South Coast Air Quality Management District v. Environmental Protection Agency

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United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued October 12, 2006 Decided December 22, 2006

No. 04-1200

SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT,
PETITIONER

v.

ENVIRONMENTAL PROTECTION AGENCY,
RESPONDENT

NATIONAL ENVIRONMENTAL DEVELOPMENT ASSOCIATION’S
CLEAN AIR REGULATORY PROJECT, ET AL.,
INTERVENORS

Consolidated with
No. 04-1201, et al.

On Petitions for Review of a Final Rule of the
Environmental Protection Agency

David S. Baron argued the cause for the Environmental
petitioners and South Coast Air Quality Management District.
 2

With him on the briefs were Howard I. Fox, Ann B. Weeks,
Jonathan F. Lewis, Barbara B. Baird, and Adam Babich. Kurt
R. Wiese entered an appearance.

William L. Pardee, Assistant Attorney General, Attorney
General’s Office of Commonwealth of Massachusetts, argued
the cause for petitioner Commonwealth of Massachusetts, et al.
With him on the briefs were Thomas F. Reilly, Attorney
General; Richard Blumenthal, Attorney General, Attorney
General’s Office of the State of Connecticut, Kimberly
Massicotte and Matthew Levine, Assistant Attorneys General;
Carl Danbert, Attorney General, Attorney General’s Office of
the State of Delaware, Valerie S. Csizmadia, Deputy Attorney
General; G. Steven Rowe, Attorney General, Attorney General’s
Office of the State of Maine, Gerald D. Reid, Assistant Attorney
General; Robert J. Spagnoletti, Attorney General, Attorney
General’s Office of the District of Columbia, Todd S. Kim,
Solicitor General, Edward S. Schwab, Deputy Attorney General,
Donna M. Murasky, Senior Litigation Counsel; Eliot Spitzer,
Attorney General, Attorney General’s Office of the State of New
York, J. Jared Snyder, David A. Munro, and Lisa S. Kwong,
Assistant Attorneys General; and Robert A. Reiley, Counsel,
Commonwealth of Pennsylvania, Department of Environmental
Protection.

John K. McManus, Assistant Attorney General, Attorney
General’s Office of State of Ohio, argued the cause for
petitioner State of Ohio. With him on the briefs was Dale T.
Vitale, Assistant Attorney General.

Frank S. Craig, III argued the cause for the Industry
petitioners. With him on the briefs were Charles H. Knauss,
Robert V. Zener, John B. King, Steven J. Levine, and Patrick
O’Hara.
 3

David J. Kaplan, Attorney, U.S. Department of Justice,
argued the cause for respondent. With him on the brief were
John C. Cruden, Assistant Attorney General, Natalia T.
Sorgente, Attorney, and Jan M. Tierney, Attorney, U.S.
Environmental Protection Agency. Eric G. Hostetler, Attorney,
U.S. Department of Justice, entered an appearance.

David S. Baron and Howard I. Fox were on the brief of the
Environmental intervenors.

Charles H. Knauss, Leslie S. Ritts, Lorane F. Hebert,
Norman W. Fichthorn, Lucinda Minton Langworthy, Allison D.
Wood, Leslie A. Hulse, Richard S. Wasserstrom, Maurice H.
McBride, Ralph J. Colleli, M. Elizabeth Cox, Jan S. Amundson,
and Quentin Riegel were on the brief of the Industry intervenors
in support of Respondent.

Frank S. Craig, III, John B. King, Geraldine E. Edens, and
Frederick R. Anderson were on the brief of amici curiae The
Chamber of Greater Baton Rouge, et al. in support of
Respondent.

Before: HENDERSON, ROGERS and BROWN, Circuit Judges.

Opinion for the Court filed by Circuit Judge ROGERS.

ROGERS, Circuit Judge: This case consolidates challenges
to the Final Phase 1 Rule To Implement the 8-Hour Ozone
National Ambient Air Quality Standard, 69 Fed. Reg. 23,951
(Apr. 30, 2004) (codified at 40 C.F.R. parts 40, 51, 81)
(hereinafter “2004 Rule”), promulgated by the Environmental
Protection Agency pursuant to the Clean Air Act (“CAA” or
“the Act”), 42 U.S.C. § 7401 et seq. Because EPA has failed to
heed the restrictions on its discretion set forth in the Act, we
grant the petitions in part, vacate portions of the rule, and
 4

remand the matter to EPA for further proceedings.

I.

The earliest clean air laws date back to the nineteenth
century, when industrial cities sought to reduce smoke
emissions. See GARY C. BRYNER, BLUE SKIES, GREEN POLITICS:
THE CLEAN AIR ACT OF 1990 AND ITS IMPLEMENTATION 98 (2d
ed. 1995). It was not until much later that the federal
government became involved. The first Clean Air Act was
passed in 1963, see Pub. L. No. 88-206, 77 Stat. 392 (1963), but
this effort, supplying little more than research funding, bore
little resemblance to the comprehensive scheme that Congress
would later impose.

The Clear Air Act Amendments of 1970 introduced the
now-familiar arrangement of state-federal cooperation. See
Clean Air Act Amendments of 1970, Pub. L. No. 91-604, 84
Stat. 1676 (1970). EPA was to prescribe a primary national
ambient air quality standard (“NAAQS”) for airborne pollutants
that was “requisite to protect the public health.” Id. § 4(a), 84
Stat. at 1678-80 (codified at 42 U.S.C. § 7409). The NAAQS
was to be attained by a state implementation plan (“SIP”),
developed by the state and approved by EPA, that introduced
sufficient pollution control techniques so as to reach attainment
by 1975, with the possibility of a one-time extension of two
more years. Id. § 4(a), 84 Stat. at 1680-82 (codified at 42 U.S.C.
§ 7410 (amended 1977)). This approach, which applied
identically to all “criteria” pollutants, proved overly ambitious.
Congress amended the Act in 1977, extending the attainment
deadlines until December 31, 1987. Pub. L. No. 95-95, §
129(b), 91 Stat. 685, 746-47 (codified at 42 U.S.C. § 7502(a)(2)
(amended 1990)).

With the new deadline approaching and penalties looming
 5

for states yet to attain, Congress stepped in again. By this time,
Congress was considering new approaches to deal with unclean
air. See Henry A. Waxman, An Overview of the Clean Air Act
Amendments of 1990, 21 ENVTL. L. 1721, 1731-33 (1991)
(hereinafter “Overview”). The existing approach, which
specified the ends to be achieved but left broad discretion as to
the means, had done little to reduce the dangers of key
contaminants. For example, Don Theiler, Director of the
Wisconsin Bureau of Air Management, appearing on behalf of
two national associations of state-and-local air-control agencies,
testified that between August 1987 and February 1989, the
number of areas violating the ozone NAAQS had increased,
from seventy to ninety, exposing as many as 95 million people
to unhealthy levels of ozone. See Clean Air Act Standards:
Hearing Before the Subcomm. on Health and the Environment
of the H. Comm. on Energy and Commerce, 101st Cong. 30
(1989). In light of such failures, Congress culminated nearly ten
years of hearings and debates by enacting the 1990 Amendments
to the Act. Pub. L. No. 101-549, 104 Stat. 2399 (Nov. 15,
1990). This version of the Act provides the backdrop for the
petitions before the court.

The 1990 Amendments abandoned the discretion-filled
approach of two decades prior in favor of more comprehensive
regulation of six pollutants that Congress found to be
particularly injurious to public health: ozone, carbon monoxide,
small particulate matter, sulfur dioxide, nitrogen dioxide, and
lead. See CAA §§ 181-192, 42 U.S.C. §§ 7511-7514a. The old
ends-driven approach that had proven unsuccessful for these
pollutants was redesignated Subpart 1 (of Part D of Title I),
which Congress instructed “shall not apply with respect to
nonattainment areas for which attainment dates are specifically
provided under other provisions of this part.” CAA §
172(a)(2)(D), 42 U.S.C. § 7502(a)(2)(D). In place of Subpart 1,
Congress enacted Subpart 2 to deal with the specific problem of
 6

ozone. See CAA §§ 181-185B, 42 U.S.C. §§ 7511-7511f.
Ozone, an essential presence in the atmosphere’s stratospheric
layer, is dangerous at ground level. There, ozone is formed by
the chemical reaction of nitrogen oxides (“NOx”) with any of a
number of volatile organic compounds (“VOCs”), in the
presence of sunlight. See West Virginia v. EPA, 362 F.3d 861,
865 (D.C. Cir. 2004). Ground-level ozone is a key component
of urban smog and exposure to high concentrations “can cause
lung dysfunction, coughing, wheezing, shortness of breath,
nausea, respiratory infection, and in some cases, permanent
scarring of the lung tissue.” Overview, supra, at 1758; see S.
REP. NO. 101-228, at 6 (1989), reprinted in 5 COMM. ON ENV’T
& PUB. WORKS, U.S. SENATE, A LEGISLATIVE HISTORY OF THE
CLEAN AIR ACT AMENDMENTS OF 1990, at 8338, 8346
(hereinafter “LEGISLATIVE HISTORY”).

No longer willing to rely upon EPA’s exercise of discretion,
Congress adopted a graduated classification scheme that
prescribed mandatory controls that each state must incorporate
into its SIP. Thus, as of the date of enactment of the 1990
Amendments, areas failing to reach attainment under the
NAAQS would become, upon such designation by EPA, subject
to Subpart 2 requirements by operation of law. See CAA §
181(a)(1), 42 U.S.C. § 7511(a)(1). Under Subpart 2, each area
was to be classified according to its design value—the measured
concentration of ground-level ozone. The statutory Table 1
provided that areas were to be classified as Marginal, Moderate,
Serious, Severe, or Extreme depending upon how much the
design value exceeded the NAAQS at the time of designation.
CAA § 181(a) tbl.1, 42 U.S.C. § 7511(a) tbl.1. Areas with
greater problems were given more time to attain the NAAQS but
a harsher set of mandatory controls, including provisions for
demonstrations of reasonable further progress, NOx control,
motor vehicle emissions control, and new source review. See
CAA § 182, 42 U.S.C. § 7511a. Areas that failed to meet a
 7

deadline were to be reclassified to a higher classification
automatically, thereby according more time to comply with the
NAAQS while subjecting that area to more stringent mandatory
controls. CAA § 181(b)(2), 42 U.S.C. § 7511(b)(2). This
protocol was prescribed whether or not that area was closer to
attainment when it missed the deadline than when it was
originally classified. For Severe and Extreme areas that still had
not reached attainment by November 15, 2005 or 2010,
respectively, the Act called for the imposition of penalties to
provide incentives for major polluters to reduce VOC emissions.
See CAA § 185, 42 U.S.C. § 7511d. Under the 1990
Amendments, the NAAQS stood at 0.12 parts per million
(“ppm”), measured as the maximum average concentration for
a one-hour period during a calendar year. See 40 C.F.R. §
50.9(a) & app. H. This regulatory scheme remained in place
until 1997.

Although Subpart 2 of the Act and its Table 1 rely upon the
then-existing NAAQS of 0.12 ppm, measured over a one-hour
period, elsewhere the Act contemplates that EPA could change
the NAAQS based upon its periodic review of “the latest
scientific knowledge useful in indicating the kind and extent of
all identifiable effects on public health” that the pollutant may
cause. CAA §§ 108(a), 109(d), 42 U.S.C. §§ 7408(a), 7409(d).
The Act provides that EPA may relax a NAAQS, but in so
doing, EPA must “provide for controls which are not less
stringent than the controls applicable to areas designated
nonattainment before such relaxation.” CAA § 172(e), 42
U.S.C. § 7502(e). This provision protects against backsliding.

In 1997, citing a new scientific understanding that
prolonged ozone exposure was more harmful to public health
than the short-term exposure then regulated, EPA promulgated
a rule setting a new NAAQS for ambient ozone. See NAAQS
for Ozone, 62 Fed. Reg. 38,856 (July 18, 1997) (codified at 40
 8

C.F.R. §§ 50.9, 50.10) (hereinafter “1997 Rule”). The new
NAAQS replaced the one-hour, 0.12 ppm standard with an
eight-hour, 0.08 ppm standard, now measured as the fourth-
highest daily level in a calendar year. Id. The new standard
thus both changed the measuring scheme and was marginally
more stringent, as EPA recognized that an eight-hour level of
0.09 ppm would have “generally represent[ed] the continuation
of the present level of protection.” Id. at 38,858. Alongside its
revised standard, EPA also announced an implementation
“guidance” indicating its intention to phase out the one-hour
standard only after “EPA determines that the area has air quality
meeting the 1-hour standard,” id. at 38,894 (codified at 40
C.F.R. § 50.9(b)), while implementing the eight-hour standard
under the generic Subpart 1 of the Act, id. at 38,873.

On petitions for review, this court held, in relevant part, that
under Chevron1 Step 1 EPA could not use the discretion-filled
Subpart 1. Congress had expressed its clear intent that the
mandatory control scheme it set forth in Subpart 2 was to be
used to regulate ozone. Am. Trucking Ass’ns v. EPA, 175 F.3d
1027, amended on reh’g, 195 F.3d 4 (D.C. Cir. 1999). On
certiorari, the Supreme Court agreed that Subpart 2
“unquestionably” “provide[s] for classifying nonattainment
ozone areas under the revised standard,” but disagreed that the
case could be resolved exclusively under Chevron Step 1.
Whitman v. Am. Trucking Ass’ns, 531 U.S. 457, 482-86 (2001).
Instead, the Court recognized that

to the extent that the new ozone standard is stricter
than the old one, the classification system of Subpart 2
contains a gap, because it fails to classify areas whose
ozone levels are greater than the new standard (and

1
Chevron U.S.A. Inc. v. Natural Res. Def. Council, Inc., 467
U.S. 837, 842-43 (1984) (employing two-step analysis).
 9

thus nonattaining) but less than the approximation of
the old standard codified by Table 1.

Id. at 483 (citations omitted). In addition to this classification
gap, the Court also found a measurement gap and a timing gap:
the one-hour averages could not well be used to evaluate eight-
hour ozone concentrations and the deadlines set forth in Table
1 would “make no sense for areas that are first classified under
a new standard after November 15, 1990.” Id. at 483-84. The
Court therefore indicated that “[t]hese gaps in Subpart 2’s
scheme prevent us from concluding that Congress clearly
intended Subpart 2 to be the exclusive, permanent means of
enforcing a revised ozone standard in nonattainment areas.” Id.
at 484. Thus, it “would defer to the EPA’s reasonable resolution
of that ambiguity” under Chevron Step 2. Id.

While recognizing the existence of these gaps, the Supreme
Court was careful to emphasize their narrow scope. EPA was
not “to render Subpart 2’s carefully designed restrictions on
EPA discretion utterly nugatory,” nor could it “construe the
statute in a way that completely nullifies textually applicable
provisions meant to limit its discretion.” Id. at 484-85. Because
“Subpart 2 was obviously written to govern implementation for
some time,” EPA’s 1997 approach, leaving Subpart 2 “abruptly
obsolete,” was “astonishing.” Id. at 485. Thus, while EPA was
invited to exercise its discretion as to the relationship between
Subparts 1 and 2, the Court instructed that the range of
reasonable interpretations was constrained.

In 2003, with the eight-hour NAAQS still awaiting
implementation by EPA, several environmental groups sued
seeking adherence by EPA to its obligation to designate
nonattainment areas under section 107(d)(1) of the Act, 42
U.S.C. § 7407(d)(1). See Air Quality Designations and
Classifications for the 8-Hour Ozone NAAQS, 69 Fed. Reg.
 10

23,858, 23,860 (Apr. 30, 2004). EPA entered into a consent
decree requiring it to issue the designations by April 15, 2004.
Id.

On April 30, 2004, EPA promulgated the implementation
rule, 69 Fed. Reg. 23,951, which announced a new approach to
ozone regulation. Reversing its 1997 position, EPA announced
that the one-hour NAAQS would be withdrawn “in full,” one
year following the effective date of the eight-hour NAAQS
designations. Id. at 23,954 (codified at 40 C.F.R. § 50.9(b)).
Under the 2004 Rule, Subpart 2 would apply only to areas that
were nonattaining under both the eight-hour standard and the
now-revoked one-hour standard. Id. at 23,958. Subpart 1 would
apply to the remaining eight-hour nonattainment areas (i.e.,
those with eight-hour design values greater than 0.08 ppm but
one-hour design values no greater than 0.12 ppm). EPA
reasoned that placing more areas under the “more flexible
provisions of the CAA” would “provide the States and Tribes
with greater discretion in determining the mix of controls
needed to expeditiously attain the 8-hour NAAQS.” Id. As a
result, 76 of 122 nonattaining areas would be governed by
Subpart 1. See Proposed Rule To Implement the 8-Hour Ozone
NAAQS, 68 Fed. Reg. 32,802, 32,814 (June 2, 2003)
(hereinafter “2003 NOPR”).

In addition to this interpretation of the classification gap,
the 2004 Rule also addressed the measurement and timing gaps.
Whereas the 1990 Amendments prescribed classifying areas as
of that date and starting the attainment clock on November 15,
1990, under the 2004 Rule, areas would be redesignated under
the eight-hour standard as covered by Subpart 1 or one of the
five categories of Subpart 2 (Marginal, Moderate, Serious,
Severe, or Extreme) according to a regulatory translation of
Table 1. Id. at 23,998 (codified at 40 C.F.R. § 50.903(a) tbl.1).
EPA’s translation meant that areas with the same percentage
 11

deviation from the one-hour NAAQS and the eight-hour
NAAQS would be classified the same. Id. at 23,957. The
deadlines for attainment set forth in Table 1 were interpreted to
restart as of the date of classification under the new standard.
See id. at 23,966-67. Because air quality had improved since
1990, the net effect of the new approach was that many areas
would have a lower classification for eight-hour ozone than they
had for one-hour ozone. Recognizing that this could result in
areas being subjected to less stringent controls, EPA interpreted
the anti-backsliding provision, section 172(e) of the Act, and
reasoned that “if Congress intended areas to remain subject to
the same level of control where a NAAQS was relaxed, they
also intended that such controls not be weakened where the
NAAQS is made more stringent.” Id. at 23,972. As a result, the
2004 Rule mandates that all “controls” from the one-hour era
must remain in place, including controls that a state was already
obligated to adopt but as yet had not. Id. However, EPA
determined that only certain of the programs established by
Congress in Subpart 2 constituted applicable “controls”; the
others would not need to be retained. So, the 2004 Rule
authorized states to remove from their SIPs one-hour New
Source Review (“NSR”), section 185 penalty provisions for
Severe and Extreme areas, conformity demonstrations, and
attainment contingency plans. Id. at 23,984-85.

II.

In these consolidated petitions, a host of parties challenge
the 2004 Rule and related EPA decisions on rehearing.2 No

2
After limited reconsideration proceedings also challenged
here, EPA reaffirmed the 2004 Rule as to NSR, see Nonattainment
Major New Source Review Implementation Under 8-Hour NAAQS:
Reconsideration, 70 Fed. Reg. 39,413 (July 8, 2005) (hereinafter
“NSR Reconsideration”), and made additional findings as to penalties,
 12

petitioner disputes that the eight-hour standard must be
implemented; instead, they differ as to how quickly it must be
attained and under what constraints. Parties with similar
concerns were grouped for briefing purposes, leaving four
principal opponents to various aspects of the 2004 Rule: the
State petitioners,3 the Environmental petitioners, the Industry
petitioners, and the State of Ohio. A subset of the petitioners
also intervened to support different aspects of the 2004 Rule to
which other petitioners objected. To summarize the challenges:
The State and Environmental petitioners contend that EPA’s
understanding of the interrelationship between Subpart 1 and
Subpart 2 contravenes the Act and led to arbitrary and capricious
choices reflected in the 2004 Rule. The State of Ohio contends
that EPA erred by establishing an unreasonable timeframe for
attainment. One Industry petitioner, the National Petrochemical
& Refiners Association (“NPRA”), contends that EPA’s
translation of the statutory one-hour Table 1, CAA § 181(a)
tbl.1, 42 U.S.C. § 7511(a) tbl.1, into a converted regulatory
eight-hour Table 1, 40 C.F.R. § 50.903(a) tbl.1, is flawed and
thus arbitrary and capricious. Another Industry petitioner, the
Chamber of Greater Baton Rouge (“Baton Rouge”), contends
that EPA lacks authority to continue to enforce any one-hour
requirements against areas with lower eight-hour classifications.
The State and Environmental petitioners, conversely, contend
that EPA should have retained more of the one-hour control
requirements to prevent backsliding, and the Environmental
petitioners contend that EPA should not have revoked the one-

timing, contingency measures, and attainment demonstrations, see
Phase 1 Implementation of the 8-Hour Ozone NAAQS:
Reconsideration, 70 Fed. Reg. 30,592 (May 26, 2005) (hereinafter
“2004 Rule Reconsideration”).
3
The State petitioners are Connecticut, Delaware, Maine,
Massachusetts, New York, and the District of Columbia.
 13

hour standard at all.

Upon review of these challenges, the court may reverse any
action found to be “arbitrary, capricious, an abuse of discretion,
or otherwise not in accordance with law.” CAA § 307(d)(9), 42
U.S.C. § 7607(d)(9). The court will defer to EPA’s statutory
interpretations in accordance with the two-step framework of
Chevron U.S.A. Inc. v. Natural Resource Defense Council, Inc.,
467 U.S. 837, 842-43 (1984); see Bluewater Network v. EPA,
372 F.3d 404, 410 (D.C. Cir. 2004). The court first asks
“whether Congress has directly spoken to the precise question
at issue.” Chevron, 467 U.S. at 842. If so, “that is the end of the
matter; for the court, as well as the agency, must give effect to
the unambiguously expressed intent of Congress.” Id. at 842-43.
However, if “the statute is silent or ambiguous with respect to
the specific issue, the question for the court is whether the
agency’s answer is based on a permissible construction of the
statute.” Id. at 843. Upon review of these challenges, for the
following reasons, we dismiss Ohio’s petition, grant the State
petition, grant the Environmental petition in part, and deny the
Industry petitions.

III.

The State of Ohio petitions for review on the ground that
the attainment dates for eight-hour ozone are unreasonably soon
and favors waiting to impose the eight-hour standard until the
one-hour standard has been achieved. The Act provides that an
aggrieved party may petition for judicial review in this court as
to any “nationally applicable regulations promulgated, or final
action taken, by the Administrator under [the Act.]” CAA §
307(b)(1), 42 U.S.C. § 7607(b)(1). However, “[o]nly an
objection to a rule or procedure which was raised with
reasonable specificity during the period for public comment
(including any public hearing) may be raised during judicial
 14

review.” CAA § 307(d)(7)(B), 42 U.S.C. § 7607(d)(7)(B). As
a result, Ohio is barred from seeking relief from the 2004 Rule.

In its petition for review, Ohio objects to the allegedly
unreasonable attainment time-frame adopted by EPA. Ohio’s
comments during rulemaking, however, express a different view
as to attainment deadlines: that “[EPA’s] approach would be a
reasonable interpretation of Subpart 2.” Ohio EPA’s Comments
on the Proposed 8-Hour Ozone Implementation Plan 2. It is
settled law that a party that presents a winning opinion before
the agency cannot reverse its position before this court. See S.
Pac. Transp. Co. v. ICC, 69 F.3d 583, 588 (D.C. Cir. 1995).

Citing Appalachian Power Co. v. EPA, 135 F.3d 791 (D.C.
Cir. 1998), Ohio insists that it preserved its challenges in the
cover letter to its comments, where it cautioned EPA that “[t]he
surest way to develop an implementation plan that holds up to
judicial scrutiny would be through an amendment to the Clean
Air Act.” Letter from Christopher Jones, Director, Ohio EPA,
to Marianne L. Horinko, Acting Administrator, EPA (Aug. 1,
2003). Under Appalachian Power, commenters must be given
some leeway in developing their argument before this court, so
long as the comment to the agency was adequate notification of
the general substance of the complaint. Id. at 817-18.
Moreover, for aggrievement that reaches “key assumptions” of
an agency, even the failure to object during the comment period
is insufficient to bar review. Id. at 818. Here, Ohio cannot
seriously claim that it put EPA on notice of its objections to the
details of the 2004 Rule merely by expressing a general
procedural preference in its cover letter. And even if the
attainment deadlines constitute a “key assumption,” nothing in
Appalachian Power supersedes the principle that commenters
may not reverse course after their preferred approach is adopted
by the agency. Therefore, Ohio has forfeited its claims and we
must dismiss its petition.
 15

IV.

The State and Environmental petitioners challenge EPA’s
resolution of the gap between Subpart 1 and Subpart 2
recognized by the Supreme Court in Whitman, 531 U.S. at 483.
The State and Environmental petitioners contend that EPA has
repeated the errors of the 1997 Rule by promulgating a
regulation where 76 of 122 nonattaining areas are projected to
be governed by Subpart 1. See 2003 NOPR, 68 Fed. Reg. at
32,814. They further contend that the Act does not support any
ozone nonattainment areas being regulated exclusively under
Subpart 1. Although Whitman forecloses the latter contention,
we agree that the manner in which the 2004 Rule treats the
relationship between Subpart 1 and Subpart 2 fails to adhere to
the statutory scheme enacted by Congress in 1990 to address
ground-level ozone in nonattainment areas.

A.
The purpose of the Clean Air Act has long been “to promote
the public health and welfare and the productive capacity of [the
Nation’s] population.” CAA § 101(b)(1), 42 U.S.C. §
7401(b)(1). The promulgation of a primary NAAQS
specifically addresses this first component, public health. CAA
§ 109(b), 42 U.S.C. § 7409(b); see Am. Petroleum Inst. v.
Costle, 665 F.2d 1176, 1181 (D.C. Cir. 1981). Because
Congress recognized that it must attain this level of air-quality
public health without resort to any “‘magic’ solutions,” it
adopted the comprehensive regulatory requirements of Subpart
2. H.R. REP. NO. 101-490, pt. 1, at 147 (1990), reprinted in 2
LEGISLATIVE HISTORY, supra, at 3021, 3171.

Had there been no scientific advancements of moment in
EPA’s view since 1990, the one-hour standard would still be in
place. Any area with a one-hour ozone level exceeding 0.121
 16

ppm would be designated nonattainment and all such
nonattainment areas would be regulated pursuant to the detailed
protocols of Subpart 2. The 1997 Rule changed two aspects of
the NAAQS: the measuring stick and the target. Changes in the
former provide no basis for the displacement of Congress’s
well-considered approach for reaching its desired level of public
health. EPA acknowledged that the level of public health
achieved by 0.121 ppm of one-hour ozone is equivalent to the
level of public health achieved by 0.09 ppm of eight-hour ozone.
See Whitman, 531 U.S. at 483; 1997 Rule, 62 Fed. Reg. at
38,858. Any area failing to achieve the equivalent of Congress’s
chosen level of public health must be covered by Congress’s
chosen prophylactic scheme. Therefore, to the extent that the
2004 Rule regulates areas with an eight-hour design value
exceeding 0.09 ppm under Subpart 1, EPA has misinterpreted
the gap where it is authorized to exercise its discretion and has
trespassed into areas where Subpart 2 unquestionably applies.

The Supreme Court in Whitman recognized three gaps in
the Act that were evident after the 1997 change in the NAAQS.
The first gap was a measurement gap: “Using the old 1-hour
averages of ozone levels . . . as Subpart 2 requires would
produce at best an inexact estimate of the new 8-hour averages.”
Whitman, 531 U.S. at 483 (citations omitted). The second gap
was a classification gap: “to the extent that the new ozone
standard is stricter than the old one, the classification system of
Subpart 2 contains a gap, because it fails to classify areas whose
ozone levels are greater than the new standard (and thus
nonattaining) but less than the approximation of the old standard
codified by Table 1. Id. (citations omitted). The third gap was
a timing gap: “Subpart 2’s method for calculating attainment
dates . . . seems to make no sense for areas that are first
classified under a new standard after November 15, 1990.” Id.

The State and Environmental petitioners read the
 17

classification gap quite narrowly. They maintain that this gap
merely authorized EPA to adjust Table 1 to incorporate newly
nonattaining areas into one of the Subpart 2 categories. Once
EPA translated Table 1, its discretion was exhausted. Under this
reading, however, all areas would be subject to Subpart 2 as a
matter of Chevron Step 1. The Supreme Court in Whitman
indicated otherwise. Although the Court referred to the gap as
a “fail[ure] to classify,” Whitman, 531 U.S. at 483, the Court
later said that it could not “conclud[e] that Congress clearly
intended Subpart 2 to be the exclusive, permanent means of
enforcing a revised ozone standard in nonattainment areas.” Id.
at 484 (emphasis added).

EPA interpreted the classification gap differently, indicating
“that there was no gap in the statute for those areas with a 1-
hour design value above 0.121 ppm.” 2004 Rule, 69 Fed. Reg.
at 23,957. This reasoning implies that EPA views the gap as a
two-dimensional void bounded by 0.121 ppm of one-hour ozone
and 0.08 ppm of eight-hour ozone. But this approach would
mean that areas with air less healthful than what Congress
thought it had addressed could be freed from Subpart 2. This is
not the gap that the Supreme Court recognized. The Court
characterized the gap as those “areas whose ozone levels are
greater than the new standard (and thus nonattaining) but less
than the approximation of the old standard codified by Table 1.”
Whitman, 531 U.S. at 483 (emphasis added). This statement
was preceded by reference to EPA’s assertion that the “8-hour
standard of 0.09 ppm rather than 0.08 ppm would have
‘generally represent[ed] the continuation of the [old] level of
protection.’” Id. (alterations in original) (quoting 1997 Rule, 62
Fed. Reg. at 38,858).

In other words, the gap identified in Whitman affords EPA
discretion only to the extent that an area is nonattaining but its
air quality is not as dangerous as the level addressed by the 1990
 18

Amendments, which now translates to 0.09 ppm on the eight-
hour scale. Thus, the gap extends only to the extent that the
standard was strengthened and not to the extent that the
measurement technique merely changed. Recall that when the
Supreme Court assessed the 1997 Rule, it thought that the one-
and eight-hour standards were to coexist. Id. at 478. But the
Court nowhere indicated that the still-present threshold for one-
hour compliance should be used to partition eight-hour
nonattaining areas. To the contrary, considering the statements
of the Court in context strengthens the conclusion that the
regulation of the eight-hour standard is to be independent of the
one-hour standard. Eight-hour nonattainment areas must be
subject to Subpart 2 wherever they have air at least as
unhealthful as Congress contemplated when enacting the 1990
Amendments. Because Chevron Step 1 controls the extent of
the gap, we need not address the State and Environmental
petitioners’ further contentions that EPA’s approach absurdly
uses one-hour ozone levels—a metric that EPA concedes is no
longer relevant—to determine how to fix eight-hour ozone
nonattainment, and that this interpretation, by treating areas with
similar eight-hour levels differently, is arbitrary and capricious.

B.
For areas with ozone levels between 0.08 and 0.09 ppm, the
2004 Rule overlaps with the gap recognized in Whitman. To
this extent, the question under Chevron Step 2 is whether EPA’s
interpretation, while not required to “represent[] the best
interpretation of the statute,” is reasonable. Smiley v. Citibank
(S.D.), N.A., 517 U.S. 735, 744-45 (1996). Obviously, EPA’s
approach must be “based on a permissible construction of the
statute.” Chevron, 467 U.S. at 843 (emphasis added).

In the 2004 Rule, EPA determined that for all areas where
it need not impose Subpart 2 requirements, it will not do so.
This conforms to “[o]ne of EPA’s stated goals . . . [,] to provide
 19

flexibility to States and Tribes on implementation approaches
and control measures within the structure of the CAA.” 2004
Rule, 69 Fed. Reg. at 23,958. EPA advances several reasons for
its approach: first, “because subpart 2 was developed by
Congress 13 years ago and our scientific understanding of the
causes of ozone pollution and the transport of ozone and its
precursors has significantly advanced,” id. at 23,960; and
second, “[b]ecause control requirements for marginal areas are
similar to those for subpart 1 areas, and because most of these
areas are projected to attain within 3 years, the distinction in
regulatory category may make no practical difference for many
of these areas,” id. at 23,961. See also 2003 NOPR, 68 Fed.
Reg. at 32,814. Even assuming (without deciding) for purposes
of this appeal that the 2004 Rule would be a reasonable
approach to reducing air pollution, it is not a reasonable
interpretation of Congress’s approach in the 1990 Amendments.

The main thrust of EPA’s interpretation is that Subpart 1 is
best because it maximizes EPA’s ability to tailor a SIP to the
situation of that state. But at no point does EPA explain how its
interpretation fits with the 1990 Amendments, which Congress
purposefully crafted to limit EPA discretion. See Whitman, 531
U.S. at 485. Further, to the extent EPA’s rationale rests on the
claims that technology has advanced since 1990, Congress
considered this possibility by providing for periodic review of
each NAAQS. See CAA § 109(d)(1), 42 U.S.C. § 7409(d)(1).
There are no comparable provisions providing that Subpart 2
requirements may be stripped away if EPA becomes convinced
that it may achieve attainment more efficiently. “[I]t is
generally presumed that Congress acts intentionally and
purposely when it includes particular language in one section of
a statute but omits it in another.” City of Chicago v. Envtl. Def.
Fund, 511 U.S. 328, 338 (1994) (internal quotation marks
omitted). The interpretation advanced by EPA cannot be
squared with Congress’s desire to limit EPA discretion by
 20

devising a plan that would reach far into the future. See
Whitman, 531 U.S. at 485. As knowledge about the causes and
cures of pollution has increased, Congress has not previously
hesitated to step in and modify its approach. That Congress has
not provided for an agency override of its methodology is
telling.

Similarly, EPA’s insistence that certain areas should not be
subjected to Subpart 2 because they will soon attain the eight-
hour NAAQS is untethered to Congress’s approach. Congress
considered the possibility of areas being classified nonattaining
but missing the target by only a small amount. These are the
Marginal areas that are required to introduce far less
burdensome ozone controls than areas with more polluted air.
See CAA § 181, 42 U.S.C. § 7511. Thus, even if “Subpart 1 is
preferable to mandating unnecessary Subpart 2 controls,” Brief
for Respondent at 46, EPA cannot replace Congress’s judgment
with its own.

We therefore hold that the 2004 Rule violates the Act
insofar as it subjects areas with eight-hour ozone in excess of
0.09 ppm to Subpart 1. We further hold that EPA’s
interpretation of the Act in a manner to maximize its own
discretion is unreasonable because the clear intent of Congress
in enacting the 1990 Amendments was to the contrary.

V.

Industry petitioner NPRA challenges the conversion of the
one-hour Table 1, codified at 42 U.S.C. § 7511(a) tbl.1, to its
eight-hour regulatory equivalent, 40 C.F.R. § 50.903(a) tbl.1.
We first address EPA’s contention that NPRA lacks Article III
standing to pursue its claims before this court.

A.
 21

The doctrine of standing enforces the limitations on the
federal judiciary stemming from the Article III case-or-
controversy requirement. See U.S. CONST. art. III, § 2; Allen v.
Wright, 468 U.S. 737, 750-51 (1984). A party’s standing is a
“predicate to any exercise of our jurisdiction.” Fla. Audubon
Soc’y v. Bentsen, 94 F.3d 658, 663 (D.C. Cir. 1996) (en banc).

As an association, NPRA “has standing to bring suit on
behalf of its members when: (a) its members would otherwise
have standing to sue in their own right; (b) the interests it seeks
to protect are germane to the organization’s purpose; and (c)
neither the claim asserted nor the relief requested requires the
participation of individual members in the lawsuit.” United
Food & Commercial Workers Union Local 751 v. Brown Group,
Inc., 517 U.S. 544, 553 (1996) (quoting Hunt v. Wash. State
Apple Adver. Comm’n, 432 U.S. 333, 343 (1977)). Only the first
element of standing can seriously be challenged here. An
individual plaintiff has standing if it can demonstrate injury-in-
fact that has been caused by the defendant and that is capable of
being redressed by this court’s order. Friends of the Earth, Inc.
v. Laidlaw Envtl. Servs. (TOC), Inc., 528 U.S. 167, 180-81
(2000); Lujan v. Defenders of Wildlife, 504 U.S. 555, 560-61
(1992).

EPA contests causation on the ground that because only the
states are directly affected by the 2004 Rule, and because EPA
has not specifically mandated controls, NPRA is only harmed
through the intervening acts of the independent third-party
states. See Nat’l Wrestling Coaches Ass’n v. Dep’t of Educ.,
366 F.3d 930, 938 (D.C. Cir. 2004). NPRA responds that it is
inevitable that NPRA members will be affected by the 2004
Rule and will be required to install controls either not previously
required or at an earlier date than previously anticipated.

In order for NPRA to have standing, there must be a
 22

“‘substantial probability’ that [EPA’s] action ‘created a
demonstrable risk, or caused a demonstrable increase in an
existing risk, of injury to the particularized interests of’” NPRA.
Nat’l Parks Conservation Ass’n v. Manson, 414 F.3d 1, 6 (D.C.
Cir. 2005) (quoting Fla. Audubon, 94 F.3d at 669). We have
little difficulty concluding that NPRA has met this threshold. It
is inconceivable that EPA’s comprehensive reworking of an Act
that specifically controls the requirements for industrial
pollution would fail to affect the requirements of even a single
NPRA member. See Am. Library Ass’n v. FCC, 406 F.3d 689,
696 (D.C. Cir. 2005); Bethlehem Steel Corp. v. EPA, 723 F.2d
1303, 1306 (7th Cir. 1983); see also Natural Res. Def. Council,
Inc. v. EPA, 902 F.2d 962, 975 n.33 (D.C. Cir. 1990), vacated in
part on other grounds, 921 F.2d 326 (D.C. Cir. 1991);
Overview, supra, at 1815.

B.
NPRA’s petition bridges the classification and timing gaps
referenced in Whitman. See supra Part IV.A. The court
“defer[s] to the EPA’s reasonable resolution of the ambiguity.”
Whitman, 531 U.S. at 484. The essence of NPRA’s challenge is
that while translating Table 1, EPA failed to acknowledge the
differences between one-hour and eight-hour ozone. NPRA
raises two main contentions: first, that eight-hour ozone is
proportionally more difficult to reduce than one-hour ozone; and
second, that EPA adopted the new approach aware that some
areas would be unable to meet the prescribed guidelines, instead
relying upon the states to reclassify themselves voluntarily.

1.
To create an updated version of Table 1, EPA considered a
number of approaches for determining the proper deadlines and
method of classification. With respect to maximum attainment
dates, EPA recognized that “a strict application of Table 1
would produce absurd results for most areas” because most of
 23

the deadlines had already passed, and “promulgat[ed] a targeted
revision of Table 1 to reflect attainment dates consistent with
Congressional intent.” 2004 Rule, 69 Fed. Reg. at 23,966.
Because the original attainment dates were linked to the date on
which most areas were designated and classified as a matter of
law, EPA proposed to use the same time periods and to start the
clock as of the time of designation for eight-hour ozone. 2003
NOPR, 68 Fed. Reg. at 32,808.

The other factor influencing attainment deadlines is the
mapping of design values onto area classes. For this purpose,
EPA proposed

to translate the classification thresholds in Table 1 of
section 181 from 1-hour values to 8-hour values in the
following manner: Determine the percentage by which
each classification threshold in Table 1 of section 181
exceeds the 1-hour ozone standard and set the 8-hour
threshold value at the same percentage above the 8-
hour ozone standard. For example, the threshold
separating marginal and moderate areas in Table 1 is
15 percent above the 1-hour standard, so we would set
the 8-hour moderate area lower threshold value at 15
percent above the 8-hour standard.

Id. at 32,812. In response to comments, EPA introduced
additional alternatives and reopened the comment period. Under
the new Alternative A, the range of the one-hour Table 1 was
narrowed so that the eight-hour table used

50 percent (instead of 100 percent) of the percentages
that the classification thresholds were above the 1-hour
NAAQS in our proposed June 2003 translation of
Table 1. In other words, since the moderate threshold
for the 1-hour NAAQS is 15 percent above the 1-hour
 24

NAAQS, we would adjust the moderate threshold for
purposes of the 8-hour NAAQS to be 7.5 percent
above . . . the lowest level in Table 1 for [this
alternative].

2004 Rule, 69 Fed. Reg. at 23,9574; see also Proposed Rule To
Implement the 8-Hour Ozone NAAQS, 68 Fed. Reg. 60,054,
60,059 (Oct. 21, 2003). The effect of this approach would be to
place more areas in higher classes, giving them more time to
attain (while subjecting them to additional mandatory controls).

NPRA maintains that EPA should have adopted the fifty-
percent approach or some other approach that delayed
attainment deadlines it considered to be unreasonable. The basis
for this objection is data provided in the rulemaking comments
of the American Petroleum Institute (“API”). See Comments of
the American Petroleum Institute on the Proposed Rule To
Implement the 8-Hour Ozone National Ambient Air Quality
Standard 7, 13-14. API presented data suggesting that eight-
hour ozone levels fell at only half the rate of one-hour ozone
levels during the twenty years ending 2001. Id. However, EPA
did not find these data compelling, explaining that “[p]rograms
designed to address the 1-hour ozone NAAQS were not
necessarily designed to reduce 8-hour ozone levels at some
prescribed rate.” Memorandum from Fred Dimmick, Group
Leader, Air Quality Trends Analysis Group, on API Comments
Regarding Relation Between Ozone 1-Hour and 8-Hour Trends
2 (Feb. 11, 2004). So the historical data (for which EPA also
contested the methodology) are not truly predictive of the
relative difficulty in reducing one- and eight-hour ozone.

4
Alternative A also utilized a different approach for
distinguishing between Subpart 1 and Subpart 2 areas. All areas with
eight-hour design values exceeding 0.091 ppm were categorized under
Subpart 2. 2004 Rule, 69 Fed. Reg. at 23,957; see supra Part IV.A.
 25

Indeed, EPA’s own data suggest that the ratio between eight-
hour and one-hour ozone is converging toward a constant
proportion, eight-tenths. See id. at 2, 4 fig.3. This implies that
reducing one-hour and eight-hour ozone levels by the same
percentage would be equally difficult. In light of these data,
NPRA fails to show that EPA was arbitrary or capricious in
adopting the percentage-deviation approach.

2.
NPRA’s second objection is that EPA acknowledged that its
classification scheme may result in some areas that will not be
able to attain by the deadline prescribed for their category. For
these “misclassified” areas, EPA has decided to rely upon the
voluntary bump-up provision of section 181(b)(3).5 See 2004
Rule, 69 Fed. Reg. at 23,959-60. NPRA contends that by
resorting to section 181(b)(3), EPA is shirking its classification
responsibility, leaving these decisions to the states contrary to
Congress’s intent. Taken to the extreme, section 181(b)(3)
could damage Congress’s approach. However, Congress
understood that the classification system would not be error-
proof and merely chose “outside limits intended to provide a
reasonable target for a large class of nonattainment areas.” H.R.
REP. NO. 101-490, pt. 1, at 229, reprinted in 2 LEGISLATIVE
HISTORY, supra, at 3253.

5
Section 181(b)(3) of the Act provides:

The Administrator shall grant the request of any State
to reclassify a nonattainment area in that State in
accordance with [Table 1] to a higher classification.
The Administrator shall publish a notice in the
Federal Register of any such request and of action by
the Administrator granting the request.

42 U.S.C. § 7511(b)(3).
 26

NPRA maintains that EPA anticipates fifteen areas,
including major metropolises, will be unable to attain within the
time allowed. However, EPA found that its chosen option
“provides sufficient time for most areas.” 2004 Rule, 69 Fed.
Reg. at 23,959. Moreover, its modeling did not incorporate
future technological advances. EPA’s “repeated experience over
the past three decades is that market forces stimulated by the
CAA have repeatedly led to technological advances and learning
through experience, making it possible over time to achieve
greater emissions reductions at lower costs than originally
anticipated.” Id.

In light of the nature of the classification scheme, the
availability of section 181(b)(3) bump-ups, and the prospects for
future technological improvements credited by EPA, we deny
NPRA’s petition.

VI.

The final set of challenges concerns what remains of the old
one-hour standard. The Environmental petitioners contend that
EPA’s revocation of the one-hour standard was unlawful and
arbitrary. Short of that, they join the State petitioners in
contending that the 2004 Rule violates the anti-backsliding
provisions of the Act. Industry petitioner Baton Rouge contends
that EPA lacks authority to require any anti-backsliding
provisions that do not relate to the eight-hour NAAQS.

A.
In 1997, EPA determined that, while it was replacing the
one-hour NAAQS with an eight-hour NAAQS, it would
continue to enforce the one-hour NAAQS until “a determination
by the EPA that an area has attained air quality that meets the 1-
hour standard.” Implementation Plan for Revised Air Quality
Standards, 62 Fed. Reg. 38,421, 38,424 (July 18, 1997); see
 27

Whitman, 531 U.S. at 478; 1997 Rule, 62 Fed. Reg. at 38,873,
38,894-95. In the 2004 Rule, EPA reversed course, opting
instead to “revoke the 1-hour standard in full, including the
associated designations and classifications, 1 year following the
effective date of the designations for the 8-hour NAAQS.” 2004
Rule, 69 Fed. Reg. at 23,954. The Environmental petitioners
contend that because Congress “codified” the one-hour standard,
EPA cannot revoke it. In the alternative, they contend that EPA
was arbitrary and capricious in revoking the standard, because
maintaining the one-hour standard would also help to reduce
eight-hour ozone levels. EPA responds that any challenge to its
1997 Rule is time-barred, and, in any event, its actions are
reasonable.

1.
The judicial review provision of the Act provides aggrieved
parties sixty days in which to petition for review. CAA §
307(b), 42 U.S.C. § 7607(b). Were the Environmental
petitioners challenging the revocation of the one-hour standard,
which occurred in the 1997 Rule revising the standard, its
petition would be out of time and the court could not entertain
it. However, we read their petition to challenge only the
revocation of the one-hour standard prior to its attainment, as
their reply brief makes clear. This objection is timely. Cf.
Clean Air Implemention Project v. EPA, 150 F.3d 1200, 1204
(D.C. Cir. 1998).

Because the EPA indicated in the 1997 Rule that it had no
intention of withdrawing the one-hour standard before all areas
had reached attainment, see 1997 Rule, 62 Fed. Reg. at 38,873,
Environmental petitioners had no reason to lodge their challenge
in 1997. The 1997 Rule did not reflect a finding that one-hour
ozone was unimportant and that continued regulation was
unnecessary. See id. at 38,872. As the Environmental
petitioners observe, it was only when EPA switched course in
 28

the 2004 Rule, opting to revoke the one-hour standard without
awaiting attainment, that their challenge became ripe. This is
not a case like Environmental Defense v. EPA, 467 F.3d 1329
(D.C. Cir. 2006), where EPA did not change its 1997 regulation
when promulgating a 2004 rule. Id. at 1333. Because the
Environmental petitioners’ challenge is timely, we turn to the
merits.

2.
Section 109(d)(1) of the Act provides that “at five-year
intervals . . . , the Administrator shall complete a thorough
review of the . . . national ambient air quality standards
promulgated under this section and shall make such revisions in
such . . . standards as may be appropriate.” 42 U.S.C. §
7409(d)(1). The anti-backsliding provision, section 172(e),
provides that in the event “the Administrator relaxes a [primary
NAAQS] after November 15, 1990, the Administrator shall . . .
provide for controls which are not less stringent than the
controls applicable to areas designated nonattainment before
such relaxation.” 42 U.S.C. § 7502(e).

The Environmental petitioners contend that the one-hour
standard cannot be withdrawn because Congress “codified” the
one-hour standard in Subpart 2. Congress contemplated,
however, the possibility that scientific advances would require
amending the NAAQS. Section 109(d)(1) establishes as much,
and section 172(e) regulates what EPA must do with revoked
restrictions. While certain other provisions in Subpart 1 are
explicitly rendered inapplicable to ozone when regulated under
Subpart 2, see CAA § 172(a)(1), (2), 42 U.S.C. § 7502(a)(1),
(2), Section 109(d)(1) is not. See Am. Trucking Ass’ns, 175 F.3d
at 1047. Therefore, EPA retains the authority to revoke the one-
hour standard so long as adequate anti-backsliding provisions
are introduced. Additionally, EPA was not, as the
Environmental petitioners contend, arbitrary and capricious in
 29

withdrawing the one-hour requirements, having found in 1997
that the eight-hour standard was “generally even more effective
in limiting 1-hour exposures of concern than is the current 1-
hour standard.” 1997 Rule, 62 Fed. Reg. at 38,863. The only
remaining requirements as to the one-hour NAAQS are the anti-
backsliding limitations.

B.
Baton Rouge takes the opposite position and contends that
no remnants of the one-hour rule may be retained, except to the
extent that controls are already incorporated into SIPs. These
controls, however, could be removed pursuant to section 110(l)
of the Act once the state demonstrates that their removal will not
“interfere with any applicable requirement concerning
attainment and reasonable further progress” toward the eight-
hour standard. 42 U.S.C. § 7410(l).

Baton Rouge has suffered from a history of near-misses in
ozone attainment. In 1990, the area was classified Serious under
Table 1, providing until 1999 to attain. When Baton Rouge
missed attainment, by just 0.002 ppm, it was bumped up to
Severe status by the terms of the Act. See CAA § 181(b)(2), 42
U.S.C. § 7511(b)(2). Baton Rouge had not finished
implementing the controls for a Severe area when the eight-hour
standard was put into place. Based on its eight-hour design
value, Baton Rouge was reclassified under Subpart 2 as
Marginal. 40 C.F.R. § 81.319.

Baton Rouge objects to the 2004 Rule insofar as it requires
the implementation of Severe controls not yet implemented that
it claims do not constitute “applicable requirements” that must
be included in SIPs. 40 C.F.R. § 51.900(f); see CAA §
172(c)(7), 42 U.S.C. § 7502(c)(7). It contends that it should be
subjected only to the requirements for a Marginal eight-hour
area, both because these requirements reflect the improved
 30

quality of Baton Rouge’s air and because they now constitute
the “applicable requirements” under the prevailing NAAQS. It
is undisputed, of course, that Baton Rouge would be subject to
all of the Severe requirements but for the change in the NAAQS.
Baton Rouge’s contention is the counterintuitive claim that the
strengthening of the NAAQS entitles it to a weaker regulatory
regime.

At the center of this dispute is EPA’s interpretation of the
anti-backsliding provision, section 172(e), 42 U.S.C. § 7502(e).
By its terms, Section172(e) applies only when EPA “relaxes” a
primary NAAQS, id., but EPA interpreted it to apply here,
reasoning that “if Congress intended areas to remain subject to
the same level of control where a NAAQS was relaxed, they
also intended that such controls not be weakened where the
NAAQS is made more stringent.” 2004 Rule, 69 Fed. Reg. at
23,972. Considered as a whole, the Act reflects Congress’s
intent that air quality should be improved until safe and never
allowed to retreat thereafter. Even if EPA set requirements that
proved too stringent and unnecessary to protect public health,
EPA was forbidden from releasing states from these burdens.
See CAA § 172(e), 42 U.S.C. § 7502(e). Even areas that
attained were not allowed to remove controls. At most, an
attaining area was allowed to shift controls from active
enforcement to the contingency plan that would be automatically
triggered should air quality again deteriorate. CAA § 175A, 42
U.S.C. § 7505a. And EPA was to enforce a high threshold for
removing controls from a SIP—no mandatory controls could be
removed and nothing could be done that would hinder an area’s
ability to achieve prescribed annual incremental emissions
reductions. CAA § 110(l), 42 U.S.C. § 7410(l). As a result,
Baton Rouge’s position that Congress intended to allow the
scenario it prefers does not withstand scrutiny.

Similarly, Baton Rouge’s position that it need not
 31

implement one-hour Serious requirements that were not a part
of its SIP when the NAAQS changed fails. A mandatory control
that a state is obligated to implement is “applicable”
notwithstanding the state’s delay in compliance with the
requirement. See 2004 Rule, 69 Fed. Reg. at 23,972. The Act
placed states onto a one-way street whose only outlet is
attainment. That Baton Rouge has found attainment more
difficult than it apparently expected does not entitle it to reverse
course. EPA’s interpretation of section 172(e) is to this extent
consistent with Congress’s expressed intent and therefore is
reasonable.

C.
After interpreting section 172(e) to apply to the
strengthening of the ozone NAAQS, EPA proceeded to limit the
scope of its interpretation. Finding ambiguity in the word
“controls,” EPA determined that one-hour NSR, which it
characterized as a growth measure, need not be continued. 2004
Rule, 69 Fed. Reg. at 23,985. The State and Environmental
petitioners challenge this reinterpretation, as well as EPA’s
treatment of one-hour penalties, rate-of-progress milestones,
contingency plans, and motor vehicle emissions budgets. We
conclude that each of these measures is a “control[]”and that
withdrawing any of them from a SIP would constitute
impermissible backsliding.

1.
NSR. NSR is a permitting process that restricts major
modifications and new construction based on an area’s air-
quality classification. See New York v. EPA, 443 F.3d 880, 883
(D.C. Cir. 2006). As relevant, NSR requires major facilities to
include technology consistent with the lowest achievable
emissions rate (“LAER”) and to offset any increased emissions
with greater reductions elsewhere. See CAA § 173, 42 U.S.C.
§ 7503. As with the rest of the Act, the severity of NSR
 32

restrictions increases as the nonattainment classification
worsens. Moving up a classification results in a narrower
definition of a “major” facility and imposes a greater offset ratio
for any increased VOC emissions. See CAA § 182, 42 U.S.C.
§ 7511a. Areas yet to attain the one-hour NAAQS were
classified at best Severe prior to the revocation of the standard.
Under one-hour NSR, they must achieve LAER for any source
exceeding 25 tons per year of VOC emissions and must offset
any increase in VOC emissions by a decrease of 1.3 times that
amount. CAA § 182(d), 42 U.S.C. § 7511a(d).

EPA decided that one-hour NSR requirements are no longer
required under the Act and that areas should be constrained only
by the NSR requirements for their eight-hour classification.
2004 Rule, 69 Fed. Reg. at 23,985. This marked a change from
its 2003 NOPR, in which EPA indicated that “the major source
applicability cut-offs and offset ratios continue to apply to the
extent that the area has a higher classification for the 1-hour
standard than for the 8-hour standard[, because w]e see no
rationale under the CAA . . . why the existing NSR requirements
should not remain ‘applicable requirements.’” 2003 NOPR, 68
Fed. Reg. at 32,821. On reconsideration, EPA affirmed the
revocation of one-hour NSR. See NSR Reconsideration, 70 Fed.
Reg. 39,413.

The result of this change is to subject fewer areas to LAER
and to offset requirements that themselves are weakened. EPA
maintains that this is proper because NSR is not a “control.”
Instead, EPA defines controls as “mandatory control measures
that can be quantified and relied upon in a modeling
demonstration to show how the measure helps an area reach
attainment.” Brief for Respondent at 95; see also Nonattainment
Major NSR Implementation Under 8-Hour Ozone NAAQS:
Reconsideration, 70 Fed. Reg. 17,018, 17,021-23 (Apr. 4, 2005).
By this reasoning, because NSR does not provide a
 33

priori quantifiable emissions reductions, it is not a control. This
interpretation does not withstand scrutiny. By attempting to
redefine what is a “control” circularly as a subset of itself, EPA
violates logic, its own past practice, and the Act’s plain
meaning.

EPA maintains that States do not rely upon NSR to actively
reduce their ozone levels and that NSR was not introduced to
achieve emissions reductions. But this is beside the point
because EPA nowhere claims that if NSR were not present, there
would be no effect on ozone levels. Its arbitrary distinction
between actively reducing levels and merely limiting growth
finds no support in the nature of “control.” Past and current
practice confirms that NSR is a control. The Act itself provides
that the NSR permit program involves “controls” when section
108(h) requires EPA to “make information regarding emission
control technology available to the States and to the general
public through a central database” and indicates that “[s]uch
information shall include all control technology information
received pursuant to State plan provisions requiring permits for
sources.” 42 U.S.C. § 7408(h). EPA has consistently found
NSR to be a control. In its NOx SIP Call, 63 Fed. Reg. 57,356,
57,442 tbl.IV-2 (Oct. 27, 1998), EPA included NSR in its list of
“controls.” In a proposed rule regarding particulate matter, EPA
sought to apply two statutory clauses because they “apply to
[SIP] provisions and control requirements, which include NSR
programs.” Proposed Rule To Implement the Fine Particle
NAAQS, 70 Fed. Reg. 65,984, 66,035 (Nov. 1, 2005); see also
id. at 66,037. In a turbine regulation earlier this year, it stated
that “emission control programs such as . . . NSR already
promote or require emission controls that would effectively
prevent emissions from increasing.” Standards of Performance
for Stationary Combustion Turbines, 71 Fed. Reg. 38,482,
38,491 (July 6, 2006). In addition, the court has previously
characterized NSR as imposing “control requirements.” New
 34

York, 443 F.3d at 883; see also Sierra Club v. Costle, 657 F.2d
298, 338 (D.C. Cir. 1981) (quoting Standards of Performance for
New Stationary Sources, 45 Fed. Reg. 8210, 8220 (Feb. 6,
1980)). Furthermore, the House Report introducing the permit
program lists NSR as a “control” at least twice. See H.R. REP.
NO. 101-490, pt. 1, at 166, 168 fig.1, reprinted in 2 LEGISLATIVE
HISTORY, supra, at 3190, 3192 fig.1 (“Modification Offsets”).

EPA tries to find ambiguity by interposing section
110(a)(2)(A) against (C) and section 172(c)(1) and (6) against
(5). The Sixth Circuit credited this approach in Greenbaum v.
EPA, 370 F.3d 527 (6th Cir. 2004). However, Greenbaum
involved a different ultimate question, namely, whether NSR is
required for attainment areas, and required that court to
determine the meaning of a different term, “measures.” Because
the term “measures” was used in the provision providing for
redesignation to attainment, the Sixth Circuit found it
appropriate to refer to other instances of “measures” elsewhere
in the Act and concluded that NSR was not a “measure.” Id. at
535-38. This has no bearing on whether NSR is a “control.” In
light of abundant other evidence that NSR is a control, EPA’s
attempt to conjure up ambiguity by referring to provisions
involving a different noun is unavailing.

We therefore conclude that there is no ambiguity as to the
meaning of “control” in Section 172(e), the anti-backsliding
provision. Something designed to constrain ozone levels is a
“control,” and this would include NSR. To conclude otherwise
would mean that Congress considered its carefully-crafted and
well-calibrated graduated restrictions on new and modified
sources less important than other provisions. If anything, the
Act and its legislative history reflect the opposite position. See
New York, 443 F.3d at 887 (citing 42 U.S.C. § 7411(a)(4)); S.
REP. NO. 101-228, at 24-25 (1989), reprinted in 5 LEGISLATIVE
HISTORY, supra, at 8364-65.
 35

2.
Penalties. The 1990 Amendments took a long-horizon
approach to the problem of ozone pollution. Recognizing that
some areas would struggle long into the future, the 1990
Amendments extended attainment dates as late as 2005 and
2010. Beyond those deadlines, the 1990 Amendments provided
for penalties, CAA § 185(a), 42 U.S.C. § 7511d(a),6 to
encourage areas still yet to attain. Because EPA promulgated
the 2004 Rule before the first penalties would have been
required in 2005, the provision has never been enforced. EPA
uses this convenient timing to argue that the section 185(a)
penalties are therefore excluded from the reference in the anti-
backsliding provision, section 172(e), to “controls applicable . . .
before . . . relaxation.” 42 U.S.C. § 7502(e).

EPA reasons that the Act “does not mandate that controls be
as stringent as those that could not be required to be imposed
until a date after the previous NAAQS no longer exists.” 2004
Rule Reconsideration, 70 Fed. Reg. at 30,593. This assertion is
untenable. By EPA’s reading, the standards could be changed
every fourteenth year—just prior to the attainment date—and a

6
Section 185(a) of the Act provides:

Each implementation plan revision required [for
Severe and Extreme ozone nonattainment areas] shall
provide that, if the area to which such plan revision
applies has failed to attain the [primary NAAQS] for
ozone by the applicable attainment date, each major
stationary source of VOCs located in the area shall,
except as otherwise provided under subsection (c) of
this section, pay a fee to the State as a penalty for
such failure . . . .

42 U.S.C. § 7511d(a).
 36

state could go unpenalized without ever attaining even the
original NAAQS referenced in the 1990 Amendments. The
Supreme Court in Whitman instructed that

Subpart 2 was obviously written to govern
implementation for some time. . . . A plan reaching so
far into the future was not enacted to be abandoned the
next time the EPA reviewed the ozone
standard—which Congress knew could happen at any
time, since the technical staff papers had already been
completed in late 1989.

531 U.S. at 485.

As Congress set the penalty deadline well into the future,
giving states and industry ample notice and sufficient incentives
to avoid the penalties, they were “applicable” before they
actually were imposed. For a provision to be “applicable” in
this context, it need not be currently enforceable. Congress
designed section 185(a) to influence state action prior to 2005,
and in this sense, it has long been “applicable.” If a group of
petitioners believed that the penalties were unlawful and would
force the implementation of unnecessary changes, they would
have had a ripe claim long ago under Abbott Laboratories v.
Gardner, 387 U.S. 136, 148-49, 153 (1967). Accord Chamber
of Commerce v. Reich, 57 F.3d 1099, 1101 (D.C. Cir. 1995).
Because these penalties were designed to constrain ozone
pollution, they are controls that section 172(e) requires to be
retained. While EPA maintains that it would be impractical to
enforce these penalties because EPA will no longer make
findings of attainment and conformity assessments as to the one-
hour standard, see 2004 Rule, 69 Fed. Reg. at 23,985, section
172(e) does not condition its strict distaste for backsliding on
EPA’s determinations of expediency; EPA must determine its
procedures after it has identified what findings must be made
 37

under the Act. For these reasons, section 185 penalties must be
enforced under the one-hour NAAQS.

3.
Milestones. Rate-of-progress milestones apply to areas
categorized Moderate and above and require annual percentage
reductions in ozone-precursor emissions. CAA § 182(b)(1),
(c)(2)(B), (d), (e), 42 U.S.C. § 7511a(b)(1), (c)(2)(B), (d), (e).
Serious areas must develop adequate plans to attain three-
percent annual reductions over each three-year period until
attainment. CAA § 182(c)(2)(B), 42 U.S.C. § 7511a(c)(2)(B);
see Sierra Club v. EPA, 356 F.3d 296, 299 (D.C. Cir. 2004).

The Environmental petitioners sought review of EPA’s
treatment of these provisions, believing them no longer to apply
to one-hour ozone levels under the 2004 Rule. EPA responded
that petitioners had misinterpreted the 2004 Rule and that rate-
of-progress plans continue in force as “applicable requirements”
based on the one-hour standard. Because there is no dispute
here, we merely take note of EPA’s interpretation of its rule.
See Alaska Prof’l Hunters Ass’n v. FAA, 177 F.3d 1030, 1033-
34 (D.C. Cir. 1999).

4.
Contingency Plans. Each SIP must include “specific
measures to be undertaken if the area fails to make reasonable
further progress, or to attain the national primary ambient air
quality standard by the attainment date.” CAA § 172(c)(9), 42
U.S.C. § 7502(c)(9); see CAA § 182(c)(9), 42 U.S.C. §
7511a(c)(9) (contingency plans for Serious areas); Sierra Club
v. EPA, 294 F.3d 155, 164 (D.C. Cir. 2002). EPA determined
that “[w]here contingency measures have not yet been triggered,
we believe it is consistent with Congressional intent to allow
areas to remove those measures (or to modify the trigger for
such measures to reflect the 8-hour standard).” 2004 Rule
 38

Reconsideration, 70 Fed. Reg. at 30,599.

EPA can point to no aspect of Congress’s approach that
suggests that the one-hour ozone levels specifically addressed by
statute can be allowed to deteriorate. Even if EPA had
determined that ozone was not nearly as damaging as previously
believed and that a level of 100 ppm was acceptable, section
172(e) would still require the automatic imposition of
contingency measures if an area were to miss the preexisting
threshold of 0.12 ppm. This is precisely the type of backsliding
contemplated by the Act. As discussed with respect to penalties,
EPA’s emphasis on whether the controls have been “triggered”
is a red herring. To conform to Congressional intent, one-hour
contingency plans must remain in place even after transitioning
away from the one-hour standard.

5.
Motor Vehicle Emissions Budgets. In enacting the 1990
Amendments, Congress was particularly concerned with
pollution arising from automobile emissions. See S. REP. NO.
101-228, at 85-86, reprinted in 5 LEGISLATIVE HISTORY, supra,
at 8425-26. As a result, it strengthened efforts to ensure that
local transportation planning conforms to pollution controls in
approved SIPs by adding section 176(c)(2)(A), 42 U.S.C. §
7506(c)(2)(A).7 See Envtl. Def. Fund v. EPA, 167 F.3d 641,

7
Section 176(c)(2)(A) provides that

no transportation plan or transportation improvement
program may be adopted by a metropolitan planning
organization . . . or be found to be in conformity by
a metropolitan planning organization until a final
determination has been made that emissions expected
from implementation of such plans and programs are
consistent with estimates of emissions from motor
vehicles and necessary emissions reductions
 39

643-44 (D.C. Cir. 1999). Conformity, in turn, requires a finding
that anticipated emissions will not frustrate a SIP’s purpose nor
contribute additional violations or delays in any area. CAA §
176(c)(1), 42 U.S.C. § 7506(c)(1). EPA implemented this
mandate by establishing motor vehicle emissions budgets not to
be exceeded by Metropolitan Planning Organizations. See 40
C.F.R. § 93.118.

In the 2004 Rule, EPA determined that “conformity
determinations [would] no longer [be] required for the 1-hour
NAAQS.” 69 Fed. Reg. at 23,985; see also Transportation
Conformity Rule Amendments for the New 8-Hour Ozone and
PM2.5 NAAQS, 69 Fed. Reg. 40,004, 40,009 (July 1, 2004)
(hereinafter “Transportation Conformity Rule Amendments”).
EPA acknowledged that “the majority of commenters that
addressed this issue objected to EPA’s proposal,” 2004 Rule, 69
Fed. Reg. at 23,986, but concluded that the Act “specifically
states that conformity applies only in” nonattainment and
maintenance areas, id. at 23,987.

Although section 176 provides a floor above which
conformity determinations are required, EPA cannot conclude
that conformity using one-hour SIP emissions budgets is
unnecessary without confronting section 172(e). Because one-
hour conformity emissions budgets constitute “controls” under
section 172(e), they remain “applicable requirements” that must
be retained. EPA cannot well respond to commenters’ concerns
that removing one-hour SIP emissions budgets from conformity
demonstrations would “allow large increases in motor vehicle
emissions” by acknowledging that “requiring conformity for
both ozone standards at the same time would be overly

contained in the applicable implementation plan.

42 U.S.C. § 7506(c)(2)(A).
 40

burdensome and confusing.” Transportation Conformity Rule
Amendments, 69 Fed. Reg. at 40,009-10. EPA is required by
statute to keep in place measures intended to constrain ozone
levels—even the ones that apply to outdated standards—in order
to prevent backsliding. This principle encompasses conformity
based on one-hour SIP emissions budgets. See 40 C.F.R. §
93.109(e); Envtl. Def. v. EPA, 467 F.3d 1329 (D.C. Cir. 2006).

VII.

Consistent with Whitman and the Act, we grant the State
petition and the Environmental petition, except with respect to
the withdrawal of the one-hour NAAQS; we also deny the
Industry petitions and we dismiss the Ohio petition.
Accordingly, we vacate those portions of the 2004 Rule that
provide for regulation of eight-hour nonattainment areas under
Subpart 1 in lieu of Subpart 2 and those portions of the 2004
Rule that allow backsliding with respect to the measures
addressed in Parts VI.C.1 through VI.C.5 of this opinion, and
remand the matter to EPA.