American Lung Ass'n v. Environmental Protection Agency , 134 F.3d 388 ( 1998 )

United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT
Argued September 26, 1997 Decided January 30, 1998
No. 96-1251
American Lung Association, et al.,
Petitioners
v.
Environmental Protection Agency and
Carol M. Browner, Administrator, United States
Environmental Protection Agency,
Respondents
Appalachian Power Company, et al.,
Intervenors
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Consolidated with
No. 96-1255
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On Petitions for Review of an Order of the
Environmental Protection Agency
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Robert E. Yuhnke argued the cause for petitioners. With
him on the briefs were Christine L. Shaver and Howard I.
Fox.
Karen L. Egbert, Attorney, U.S. Department of Justice,
argued the cause for respondents. With her on the brief
were Lois J. Schiffer, Assistant Attorney General, and Mi-
chael L. Goo, Counsel, Environmental Protection Agency.
Gerald K. Gleason, Counsel, entered an appearance.
Andrea Bear Field, Henry V. Nickel, Linda C. Trees, and
James R. Bieke were on the brief for intervenor Appalachian
Power Company, et al. Ross S. Antonson entered an appear-
ance.
Before: Edwards, Chief Judge, Ginsburg and Tatel,
Circuit Judges.
Opinion for the Court filed by Circuit Judge Tatel.
Tatel, Circuit Judge: On behalf of the nation's nearly nine
million asthmatics, the American Lung Association and the
Environmental Defense Fund challenge the Environmental
Protection Agency's refusal to revise the primary national
ambient air quality standards for sulfur dioxide
(SO2). Declining to promulgate a more stringent national
standard, the EPA Administrator concluded that the substan-
tial physical effects experienced by some asthmatics from
exposure to short-term, high-level SO2 bursts do not amount
to a public health problem. Because the Administrator failed
adequately to explain this conclusion, we remand for further
elucidation.
I
Driven by its "deep concern for protection of the health of
the American people," Sen. Rep. No. 91-1196, at 1 (1970)
("Senate Report"), Congress enacted the Clean Air Act
Amendments of 1970, Pub. L. No. 91-604, 84 Stat. 1676 (1970)
(codified as amended at 42 U.S.C. ss 7401-7671q (1994)),
mandating a "massive attack on air pollution," Senate Report
at 1. As amended, the Clean Air Act erects a comprehensive
system of national ambient air quality standards ("NAAQS")
to regulate health-threatening air pollutants. The statute
defines primary NAAQS as "ambient 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).
Once the EPA Administrator concludes that a pollutant
"may reasonably be anticipated to endanger public health or
welfare" and that it comes from "numerous or diverse mobile
or stationary sources," id. s 7408(a)(1)(A)-(B), the Act re-
quires the Administrator to produce "criteria," defined as the
latest scientific data on "all identifiable effects on public
health" caused by that pollutant. Id. s 7408(a)(2). Based on
these comprehensive criteria and taking account of the "pre-
ventative" and "precautionary" nature of the act, Lead Indus-
tries Ass'n, Inc. v. EPA, 647 F.2d 1130, 1155 (D.C. Cir. 1980),
the Administrator must then decide what margin of safety
will protect the public health from the pollutant's adverse
effects--not just known adverse effects, but those of scientific
uncertainty or that "research has not yet uncovered." Id. at
1153. Then, and without reference to cost or technological
feasibility, the Administrator must promulgate national stan-
dards that limit emissions sufficiently to establish that margin
of safety. See 42 U.S.C. s 7409(b)(1); American Petroleum
Inst. v. Costle, 665 F.2d 1176, 1181-82 (D.C. Cir. 1981)
(describing NAAQS promulgation procedure); Lead Indus-
tries, 647 F.2d at 1148-50 (in establishing NAAQS, Congress
deliberately subordinated economic and technological feasibil-
ity concerns to the achievement of public health goals).
States bear primary responsibility for attaining, maintaining,
and enforcing these standards. See 42 U.S.C. s 7410.
In its effort to reduce air pollution, Congress defined public
health broadly. NAAQS must protect not only average
healthy individuals, but also "sensitive citizens"--children, for
example, or people with asthma, emphysema, or other condi-
tions rendering them particularly vulnerable to air pollution.
Senate Report at 10; Lead Industries, 647 F.2d at 1152. If a
pollutant adversely affects the health of these sensitive indi-
viduals, EPA must strengthen the entire national standard.
Lead Industries, 647 F.2d at 1153 (NAAQS "must be set at a
level at which there is 'an absence of adverse effect' on [ ]
sensitive individuals") (quoting Senate Report at 10).
Sulfur Dioxide and Asthmatics
A highly reactive colorless gas smelling like rotten eggs,
sulfur dioxide derives primarily from fossil fuel combustion.
Best known for causing "acid rain," at elevated concentrations
in the ambient air, SO2 also directly impairs human health.
As the Administrator explains in the Final Decision on review
here, at concentrations above 2.0 parts per million ("ppm"),
SO2 can affect healthy nonasthmatic individuals; below 2.0
ppm, it primarily affects people with asthma. National Am-
bient Air Quality Standards for Sulfur Oxides (Sulfur Diox-
ide)--Final Decision, 61 Fed. Reg. 25,566, 25,570 (1996).
Following the passage of the Clean Air Act, EPA promul-
gated the SO2 NAAQS in effect today. The primary stan-
dards consist of a 24-hour standard (0.14 ppm averaged over
24 hours not to be exceeded more than once a year) and an
annual standard (0.03 ppm annual arithmetic mean). Id. at
25,568. EPA also established a "secondary" three-hour stan-
dard (0.50 ppm averaged over three hours not to be exceeded
more than once a year), designed to protect the "public
welfare" against non-health-related effects such as visibility
impairment or environmental degradation, see 42 U.S.C.
s 7409(b)(2). Petitioners do not challenge these existing
standards.
Approximately four percent of the nation's population suf-
fers from asthma. Characterized by bronchoconstriction--
shortness of breath, coughing, wheezing, chest tightness, and
sputum production--asthma is triggered by many different
stimuli, including cold or dry air, exercise or pollen as well as
airborne pollutants. The effects of bronchoconstriction can
vary from short-term discomfort, such as an hour-long reac-
tion with no lasting after-effects, to asthma attacks requiring
medication or hospitalization. Although rare, death can re-
sult.
Sulfur dioxide induces bronchoconstriction in asthmatics,
but only under certain conditions. To experience adverse
effects from SO2 concentrations below 1.0 ppm, asthmatics
must be exposed for five minutes or longer while breathing
quickly and heavily through both nose and mouth, the sort of
breathing induced by light exercise, shoveling snow, climbing
several flights of stairs, or jogging to catch a bus. At
concentrations above 2.0 ppm, SO2 causes adverse effects
even if the exposure lasts less than five minutes or the
asthmatic breathes regularly. See Second Addendum to Air
Quality Criteria for Particulate Matter and Sulfur Oxides
(1982): Assessment of Newly Available Health Effects Infor-
mation (1986).
The Challenged Final Decision
This case concerns the effect on asthmatics of what are
known as high-level SO2 bursts, defined as emissions of 0.50
ppm or more lasting at least five minutes. Occurring sporad-
ically and from specific sources, SO2 bursts come primarily
from power utilities; the rest come from nonutility sources
such as industrial boilers, petroleum refineries, pulp and
paper mills, sulfuric acid plants, and aluminum smelters.
Citing the health concerns of asthmatics and relying on a
1977 amendment to the Clean Air Act, in which Congress
ordered the Agency to review and revise all criteria and
NAAQS by 1980 and at five-year intervals thereafter, 42
U.S.C. s 7409(d), petitioners urged EPA to issue a new
NAAQS limiting short-term SO2 bursts. Not until 1996, after
petitioners sued twice to compel a decision, see Environmen-
tal Defense Fund v. Thomas, 870 F.2d 892 (2d Cir. 1989);
American Lung Ass'n v. Browner, Civil Action No. 92-5316
(E.D.N.Y. Nov. 12, 1992), and after two rounds of public
notice and comment, did EPA issue its final decision regard-
ing SO2 NAAQS. See NAAQS for Sulfur Oxides (Sulfur
Dioxide)--Reproposal, 59 Fed. Reg. 58,958 (1994); Proposed
Decision Not To Revise the National Ambient Air Quality
Standards for Sulfur Oxides (Sulfur Dioxide), 53 Fed. Reg.
14,926 (1988). Rejecting petitioners' arguments, EPA con-
cluded not only that the annual and 24-hour primary stan-
dards needed no revision, but also that an additional five-
minute standard was unnecessary to protect asthmatics. See
Final Decision at 25,575-76.
In arriving at her final decision, the Administrator re-
viewed a decade of data on the extent of high-level short-term
SO2 bursts and their effects on public health. See Review of
the National Ambient Air Quality Standards for Sulfur Ox-
ides: Assessment of Scientific and Technical Information:
Supplement to the 1986 OAQPS Staff Paper Addendum (Sept.
1994); Supplement to the Second Addendum (1986) to Air
Quality Criteria for Particulate Matter and Sulfur Oxides
(1982): Assessment of New Findings on Sulfur Dioxide Acute
Exposure Health Effects in Asthmatic Individuals (Aug.
1994). Based on clinical studies of mild to moderate asthmat-
ics, she found that when such individuals breathe rapidly
while exposed to SO2 concentrations of 0.60 ppm for five
minutes, "substantial percentages (>= 25 percent)" experience
effects "distinctly exceeding ... [the] typical daily variation in
lung function" that asthmatics routinely experience. Final
Decision at 25,572. The severity of these atypical effects, she
found, "is likely to be of sufficient concern to cause disruption
of ongoing activities, use of bronchodilator medication, and/or
possible seeking of medical attention." Id.
The scientific community disagreed about the medical sig-
nificance of these effects and whether they should be consid-
ered "adverse." Some experts took the position that such
symptoms usually have no lasting impact, amounting at worst
to a brief period of reversible discomfort; others argued that
even a one-hour disruption of activity can amount to a worri-
some adverse health effect. The Administrator left this
dispute unresolved. Instead, she discerned in the medical
debate a consensus, which she adopted, that "repeated occur-
rences of such effects should be regarded as significant from
a public health standpoint." Id. at 25,573 (emphasis added).
The Administrator then discussed the three exposure anal-
yses on which the 1994 version of the proposed rule rested.
These studies estimated that from 180,000 to 395,000 "expo-
sure events"--defined as a heavily breathing asthmatic ex-
posed to an SO2 burst--occur annually, affecting from 68,000
to 166,000 asthmatic individuals. Id. at 25,574. In view of
the Administrator's previous finding, reiterated by agency
counsel at oral argument, that at least 25 percent of asthmat-
ics experience atypical effects from exposure events, these
data suggest that as many as 41,500 (>= 25 percent of 166,000)
asthmatics experience atypical effects from repeated SO2
bursts each year. At the same time, the Administrator
acknowledged that subsequent industry studies of four nonu-
tility sources suggest that the 1994 studies may have overesti-
mated exposure for certain SO2 sources, id., meaning that the
number of affected asthmatics could be lower. The Adminis-
trator did not resolve the conflict between the studies.
Armed with all these data, the Administrator concluded
that "the likelihood that asthmatic individuals will be exposed
... is very low when viewed from a national perspective,"
that "5-minute peak SO2 levels do not pose a broad public
health problem when viewed from a national perspective,"
and that "short-term peak concentrations of SO2 do not
constitute the type of ubiquitous public health problem for
which establishing a NAAQS would be appropriate." Id. at
25,575. Describing SO2 bursts as "localized, infrequent and
site-specific," she concluded that a new national standard was
unnecessary. Id. The Administrator nevertheless decided
to encourage individual states to address short-term high-
level SO2 emissions, initiating a rulemaking to provide appro-
priate guidance. Proposed Implementation Requirements for
Reduction of Sulfur Oxide (Sulfur Dioxide) Emissions, 62
Fed. Reg. 210 (Jan. 2, 1997) ("Proposed State Guidelines
Rulemaking") (soliciting public comment on proposed guide-
lines for state monitoring and regulation of five-minute peaks
of SO2).
Petitioners now challenge the Administrator's decision de-
clining to promulgate a new NAAQS. They assert that by
failing to establish a five-minute NAAQS capping SO2 emis-
sions at 0.60 ppm, EPA has violated its statutory responsibili-
ty to protect the public health. We review the Administra-
tor's decision pursuant to 42 U.S.C. s 7607(d)(9)(A)-(C)
("[C]ourt may reverse any such [agency] action found to be
... arbitrary, capricious, an abuse of discretion, or otherwise
not in accordance with law; ... [or] in excess of statutory ...
authority, or limitations....").
II
Petitioners challenge much of the data the Administrator
relied on, as well as the conclusions she drew. Generally
speaking, we will not second-guess EPA in its area of special
expertise. See Natural Resources Defense Council v. United
States EPA, 824 F.2d 1146, 1163 (D.C. Cir. 1987) (en banc);
American Petroleum Institute, 665 F.2d at 1184. Applying
this deferential standard of review, we accept the Administra-
tor's analysis of the exposure studies in the record, as well as
the implication of her analysis--that thousands of asthmatics
can be expected to react atypically to SO2 bursts each year.
Petitioners contend that the Administrator's analysis
amounts to a conclusive finding that SO2 bursts adversely
affect asthmatics' health, thus triggering her duty to promul-
gate a new NAAQS. See Lead Industries, 647 F.2d at 1153.
At oral argument, counsel for EPA vigorously disputed peti-
tioners' contention that the Administrator "found" an adverse
health effect. As we read the record, agency counsel appears
to be correct: The Administrator did not decide whether
asthmatic reaction to SO2 bursts--"disruption of ongoing
activities, use of bronchodilator medication, and/or possible
seeking of medical attention"--amounts to an adverse health
effect or merely, as some medical experts argued, run-of-the-
mill asthma symptoms indistinguishable from bronchodilation
due to cold air or exercise. Final Decision at 25,572-73.
Skipping this disputed question, the Administrator concluded
that, regardless of the impact of single occurrences, "repeated
occurrences of such effects should be regarded as significant
from a public health standpoint." Id. at 25,573.
Disagreeing with this approach, petitioners argue that the
Administrator had to answer the subsidiary "adverse effects"
question, pointing to her warning to all states in the subse-
quent rulemaking that "[a]lthough these episodes are few, it
is clear that 5-minute SO2 ambient concentration peaks pose
a health threat to sensitive exposed populations," Proposed
State Guidelines Rulemaking at 211. We need not decide
that issue at this time, however, because we think the Admin-
istrator has failed to explain the answer she did give, i.e., that
SO2 bursts do not amount to a "public health" problem within
the meaning of the Act. The link between this conclusion and
the factual record as interpreted by EPA--that "repeated"
exposure is "significant" and that thousands of asthmatics are
exposed more than once a year--is missing. Why is the fact
that thousands of asthmatics can be expected to suffer atypi-
cal physical effects from repeated five-minute bursts of high-
level sulfur dioxide not a public health problem? Why are
from 180,000 to 395,000 annual "exposure events" (the range
indicated by the 1994 studies) or some fewer number (as
suggested by the industry studies) so "infrequent" as to
warrant no regulatory action? Why are disruptions of ongo-
ing activities, use of medication, and hospitalization not "ad-
verse health effects" for asthmatics? Answers to these ques-
tions appear nowhere in the administrative record.
In her only statement resembling an explanation for her
conclusion that peak SO2 bursts present no public health
hazard, the Administrator characterizes the bursts as "local-
ized, infrequent and site-specific." Final Decision at 25,575.
But nothing in the Final Decision explains why "localized,"
"site-specific" or even "infrequent" events might nevertheless
create a public health problem, particularly since, in some
sense, all pollution is local and site-specific, whether spewing
from the tailpipes of millions of cars or a few offending smoke
stacks. From the record, we know that at least six communi-
ties experience "repeated high 5-minute peaks greater than
0.60 ppm SO2," id., and agency counsel told us at oral
argument that these so-called "hot spots" are not the only
places where repeated exposure occurs. Nowhere, however,
does the Administrator explain why these data amount to no
more than a "local" problem.
Without answers to these questions, the Administrator
cannot fulfill her responsibility under the Clean Air Act to
establish NAAQS "requisite to protect the public health," 42
U.S.C. s 7409(b)(1), nor can we review her decision. Judicial
deference to decisions of administrative agencies like EPA
rests on the fundamental premise that agencies engage in
reasoned decision-making. See Vermont Yankee Nuclear
Power Corp. v. Natural Resources Defense Council, 435 U.S.
519, 524-25, 544-45, 558 (1978); SEC v. Chenery Corp., 332
U.S. 194, 209 (1947) (agency's experience, appreciation of
complexities and policies, and responsible treatment of the
facts "justifies the use of the administrative process"). With
its delicate balance of thorough record scrutiny and deference
to agency expertise, judicial review can occur only when
agencies explain their decisions with precision, for "[i]t will
not do for a court to be compelled to guess at the theory
underlying the agency's action...." SEC v. Chenery Corp.,
332 U.S. at 196-97. Where, as here, Congress has delegated
to an administrative agency the critical task of assessing the
public health and the power to make decisions of national
import in which individuals' lives and welfare hang in the
balance, that agency has the heaviest of obligations to explain
and expose every step of its reasoning. For these compelling
reasons, we have always required the Administrator to "co-
gently explain why [she] has exercised [her] discretion in a
given manner." Motor Vehicle Mfrs. Ass'n v. State Farm
Mut. Auto. Ins., 463 U.S. 29, 48 (1983).
In this case, the Administrator may well be within her
authority to decide that 41,500 or some smaller number of
exposed asthmatics do not amount to a public health problem
warranting national protective regulation, or that three or six
or twelve annual exposures present no cause for medical
concern. But unless she describes the standard under which
she has arrived at this conclusion, supported by a "[ ]plausi-
ble" explanation, id. at 43, we have no basis for exercising our
responsibility to determine whether her decision is "arbitrary,
capricious, an abuse of discretion, or otherwise not in accor-
dance with law; ... [or] in excess of statutory ... authority,
or limitations...." 42 U.S.C. s 7607(d)(9)(A)-(C).
Given the gaps in the Final Decision's reasoning, we must
remand this case to permit the Administrator to explain her
conclusions more fully. We therefore need not resolve the
debate between the parties over whether the Clean Air Act
authorizes the Administrator to decline to protect an identifi-
able group of asthmatics from a known adverse health effect.
Although our cases make clear that the Administrator has
broad discretion to establish an "adequate margin of safety"
above and beyond what scientific certainty prescribes and to
craft regulations that protect against unknown harms, see
Lead Industries, 647 F.2d at 1153-55 (Administrator must
"err on the side of caution" when establishing the margin of
safety, even where the "medical significance [of the effects] is
a matter of disagreement"), they do not necessarily establish
the converse proposition--that the Administrator may decline
to establish a margin of safety in the face of documented
adverse health effects. Since in this case the Administrator
has failed adequately to explain her conclusion that no public
health threat exists, we can leave the issue of the scope of her
authority for another day.
We remand this case to the agency for further proceedings
consistent with this opinion.
So ordered.