UNITED STATES COURT OF APPEALS FOR THE D.C. CIRCUIT


AMER TRK ASSN INC

v.

EPA


97-1440a

D.C. Cir. 1999


*	*	*


Opinion for the Court filed PER CURIAM.1


Separate opinion dissenting from Part I filed by Circuit  Judge


PER CURIAM:


Introduction


The Clean Air Act requires EPA to promulgate and period- ically revise
national ambient air quality standards  


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n


1Judge Williams wrote Parts I and III.B; Judge Ginsburg wrote  Parts
II, III.A, and IV.D; Judge Tatel wrote Parts IV.A-C. 


("NAAQS") for each air pollutant identified by the agency as  meeting
certain statutory criteria. See Clean Air Act  ss 108-09, 42 U.S.C. ss
7408-09. For each pollutant, EPA  sets a "primary standard"--a
concentration level "requisite to  protect the public health" with an
"adequate margin of safe- ty"--and a "secondary standard"--a level
"requisite to pro- tect the public welfare." Id. s 7409(b).


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


In Part I we find that the construction of the Clean Air Act  on which
EPA relied in promulgating the NAAQS at issue  here effects an
unconstitutional delegation of legislative pow- er. See U.S. Const.
art. I, s 1 ("All legislative powers herein  granted shall be vested
in a Congress of the United States.").  We remand the cases for EPA to
develop a construction of  the act that satisfies this constitutional
requirement.


In Part II we reject the following claims: that s 109(d) of  the Act
allows EPA to consider costs; that EPA should have  considered the
environmental damage likely to result from  the NAAQS' financial
impact on the Abandoned Mine Recla- mation Fund; that the NAAQS
revisions violated the Nation- al Environmental Policy Act ("NEPA"),
Unfunded Mandates  Reform Act ("UMRA"), and Regulatory Flexibility Act


In Part III we decide two ozone-specific statutory issues,  holding
that the 1990 revisions to the Clean Air Act limit  EPA's ability to
enforce new ozone 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
agree with petitioners that EPA's choice of  PM10 as the indicator for
coarse particulate matter was  arbitrary and capricious; we reject
petitioners' claims that  EPA must treat PM2.5 as a "new pollutant,"
that EPA must  identify a biological mechanism explaining PM's harmful
ef- fects, and that the Clean Air Act requires secondary NAAQS  to be
set at levels that eliminate all adverse visibility effects.


The remaining issues cannot be resolved until such time as  EPA may
develop a constitutional construction of the act  (and, if
appropriate, modify the disputed NAAQS in accor- dance with that


I. Delegation


Certain "Small Business Petitioners" argue in each case  that EPA has
construed ss 108 & 109 of the Clean Air Act so  loosely as to render
them unconstitutional delegations of  legislative power. We agree.
Although the factors EPA  uses in determining the degree of public
health concern  associated with different levels of ozone and PM are
reason- able, EPA appears to have articulated no "intelligible princi-
ple" to channel its application of these factors; nor is one  apparent
from the statute. The nondelegation doctrine re- quires such a
principle. See J.W. Hampton, Jr. & Co. v.  United States, 276 U.S.
394, 409 (1928). Here it is as though  Congress commanded EPA to
select "big guys," and EPA  announced that it would evaluate
candidates based on height  and weight, but revealed no cut-off point.
The announce- ment, though sensible in what it does say, is fatally
incom- plete. The reasonable person responds, "How tall? How 


EPA regards ozone definitely, and PM likely, as non- threshold
pollutants, i.e., ones that have some possibility of  some adverse
health impact (however slight) 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's 


judgment, to identify [an ozone concentration] level at which  it can
be concluded with confidence that no 'adverse' effects  are likely to
occur."); National Ambient Air Quality Stan- dards for Ozone and
Particulate Matter, 61 Fed. Reg. 65,637,  65,651/3 (1996) (proposed
rule) ("[T]he single most important  factor influencing the
uncertainty associated with the risk  estimates is whether or not a
threshold concentration exists  below which PM-associated health risks
are not likely to  occur."). For convenience, we refer to both as
non-threshold  pollutants; the indeterminacy of PM's status 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 that EPA must set each standard at  the level
"requisite to protect the public health" with an  "adequate margin of
safety." 42 U.S.C. s 7409(b)(1). These  are also the criteria by which
EPA must determine whether a  revision to existing NAAQS is
appropriate. See 42 U.S.C.  s 7409(d)(1) (EPA shall "promulgate such
new standards as  may be appropriate in accordance with ... [s
7409(b)]"); see  also infra Part II.A. For EPA to pick any non-zero
level it  must explain the degree of imperfection permitted. The 
factors that EPA has elected to examine for this purpose in 
themselves pose no inherent nondelegation problem. But  what EPA lacks
is any determinate criterion for drawing  lines. It has failed to


We begin with the criteria EPA has announced for assess- ing health
effects in setting the NAAQS for non-threshold  pollutants.1 They are
"the nature and severity of the health 




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n


1Technically, EPA describes the criteria as used only for  setting the
"adequate margin of safety." There might be thought  to be a separate
step in which EPA determines what standard  would protect public
health without any margin 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, 902 F.2d 963, 


effects involved, the size of the sensitive population(s) at risk,  the
types of health information available, and the kind and  degree of
uncertainties that must be addressed." Ozone  Final Rule, 62 Fed. Reg.
at 38,883/2; EPA, "Review of the  National Ambient Air Quality
Standards for Particulate Mat- ter: Policy Assessment of Scientific
and Technical Informa- tion: OAQPS Staff Paper," at II-2 (July 1996)
("PM Staff  Paper") (listing same factors). Although these criteria,
so  stated, are a bit vague, they do focus the inquiry on pollu-
tion's effects on public health. And most of the vagueness in  the
abstract formulation melts away as EPA applies the  criteria: EPA
basically considers severity of effect, certainty  of effect, and size
of population affected. These criteria, long  ago approved by the
judiciary, see Lead Industries Ass'n v.  EPA, 647 F.2d 1130, 1161
(D.C. Cir. 1980) ("Lead Indus- tries"), do not themselves speak to the


Read in light of these factors, EPA's explanations for its  decisions
amount to assertions that a less stringent standard  would allow the
relevant pollutant to inflict a greater quan- tum of harm on public
health, and that a more stringent  standard would result in less harm.
Such arguments only  support the intuitive proposition that more
pollution will not  benefit public health, not that keeping pollution
at or below  any particular level is "requisite" or not requisite to
"protect  the public health" with an "adequate margin of safety," the 
formula set out by s 109(b)(1).


Consider EPA's defense of the 0.08 ppm level of the ozone  NAAQS. EPA
explains that its choice is superior to retain- ing the existing
level, 0.09 ppm, because more people are  exposed to more serious
effects at 0.09 than at 0.08. See  Ozone Final Rule, 62 Fed. Reg. at
38,868/1. In defending the  decision not to go down to 0.07, EPA never
contradicts the  intuitive proposition, confirmed by data in its Staff
Paper,  that reducing the standard to that level would bring about 
comparable changes. See EPA, "Review of National Ambient  Air Quality
Standards for Ozone: Assessment of Scientific 




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n 973 (D.C. Cir. 1990). Thus, the criteria mentioned in the text 
govern the whole standard-setting process. 


and Technical Information: OAQPS Staff Paper," at 156  (June 1996)
("Ozone Staff Paper"). Instead, it gives three  other reasons. The
principal substantive one is based on the  criteria just discussed:


The most certain O3-related effects, while judged to be  adverse, are
transient and reversible (particularly at O3  exposures below 0.08
ppm), and the more serious effects  with greater immediate and
potential long-term impacts  on health are less certain, both as to
the percentage of  individuals exposed to various concentrations who
are  likely to experience such effects and as 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
levels of exposure. This seems to be nothing more  than a statement
that lower exposure levels are associated  with lower risk to public
health. The dissent argues that in  setting the standard at 0.08, EPA
relied on evidence that  health effects occurring below that level are
"transient and  reversible," Dissent at 5, evidently assuming that
those at  higher levels are not. But the EPA language quoted above 
does not make the categorical distinction the dissent says it  does,
and it is far from apparent that any health effects  existing above
the level are permanent or irreversible.


In addition to the assertion quoted above, EPA cited the  consensus of
the Clean Air Scientific Advisory Committee  ("CASAC") that the
standard should not be set below 0.08.  That body gave no specific
reasons for its recommendations,  so the appeal to its authority, also
made in defense of other  standards in the PM Final Rule, see PM Final
Rule, 62 Fed.  Reg. at 38,677/2 (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 dissent stresses the 
undisputed eminence of CASAC's members, Dissent at 4, but  the
question whether EPA acted pursuant to lawfully delegat- ed authority
is not a scientific one. Nothing in what CASAC  says helps us discern
an intelligible principle derived by EPA  from the Clean Air Act.


Finally, EPA argued that a 0.07 standard would be "closer  to peak
background levels that infrequently occur in some  areas due to
nonanthropogenic sources of O3 precursors, and  thus more likely to be
inappropriately targeted in some 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 back- ground observation fell between 0.07 and 0.08, and says
that  EPA's decision "ensured that if a region surpasses the 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 backhanded way of saying that, given  the national character
of the NAAQS, it is inappropriate to  set a standard below a level
that can be achieved throughout  the country without action
affirmatively extracting chemicals  from nature. That may well be a
sound reading of the  statute, but EPA has not explicitly adopted


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


The arguments EPA offers here show only that EPA is  applying the
stated factors and that larger public health  harms (including
increased probability of such harms) are, as  expected, associated
with higher pollutant concentrations.  The principle EPA invokes for
each increment in stringency 


(such as for adopting the annual coarse particulate matter  standard
that it chose here)--that it is "possible, but not  certain" that
health effects exist at that 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  indeterminacy prevails in EPA's
decisions not to pick a still  more stringent level. For example,
EPA's reasons for not  lowering the ozone standard from 0.08 to 0.07
ppm--that "the  more serious effects ... are less certain" at the
lower levels  and that the lower levels are "closer to peak background
 levels," see Ozone Final Rule, 62 Fed. Reg. at 38,868/2--could  also
be employed to justify a refusal to reduce levels below  those
associated with London's "Killer Fog" of 1952. In that  calamity, very
high PM levels (up to 2,500 Sg/m3) are believed  to have led to 4,000
excess deaths in a week.3 Thus, the  agency rightly recognizes that
the question is one of degree,  but offers no intelligible principle
by which to identify a  stopping point.


The latitude EPA claims here seems even broader than  that OSHA
asserted in International Union, UAW v. OSHA  ("Lockout/Tagout I"),
938 F.2d 1310, 1317 (D.C. Cir. 1991),  which was to set a standard
that would reduce a substantial  risk and that was not infeasible. In
that case, OSHA thought  itself free either to "do nothing at all" or
to "require precau- tions that take the industry to the brink of
ruin," with "all  positions in between ... evidently equally valid."
Id. Here,  EPA's freedom of movement between the poles is equally 
unconstrained, but the poles are even farther apart--the  maximum
stringency would send industry not just to the 




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2EPA did cite qualitative evidence for further support for its  annual
standard, and argued that the evidence "does not provide  evidence of
effects below the range of 40-50 Sg/m3," the standard  level. PM Final
Rule, 62 Fed. Reg. at 38,678/3. The referenced  document, however,
bears no indication that the qualitative evidence  demonstrates
effects at the level of the standard, either. See EPA,  "Air Quality
Criteria for Particulate Matter," at 13-79 (April 1996). 


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


brink of ruin but hurtling over it, while the minimum strin- gency may
be close to doing nothing at all.


In Lockout/Tagout I certain special conditions that have  justified an
exceptionally relaxed application of the nondele- gation doctrine were
absent, id. at 1317-18, and they are  equally absent here. The
standards in question affect the  whole economy, requiring a "more
precise" delegation than  would otherwise be the case, see A.L.A.
Schechter Poultry  Corp. v. United States, 295 U.S. 495, 553 (1935).
No "special  theories" justifying vague delegation such as the war
powers  of the President or the sovereign attributes of the delegatee 
have been or could be asserted. Nor is there some inherent 
characteristic of 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
uncertainty about the health effects of concentrations  of a
particular pollutant within a particular range, EPA may  use its
discretion to make the "policy judgment" to set the  standards at one
point within the relevant range rather than  another. NRDC v. EPA, 902
F.2d 962, 969 (D.C. Cir. 1990);  American Petroleum 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 addressed
the  claim of undue delegation that we face here, and accordingly  had
no occasion to ask EPA for coherence (for a "principle,"  to use the
classic term) in making its "policy judgment." The  latter phrase is
not, after all, a self-sufficient justification for  every refusal to


It was suggested at oral argument that EPA's vision of its  discretion
in application of s 109(b)(1) is no broader than that  asserted by
OSHA after 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 some- where between maximum feasible stringency and
some "mod- erate" departure from 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 any point between  zero and
a hair below the concentrations yielding London's  Killer Fog.


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


Where (as here) statutory language and an existing agency 
interpretation involve an unconstitutional delegation of power,  but
an interpretation without the constitutional weakness is  or may be
available, our response is not to strike down the  statute but to give
the agency an opportunity to extract a  determinate standard on its
own. Lockout/Tagout I, 938 F.2d  at 1313. Doing so serves at least two
of three basic rationales  for the nondelegation doctrine. If the
agency develops deter- minate, binding standards for itself, it is
less likely to exercise  the delegated authority arbitrarily. See
Amalgamated Meat  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 that meaningful judicial review will
 prove feasible. See id. at 759. A remand of this sort of  course does
not serve the third key function of non-delegation  doctrine, to
"ensure[ ] to the extent consistent with orderly  governmental
administration 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
agency  will make the fundamental policy choices. But the remand  does
ensure that the courts not hold unconstitutional a statute 


that an agency, with the application of its special expertise,  could
salvage. In any event, we do not read current Supreme  Court cases as
applying the strong form of the nondelegation  doctrine voiced in
Justice Rehnquist's concurrence. See Mis- tretta v. United States, 488
U.S. 361, 377-79 (1989).


What sorts of "intelligible principles" might EPA adopt?  Cost-benefit
analysis, 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 s 109(b)(1) as barring  EPA from considering any factor other
than "health effects  relating to pollutants in the air." NRDC, 902
F.2d at 973;  see also Lead Industries, 647 F.2d at 1148; American
Lung  Ass'n v. EPA, 134 F.3d 388, 389 (D.C. Cir. 1998); American 
Petroleum Inst., 665 F.2d at 1185 (echoing the same themes).


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


EPA's past behavior suggests some readiness to adopt  standards that
leave non-zero residual risk. For example, it  has employed commonly
used clinical criteria to determine  what qualifies as an adverse
health effect. See Ozone Staff  


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4A zero-risk policy might seem to imply de-industrialization,  but in
fact even that seems inadequate to the task (and even if the  calculus
is confined to direct risks from pollutants, as opposed to  risks from
the concomitant poverty). First, PM (at least) results  from almost
all combustion, so only total prohibition of fire or  universal
application of some heretofore unknown control technolo- gy would
reduce manmade emissions to zero. See PM Staff Paper  at IV-1. Second,
the combustion associated with pastoral life  appears to be rather
deadly. See World Bank, World Development  Report 1992: Development
and 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 smoke
from biomass burning "contributes to  acute respiratory infections
that cause an estimated 4 million deaths  annually among infants and


Paper at 59-60 (using American Thoracic Society standards  to
determine threshold for "adverse health effect" from  ozone). On the
issue of likelihood, for some purposes it might  be appropriate to use
standards drawn from other areas of  the law, such as the familiar
"more probable than not"  criterion.


Of course a one-size-fits-all criterion of probability would  make
little sense. There is no reason why the same probabil- ity should
govern assessments of a risk of thousands of  deaths as against risks
of a handful of people suffering  momentary shortness of breath. More
generally, all the  relevant variables seem to range continuously from
high to  low: the possible effects of pollutants vary from death to 
trivialities, and the size of the affected population, the proba-
bility of an effect, and the associated uncertainty range from 
"large" numbers of persons with point estimates of high  probability,
to small numbers and vague ranges of probabili- ty. This does not seem
insurmountable. Everyday life com- pels us all to make decisions
balancing remote but severe  harms against a probability distribution
of benefits; people  decide whether to proceed with an operation that
carries a  1/1000 possibility of death, and (simplifying) a 90% chance
of  cure and a 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 effort at coherence under  s
109(b)(1) would need to be more comprehensive. For  example, a range
of ailments short of death might need to be  assigned weights.
Nonetheless, an agency wielding the pow- er over American life
possessed by EPA should be capable of  developing the rough equivalent
of a generic unit of harm  that takes into account population
affected, severity and  probability. Possible building blocks for such
a principled  structure might be found in the approach Oregon used in 
devising its health plan for the poor. In determining what  conditions
would be eligible for treatment under its version of  Medicaid, Oregon
ranked treatments by the amount of im- provement in "Quality-Adjusted


treatment, divided by the cost of the treatment.5 Here, of course, EPA
may not consider cost, and indeed may well find  


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n


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


Oregon was twice forced to revise its system because the United  States
Department of Health & Human Services determined that  the original
proposal and a revision violated the Americans with  Disabilities Act,
42 U.S.C. ss 12101-12213. The reason given for  this determination was
that both versions undervalued the lives of  persons with
disabilities: The original plan measured quality of life  according to
the attitudes of the general population rather than the  attitudes of
persons with disabilities. See HHS, "Analysis Under  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 disabling conditions were consid- ered
"symptoms." See Letter from Timothy B. Flanagan, Assistant  Attorney
General, to Susan K. Zagame, Acting General Counsel,  HHS (Jan. 19,
1993), reprinted in 9 Issues in L. & Med. 397, 418,  421 (1994). The
Department's determination was extensively criti- cized when issued.
See Maxwell J. Mehlman et al., "When Do  Health Care Decisions
Discriminate Against Persons with Disabili- ties?" 22 J. Of Health
Politics, Policy & L. 1385, 1390 (1997)  (HHS's "decision provoked a


We take no position on whether HHS's view was correct, or if the 
underlying norm also governs EPA's decisions under s 109(b)(1).  An
affirmative answer, however, would not seem to preclude use of  some
of Oregon's approach. The first step would be giving appro- priate
weight to the views of persons with disabilities. The second  might be
measuring the seriousness of a pollution-induced health  effect by the
absolute level of well-being that the effect brings  about, 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
asthma constitutes a disability has a well-being of  80 in the absence
of air pollution (according to a measure that  appropriately considers
asthmatics' own assessments of their condi-


a completely different method for securing reasonable coher- ence.
Alternatively, if EPA concludes that there is no princi- ple
available, it can so report to the Congress, along with such 
rationales as it has for the levels it chose, and seek legislation 


We have discussed only the primary standards. Because  the secondary
standards are at least in part based on those,  see Ozone Final Rule,
62 Fed. Reg. at 38,875/3-76/1; PM  Final Rule, 62 Fed. Reg. at
38,680/3, we also remand the  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 erroneous- ly failed to
consider a host of factors in revising the PM and  ozone NAAQS. We
reject each of these claims in turn.


A.Consideration of Cost in Revising Standards As this court long ago
made clear, in setting NAAQS under  s 109(b) of the Clean Air Act, the
EPA is not permitted to  consider the cost of implementing those
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  particulate matter NAAQS); American Petroleum Inst., 665 
F.2d at 1185 (same, in reviewing ozone NAAQS). The peti- tioners make
four unsuccessful attempts to distinguish Lead  Industries and its


First, the petitioners claim that in Lead Industries we held  only that
the Clean Air Act does not compel the EPA to  consider the costs of
implementation in setting a NAAQS; on  the contrary, we held that the
Act precludes the EPA from  doing so. See Lead Industries, 647 F.2d at
1148 ("the statute  


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n tion), then a response to air pollution that reduces the asthmatics' 
well-being to 70 could be counted as an effect of magnitude 30 (the 
difference from full health), rather than 10 (the difference from the 
level without the pollution). That approach would ensure that  effects
on persons with disabilities were not underestimated, even in  the
broad sense of that term apparently adopted by HHS. 


and its legislative history make clear that economic consider- ations
play no part in the promulgation of [NAAQS]").


Second, that we decided Lead Industries prior to the  Supreme Court's
decision in Chevron U.S.A. Inc. v. NRDC,  467 U.S. 837 (1984) does
not, as the petitioners suggest,  require us to revisit the earlier
case. The Lead Industries  decision was made in Chevron step one
terms, see id., as the  post-Chevron progeny of Lead Industries have
made clear.  See NRDC, 902 F.2d at 973 ("Consideration of costs ... 
would be flatly inconsistent with the statute, legislative histo- ry
and case law on this point"); NRDC v. EPA, 824 F.2d  1146, 1158C59
(D.C. Cir. 1987) (in banc) ("Vinyl Chloride")  ("[S]tatute on its face
does not allow consideration of techno- logical or economic
feasibility.... Congress considered the  alternatives and chose to
close down sources or even indus- tries rather than to allow risks to


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


complete a thorough review of the criteria published  under section
7408 of this title and the [NAAQS] promul- gated under this section
and [to] make such revisions in  such criteria and standards and
promulgate such new  standards as may be appropriate in accordance
with  section 7408 of this title and subsection (b) of this section.


42 U.S.C. s 7409(d)(1). The petitioners contend that consid- eration of
costs is one pertinent factor in determining wheth- er revision of a
NAAQS is "appropriate," but this argument  ignores the clause
immediately following "appropriate," which  incorporates s 109(b) and
thereby affirmatively precludes  consideration of costs in revising
NAAQS. Section 108(b), 42  U.S.C. s 7408(b), does require the EPA to
provide the States  with information on the cost of implementing
NAAQS, but the  reference to s 108 does not permit consideration of
costs in  setting NAAQS because it clearly relates back to the


ment that the EPA "make ... revisions in ["the criteria  published
under section 7408"] ... as may be appropriate."  And insofar as the
air quality criteria do apply to the setting  of NAAQS, they do so
through s 109(b), which (again) pre- cludes the consideration of costs
and which is explicitly  incorporated into s 109(d)(1). See id. s
7409(b)(1) (primary  NAAQS to be "based on [the air quality] criteria"
issued  under s 108).


Fourth, the petitioners point to s 109(d)(2), which creates  the CASAC
and requires it to advise the EPA about, among  other things, "any
adverse public health, welfare, social, eco- nomic, or energy effects
which may result from various  strategies for attainment and
maintenance of such [NAAQS]."  Id. s 7409(d)(2)(C)(iv). Why, ask the
petitioners, would the  CASAC be required to advise the EPA about
these matters if  the EPA were not then supposed to consider its
advice in the  course of revising the NAAQS? As above, however, the 
petitioners overlook that s 109(d)(1) directs the EPA to re- view and
to revise, as appropriate, the air quality standards  issued under s
108 as well as the NAAQS promulgated under  s 109(b). The advice
required in s 109(d)(2)(C)(iv) is perti- nent only to the EPA's duty
under s 108 to provide the  States with control strategy


B.Environmental Consequences of Implementing  NAAQS


The State Petitioners argue that the EPA erred in failing  "to consider
the environmental consequences resulting from  the financial impact of
the [revised PM2.5 and ozone NAAQS]  on the federal Abandoned Mine
Reclamation Fund Act."  This argument is squarely foreclosed by our
decision in  NRDC. In reviewing the EPA's previous revision of the PM 
NAAQS, we rejected the argument that the EPA "erred in  refusing to
consider the health consequences of unemploy- ment in determining the
primary [NAAQS] for particulate  matter" and held that "[i]t is only
health effects relating to  pollutants in the air that EPA may
consider." 902 F.2d at  972-73 (emphasis in original). Unlike the
positive health  benefits of ozone that we hold (in Part III.B, below)


must consider, any detrimental health effects resulting from  the
financial impact upon the mine fund, like the health  consequences of
unemployment, are traceable to the cost of  complying with the revised
PM2.5 and ozone NAAQS and not  to the presence of those pollutants in
the air.


C.The National Environmental Policy Act


In challenging both the revised PM2.5 and ozone NAAQS,  the State
Petitioners also argue that the EPA failed to  comply with certain
requirements of the NEPA. The peti- tioners recognize that the
Congress has exempted all actions  under the Clean Air Act, including
the setting of NAAQS,  from the central requirement of the NEPA,
namely, the  preparation of an Environmental Impact Statement. Com-
pare 42 U.S.C. s 4332(2)(C)-(D) (agency must prepare EIS  in all
"major Federal actions significantly affecting the quality  of the
human environment"), with 15 U.S.C. s 793(c)(1) ("No  action taken
under the Clean Air Act shall be deemed a major  Federal action
significantly affecting the quality of the human  environment within
the meaning of the [NEPA]"). Nonethe- less, they suggest that the EPA
is required to complete the  functional equivalent of an EIS and also
to comply with other  requirements in the NEPA, see 42 U.S.C. s
4332(2)(B), (E),  (G). State Petitioners' PM Brief at 20; State
Petitioners'  Ozone Brief at 19. We reject each of these


First, the State Petitioners contend that this court has  "recognized
that the '[CAA], properly construed, requires the  functional
equivalent of 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  petitioners misrepresent our interpretation of a single
section  of the Clean Air Act, dealing with emission standards for 
stationary sources, as an interpretation of the entire Act.  Even if
the petitioners were correct, however, Portland Ce-


ment predated, and is now superseded by, the statutory  exemption in 15
U.S.C. s 793(c)(1), which the Congress added  in 1974.


Second, the State Petitioners contend that a provision of  the NEPA
"requires that EPA weigh 'economic consider- ations.' " The section to
which the petitioners refer reads as  follows: "all agencies of the
Federal Government shall ...  identify and develop methods and
procedures ... which will  insure that presently unquantified
environmental amenities  and values may be given appropriate
consideration in deci- sionmaking along with economic and technical
consider- ations." 42 U.S.C. s 4332(2)(B). Even if this section is 
properly read generally to require an agency to consider 
implementation costs, s 109(d)(1) specifically prohibits the  EPA from
doing so. And the NEPA provides that it shall not  "in any way affect
the specific statutory obligations of any  Federal agency ... to
comply with criteria or standards of  environmental quality." 42
U.S.C. s 4334(1). Therefore,  s 4332(2)(B) cannot require the EPA to
disregard the prohi- bition in s 109(d)(1) upon the consideration of


The State Petitioners' remaining arguments--that the EPA  failed to
comply with two other sections of the NEPA--fare  little better.
Section 4332(2)(E) requires federal agencies to  "study, develop, and
describe appropriate alternatives to rec- ommended courses of action
in any proposal which involves  unresolved conflicts concerning
alternative uses of available  resources." As with s 4332(2)(B),
insofar as s 4332(2)(E) can  be read to require the EPA to consider
the costs of imple- menting NAAQS when revising those standards,
contrary to  the prohibition in s 109(d)(1), s 4334(1) prevents it


If, on the other hand, s 4332(2)(E) is understood in the  context of
the Clean Air Act to require the EPA merely to  discuss implementation
alternatives, then it, like the similar  s 4332(2)(G) with which the
petitioners also claim the EPA  failed to comply, is the functional
equivalent of s 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 alternative methods of prevention and control  of air
pollution." As we recognize with regard to the require- ment that the
agency prepare an EIS, "[c]ompliance with  NEPA's ... requirement[s]
has not been considered neces- sary when the agency's organic
legislation mandates proce- dures for considering the environment that
are 'functional  equivalents' of the [NEPA's] process." Izaak Walton
League  of Am. v. Marsh, 655 F.2d 346, 367 n.51 (1981). The rationale 
for the functional equivalence doctrine is the well-established 
principle that a "general statutory rule usually does not  govern
unless there is no more specific rule." Green v. Bock  Laundry Mach.
Co., 490 U.S. 504, 524 (1989); see also  Alabama ex rel. Siegelman v.
EPA, 911 F.2d 499, 504-05  (11th Cir. 1990) (citing cases). The NEPA
is the general  statute requiring agencies to consider environmental
harms,  whereas the Clean Air Act is the more specific and its 
equivalent provisions apply in place of those in the NEPA.  See
Portland Cement, 486 F.2d at 386 (finding functional  equivalence when
more specific statute strikes "workable  balance between some of the
advantages and disadvantages of  full application of NEPA").


Our analysis of the petitioners' contentions leads us to  conclude that
nothing in the NEPA requires the EPA in  setting NAAQS to consider or
to discuss matters 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
Bliley in the ozone case both contend that the  EPA is required by the
Unfunded Mandates Reform Act, 2  U.S.C. s 1501 et seq., to prepare a
Regulatory Impact State- ment (RIS) when setting a NAAQS, see id. s
1532, and to  choose the least burdensome from a range of alternative 
permissible NAAQS, see id. s 1535. Even if the petitioners  and the
amicus are correct regarding the interaction of the  UMRA and the
CAA--a point the EPA strongly contests-- we can provide them with no
relief. See id. s 1571(a)(3)  ("[T]he inadequacy or failure to prepare
[a RIS] ... shall not  be used as a basis for staying, enjoining,
invalidating or 


otherwise affecting [an] agency rule"); id. s 1571(b) ("Except  as
provided in [s 1571(a), which does not mention s 1535,]  ... any
compliance or noncompliance with the provisions of  this chapter ...
shall not be subject to judicial review; 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
review in s 1571, contend that the EPA's failure to  prepare a RIS can
nonetheless render the NAAQS arbitrary  and capricious, see 42 U.S.C.
s 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 RIS be included in the record for judicial 
review and precluded judicial review of an agency's compli- ance with
the RIS requirement. We held that a "reviewing  court will consider
the contents of the [RIS], along with the  rest of the record, in
assessing not the agency's compliance  with the [requirement to
prepare the RIS], but the validity of  the rule under other provisions
of law." Id. at 405. No  information in a RIS, however, could lead us
to conclude that  the EPA improperly set the PM and ozone NAAQS; the
only  information such a statement would add to the rulemaking  record
for a NAAQS would pertain to the costs of implemen- tation, see 2
U.S.C. s 1532(a), and the EPA is 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
Petitioners argue that the EPA improperly certified  that the revised
NAAQS would not have a significant impact  upon a substantial number
of small entities. The Regulatory  Flexibility Act, 5 U.S.C. s 601 et
seq., as amended in 1996 by  the Small Business Regulatory Enforcement
Fairness Act,  Pub. L. No. 104-121, tit. II, 110 Stat. 857-74
("SBREFA"),  requires an agency, when engaging in notice and comment 
rulemaking, to "prepare and make available for public com- ment an
initial regulatory flexibility analysis.... [that] de-


scribe[s] the impact of the proposed rule on small entities," 5  U.S.C.
s 603(a), including small businesses, small organiza- tions, and small
governmental jurisdictions, see id. s 601(6).  When promulgating a
final rule, an agency must describe "the  steps ... taken to minimize
the significant economic impact  on small entities." Id. s 604(a)(5).
According to the petition- ers, if the EPA had complied with the RFA,
it would likely  have promulgated less stringent PM and ozone NAAQS
than  those actually chosen, 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
significant economic impact on a substantial number of  small
entities." Id. s 605(b). Further, the SBREFA made  no change in the
requirement that a regulatory flexibility  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 the requirement." 5 U.S.C. s
603(b)(3)-(4). We  have consistently interpreted the RFA, based upon
these  sections, to impose no obligation upon an agency "to conduct  a
small entity impact analysis of effects on entities which it  does not
regulate." Motor & Equip. Mfrs. Ass'n v. Nichols,  142 F.3d 449, 467 &


The EPA certified that its revised NAAQS will "not have a  significant
economic impact on small entities within the mean- ing of the RFA." PM
Final Rule, 62 Fed. Reg. at 38,702/2;  Ozone Final Rule, 62 Fed. Reg.
at 38,887/2-3. According to  the EPA, the NAAQS themselves impose no
regulations upon  small entities. Instead, the several States regulate
small  entities through the state implementation plans (SIPs) that 
they are required by the Clean Air Act to develop. See 42  U.S.C. s
7410. Because the NAAQS therefore regulate small  entities only
indirectly--that is, insofar as they affect the  planning decisions of
the States--the EPA concluded that  small entities are not "subject to
the proposed regulation."  See Mid-Tex Elec. Coop., Inc. v. FERC, 773
F.2d 327, 342  (D.C. Cir. 1985); see also id. at 343 ("Congress did
not intend  to require that every agency consider every indirect


that any regulation might have on small businesses in any  stratum of
the national economy.").


The EPA's description of the relationship between NAAQS,  SIPs, and
small entities strikes us as incontestable. The  States have broad
discretion in determining the manner in  which they will achieve
compliance with the NAAQS. The  EPA "is required to approve a state
plan which provides for  the timely attainment and subsequent
maintenance of am- bient air standards" and cannot reject a SIP based
upon its  view of "the wisdom of a State's choices of emission limita-
tions," 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 State may, if it
chooses, avoid imposing upon small entities  any of the burdens of
complying with a revised NAAQS.  Only if a State does not submit a SIP
that complies with  s 110, 42 U.S.C. s 7410, must the EPA adopt an
implementa- tion plan of its own, which would require the EPA to
decide  what burdens small entities should bear. The agency has 
stated, however, that it will do a regulatory flexibility analysis 
before adopting an implementation plan 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. Reg. at 38,705/3.


The responses of the Small Business Petitioners do not  persuade us to
reject the 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 the Small  Business Administration's interpretation
of the Act, as ex- pressed in a letter to the EPA from the SBA's Chief
Counsel  for Advocacy, that the NAAQS do impose requirements upon 
small entities. The SBA, however, neither administers nor  has any
policymaking role under the RFA; at most its role is  advisory. See,
e.g., 5 U.S.C. ss 601(3), 602(b), 603(a), 605(b),  609(b)(1), 612.
Therefore, we do not defer to the SBA's  interpretation of the 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 agency  interpretation of statute it does not administer). Nor


defer to the EPA'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
both that the NAAQS will have no effect upon  small entities and that
it will have positive health effects.  Clearly, however, the EPA can
maintain that the NAAQS will  have health effects because the Clean
Air Act empowers the  agency to ensure that such benefits accrue; and
it can  maintain that the NAAQS will not directly affect small enti-
ties because it has no authority (short of imposing its own 
implementation plan upon a non-complying state) to impose  any burdens
upon such entities.


Third, the Small Business Petitioners attempt to distin- guish the
possible effects upon small entities in this case from  the indirect
effects that, as we found in Mid-Tex, are not  within the
contemplation of the RFA. But Mid-Tex is not so  easily distinguished.
The petitioners in that case argued that  the RFA required the FERC to
consider economic effects not  only upon regulated industries but also
upon the small enti- ties that are their wholesale customers, even
though the  customers were not directly regulated by the FERC. We 
rejected that argument, finding a "clear indication" in the  language
of s 603 that the RFA is "limited to small entities  subject to the
proposed 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
distinguishes between small entities  subject to an agency rule, to
which its requirements apply,  and those not subject to the rule, to
which the requirements  do not apply."); United Distribution Cos. v.
FERC, 88 F.3d  1105, 1170 (1996) (regulatory flexibility analysis
provision  applies only to "small entities that are subject to the
require- ments of the rule") (emphasis in original). That the Clean 
Air Act requires the States to submit SIPs that will achieve 
compliance with the NAAQS does not, in view of the States'  nearly
complete discretion to determine which entities will  bear the burdens
of a revised NAAQS, make such small  entities as the SIPs may regulate


EPA's regulation than were the wholesalers in Mid-Tex  subject to
regulation by the FERC.


Finally, the Small Business Petitioners suggest that the  Congress in
enacting the SBREFA overruled our prior inter- pretation of the RFA in
Mid-Tex and its progeny. The  SBREFA made a number of changes in the
RFA, but it did  not change anything in s 603 upon which we relied in
Mid- Tex. And although the Congress made a slight modification  in s
605(b), we do not understand it to alter our analysis in  Mid-Tex.
Prior to 1996, s 605(b) required an agency to  provide "a succinct
statement explaining the reasons" for its  certification that the
promulgated rule would not have a  significant economic impact upon
small entities. That section  now requires "a statement providing the
factual basis for such  certification." Our decision in Mid-Tex
contemplates that an  agency may justify its certification under the
RFA upon the  "factual basis" that the rule does not directly regulate
any  small entities. Nothing in the change to s 605(b) suggests  that
basis for certification is no longer permissible. (Indeed,  the
section of the statute amending s 605(b) is labeled "Tech- nical and
Conforming Amendments," see SBREFA s 243, 110  Stat. at 866.) We
therefore conclude that the EPA properly  certified that its NAAQS
would not have a significant impact  upon a substantial number of


III. Ozone


A.Subpart 2 and the Revised Ozone Standard


In 1990 the Congress substantially revised the Clean Air  Act by, among
other things, adding specific enforcement  provisions for carbon
monoxide, particulate matter, sulfur  oxides, nitrogen dioxide, lead,
and as pertinent here, ozone.  Previously, the Act required that all
areas of the country not  attaining the primary ozone standard, no
matter how far from  attainment, come into compliance "as
expeditiously as practi- cable but not later than December 31, 1987."
42 U.S.C.  s 7502 (1988). Many areas had not attained the primary 
ozone NAAQS by that date; some were still a long way from 


doing so. The Congress responded to the continued ozone  problem by
enacting a new enforcement scheme, which it  codified as Subpart 2 of
Part D of the Clean Air Act, 42  U.S.C. ss 7511-7511f, redesignating
the original provisions as  Subpart 1.


Subpart 2 requires the EPA to classify nonattainment  areas based upon
their design value, which is a rough mea- sure of whether an area
complies with the 0.12 ppm, 1-hour  primary ozone standard.6 A table
in Subpart 2, set out here in  the margin,7 establishes
classifications ranging from marginal  


__________

n


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


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


TABLE 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 
classification for ozone nonattainment areas. See id. s 7511(a)(2) 


to extreme, and provides an attainment date for each class.  See id. s
7511(a)(1)-(2). Subpart 2 also specifies, for each  class of
nonattainment areas, both measures that the States  must take to
reduce emissions of the chemicals that are  precursors of ozone and
information that the States must  report to the EPA. See id. s 7511a.
In short, Subpart 2 is  the Congress's comprehensive plan for reducing
ozone levels  throughout the country.


The State and Non-State Petitioners, along with Congress- man Bliley
appearing as an amicus curiae, argue that Subpart  2 precludes the EPA
from revising the primary and second- ary ozone NAAQS. We reject this
argument (in Part III.A.1)  insofar as it pertains to the EPA's
continued ability to  promulgate a revised ozone NAAQS or to designate
areas as  not in attainment with a revised NAAQS. We agree (in Part 
III.A.2) with those petitioners, however, insofar as they main- tain,
based upon the text and structure of Subparts 1 and 2,  that the EPA
is precluded from enforcing a revised primary  ozone NAAQS other than
in accordance with the classifica- tions, attainment dates, and
control measures set out in  Subpart 2. Further, we conclude (in Part
III.A.3) that the  EPA may not require a State to comply with a
revised  secondary ozone 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
that provides for setting and revising primary and  secondary NAAQS.
See 42 U.S.C. s 7409. The Administra- tor, therefore, still must "at
five-year intervals [from Decem- ber 31, 1980] ... complete a thorough
review of ... the  [NAAQS] promulgated under this section and ... make
such  revisions in such ... standards ... as may be appropriate."  Id.
s 7409(d)(1). The Second Circuit held that this section  continues to
"set[ ] forth a bright-line rule for agency action," 




__________

n ("Notwithstanding table 1, [for] a severe area with a 1988 ozone 
design value between 0.190 and 0.280 ppm, the attainment date shall be
17 years ... after November 15, 1990"). 


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 revision of 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 amend- ments, then "the Administrator shall ...
promulgate require- ments applicable to all areas which have not
attained that  [relaxed] standard as of the date of such
relaxation....  [which] shall provide for controls ... not less
stringent than  the controls applicable to areas designated
nonattainment  before such relaxation." 42 U.S.C. s 7502(e). Although
two  other subsections of s 172 are expressly made inapplicable to 
the ozone regulations in Subpart 2, see id. s 7502(a)(1)(C), 
(a)(2)(D), this so-called anti-backsliding provision contains no  such
exemption. Accordingly, as the EPA notes, this section  specifically
contemplates that the agency may relax its ozone  NAAQS and,
therefore, necessarily implies that it retains the  authority to
revise that NAAQS. Tellingly, neither the peti- tioners nor the amicus


The petitioners and amicus raise two other arguments to  support their
position that 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
revision of the ozone NAAQS "inappropriate" within  the meaning of s
109(d)(1), which provides the EPA shall  "make such revisions in such
... standards ... as may be  appropriate." 42 U.S.C. s 7409(d)(1).
This argument, how- ever, pointedly ignores the text immediately
following the  word "appropriate," which specifies that
appropriateness is to  be determined "in accordance with section 7408
... and  [s 7409(b)]" (and which, as we read it, means exclusively in 
accord with those 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 s 109(d)(1) nor incorporated by 


reference in either s 108, id. s 7408, or s 109(b), it cannot  render
revision of the ozone NAAQS inappropriate.


Second, the State Petitioners and Congressman Bliley ar- gue, based
upon the classification table in s 181(a)(1), id.  s 7511(a)(1), that
Subpart 2 codified the 0.12 ppm ozone  NAAQS and, therefore, only the
Congress can promulgate a  revised NAAQS. Yet not all areas designated
nonattainment  for ozone will have design values of 0.121 ppm or
higher. In  fact, this was true of areas designated nonattainment for 
ozone as a result of the 1990 amendments, see Ozone Final  Rule, 62
Fed. Reg. at 38,884/3, at least in part because of the  stringent
criteria in the Clean Air Act for changing the  designation of an area
to attainment from nonattainment.  See 42 U.S.C. Sec.
7407(d)(3)(E)(iii) (redesignation permissible  only if area's
attainment of NAAQS "is due to permanent and  enforceable reductions
in emissions"). In short, although the  numbers in the classification
table are based upon the 0.12  ppm ozone NAAQS, they are neither
equivalent to nor a  codification of the NAAQS.


Not only does the EPA, as we conclude above, retain  authority to
promulgate a revised ozone NAAQS; the agency  is still required, "in
no case later than 2 years from the date  of promulgation" of a
revised NAAQS, to designate areas as  attainment, nonattainment, or
unclassifiable under that  NAAQS. Id. s 7407(d)(1)(B). Although the
1990 amend- ments extended by roughly 18 months the maximum time 
between promulgation of a revised NAAQS and designation of 
nonattainment areas under that NAAQS, see 42 U.S.C.  s 7407(d)(1)-(2)
(1988), they made no substantive change in  the EPA's authority to
designate areas as nonattainment  under a revised NAAQS. Therefore, we
hold that the EPA  retains the power to designate areas as
nonattainment under  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
revise the ozone NAAQS or to designate areas as  nonattainment for
ozone does not, however, compel the con-


clusion that Subpart 2 has no effect upon the EPA's authority  to
enforce a revised primary ozone NAAQS. (We consider  the enforcement
of secondary ozone NAAQS in Part III.A.3,  below.) In fact, the text
and structure of Subparts 1 and 2  suggest precisely the opposite
conclusion. After designating  an area as nonattainment under a NAAQS,
the EPA normally  looks to Subpart 1 for authority to "classify the
area for the  purpose of applying an attainment date." 42 U.S.C.  s
7502(a)(1)-(2). The cited provisions, however, do not apply  "with
respect to nonattainment areas for which classifications  [and
attainment dates] are specifically provided under other  provisions of
[Part D of Subchapter 1 of the Clean Air Act]."  Id. s 7502(a)(1)(C),


The EPA argues that Subpart 2 specifically provides classi- fications
and attainment dates only for nonattainment desig- nations under the
0.12 ppm ozone NAAQS. The State and  Non-State Petitioners counter
that Subpart 2 specifically  provides classifications and dates for
all areas designated  nonattainment under 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,  under table 1, by operation of law, as a Marginal Area,
a  Moderate Area, a Serious Area, a Severe Area, or an  Extreme


Id. s 7511(a)(1). As the petitioners note, s 107(d), 42 U.S.C.  s
7407(d), specifies three different times at which an area can  be
designated "nonattainment for ozone": immediately follow- ing
enactment of the 1990 amendments, id. s 7407(d)(4);  after the EPA
revises the ozone NAAQS, id. s 7407(d)(1);  and when an area that was
in attainment, either when the  Congress enacted the 1990 amendments
or when the EPA  promulgated a revised ozone NAAQS, later ceases to
comply,  id. s 7407(d)(3). The petitioners conclude from the general 
reference to s 107(d) that the classifications and attainment 


dates in Subpart 2 apply to areas designated under  ss 107(d)(1), (3),
and (4). The EPA gamely responds that the  reference to s 107(d)
includes only subsection (4), but we do  not defer to the agency's
interpretation because we find that  the Congress has spoken on the
"precise question at issue"  and we "must give effect to the
unambiguously expressed  intent of Congress." Chevron U.S.A. Inc., 467
U.S. 837, 842- 43 & n.9 (1984). We canvass the two reasons that lead
us to  this conclusion before returning to the EPA's argument.


First, the reference to s 107(d) in s 181(a)(1) appears to  have been
purposeful and not the drafting error that the  EPA's interpretation
implies. The Congress considered but  did not adopt bills that clearly
would have limited the reach of  Subpart 2 to nonattainment
designations made immediately  following enactment of the 1990
amendments. The Senate  bill contained a version of Subpart 2 that
classified only those  areas designated nonattainment for ozone under
its equiva- lent of s 107(d)(4). See S. 1630, 101st Cong. ss 101, 107,
 reprinted in III Legislative History of the Clean Air Act  Amendments
of 1990, at 4124-25, 4195 [hereinafter 1990  Legislative History]. The
version of Subpart 2 in the House  bill, as originally introduced,
similarly referred only to desig- nations made under its equivalent of
s 107(d)(4). See H.R.  3030, 101st Cong. ss 101(a), 103, reprinted in
II 1990 Legisla- tive History, at 3748-49, 3795-96. The House
committee,  however, replaced the specific reference to what is now  s
107(d)(4) with a general reference to s 107(d). See H.R.  Rep. No.
101-490, at 3-6, 17 (1990), reprinted in II 1990  Legislative History,
at 3027-30, 3041. The Conference com- mittee then reported the text of
the House bill rather than  that of the Senate. See H.R. Rep. No.
101-952, at 335 (1990),  reprinted in I 1990 Legislative History, at


Second, our conclusion that the Congress intentionally re- ferred to s
107(d) as a whole is supported by a comparison of  Subparts 1 and 2.
The Congress enacted Subpart 2 because  of the failure of the controls
in Subpart 1 to bring areas into  attainment with the 0.12 ppm
standard in the allotted time.  See H.R. Rep. No. 101-490, at 145-50,
reprinted in II 1990  Legislative History, at 3169-74. Rather than
continue treat-


ing all ozone nonattainment areas alike, the Congress allowed  the
various areas between 3 and 20 years to attain the ozone  NAAQS,
depending upon the extent of the area's ozone  problem. See id. at
146-47 ("In 1977, Congress tried to  waive [sic] a 'magic wand' and
command that all nonattain- ment areas [for ozone] will meet 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  petitioners argue, because the 1990 amendments extended the 
time for nonattainment areas to comply with the 0.12 ppm  ozone NAAQS,
they must preclude the EPA from requiring  areas to comply either more
quickly or with a more stringent  ozone NAAQS.


Subpart 1 requires compliance with a primary NAAQS "as  expeditiously
as practicable, but no later than 5 years from  the date such area was
designated nonattainment." 42  U.S.C. s 7502(a)(2)(A). All
nonattainment areas would have  until 2012 to comply with the revised
ozone NAAQS if the  EPA and the States were to take the full time
authorized in  Subpart 1 for making attainment designations and the
EPA  were to approve every possible extension for each area. See  id.
ss 7407(d)(1)(A)-(B), 7502(a)(2)(A), (C). Such wide discre- tion is
inconsistent, however, with Subpart 2, in which the  Congress stripped
the EPA of discretion to decide which  ozone nonattainment areas
should receive more time to reach  attainment (with two limited
exceptions not relevant here, see  id. s 7511(a)(4), (5)). Moreover,
under s 181(a) of Subpart 2,  Los Angeles, the nation's only Extreme
Area, has until 2010  to attain the 0.12 ppm ozone NAAQS, and the
possibility of  extending that deadline until 2012. That Los Angeles
should  also have to attain a more stringent ozone standard by that 
same year, if not earlier, clearly runs counter to the compre- hensive
enforcement scheme enacted in Subpart 2.


The EPA offers two arguments against this interpretation  of Subparts 1
and 2. First, the EPA contends that a recent  statute confirms its
power to designate nonattainment areas  under the revised ozone
standard. See Pub. L. No. 105-178,  s 6103(a), 112 Stat. 465 (1998)
(extending time to two years 


from one year for governor to submit proposed designation  under 0.08
ppm ozone NAAQS). That statute also specifically  states, however,
that "[n]othing in section[ ] ... 6103 shall be  construed by the
Administrator of Environmental Protection  Agency or any court ... to
affect any pending litigation or to  be a ratification of the ozone
... standard[ ]." Id. s 6104.  Further, even if the EPA were correct
that s 6103 confirms  the agency's power to designate areas under a
revised ozone  NAAQS, that power was never in doubt, as we concluded 
above. Indeed, s 6104 simply does not bear upon the ques- tion we
address here: whether Subpart 1 or Subpart 2  provides the applicable
enforcement mechanisms for an area  designated nonattainment under a
revised ozone NAAQS.


Second, the EPA argues that read in context the reference  to s 107(d)
in s 181(a)(1) relates only to designations made  under s 107(d)(4).
Because the table in s 181(a)(1) classifies  areas based upon a design
value that roughly measures  attainment of the 0.12 ppm ozone NAAQS,
the EPA contends  that the nonattainment designations referenced in s
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 refer to s 107(d)(4)  specifically or the
long-term nature of the attainment scheme  enacted in Subpart 2; on
the EPA's interpretation, that  scheme would have been stillborn had
the EPA revised the  ozone NAAQS immediately after the Congress
enacted the  1990 amendments.


The EPA points next to s 181(b)(1), which specifies the  attainment
dates for areas that met the 0.12 ppm standard  when the Congress
enacted the 1990 amendments but that  later cease to comply. That
section, however, applies only to  areas designated under s 107(d)(3)
that previously were "des- ignated attainment or unclassifiable for
ozone under section  [107(d)(4)]." That s 181(b)(1) provides special
rules for such  areas, but not for areas designated under s 107(d)(3)
that had  previously been designated attainment for ozone or
unclassifi- able under s 107(d)(1), does not support the EPA's
argument  that the phrase in s 181(a)(1) "designated nonattainment for
 ozone pursuant to section 107(d)" denotes only those designa-


tions made under s 107(d)(4). If anything, the specification  of s
107(d)(4) in s 181(b)(1) makes its absence from  s 181(a)(1) all the
more striking.


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


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


3. The Secondary Ozone NAAQS


The Non-State Petitioners briefly contend that our conclu- sion that
Subpart 2 provides the classifications and attain- ment dates for
areas designated nonattainment under a re- vised primary ozone NAAQS
is equally applicable to the  enforcement of a revised secondary ozone
NAAQS. We find  it impossible to conclude, however, that Subpart 2
"specifical- ly provide[s]" for classifications and attainment dates
for  areas designated nonattainment with a revised secondary  ozone
NAAQS; s 181(a)(1) expressly refers only to primary 


NAAQS and Subpart 2 not once mentions secondary NAAQS.  Further,
attainment dates in Subpart 1 for secondary stan- dards are less
stringent than for primary standards, making  comparison with the more
lenient dates in Subpart 2 less  troubling. Compare id. s
7502(a)(2)(B) (attainment of sec- ondary NAAQS "shall be ... achieved
as expeditiously as  practicable after the date such area was
designated nonattain- ment"), with id. s 7502(a)(2)(A) (attainment of
primary  NAAQS "shall be ... achieved as expeditiously as practica-
ble, but no later than 5 years from the date such area was  designated
nonattainment"). Nonetheless, we understand  Subpart 2 to codify the
Congress's judgment as to what is "as  expeditiously as practicable"
in reducing an area's level of  ozone. Consequently, the EPA is
precluded from requiring  any steps toward compliance with a revised
secondary ozone  NAAQS prior to an area's attainment of the 0.12 ppm
stan- dard. In areas that meet the 0.12 ppm standard, however, 
Subpart 2 erects no bar to the EPA's requiring compliance  with a
revised secondary ozone NAAQS "as expeditiously as  practicable."


B.Ozone's Health Benefits


Petitioners presented evidence that according to them  shows the health
benefits of tropospheric ozone as a shield  from the harmful effects
of the sun's ultraviolet rays--includ- ing cataracts and both melanoma
and nonmelanoma skin  cancers. In estimating the effects of ozone
concentrations,  EPA explicitly disregarded 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 to be "based on [the] criteria"  that EPA has
published for that pollutant. 42 U.S.C.  s 7409(b)(1) & (2). The
"criteria," in turn, are to "reflect the  latest scientific knowledge
useful in indicating the kind and  extent of all identifiable effects
on public health or welfare  which may be expected from the presence
of such pollutant in  the ambient air, in varying quantities." Id. s
7408(a)(2).  The reference to "all identifiable effects" would seem on
its  face to include beneficent effects.


EPA attempts to avoid this straightforward reading in  several ways.
First, it points to the term "such pollutant,"  arguing that the
statute requires it to focus exclusively on the  characteristics that
make the substance a "pollutant." But  the phrase "pollutant" is
simply a label used to identify a  substance to be listed and
controlled by the statute. While it  is perfectly true that a
substance known to be utterly without  adverse effects could not make
it onto the list, this fact of  nomenclature does not visibly manifest
a congressional intent  to banish consideration of whole classes of


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


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


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


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


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


Id. s 7408(a)(2) (emphasis added). EPA's argument would  be of
uncertain force even if all three types of effects specifi- cally
required to be considered were spoken of as "adverse  effects"; there
is no reason to read "adverse" back into the  "all identifiable
effects" of s 108(a)(2). But as one of the  three specified classes
refers to "effects" unmodified, id.  s 7408(a)(2)(A), we can reject
EPA's argument without even  reaching that issue. That Congress
qualified "effects" in  clauses (B) and (C) with "adverse" seems only
to strengthen  the supposition that in (A)--and in the general
mandate--it  intended to cover all health or welfare effects.
Therefore if  petitioners' contentions are right, clause (A) applies


the presence of ultraviolet radiation at various levels "alter[s]  the
effects [of ozone] on public health or welfare" by making  them on the
whole less malign--perhaps even beneficial.


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


Finally, EPA directs us towards legislative history from the  1970 and
1990 Clean Air Act Amendments. The "all identifi- able effects"
language, however, dates to the 1967 Amend- ments. Legislative history
from the 1970 and 1990 Congress- es cannot be "an authoritative
interpretation of what the  [1967] statute meant," because it is "the
function of the courts  and not the Legislature, much less a Committee
of one House  of the Legislature, 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
"the statute is silent or ambiguous with respect to  the specific
issue" and "the agency's answer is based on a  permissible
construction of the statute." 467 U.S. at 843.  We find no such
ambiguity in this case. Further, EPA's  interpretation fails even the
reasonableness standard of Chev- ron's second part: it seems bizarre
that a statute intended to  improve human health would, as EPA claimed
at argument,  lock the agency into looking at only one half of a
substance's  health effects in determining the maximum level for that 
substance. At oral argument even EPA counsel seemed  reluctant to
claim that the statute justified disregard of the  beneficent effects
of a pollutant bearing directly on the health  symptoms that accounted
for its being thought a pollutant at  all (suppose, for example, a
chemical that both impedes and  enhances breathing, depending on the
person or circum- stances); he also seemed unable to distinguish that


the one here--where the chemical evidently impedes breath- ing but
provides defense against various cancers.


Legally, then, EPA must consider positive identifiable ef- fects of a
pollutant's presence in the ambient air in formulat- ing air quality
criteria under s 108 and NAAQS under s 109.  EPA's other arguments are
technical, and are of two sorts:  those that allegedly show
petitioners' studies to be fatally  flawed and those that allegedly
show specific inflation of  results in these studies. We need only
consider the first sort,  for EPA chose to give the studies no weight


Petitioners rely primarily on studies by Lutter and Cupitt.  EPA found
that these could be ignored because the marginal  benefits are
difficult, if not impossible, to quantify reliably  and because there
is "no convincing basis 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 quantifiabili- ty, see, e.g., Ozone Final Rule, 62 Fed.
Reg. at 38,860/3  (admitting that "quantitative risk estimates could
not be  developed" for certain adverse effects of ozone on which EPA 
regulated); EPA Ozone Brief at 48 (defending consideration  of various
effects that "played an important role in the  Administrator's final
decision" despite absence of quantifica- tion: "EPA did not estimate
the risk for such effects because  'information [was] too limited to
develop quantitative esti- mates,'--not because there is doubt the
effects occur.") (alter- ation and emphasis in original) (citation
omitted), or any  specific level of significance. As we can see no
reason for  imposing a higher information threshold for beneficent
effects  than for maleficent ones, 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
decision criteria for its ordinary object of analysis-- ill effects.
We leave it to the agency on remand to determine  whether, using the
same approach as it does for those,  tropospheric ozone has a
beneficent effect, and if so, then to  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
coarse particulate pollution. Both the 1987  NAAQS and the proposed
standards regulate all particles  with diameters under 10 micrometers,
signified by the indica- tor PM10. The PM10 spectrum includes both
coarse and fine  particles. While the main distinction between coarse
and fine  particles is the process by which they are produced, EPA and
 epidemiologists who study the health effects of particulate 
pollution identify coarse and fine particles through rough 
approximations of those particles' diameters. Coarse parti- cles,
which become airborne usually from the crushing and  grinding of
solids, generally have diameters between 2.5 and  10 micrometers and
can thus be identified by the indicator  PM10-2.5. Fine particles,
indicated in these new NAAQS by  PM2.5, come mainly from combustion or
gases and generally  have diameters of 2.5 micrometers or less.


Despite EPA's conclusion that coarse and fine particles  pose
independent and distinct threats to public health, the  Agency chose
not to adopt an indicator, such as PM10-2.5, that  would measure only
the coarse fraction of PM10. Petitioners  make two arguments: that
there is no scientific basis for  regulating coarse particles at all,
and that even if there were,  retention of the PM10 indicator
simultaneously with the estab- lishment of the new fine particle
indicator is unsupported by  evidence in the record and arbitrary and
capricious. We  agree with this latter argument.


Beginning with petitioners' first challenge, we think the  record
contains sufficient evidence to justify the Agency's  decision to
regulate coarse particulate pollution. While the  relationship between
PM10 pollution and adverse health ef- fects justifying the 1987 NAAQS
was well-established, see  NRDC v. EPA, 902 F.2d 962, 967-68 (D.C.
Cir. 1990), two  studies contained in the record of these proceedings
concen- trated specifically on the health effects caused by the coarse
 fraction of PM10 pollution. See Mary Ellen Gordian et al., 
"Particulate Air Pollution and Respiratory Disease in Anchor-


age, Alaska," 104 Envtl. Health Persp. 290 (1996) (studying  volcanic
ash); Brockton J. Hefflin et al., "Surveillance for  Dust Storms and
Respiratory Diseases in Washington State,  1991," 49 Archives of
Envtl. Health 170 (1994) (studying  fugitive dust). In addition, the
record contains at least nine  multivariate analyses finding
statistically significant relation- ships with health effects for both
PM2.5 and PM10, suggesting  that the portion of PM10 pollution
unaccounted for by PM2.5  (i.e., coarse particles) explains some of
the observed adverse  health effects. In other words, because
regression analysis  holds the PM2.5 component constant, the PM10
effect recog- nized in these equations actually evidences results from
 coarse particulate pollution. To be sure, petitioners have  pointed
to some evidence to the contrary. But given that our  review is
limited to "ascertaining that the choices made by  the Administrator
were reasonable and supported by the  record," and does not include
"judg[ing] the merits of compet- ing expert views," Lead Industries,
647 F.2d at 1160, we find  ample support for EPA's decision to
regulate coarse particu- late pollution above the 1987 levels.


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 "surrogate for  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 coarse particle indicator, EPA offers three 
justifications for its decision to use PM10 instead: (1) Both the 
Gordian and Hefflin studies used PM10, not PM10-2.5, as the  variable
in their models, (2) the PM10 standards will work in  conjunction with
the PM2.5 standards by regulating the por- tion of particulate
pollution not regulated by the PM2.5 stan- dards, and (3) a nationwide
monitoring program for PM10  already exists. We find none of these
explanations persua- sive.


As to the first argument, while acknowledging that the  indicator used
in the studies captures both coarse and fine  particles, EPA
nevertheless maintains that PM10 is an effec- tive indicator for the
regulation of coarse particulate pollu-


tion. "Adopting the indicator used in the studies," the Agen- cy says,
"increases the likelihood that the level selected will  result in the
health protections predicted." But as EPA's  own staff paper suggests,
PM10 is "inherently confounded" by  the presence of PM2.5 particles,
meaning that any regulation  of PM10 pollution will include both
coarse and fine particles.  See PM Staff Paper at V-59. Using PM10 as
the coarse  particle indicator, instead of PM10-2.5, will thus
regulate more  than just the coarse fraction of PM10, and the amount
of  coarse particulate pollution permitted will depend (quite arbi-
trarily) on the amount of PM2.5 pollution in the air. For  example,
assuming the 50 microgram annual PM10 level  adopted by the Agency and
a region with an annual PM2.5  pollution level of 15 micrograms, the
PM10 indicator would  prohibit coarse particulate (PM10-2.5) pollution
from exceeding  35 micrograms. But in an area with only 5 micrograms
of  PM2.5 pollution, the NAAQS would permit coarse particulate 
pollution to reach as high as 45 micrograms.


EPA's second argument--that the PM10 standard will work  in conjunction
with the PM2.5 standard--suffers from the  same deficiency. Accepting
EPA's finding of "profound phy- sicochemical differences" between
coarse and fine PM, 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 fraction of PM10. EPA  provides
no explanation to aid us in understanding its deci- sion. In fact, as
the example above indicates, it is the very  presence of a separate
PM2.5 standard that makes retention of  the PM10 indicator arbitrary
and capricious. Far from work- ing 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 PM10-2.5 component since the amount of
PM10-2.5 permitted  will always depend on the amount of PM2.5 in the


EPA's final argument is pragmatic. It maintains that PM10  is a better
indicator than PM10-2.5 for coarse particulate  pollution because a
nationwide monitoring program for PM10 


already exists. But as EPA acknowledges elsewhere in its  brief, NRDC
bars EPA from considering factors unrelated to  public health in
setting air quality standards. Echoing our  decision in Vinyl
Chloride, NRDC held that "the Administra- tor may not consider cost
and technological feasibility in  determining what is 'safe'; such a
determination 'must be  based solely upon the risk to health.' " NRDC,
902 F.2d at  973 (quoting Vinyl Chloride, 824 F.2d 1146, 1166 (D.C.
Cir.  1990) (in banc)); see also American Petroleum Inst. v. Costle, 
665 F.2d 1176, 1185 (D.C. Cir. 1981); Lead Industries, 647  F.2d at
1148-55. The administrative convenience of using  PM10 cannot justify
choosing an indicator poorly matched to  the relevant pollution


In view of our conclusion that PM10 amounts to an arbitrary  indicator
for coarse particle pollution, we need not address  petitioners'
separate challenge to the PM10 levels or second- ary standards. We
note, however, that whatever levels the  Agency ultimately selects for
coarse particle pollution will  need 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 Virgi- nia ("state
petitioners") argue that EPA is regulating PM2.5  for the first time.
Because they consider PM2.5 to be a "new  pollutant," they argue that
s 108 of the Clean Air Act re- quires EPA to conduct further research
on PM2.5's health  effects before listing it as a pollutant, to issue
an air quality  criteria document reflecting the latest science on the
health  effects of the pollutant, and to assist states by developing 
"data relating to the cost of installation and operation, energy 
requirements, emission reduction benefits, and environmental  impact
of the emission control technology." 42 U.S.C.  s 7408(b)(1).


Although EPA never responds to this argument, five north- eastern
states (as respondent intervenors and amici) do.  Pointing out that
previous NAAQS have always included  PM2.5, these attorneys general
support the EPA's decision not  to list PM2.5 separately as a new
pollutant. We agree.


The state petitioners cannot escape the fact that the origi- nal
standards for particulate pollution using Total Suspended 
Particulates (TSP) as indicator, as well as the 1987 NAAQS  that used
PM10, included by definition every particle 2.5  micrometers and
smaller. Moreover, in some areas fine  particles often dominate PM10
pollution. See PM Staff Paper  at V-63. By refining the NAAQS to focus
on smaller parti- cles that EPA found posed distinct threats to public
health,  EPA has done with these regulations exactly what we held it 
could do in 1987 when it made the change from Total Sus- pended
Particulates to PM10. See NRDC, 902 F.2d at 965-66.  EPA's decision to
update the NAAQS to focus on PM2.5  merely continues a trend based on
evolving science. It does  not violate the provisions of s 108 of the


C.Failure to Identify a Biological Mechanism for Particu- late
Pollution's Relationship to Adverse Health Effects


Also challenging the establishment of a fine particle stan- dard,
non-state petitioners argue that EPA failed to explain  the biological
mechanism through which particulate pollution  causes adverse health
effects. Even if epidemiological stud- ies show robust statistical
relationships between pollution and  health effects, they say, the
absence of proof of causation-- i.e., how particles actually interact
with cells and organs to  cause sickness and death--is fatal to the
standard. We  disagree.


To begin with, the statute itself requires no such proof.  The
Administrator may regulate air pollutants "emissions of  which, in his
judgment, cause or contribute to air pollution  which may reasonably
be anticipated to endanger public  health or welfare." 42 U.S.C. s
7408(a)(1)(A) (1994) (empha- sis added). Moreover, this court has
never required the type  of explanation petitioners seek from EPA. In
fact, we have  expressly held that EPA's decision to adopt and set air
 quality standards need only be based on "reasonable extrapo- lations
from some reliable evidence." NRDC v. Thomas, 805  F.2d 410, 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 it first
recognizes clear trends 


of mortality or morbidity in areas dominated by a particular 
pathogen.


The numerous epidemiological studies appearing in this  record, some of
which EPA also used to support the 1987  NAAQS, easily satisfy the
standard articulated in the statute  and emphasized repeatedly in
decisions of this court. Cover- ing diverse geographic locations with
widely varying mixes of  air pollution, the studies found
statistically significant rela- tionships between air-borne
particulates signified by a variety  of indicators and adverse health
effects. Given EPA's statu- tory mandate to establish standards based
on "the latest  scientific knowledge," 42 U.S.C. ss 7408(a)(2),
7409(d), the  growing empirical evidence demonstrating a relationship
be- tween fine particle pollution and adverse health effects amply 
justifies establishment of new fine particle standards.


D.Visibility Effects


The Environmental Petitioners challenge the EPA's deci- sion to set the
secondary PM2.5 NAAQS at levels equivalent to  the primary NAAQS.
According to the petitioners, the  EPA's failure to set the secondary
NAAQS at more stringent  levels will result in "adverse visibility
impacts" in parts of the  country. In view of our conclusion in Part
I, above, that the  EPA has not adequately explained the principles
upon which  it relied in setting the levels in the NAAQS for PM, we
need  not reach the main thrust of the petitioners' challenge to the 
secondary NAAQS. On the other hand, the Environmental  Petitioners
have also raised a question of statutory interpre- tation, the
resolution of which should assist the EPA if it  revisits its decision
to set the secondary PM2.5 NAAQS.


In the PM Final Rule, the EPA decided "to address the  welfare effects
of PM on visibility by setting secondary  standards identical to the
suite of PM2.5 primary standards, in  conjunction with the
establishment of a regional haze pro- gram under s 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 mandatory class I Federal areas ...
result[ing]  from manmade air pollution." 42 U.S.C. s 7491. Mandatory


class I areas include all international parks, and national  parks and
wilderness areas of a certain size. See 42 U.S.C.  s 7472(a). The EPA
concluded that reduction of PM2.5 levels  in class I areas would
benefit the surrounding areas as well  because "the same haze that
degrades visibility within or  looking out from a national park also
degrades visibility  outside it." PM Final Rule, 62 Fed. Reg. at


The Environmental Petitioners argue that s 109(b)(2), 42  U.S.C. s
7409(b)(2), requires the EPA to set secondary  NAAQS at a level
sufficient to eliminate all adverse visibility  effects and that it
leaves the EPA no discretion to decide that  some visibility
impairment is better remedied through anoth- er program. This argument
must be wrong. For, as the  EPA argues, the Congress required the EPA
to implement a  regional haze program specifically in order to address
ad- verse visibility effects that persist in class I areas after 
attainment of the secondary NAAQS. See 42 U.S.C.  s 7470(1) (purpose
of this part of Clean Air Act is "to protect  public ... welfare from
any 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 secondary NAAQS to eliminate all adverse  visibility
effects and, therefore, that the EPA acted within the  scope of its
authority in deciding to rely upon the regional  haze program to
mitigate some of the adverse visibility  effects caused by PM2.5.


Conclusion


We remand the cases to EPA for further consideration of  all standards
at issue. We do not vacate the new ozone  standards because the
standard is unlikely to engender costly  compliance activities in
light of our determination that it  cannot be enforced by virtue of
Clean Air Act s 181(a), 42  U.S.C. s 7511(a). We vacate the challenged
coarse particu- late matter standards because EPA will have to develop
 different standards when it corrects the arbitrarily chosen  PM10
indicator. As to the fine particulate matter standards, 


we invite briefing on the question of remedy: possibilities  include
but 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
and the many unresolved issues bearing on  application of whatever
standards may emerge, this panel will  in the interest of judicial
economy retain jurisdiction over the  cases following remand. See
Sierra Club v. Gorsuch, 715  F.2d 653, 661 (D.C. Cir. 1983).





__________

n


8Briefing should address the possibility that the previous  particulate
matter standard will spring back to life in response to  our decision
to vacate 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
by Congress numerous times, and has been  the subject of regular
congressional oversight hearings. The  Act has been parsed by this
circuit no fewer than ten times in  published opinions delineating EPA
authority in the NAAQS- setting process. Yet this court now threatens
to strike down  section 109 of the Act as an unconstitutional
delegation of  congressional authority unless EPA can articulate an
intelligi- ble principle cabining its discretion. In doing so, the
court  ignores the last half-century of Supreme Court nondelegation 
jurisprudence, apparently viewing these permissive prece- dents as
mere exceptions to 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 of authority is  narrower and more
principled than delegations the Supreme  Court and this court have
upheld since Schechter Poultry,  and because the record in this case
demonstrates that EPA's  discretion was in fact cabined by section


Section 109 requires EPA to publish air quality standards  "the
attainment and maintenance of which in the judgment of  the
Administrator, based on such criteria and allowing an  adequate margin
of safety, are requisite to protect the public  health." 42 U.S.C. s
7409(b)(1) (1994). Compare section 109  to the language of section 303
of the Communications Act of  1934, which gave the FCC authority to
regulate broadcast  licensing in the "public interest," and which the
Supreme  Court sustained in National Broadcasting Co. v. United 
States, 319 U.S. 190, 225-26 (1943). The FCC's general  authority to
issue regulations "as public convenience, interest,  or necessity
requires" was sustained in United States v.  Southwestern Cable Co.,
392 U.S. 157, 178 (1968). The Su- preme Court has sustained equally
broad delegations to other  agencies, including the Price
Administrator's authority to fix  "fair and equitable" commodities
prices, Yakus v. United  States, 321 U.S. 414, 426-27 (1944), the
Federal Power Com- mission's authority to determine "just and


FPC v. Hope Natural Gas Co., 320 U.S. 591, 600 (1944), the  War
Department's authority to recover "excessive profits"  earned on
military contracts, Lichter v. United States, 334  U.S. 742, 778-786
(1948), and the Attorney General's authori- ty to regulate new drugs
that pose an "imminent hazard to  public safety," Touby v. United
States, 500 U.S. 160, 165  (1991). See also Milk Indus. Foundation v.
Glickman, 132  F.3d 1467, 1475 (D.C. Cir. 1998) (upholding delegation
to  Secretary of Agriculture to approve interstate compacts upon  a
finding of "compelling public interest").


Given this extensive Supreme Court precedent sustaining  general
congressional delegations, no wonder the First Cir- cuit rejected a
similar nondelegation challenge to the Clean  Air Act's "requisite to
protect the public health" language:


The power granted to EPA is not "unconfined and  vagrant". [Schechter
Poultry, 295 U.S. at 551 (Cardozo,  J., concurring).] The Agency has
been given a well  defined task by Congress--to reduce pollution to
levels  "requisite to protect the public health", in the case of 
primary standards. The Clean Air Act outlines the  approach to be
followed by the Agency and describes in  detail many of its powers....
Yet there are many  benchmarks to guide the Agency and the courts in 
determining whether or not EPA is exceeding its powers,  not the least
of which is that the rationality of the means  can be tested against
goals capable of fairly precise  definition in the language of


Administrative agencies are created by Congress be- cause it is
impossible for the Legislature to acquire  sufficient information to
manage each detail in the long  process of extirpating the abuses
identified by the legis- lation; the Agency must have flexibility to
implement the  congressional mandate. Therefore, although the delega-
tion to EPA was a broad one, ... we have little 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"), requires a
different result. That case  remanded to OSHA for a more precise
definition of section  3(8) of the Occupational Safety and Health Act,
which granted  the Agency authority to enact workplace safety
standards  "reasonably necessary or appropriate to provide safe or 
healthful employment or places of employment." Id. at 1316.  The Clean
Air Act does not delegate to EPA authority to do  whatever is
"reasonably necessary or appropriate" to protect  public health.
Instead, the statute directs the Agency to  fashion standards that are
"requisite" to protect the public  health. In other words, EPA must
set pollution standards at  levels necessary to protect the public
health, whether "rea- sonable" 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 standards on "air quality crite- ria" that "accurately
reflect the latest scientific knowledge  useful in indicating the kind
and extent of all identifiable  effects on public health or welfare
which may be expected  from the presence of such pollutant in the
ambient air, in  varying quantities." 42 U.S.C. s 7408(a)(2); see id. 
s 7409(b)(1); see also id. s 7408(a)(2) (requiring air quality 
criteria, "to the extent practicable," to "include information 
on--(A) those variable factors (including atmospheric condi- tions)
which of themselves or in combination with other  factors may alter
the effects on public health or welfare of  such air pollutant; (B)
the types of air pollutants which, when  present in the atmosphere,
may interact with 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 those this court sustained in
Lockout/Tag- out II, i.e., that OSHA must identify a " '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


not reasonably requisite--to protect the public health with  "an
adequate margin of safety," the Clean Air Act tells EPA  exactly the
same thing, i.e., ensure a high degree of protec- tion.


Although this court's opinion might lead one to think that  section
109's language permitted EPA to exercise unfettered  discretion in
choosing NAAQS, the record shows that EPA  actually adhered to a
disciplined decisionmaking process con- strained by the statute's
directive to set standards "requisite  to protect the public health"
based on criteria reflecting the  "latest scientific knowledge." To
identify which health effects  were "significant enough" to warrant
protection, EPA fol- lowed guidelines published by the American
Thoracic Society.  See National Ambient Air Quality Standards for
Ozone:  Proposed Decision, 61 Fed. Reg. 65,716, 65,722/1 (1996). It 
then set the ozone and fine particle standards within ranges 
recommended by CASAC, the independent scientific advisory  committee
created pursuant to section 109 of the Act. See 42  U.S.C. s


CASAC must consist of at least one member of the Nation- al Academy of
Sciences, one physician, and one person repre- senting state air
pollution control agencies. See id.  s 7409(d)(2)(A). In this case,
CASAC also included medical  doctors, epidemiologists, toxicologists
and environmental sci- entists from leading research universities and
institutions  throughout the country. EPA must explain any departures 
from CASAC's recommendations. See id. s 7607(d)(3).  Bringing
scientific methods to their evaluation of the Agen- cy's Criteria
Document and Staff Paper, CASAC provides an  objective justification
for the pollution standards the Agency  selects. Cf. Daubert v.
Merrell Dow Pharmaceuticals, Inc.,  509 U.S. 579, 593 (1993) ("
'Scientific methodology today is  based on generating hypotheses and
testing them to see if  they can be falsified; indeed, this
methodology today is what  distinguishes science from other fields of
human inquiry.' ")  (citation omitted). Other federal agencies with
rulemaking  responsibilities in technical fields also rely heavily on
the  recommendations, policy advice, and critical review that scien-
tific advisory committees provide. See, e.g., 21 U.S.C. 


s 355(n) (describing scientific advisory panels for the Food  and Drug
Administration); 49 U.S.C. s 44912(c) (creating a  scientific advisory
panel for the Federal Aviation Administra- tion).


Beginning with CASAC's ozone recommendations--not one  member
recommended going below .08 ppm--EPA gave two  perfectly rational
explanations for the level it selected. First,  it set the annual
level based on the different types 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 tran- sient and reversible." National Ambient Air Quality
Stan- dards for Ozone, 62 Fed. Reg. 38,856, 38,868/2 (1997) (empha-
sis added). Characterizing this explanation as saying nothing  more
than that "lower exposure levels are associated with  lower risk to
public health," Maj. Op. at 10, my colleagues  find the Agency's
reasoning unintelligible. But EPA did not  find simply that public
health risks decrease at lower levels.  Instead, it found that public
health effects differ below .08  ppm, i.e., that they are "transient


Second, EPA explained that the level should not be set  below naturally
occurring background ozone concentrations.  The Agency selected .08
ppm because it found that "a 0.07  ppm level would be closer to peak
background levels that  infrequently occur in some areas due to
nonanthropogenic  sources of [ozone] precursors, and thus more likely
to be  inappropriately targeted in some areas on such sources." 62 
Fed. Reg. at 38,868/3. Of course, any level of ozone pollution  above
background concentrations is closer to background  levels than one
just above it. See Maj. Op. at 11. But as I  read EPA's explanation,
the Agency found that peak back- ground levels sometimes occur at .07
ppm, not at .08 ppm.  Indeed, the data EPA provided in its "Responses
to Signifi- cant Comments" show a range of background concentrations 
from a low of .042 ppm in Olympic National Park in Washing- ton to a
high of .075 ppm in Quachita National Forest in  Arizona. No region
registered background levels above .075  ppm. See U.S. Environmental
Protection Agency, Responses  to Significant Comments on the 1996


National Ambient 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 that if a region  surpasses the ozone standard, it
will do so because of control- lable human activity, not because of
uncontrollable natural  levels of ozone.


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


Recognizing that its decision must "accurately reflect the  latest
scientific knowledge useful in indicating the kind and  extent of all
identifiable effects on public health," 42 U.S.C.  s 7408(a)(2), EPA
focused on three studies in the record that  displayed a statistically
significant relationship between fine  particle pollution and adverse
health effects: Joel Schwartz et  al., Is Daily Mortality Associated
Specifically with Fine  Particles?, 46 J. Air & Waste Mgmt. Ass'n 927
(1996); Joel  Schwartz et al., Acute Effects of Summer Air Pollution
on  Respiratory Symptom Reporting in Children, 150 Am. J.  Respiratory
& Critical Care Med. 1234 (1994); and Douglas  W. Dockery et al., An
Association between Air Pollution and  Mortality in Six U.S. Cities,
329 New Eng. J. Med. 1753  (1993). The Agency explained that "there is
generally great- est statistical confidence in observed associations
[between  fine particle pollution and adverse health effects] for
levels at  and above the mean concentration [of pollution observed in 
the studies that showed a statistically significant relation- ship]."
National Ambient Air Quality Standards for Partic- ulate Matter, 62
Fed. Reg. 38,652, 38,676/1 n.42 (1997) (em- phasis added). Allowing
"an adequate margin of safety,"  EPA then set the annual fine particle
standard just below the  lowest mean pollution levels observed in
those studies, at 15  Sg/m3. See id. at 38,676/1 ("An examination of
the long-term  means from the combined six city analyses of daily
mortality  [Schwartz et al. (1996)] and morbidity [Schwartz et al.


together with those from studies in individual cities for which 
statistically significant PM-effects associations are reported  ...
finds mean concentrations ranging from about 16 to about  21
Sg/m3...."); id. at 38,676/2 ("[The EPA] Staff Paper  assessment of
the concentration-response results [from Dock- ery et al. (1993)],
concluded that the evidence for increased  risk was more apparent at
annual concentrations at or above  15 Sg/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
reasonable level for setting the fine  particle NAAQS:


The mean (or median) concentration may serve as a  reasonable cutpoint
of increased PM health risk since at  this point there is generally
the greatest confidence (i.e.,  the smallest confidence intervals) in
the association and  the reported [relative risk] estimates. The mean
concen- tration considered by staff as most informative to test 
implications of potential alternative concentration- response
functions is the minimum mean concentration  associated with a study
or studies reporting statistically  significant increases in risk
across a number of study  locations....


Office of Air Quality Planning and Standards, U.S. Environ- mental
Protection Agency, Review of National Ambient Air  Quality Standards
for Particulate Matter: Policy Assess- ment of Scientific and
Technical Information, at E-4 (1996)  (emphasis added).


EPA thus did not, as my colleagues charge, arbitrarily pick  points on
the ozone and particulate pollution continua indis- tinguishable from
any other. Instead, acting pursuant to  section 109's direction that
it establish standards that, 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 ozone level just above peak background
concentrations  where the most certain health effects are not
transient and  reversible, and the fine particle level at the lowest


mean concentration observed in studies that showed a statisti- cally
significant relationship between fine particle pollution  and adverse
health effects. Whether EPA arbitrarily select- ed the studies it
relied upon or drew mistaken conclusions  from those studies (as
petitioners argue), or whether EPA  failed to live up to the
principles it established for itself (as  my colleagues believe, see
Maj. Op. at 9-12), has nothing to do  with our inquiry under the
nondelegation doctrine. Those  issues relate to whether the NAAQS are
arbitrary and capri- cious. See NRDC v. EPA, 902 F.2d 962, 969, 971
(D.C. Cir.  1989). The Constitution requires that Congress articulate 
intelligible principles; Congress has done so here.


A final point. Unlike OSHA, which Lockout/Tagout I  recognized has
authority to reach into every workplace to  dictate what is safe, to
impose extensive civil and criminal  penalties, and "to decide which
firms will live and which will  die," Lockout/Tagout I, 938 F.2d at
1318, EPA regulates  primarily by setting standards for states to
develop their own  plans. See 42 U.S.C. s 7401(a)(3) (Congress finds
"that air  pollution prevention ... and air pollution control at its
source  is the primary responsibility of States and local govern-
ments."). Indeed, because states have three years to submit 
implementation plans, which are themselves subject to notice, 
comment, public hearing, and frequent renegotiation, we will  not know
for years precisely how the ozone and particle  NAAQS will actually
affect individual businesses. Only if a  state fails to produce an
acceptable plan can EPA terminate  federal highway funds or impose its
own implementation plan.  Because the Clean Air Act gives politically
accountable state  governments primary responsibility for determining
how to  distribute the burdens of pollution reduction and therefore 
how the NAAQS will affect specific industries and individual 
businesses, courts have less reason to second-guess the speci- ficity
of the congressional delegation. Moreover, if the states  disagree
with the standards EPA has set, they have 535  representatives in
Congress to turn to for help. In fact,  legislation to overturn the
very NAAQS at issue in this case  was introduced in the last Congress.
See H.R. 1984, 105th  Cong. (1997) ("A bill to provide for a four-year


the establishment of new standards for ozone and fine partic- ulate
matter under the Clean Air Act, pending further imple- mentation of
the Clean Air Act Amendments of 1990, addi- tional review and air
quality monitoring under that Act.");  S. 1084, 105th Cong. (1997) ("A
bill to establish a research  and monitoring program for the national
ambient air quality  standards for ozone and particulate matter and to
reinstate  the original standards under the Clean Air Act, and for
other  purposes.").