inducedhealth effect by the absolute level of well-being that the effect bringsabout, not by the decrease in level that the effect causes. In other words,if the maximum well-being level is 100 and the average asthmatic whose asthmaconstitutes a disability has a well-being of 80 in the absence of air pollution(according to a measure that appropriately considers asthmatics' own assessmentsof their condition), then a response to air pollution that reduces the asthmatics'well-being to 70 could be counted as an effect of magnitude 30 (the differencefrom full health), rather than 10 (the difference from the level withoutthe pollution). That approach would ensure that effects on persons withdisabilities were not underestimated, even in the broad sense of that termapparently adopted by HHS.

6 More specifically, the design value is the fourth-highest daily maximumozone concentration in an area over three consecutive years for which thereare sufficient data. If that value is less than or equal to 0.12 ppm, thenan area will have only three expected values above that level and it willbe in attainment with the ozone NAAQS. See EPA, The Clean Air Act OzoneDesign Value Study: Final Report 1-1 to 1-22 (1994) (filed pursuant to 42U.S.C. § 7511b(g), which required the EPA to conduct "a studyof whether the [existing design value] methodology . . . provides a reasonableindicator of the ozone air quality of ozone nonattainment areas"; theEPA concluded it did).

7 This table appears in Clear Air Act § 181(a)(1), 42 U.S.C. §7511(a)(1):



Area Class       Design value [ppm]       Primary standard attainment date


Marginal . . . . . . . . 0.121 up to 0.138 . . . . . . . 3 years after November 15, 1990

Moderate . . . . . . . 0.138 up to 0.160 . . . . . . . 6 years after November 15, 1990

Serious . . . . . . . . . 0.160 up to 0.180 . . . . . . .9 years after November 15, 1990

Severe . . . . . . . . . 0.180 up to 0.280 . . . . . . . 15 years after November 15, 1990

Extreme . . . . . . . . 0.280 and above . . . . . . . . 20 years after November 15, 1990

The Severe Area category is later subdivided, creating a sixth classificationfor ozone nonattainment areas. See id. § 7511(a)(2) ("Notwithstandingtable 1, [for] a severe area with a 1988 ozone design value between 0.190and 0.280 ppm, the attainment date shall be 17 years . . . after November15, 1990").

8 Briefing should address the possibility that the previous particulatematter standard will spring back to life in response to our decision tovacate the new coarse particulate matter standard.

TATEL, Circuit Judge, dissenting from Part I:

The Clean Air Act has been on the books for decades, has been amended byCongress numerous times, and has been the subject of regular congressionaloversight hearings. The Act has been parsed by this circuit no fewer thanten times in published opinions delineating EPA authority in the NAAQS-settingprocess. Yet this court now threatens to strike down section 109 of theAct as an unconstitutional delegation of congressional authority unlessEPA can articulate an intelligible principle cabining its discretion. Indoing so, the court ignores the last half-century of Supreme Court nondelegationjurisprudence, apparently viewing these permissive precedents as mere exceptionsto the rule laid down 64 years ago in A.L.A. Schechter Poultry Corp. v.United States, 295 U.S. 495 (1935). Because section 109's delegation ofauthority is narrower and more principled than delegations the Supreme Courtand this court have upheld since Schechter Poultry, and because the recordin this case demonstrates that EPA's discretion was in fact cabined by section109, I respectfully dissent.

Section 109 requires EPA to publish air quality standards "the attainmentand maintenance of which in the judgment of the Administrator, based onsuch criteria and allowing an adequate margin of safety, are requisite toprotect the public health." 42 U.S.C. § 7409(b)(1) (1994). Comparesection 109 to the language of section 303 of the Communications Act of1934, which gave the FCC authority to regulate broadcast licensing in the"public interest," and which the Supreme Court sustained in NationalBroadcasting Co. v. United States, 319 U.S. 190, 225-26 (1943). The FCC'sgeneral authority to issue regulations "as public convenience, interest,or necessity requires" was sustained in United States v. SouthwesternCable Co., 392 U.S. 157, 178 (1968). The Supreme Court has sustained equallybroad delegations to other agencies, including the Price Administrator'sauthority to fix "fair and equitable" commodities prices, Yakusv. United States, 321 U.S. 414, 426-27 (1944), the Federal Power Commission'sauthority to determine "just and reasonable" rates, FPC v. HopeNatural Gas Co., 320 U.S. 591, 600 (1944), the War Department's authorityto recover "excessive profits" earned on military contracts, Lichterv. United States, 334 U.S. 742, 778-786 (1948), and the Attorney General'sauthority to regulate new drugs that pose an "imminent hazard to publicsafety," Touby v. United States, 500 U.S. 160, 165 (1991). See alsoMilk Indus. Foundation v. Glickman, 132 F.3d 1467, 1475 (D.C. Cir. 1998)(upholding delegation to Secretary of Agriculture to approve interstatecompacts upon a finding of "compelling public interest").

Given this extensive Supreme Court precedent sustaining general congressionaldelegations, no wonder the First Circuit rejected a similar nondelegationchallenge to the Clean Air Act's "requisite to protect the public health"language:

The power granted to EPA is not "unconfined and vagrant". [SchechterPoultry, 295 U.S. at 551 (Cardozo, J., concurring).] The Agency has beengiven a well defined task by Congress-to reduce pollution to levels "requisiteto protect the public health", in the case of primary standards. TheClean Air Act outlines the approach to be followed by the Agency and describesin detail many of its powers. . . . Yet there are many benchmarks to guidethe Agency and the courts in determining whether or not EPA is exceedingits powers, not the least of which is that the rationality of the meanscan be tested against goals capable of fairly precise definition in thelanguage of science.

Administrative agencies are created by Congress because it is impossiblefor the Legislature to acquire sufficient information to manage each detailin the long process of extirpating the abuses identified by the legislation;the Agency must have flexibility to implement the congressional mandate.Therefore, although the delegation to EPA was a broad one, . . . we havelittle difficulty concluding that the delegation was not excessive.

South Terminal Corp. v. EPA, 504 F.2d 646, 677 (1st Cir. 1974).

I do not agree with my colleagues that International Union, UAW v. OSHA,938 F.2d 1310 (D.C. Cir. 1991) ("Lockout/Tagout I"), requiresa different result. That case remanded to OSHA for a more precise definitionof section 3(8) of the Occupational Safety and Health Act, which grantedthe Agency authority to enact workplace safety standards "reasonablynecessary or appropriate to provide safe or healthful employment or placesof employment." Id. at 1316. The Clean Air Act does not delegate toEPA authority to do whatever is "reasonably necessary or appropriate"to protect public health. Instead, the statute directs the Agency to fashionstandards that are "requisite" to protect the public health. Inother words, EPA must set pollution standards at levels necessary to protectthe public health, whether "reasonable" or not, whether "appropriate"or not.

Moreover, in setting standards "requisite to protect the public health"EPA discretion is not unlimited. The Clean Air Act directs EPA to base standardson "air quality criteria" that "accurately reflect the latestscientific knowledge useful in indicating the kind and extent of all identifiableeffects on public health or welfare which may be expected from the presenceof such pollutant in the ambient air, in varying quantities." 42 U.S.C.§ 7408(a)(2); see id. § 7409(b)(1); see also id. § 7408(a)(2)(requiring air quality criteria, "to the extent practicable,"to "include information on-(A) those variable factors (including atmosphericconditions) which of themselves or in combination with other factors mayalter the effects on public health or welfare of such air pollutant; (B)the types of air pollutants which, when present in the atmosphere, may interactwith such pollutant to produce an adverse effect on public health or welfare;and (C) any known or anticipated adverse effects on welfare"). Indeed,the principles constraining EPA discretion are at least as specific as thosethis court sustained in Lockout/Tagout II, i.e., that OSHA must identifya " 'significant' safety risk, to enact a safety standard that provides'a high degree of worker protection'." International Union, UAW v.OSHA, 37 F.3d 665, 669 (D.C. Cir. 1994) ("Lockout/ Tagout II").By directing EPA to set NAAQS at levels "requisite"-not reasonablyrequisite-to protect the public health with "an adequate margin ofsafety," the Clean Air Act tells EPA exactly the same thing, i.e.,ensure a high degree of protection.

Although this court's opinion might lead one to think that section 109'slanguage permitted EPA to exercise unfettered discretion in choosing NAAQS,the record shows that EPA actually adhered to a disciplined decisionmakingprocess constrained by the statute's directive to set standards "requisiteto protect the public health" based on criteria reflecting the "latestscientific knowledge." To identify which health effects were "significantenough" to warrant protection, EPA followed guidelines published bythe American Thoracic Society. See National Ambient Air Quality Standardsfor Ozone: Proposed Decision, 61 Fed. Reg. 65,716, 65,722/1 (1996). It thenset the ozone and fine particle standards within ranges recommended by CASAC,the independent scientific advisory committee created pursuant to section109 of the Act. See 42 U.S.C. § 7409(d)(2).

CASAC must consist of at least one member of the Nation- al Academy of Sciences,one physician, and one person representing state air pollution control agencies.See id. § 7409(d)(2)(A). In this case, CASAC also included medicaldoctors, epidemiologists, toxicologists and environmental scientists fromleading research universities and institutions throughout the country. EPAmust explain any departures from CASAC's recommendations. See id. §7607(d)(3). Bringing scientific methods to their evaluation of the Agency'sCriteria Document and Staff Paper, CASAC provides an objective justificationfor the pollution standards the Agency selects. Cf. Daubert v. Merrell DowPharmaceuticals, Inc., 509 U.S. 579, 593 (1993) ("'Scientific methodologytoday is based on generating hypotheses and testing them to see if theycan be falsified; indeed, this methodology today is what distinguishes sciencefrom other fields of human inquiry.'") (citation omitted). Other federalagencies with rulemaking responsibilities in technical fields also relyheavily on the recommendations, policy advice, and critical review thatscientific advisory committees provide. See, e.g., 21 U.S.C. § 355(n)(describing scientific advisory panels for the Food and Drug Administration);49 U.S.C. § 44912(c) (creating a scientific advisory panel for theFederal Aviation Administration).

Beginning with CASAC's ozone recommendations- not one member recommendedgoing below .08 ppm- EPA gave two perfectly rational explanations for thelevel it selected. First, it set the annual level based on the differenttypes of health effects observed above and below .08 ppm. Particularly below.08, the Agency determined, "[t]he most certain [ozone-]related effects,while judged to be adverse, are transient and reversible." NationalAmbient Air Quality Standards for Ozone, 62 Fed. Reg. 38,856, 38,868/2 (1997)(emphasis added). Characterizing this explanation as saying nothing morethan that "lower exposure levels are associated with lower risk topublic health," Maj. Op. at 10, my colleagues find the Agency's reasoningunintelligible. But EPA did not find simply that public health risks decreaseat lower levels. Instead, it found that public health effects differ below.08 ppm, i.e., that they are "transient and reversible."

Second, EPA explained that the level should not be set below naturally occurringbackground ozone concentrations. The Agency selected .08 ppm because itfound that "a 0.07 ppm level would be closer to peak background levelsthat infrequently occur in some areas due to nonanthropogenic sources of[ozone] precursors, and thus more likely to be inappropriately targetedin some areas on such sources." 62 Fed. Reg. at 38,868/3. Of course,any level of ozone pollution above background concentrations is closer tobackground levels than one just above it. See Maj. Op. at 11. But as I readEPA's explanation, the Agency found that peak background levels sometimesoccur at .07 ppm, not at .08 ppm. Indeed, the data EPA provided in its "Responsesto Significant Comments" show a range of background concentrationsfrom a low of .042 ppm in Olympic National Park in Washington to a highof .075 ppm in Quachita National Forest in Arizona. No region registeredbackground levels above .075 ppm. See U.S. ENVIRONMENTAL PROTECTION AGENCY,RESPONSES TO SIGNIFICANT COMMENTS ON THE 1996 PROPOSED RULE ON THE NATIONALAMBIENT AIR QUALITY STANDARDS FOR OZONE 94-96 (July 1997). In other words,by setting the annual standard at .08 rather than .07 ppm, EPA ensured thatif a region surpasses the ozone standard, it will do so because of controllablehuman activity, not because of uncontrollable natural levels of ozone.

EPA offered an equally reasonable explanation for the fine particle pollutionstandard. Again limiting itself to the range approved by CASAC, EPA setthe annual standard for PM2.5 pollution at the lowest level where it hadconfidence that the epidemiological evidence (filtered through peer-reviewed,published studies) displayed a statistically significant relationship betweenair pollution and adverse public health effects.

Recognizing that its decision must "accurately reflect the latest scientificknowledge useful in indicating the kind and extent of all identifiable effectson public health," 42 U.S.C. § 7408(a)(2), EPA focused on threestudies in the record that displayed a statistically significant relationshipbetween fine particle pollution and adverse health effects: Joel Schwartzet al., Is Daily Mortality Associated Specifically with Fine Particles?,46 J. AIR & WASTE MGMT. ASS'N 927 (1996); Joel Schwartz et al., AcuteEffects of Summer Air Pollution on Respiratory Symptom Reporting in Children,150 AM. J. RESPIRATORY & CRITICAL CARE MED. 1234 (1994); and DouglasW. Dockery et al., An Association between Air Pollution and Mortality inSix U.S. Cities, 329 NEW ENG. J. MED. 1753 (1993). The Agency explainedthat "there is generally greatest statistical confidence in observedassociations [between fine particle pollution and adverse health effects]for levels at and above the mean concentration [of pollution observed inthe studies that showed a statistically significant relationship]."National Ambient Air Quality Standards for Particulate Matter, 62 Fed. Reg.38,652, 38,676/1 n.42 (1997) (emphasis added). Allowing "an adequatemargin of safety," EPA then set the annual fine particle standard justbelow the lowest mean pollution levels observed in those studies, at 15µg/m3. See id. at 38,676/1 ("An examination of the long-termmeans from the combined six city analyses of daily mortality [Schwartz etal. (1996)] and morbidity [Schwartz et al. (1994)], together with thosefrom studies in individual cities for which statistically significant PM-effectsassociations are reported . . . finds mean concentrations ranging from about16 to about 21 µg/m3. . . ."); id. at 38,676/2 ("[The EPA]Staff Paper assessment of the concentration-response results [from Dockeryet al. (1993)], concluded that the evidence for increased risk was moreapparent at annual concentrations at or above 15 µg/m3. . . .").

In a passage directly answering this court's concerns, see Maj. Op. at 11-12,the Staff Paper explained why the long-term mean served as a reasonablelevel for setting the fine particle NAAQS:

The mean (or median) concentration may serve as a reasonable cutpoint ofincreased PM health risk since at this point there is generally the greatestconfidence (i.e., the smallest confidence intervals) in the associationand the reported [relative risk] estimates. The mean concentration consideredby staff as most informative to test implications of potential alternativeconcentration-response functions is the minimum mean concentration associatedwith a study or studies reporting statistically significant increases inrisk across a number of study locations. . . .


EPA thus did not, as my colleagues charge, arbitrarily pick points on theozone and particulate pollution continua indistinguishable from any other.Instead, acting pursuant to section 109's direction that it establish standardsthat, based on the "latest scientific knowledge" are "requisite"to protect the public health with "an adequate margin of safety,"and operating within ranges approved by CASAC, the Agency set the ozonelevel just above peak background concentrations where the most certain healtheffects are not transient and reversible, and the fine particle level atthe lowest long-term mean concentration observed in studies that showeda statistically significant relationship between fine particle pollutionand adverse health effects. Whether EPA arbitrarily selected the studiesit relied upon or drew mistaken conclusions from those studies (as petitionersargue), or whether EPA failed to live up to the principles it establishedfor itself (as my colleagues believe, see Maj. Op. at 9-12), has nothingto do with our inquiry under the nondelegation doctrine. Those issues relateto whether the NAAQS are arbitrary and capricious. See NRDC v. EPA, 902F.2d 962, 969, 971 (D.C. Cir. 1989). The Constitution requires that Congressarticulate intelligible principles; Congress has done so here.

A final point. Unlike OSHA, which Lockout/Tagout I recognized has authorityto reach into every workplace to dictate what is safe, to impose extensivecivil and criminal penalties, and "to decide which firms will liveand which will die," Lockout/Tagout I, 938 F.2d at 1318, EPA regulatesprimarily by setting standards for states to develop their own plans. See42 U.S.C. § 7401(a)(3) (Congress finds "that air pollution prevention. . . and air pollution control at its source is the primary responsibilityof States and local governments."). Indeed, because states have threeyears to submit implementation plans, which are themselves subject to notice,comment, public hearing, and frequent renegotiation, we will not know foryears precisely how the ozone and particle NAAQS will actually affect individualbusinesses. Only if a state fails to produce an acceptable plan can EPAterminate federal highway funds or impose its own implementation plan. Becausethe Clean Air Act gives politically accountable state governments primaryresponsibility for determining how to distribute the burdens of pollutionreduction and therefore how the NAAQS will affect specific industries andindividual businesses, courts have less reason to second-guess the specificityof the congressional delegation. Moreover, if the states disagree with thestandards EPA has set, they have 535 representatives in Congress to turnto for help. In fact, legislation to overturn the very NAAQS at issue inthis case was introduced in the last Congress. See H.R. 1984, 105th Cong.(1997) ("A bill to provide for a four-year moratorium on the establishmentof new standards for ozone and fine particulate matter under the Clean AirAct, pending further implementation of the Clean Air Act Amendments of 1990,additional review and air quality monitoring under that Act."); S.1084, 105th Cong. (1997) ("A bill to establish a research and monitoringprogram for the national ambient air quality standards for ozone and particulatematter and to reinstate the original standards under the Clean Air Act,and for other purposes.").



No. 97-1440


Nos. 97-1440, 97-1546, 97-1548, 97-1551 to 97-1553,
97-1555, 97-1559, 97-1561, 97-1562, 97-1565, 97-1567,
97-1571, 97-1573, 97-1574, 97-1576, 97-1578, 97-1579,
97-1582,97-1585 to 97-1588, 97-1592,
97-1594, 97-1596 to 97-1598
Nos. 97-1441, 97-1502, 97-1505, 97-1508 to 97-1510, 97-1512 to 97-1514,97-1518, 97-1519, 97-1526, 97-1531, 97-1539, 97-1566, 97-1568, 97-1570,97-1572, 97-1575, 97-1584, 97-1589, 97-1591, 97-1595, 97-1619

[Filed October 29, 1999]


Opinion PER CURIAM on petitions for rehearing.

Opinion concurring in partial grant of rehearing and dissenting in partfrom the panel's denial of rehearing filed by Circuit Judge TATEL.



This matter is before the court for consideration of respondent EnvironmentalProtection Agency's (EPA) petition for panel rehearing in Nos. 97-1440 and97-1441, the responses thereto, and the petitions for panel rehearing ofintervenors-respondents New Jersey and Massachusetts in Nos. 97-1440 and97-1441, Citizen for Balanced Transportation, et al. in No. 97-1440, andthe American Lung Association in Nos. 97-1440 and 97-1441. Upon considerationof the foregoing, it is

ORDERED that the petitions of EPA, New Jersey and Massachusetts, and theAmerican Lung Association be granted in part. The court accordingly modifiesParts III.A.2 & .3 and the conclusion of the court's original opinionas set forth in the opinion of the court filed herein this date. It is

FURTHER ORDERED that the remainder of EPA, New Jersey and Massachusetts,and the American Lung Association's petitions be denied and that Citizenfor Balanced Transportation's petition be denied.

Opinion for the Court filed PER CURIAM:

The Environmental Protection Agency petitions for rehearing, challengingthis court's holdings that: (1) with respect to the factors the agency usesto determine the degree of public health concern associated with differentlevels of a pollutant, it "appears to have articulated no 'intelligibleprinciple' to channel its application of these factors; nor is one apparentfrom the statute," American Trucking Ass'ns v. United States EnvironmentalProtection Agency, 175 F.3d 1027, 1034 (D.C. Cir. 1999); (2) "Subpart2, not Subpart 1, provides the classifications and attainment dates forany areas designated nonattainment under a revised primary ozone NAAQS,and the EPA must enforce any revised primary ozone NAAQS under Subpart 2,"id. at 1050; and (3) "EPA must consider positive identifiable effectsof a pollutant's presence in the ambient air in formulating air qualitycriteria under § 108 and NAAQS under § 109," id. at 1052.For the following reasons, we grant the petition for rehearing in part anddeny it in part.

I. Delegation

In the EPA's petition for rehearing, counsel for the agency argue that §109 of the Clean Air Act contains the following principle limiting the agency'sdiscretion: "The levels [set in a NAAQS] must be necessary for publichealth protection: neither more nor less stringent than necessary, but 'requisite.'"EPA Pet. at 8 (emphases in original). Further, counsel claim that in settingthe NAAQS at issue in this case the agency applied corollaries of this principle,one for particulate matter, one for ozone,1 to derive determinate standards.

In denying the EPA's petition for rehearing on this issue, we note thatthe agency previously put forward neither the assertedly intelligible principleits counsel now claim to find in the statute nor the corollaries its counselnow implicitly derive therefrom. To be sure, in the rulemakings that setthe NAAQS, the EPA mentioned the corollary propositions its counsel nowclaim served as intelligible limiting principles, but the agency did notidentify either as a limit upon its discretion; the EPA never suggestedthat it could not (or in a later rulemaking would not) base a NAAQS uponevidence that did not meet the 95 percent confidence level or that revealedadverse but transient effects.2 In its briefs defending the NAAQS, the EPAmerely asserted that the Clean Air Act provides an intelligible principle;it failed both to state that principle and to argue that its revised NAAQSwere promulgated in accordance with that principle. EPA PM Brief at 145-49;EPA Ozone Brief at 77-80. Indeed, the EPA's briefs in each of these twocases contained the same four sentences assuring the court that the statuteprovides a principle without explaining what the agency understands thatprinciple to be:

[Section] 109(b)(1) requires EPA to promulgate NAAQS based on air qualitycriteria issued under § 108 that are "requisite to protect thepublic health" with "an adequate margin of safety." Thislanguage and related legislative history provide directions for EPA to followin setting the NAAQS. Moreover, EPA has consistently interpreted §109(b)(1) to provide further decisionmaking criteria to guide the standardsetting process. Thus, the CAA provides a more than sufficient "intelligibleprinciple" to guide EPA's discretion. EPA Ozone Brief at 78; see alsoEPA PM Brief at 148.

These sentences begged the key question about that intelligible principle:"What is it?"

As we noted in our first opinion in this case, when "statutory languageand an existing agency interpretation involve an unconstitutional delegationof power, but an interpretation without the constitutional weakness is ormay be available, our response is not to strike down the statute but togive the agency an opportunity to extract a determinate standard on itsown." 175 F.3d at 1038. Counsel for the EPA have now extracted fromthe statute what they contend is an intelligible principle limiting theEPA's discretion. We express no opinion upon the sufficiency of that principle;only after the EPA itself has applied it in setting a NAAQS can we say whetherthe principle, in practice, fulfills the purposes of the nondelegation doctrine.See Yakus v. United States, 321 U.S. 414, 424-26 (1944); Amalgamated MeatCutters v. Connally, 337 F. Supp. 737, 759 (D.D.C. 1971) (Leventhal, J.,for three-judge panel).

A final word about our nondelegation holding: The Supreme Court has longheld that an ambiguous principle in a statute delegating power to an agencycan gain "meaningful content from the purpose of the Act, its factualbackground and the statutory context in which [it] appear[s]." AmericanPower & Light Co. v. SEC, 329 U.S. 90, 104 (1946); see also FederalRadio Comm'n v. Nelson Bros. Bond & Mort. Co, 289 U.S. 266, 285 (1933)(upholding delegation to Federal Radio Commission to grant licenses "aspublic convenience, interest or necessity requires" in light of "itscontext [and] the nature of radio transmission and reception"; Faheyv. Mallonee, 332 U.S. 245, 250 (1947) (upholding delegation to the FederalHome Loan Bank Board to promulgate regulations for the appointment of aconservator for savings and loan associations in view of the banking industry's"well-defined practices for the appointment of conservators").This court has done the same. See, e.g., National Ass'n of Broadcastersv. Copyright Royalty Tribunal, 675 F.2d 367, 376 n.12 (1982) (finding anintelligible principle to guide the tribunal in disbursing cable royaltyfees in "specific statements in the legislative history and in thegeneral philosophy of the Act itself"); Amalgamated Meat Cutters, 337F. Supp. at 747-49 (interpreting the Economic Stabilization Act of 1970in light of "the historic context of government stabilization measures"in order to "negative[ ] a conclusion that the whole program was setadrift without a rudder"). To choose among permissible interpretationsof an ambiguous principle, of course, is to make a policy decision, andsince Chevron it has been clear that "[t]he responsibilities for assessingthe wisdom of such policy choices . . . are not judicial ones." ChevronU.S.A. Inc. v. NRDC, 467 U.S. 837, 866 (1984). Accordingly, just as we mustdefer to an agency's reasonable interpretation of an ambiguous statutoryterm, we must defer to an agency's reasonable interpretation of a statutecontaining only an ambiguous principle by which to guide its exercise ofdelegated authority. But see Kenneth Culp Davis, A New Approach to Delegation,36 U. Chi. L. Rev. 713, 713 (1969) (arguing that "judicial inquiries[under the nondelegation doctrine] should shift from statutory standardsto administrative safeguards"). In sum, the approach of the Benzenecase, in which the Supreme Court itself identified an intelligible principlein an ambiguous statute, has given way to the approach of Chevron. See IndustrialUnion Dep't v. American Petroleum Inst. (Benzene), 448 U.S. 607, 642, 646(1980) (Stevens, J., plurality) (interpreting § 3(8) of the OccupationalHealth and Safety Act to require "a threshold finding . . . that significantrisks are present," thereby finding in the statute an intelligibleprinciple).3

II. Subpart 2 and the Revised Ozone Standard

In its petition for rehearing, the EPA challenges the holdings in PartsIII.A.2 and III.A.3 of our original opinion, see 175 F.3d at 1048-51, aswell as our jurisdiction to reach those issues. We address the jurisdictionalpoint first.

A. Jurisdiction

The EPA argues that because it has taken no final action implementing therevised NAAQS this court lacks jurisdiction to reach the question whetherSubpart 2 prevents the agency from implementing a revised ozone NAAQS underSubpart 1. See 42 U.S.C. § 7607(b) (limiting this court's jurisdictionto review of "nationally applicable regulations promulgated, or finalagency action taken, by the Administrator"); see also Sierra Club v.Thomas, 828 F.2d 783, 792 (D.C. Cir. 1987).4 That this claim is raised forthe first time in a petition for rehearing does not, of course, alter ourobligation to "satisfy [our]self . . . of [our] own jurisdiction."Steel Co. v. Citizens for a Better Environment, 118 S. Ct. 1003, 1012-13(1998).

Whether agency action is final for purposes of § 7607(b) entails afunctional, not a formal, inquiry. See NRDC v. EPA, 22 F.3d 1125, 1132-33(D.C. Cir. 1994); Ciba-Geigy Corp. v. EPA, 801 F.2d 430, 436 (D.C. Cir.1986) ("Once the agency publicly articulates an unequivocal position. . . and expects regulated entities to alter their primary conduct to conformto that position, the agency has voluntarily relinquished the benefit ofpostponed judicial review"). In this case, "there is nothing tentativeabout the EPA's interpretation of [Subpart 2]; it is unambiguous and devoidof any suggestion that it might be subject to subsequent revision."Her Majesty the Queen ex rel. Ontario v. EPA, 912 F.2d 1525, 1532 (D.C.Cir. 1990); see also Final Rule: National Ambient Air Quality Standardsfor Ozone, 62 Fed. Reg. 38,856, 38,885/2 (1997) ("There is no languagein sections 181 or 182 that precludes the implementation of a different[ozone] standard under other authority [i.e., Subpart 1]; those provisions[i.e., Subpart 2] simply govern the implementation of the 1-hour, 0.12 ppmO3 standard"). Moreover, by promulgating a revised ozone NAAQS theEPA has triggered the provisions of §§ 107(d)(1) and 172, whichimpose a number of requirements upon the states, the first being that theGovernor of each state must determine which areas do not presently complywith the revised NAAQS; those areas that do not comply will ultimately berequired to do so. The EPA, therefore, has reached a final decision regardingits power to implement its revised ozone standard, which this court hasjurisdiction to review.5

The EPA also argues that the statements in its preamble regarding implementationare not "ripe for review," a point which it raised in a singlesentence in its original brief to this court. EPA Pet. at 19; EPA OzoneBrief at 74. The question whether Subpart 2 prevents the EPA from designatingan area as nonattainment under its revised ozone standard or from implementingthat designation except in conformity with Subpart 2 is a pure questionof law, the resolution of which would not benefit from a more concrete setting.As the agency's action is undoubtedly final, the question is fit for review.See Rio Grande Pipeline Co. v. FERC, 178 F.3d 533, 540-41 (D.C. Cir. 1999).

B. Subpart 2 and the EPA's Authority to Enforce a Revised Ozone Standard

The EPA's arguments in its petition for rehearing do not convince us thatwe erred in rejecting the EPA's contention that "the reference to §107(d)in §181(a)(1) relates only to designations made under § 107(d)(4),"175 F.3d at 1050, and in holding instead that "§ 181(a) clearlyencompasses nonattainment designations made under all subsections of §107(d)." Id. Indeed, we note that the EPA has abandoned its originalposition, arguing now that the "most logical reading" of §181(a) is that the reference to § 107(d) includes §§ 107(d)(1)(C)and 107(d)(4). EPA Pet. at 24. We find this new reading no more persuasivethan the old. As the EPA notes, all five Subparts of the Clean Air Act providingrequirements for nonattainment areas begin with a reference to § 107(d).See 42 U.S.C. §§ 7502(a)(1)(A), 7511(a)(1), 7512(a)(1), 7513(a),7514(a). It is by no means clear, however, that the references to §107(d) in Subparts 1 and 3 through 5 include only designations made under§§ 107(d)(1)(C) and (d)(4). Not only does the EPA never arguethat they are so limited, but on its theory the reference to § 107(d)in Subpart 1 also encompasses designations made under § 107(d)(1)(A).EPA Pet. at 25. Accordingly, we reject the EPA's new interpretation of §181(a), for it is contrary to "the normal rule of statutory constructionthat identical words used in different parts of the same act are intendedto have the same meaning." Gustafson v. Alloyd Co., 513 U.S. 561, 570(1995).

Still, the EPA does raise two points relating to Subpart 2 which lead usto grant the EPA's petition for rehearing in part and to make the followingrevisions to our opinion.

The EPA correctly points out that we erroneously treated the attainmentdates in the table in Subpart 2 as representing the Congress's judgmentabout what is "as expeditiously as practicable" in reducing thelevel of ozone in an area; in fact, those dates represent what the Congressset as outer limits. See 42 U.S.C. § 7511(a)(1) ("For each areaclassified under this subsection, the primary standard attainment date forozone shall be as expeditiously as practicable but not later than the dateprovided in table 1"). EPA Pet. at 25 n.35. Accordingly, we grant theEPA's petition for rehearing to the extent of deleting the final three sentencesof Part III.A.3, see 175 F.3d at 1051, and substituting for them the followingsentence:

Therefore, we conclude that Subpart 2 erects no bar to the EPA's requiringcompliance with a revised secondary ozone NAAQS "as expeditiously aspracticable."

The EPA also contends that the conclusion to Part III.A.2, see id. at 1050("the EPA must enforce any revised primary ozone NAAQS under Subpart2"), conflicts with our description of that same conclusion at theend of the opinion, see id. at 1057 (revised ozone NAAQS "cannot beenforced by virtue of [Subpart 2]"). We agree that the two sentencesare in tension. To clarify the matter, we grant the EPA's petition for rehearingto the extent of making the following two revisions to our original opinion.First, we replace the final paragraph of Part III.A.2, see id. at 1050,with the following:

In sum, because the reference to §107(d) in § 181(a)(1) includesthe designation of an area as nonattainment for ozone under a revised ozoneNAAQS, that is, under § 107(d)(1), the EPA can enforce a revised primaryozone NAAQS only in conformity with Subpart 2.

Second, we replace the second sentence of the Conclusion, see id. at 1057,with the following:

We do not vacate the new ozone standards because the parties have not shownthat the standard is likely to engender costly compliance activities inlight of our determination that it can be enforced only in conformity withSubpart 2.

As with the PM2.5 NAAQS, our decision not to vacate the ozone NAAQS "iswithout prejudice to the ability of any party to apply for vacatur in thefuture, should circumstances develop in which the presence of this standardthreatens a more imminent harm." American Trucking Ass'ns, Inc. v.EPA, No. 97-1440 (D.C. Cir. Jun. 18, 1999).

III. Beneficent Health Effects

The arguments in the EPA's petition for rehearing give us no reason to doubtthe correctness of our conclusion that "all identifiable effects,"as used in CAA §108(a)(2), "on its face . . . include[s] beneficenteffects." 175 F.3d at 1051. Nor do those arguments warrant considerationin a published opinion. We express no opinion, of course, upon the effect,if any, that studies showing the beneficial effects of tropospheric ozone,see id. at 1052, might have upon any ozone standard the EPA may promulgateon remand.

IV. Conclusion

For the above reasons, the EPA's petition for rehearing is

Granted in part and denied in part.

1 For particulate matter, counsel now statethat the EPA's decision was determined by the norm of "the 95 percentconfidence level to separate results that could be the product of chancefrom more convincing evidence of causation." EPA Pet. at 15. For ozone,counsel now state that EPA inferred the existence of effects below 0.08ppm, but nonetheless concluded that they were "less serious becausethey are 'transient and reversible.'" EPA Pet. at 16.

2 The court's opinion mentioned EPA's observation in the record that effectsof ozone concentrations below the standard selected were "transientand reversible," 175 F.3d at 1035, but only in connection with thedissent's suggestion, see id. at 1059, that this was the controlling principle.

3 We note that Judge Silberman's dissent from the denial of rehearing enbanc turns largely on his dim view of the Court's use of the non-delegationdoctrine in Benzene, which he characterizes as "only a makeweight,tossed into the analysis . . . to help justify the result." Whateverthe merits of Judge Silberman's critique of Benzene, we do not see how alower court can properly rest its jurisprudence on the rejection of a SupremeCourt decision.

4 The EPA has yet to designate an area nonattainment. Therefore, althoughthe agency does not so argue, if it were correct, then this court wouldalso lack jurisdiction to decide, as it did, that Subpart 2 does not alterthe agency's power to designate areas as nonattainment under a revised NAAQS.See 175 F.3d at 1047-48.

5 The EPA attempts to buttress its jurisdictional argument by referenceto 42 U.S.C. § 7502(a)(1)(B), which it claims "defers challengesto EPA's implementation decisions classifying areas for setting attainmentdates until EPA takes final action on a SIP . . . or triggers sanctions. . . [after] a state fails to submit a SIP." EPA Pet. at 19. The sectionto which the EPA refers states as follows: "The Administrator shallpublish a notice in the Federal Register announcing each [attainment ornonattainment] classification. . . . Such classification . . . shall notbe subject to judicial review until the Administrator takes final actionunder [the statutes the EPA cites in its petition]." That is, the EPA'sdecision to classify a particular area as attainment or nonattainment isnot subject to review merely because the EPA published that decision inthe Federal Register. Neither this section nor the analogous § 7511(a)(3),to which the EPA also cites, prevents a court from deciding, prior to theclassification of a particular area, whether the agency has validly promulgateda revised standard.

TATEL, Circuit Judge, concurring in part and dissenting in part:

I concur in the partial grant of rehearing with respect to enforcement ofthe revised ozone standard because, as modified, the opinion now leavesopen the possibility that EPA can enforce the new ozone NAAQS without conflictingwith Subpart 2's classifications and attainment dates. While I too thinkthat we have jurisdiction to decide the enforcement issue, I write separatelybecause I do not entirely agree with the rationale of the modified panelopinion.

The panel understood EPA's original position to be that, although Subpart2 limited the Agency's enforcement of the pre-existing one-hour 0.12 ppmozone NAAQS, it "has no effect upon the EPA's authority to enforcea revised primary ozone NAAQS." American Trucking Associations v. EPA,175 F.3d 1027, 1048 ("ATA"). That interpretation, the panel held,not only conflicted with section 7511(a)(1)'s text and legislative history,see id., 175 F.3d at 1048-49, but by leaving the Agency free to "requir[e]areas to comply either more quickly or with a more stringent ozone NAAQS,"it defied Congress's clear intent to "extend[ ] the time for nonattainmentareas to comply with the 0.12 ppm ozone NAAQS." Id. at 1049.

Having rejected the Agency's interpretation, the panel went on to agreewith petitioners that Subpart 2 embodies "a comprehensive enforcement

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