# Legal Consequences of EPA’s Endangerment Finding for New Motor Vehicle Greenhouse Gas Emissions

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URL: https://www.frixlaw.com/law-library/documents/crs%3AR40984

## Record

- **Collection:** Congressional research report
- **Document type:** CRS Report
- **Published:** December 15, 2009
- **Citation:** R40984

## Text

Legal Consequences of EPA’s Endangerment
Finding for New Motor Vehicle Greenhouse
Gas Emissions
(name redacted)
Legislative Attorney
December 15, 2009

Congressional Research Service
7-....
www.crs.gov
R40984

CRS Report for Congress
Prepared for Members and Committees of Congress

Endangerment Finding for New Motor Vehicle Greenhouse Gas Emissions

Summary
On December 15, 2009, the Environmental Protection Agency (EPA) took its most important
action to date related to climate change. EPA published its final determination that the combined
greenhouse gas (GHG) emissions from new motor vehicles in the United States contribute to an
“endangerment” from climate change. More precisely, EPA found that such emissions, in the
words of Clean Air Act (CAA) section 202(a), “cause or contribute to air pollution that may
reasonably be anticipated to endanger public health or welfare.” Under section 202(a), this
finding requires that EPA promulgate “standards” to control such emissions—as the agency
proposed to do for light-duty motor vehicles in advance of its endangerment determination.
Some groups have objected to the endangerment determination and the emission standards to
follow, arguing they will trigger a “cascade” of unacceptable regulatory consequences under other
CAA provisions. These regulatory consequences, they say, would impose unattainable GHGconcentration goals on EPA and the states, and/or economically and administratively
unreasonable burdens. This report examines the CAA provisions that have figured in this debate
to see whether this alleged cascade of legal consequences likely would occur.
First, the report examines CAA sections that, like section 202(a), are triggered by endangerment
findings. Of these, the one most likely to require EPA regulatory action after the 202(a)
endangerment finding is section 111, authorizing new source performance standards—but only as
to stationary source categories emitting the largest amounts of GHGs. Section 111, however,
affords EPA wide discretion in setting new source performance standards. Two other sections that
arguably might be triggered are 108, requiring national ambient air quality standards, and 115,
which requires states to revise their implementation plans to prevent or eliminate the
endangerment of public health or welfare in a foreign country. As to these sections, however, the
arguable infeasibility of the regulatory goals—even if GHG emissions in the United States are
significantly reduced, atmospheric concentrations would decline little—will give EPA room to
argue that regulatory action is not mandatory. Other endangerment-triggered sections of the CAA
can be distinguished from section 202(a) by their explicit terms, and thus would likely not be
triggered by the 202(a) endangerment finding.
Second, the report looks at CAA provisions having no endangerment trigger. Of these, EPA has
conceded that two require the agency to act after it promulgates the required emission standards
following the 202(a) endangerment finding. One provision would require EPA to impose “best
available control technology” (BACT) on GHG emissions from any major emitting facility
proposed to be constructed in a Prevention of Significant Deterioration area. The other, Title V,
creates an operating permit program for stationary sources of emissions, and would require
stationary sources subject to BACT under the first provision to also apply for Title V permits. As
to each of these requirements, EPA has proposed a “tailoring rule” setting emission thresholds far
higher than in the CAA, at least for a few years. EPA justifies the departure from statutory
language under the case law doctrines of “absurd results” and “administrative necessity.”
A caveat: the issue analyzed in this report is important primarily if Congress does not enact
climate change legislation that puts regulation of GHGs beyond the reach of some of the CAA
provisions discussed here. In particular, the House-passed climate change bill, H.R. 2454 (the
American Clean Energy and Security Act of 2009), states that three of the CAA sections treated
in this report, and one CAA title, may not be used to address air pollutants based on their climate
change impacts.

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Endangerment Finding for New Motor Vehicle Greenhouse Gas Emissions

Contents
Part One: Introduction.................................................................................................................1
Part Two: The Path to Now .........................................................................................................2
Part Three: CAA Sections with Endangerment Triggers Other Than Section 202(a) .....................4
Fuels and Fuel Additives .......................................................................................................5
National Ambient Air Quality Standards................................................................................6
New or Modified Stationary Sources .....................................................................................8
Non-202(a) Mobile Sources of Air Pollution ....................................................................... 10
Non-road Engines and Non-road Vehicles ..................................................................... 10
Aircraft Engines............................................................................................................ 10
Air Pollutants from the Loading and Unloading of Tank Vessels.................................... 11
Stratospheric Ozone Protection ........................................................................................... 11
Pollution in a Foreign Country Caused by Emission Sources in the United States ................ 12
Part Four: CAA Sections Having No Endangerment Trigger...................................................... 14
New Source Review in PSD Areas ...................................................................................... 14
Title V Permitting ............................................................................................................... 17
“Absurd Results” and “Administrative Necessity”............................................................... 18
Part Five: Final Thoughts .......................................................................................................... 20

Contacts
Author Contact Information ...................................................................................................... 21

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Endangerment Finding for New Motor Vehicle Greenhouse Gas Emissions

Part One: Introduction
On December 15, 2009, the Environmental Protection Agency (EPA) published its most
important action to date related to climate change. It found that the combined greenhouse gas
(GHG) emissions from new motor vehicles in the United States contribute to an “endangerment”
from climate change. 1 More precisely, EPA found that such emissions, in the words of Clean Air
Act (CAA) section 202(a),2 “cause or contribute to air pollution that may reasonably be
anticipated to endanger public health or welfare.”3 Under section 202(a), this final determination
requires that EPA promulgate “standards” to control such emissions from new motor vehicles.
It is not, however, the likelihood of standards for new motor vehicle GHG emissions that has
sparked controversy. Indeed, EPA’s proposed standards for emissions of carbon dioxide (CO2, the
principal GHG) from new light-duty vehicles were set so as to align with the Department of
Transportation’s simultaneously proposed fuel economy standards, and are reported to be
achievable with presently available technology. 4 Rather, objection has been raised to the section
202 endangerment finding for GHGs and the upcoming motor vehicle GHG emission standards
because of the argument they will trigger a cascade of unacceptable regulatory consequences
under other CAA provisions. These regulatory consequences, objectors say, would impose
unattainable air quality goals on EPA and the states, and/or economically and administratively
unreasonable burdens on both EPA and regulated entities.
This report examines the CAA provisions that have figured in this debate to assess whether this
alleged “cascade” of legal consequences would likely occur as the result of EPA’s endangerment
finding under 202(a) and resulting emission standards. Looked at another way, the report assesses
the legal leeway EPA has should it wish to limit its expansion of GHG regulation beyond new
motor vehicles under section 202(a).5 The reader also may wish to consult EPA’s own analysis of
this issue in an Advance Notice of Proposed Rulemaking (ANPR) issued in 2008,6 and the
analyses submitted to EPA in response to the ANPR. The policy pros and cons of using CAA
provisions other than 202(a) to address GHGs are treated in CRS Report R40585, Climate
Change: Potential Regulation of Stationary Greenhouse Gas Sources Under the Clean Air Act, by
(name redacted) and (name redacted).

1
74 Fed. Reg. 66,496 (December 15, 2009). EPA announced its determination and posted it on its website a week
earlier, on December 7, 2009, but it is publication in the Federal Register that starts the 30-day period before the
determination takes effect.
2
42 U.S.C. § 7521(a).
3
The term “welfare” is defined by the CAA to include, but not be limited to, effects on “soils, water, crops, vegetation,
manmade materials, animals, wildlife, weather, visibility, and climate, damage to or deterioration of property, and
hazards to transportation, as well as effects on economic values and on personal comfort and well-being….” 42 U.S.C.
§ 7602(h). In the preamble to the endangerment finding, EPA clarifies that its focus was on “public health and welfare”
in the United States. 74 Fed. Reg. at 66,497.
4
See Proposed Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate
Average Fuel Economy Standards, 74 Fed. Reg. 49,454 (September 28, 2009) (proposed jointly by EPA and the
Department of Transportation’s National Highway Traffic Safety Administration).
5
See, e.g., EPA chief signals opposition to Clean Air Act curbs on GHGs, in GREENWIRE (December 8, 2009).
(reporting the EPA Administrator’s position that the agency opposes the use of national ambient air quality standards to
reduce atmospheric concentrations of GHGs).
6
73 Fed. Reg. 44,354 (July 30, 2008). EPA concludes in the ANPR that “[a]n endangerment finding for GHGs under
one provision of the Act could thus have ramifications under other sections of the Act.” Id. at 44,418.

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A caveat: the issue analyzed here is important primarily if Congress does not enact climate
change legislation that puts regulation of emissions based on their climate change impacts beyond
the reach of some of the CAA provisions discussed here. In particular, the House-passed climate
change bill, H.R. 2454, states that sections 108 (national ambient air quality standards) and 115
(international air pollution) may not be used to address air pollutants based on their climate
change impacts. The bill also would prohibit the use of section 165 (requiring preconstruction
“new source review” in Prevention of Significant Deterioration areas) to regulate GHG
emissions, and specifies that no stationary source of GHGs could be required to obtain a permit
under Title V of the CAA solely because of its GHG emissions.
Part Two of this report offers some history as to how EPA came to issue its endangerment
determination for new motor vehicle GHGs on December 15, 2009. Part Three assesses EPA’s
leeway, following its endangerment determination, in deciding whether to regulate GHG
emissions from other sources—where those sources are covered by CAA provisions that, like
section 202(a), have an “endangerment” finding as the trigger. Part Four gauges the effect of the
same endangerment determination, or more accurately the standards that must follow, under CAA
provisions that lack an endangerment determination trigger. Part Five offers a summary and
comment.

Part Two: The Path to Now
The events leading up to EPA’s endangerment finding for new motor vehicle GHGs in 2009
began a decade earlier. In 1999, 19 organizations and 13 states petitioned EPA to regulate the four
GHGs emitted by new motor vehicles (carbon dioxide, methane, nitrous oxide, and
hydrofluorocarbons). Petitioners invoked CAA section 202(a):
The [EPA] Administrator shall by regulation prescribe … standards applicable to the
emission of any air pollutant from any class or classes of new motor vehicles … which in his
judgment cause, or contribute to, air pollution which may reasonably be anticipated to
endanger public health or welfare.

Petitioners argued that GHGs are “air pollutants” under the term’s definition in CAA section
302(g), 7 and that GHGs “endanger public health and welfare” because of their impact on global
climate. Thus, petitioners concluded, EPA must regulate such emissions through standards under
section 202(a).
EPA rejected the petition in 2003, concluding that GHGs are not “air pollutants” under the CAA
so the agency lacked authority to regulate GHG emissions from new motor vehicles based on
their climate change effects.8 Moreover, said EPA, even if it did have the authority, it would be
imprudent for the agency to exercise it at that time because of political opposition in Congress
and various Bush Administration policies opposing mandatory controls on GHGs. EPA’s rejection

7

The term “air pollutant” means any air pollution agent or combination of such agents, including any physical,
chemical, biological, radioactive (including source material, special nuclear material, and byproduct material)
substance or matter which is emitted into or otherwise enters the ambient air. Such term includes any precursors to
the formation of any air pollutant, to the extent the Administrator has identified such precursor or precursors for
the particular purpose for which the term “air pollutant” is used. CAA § 302(g); 42 U.S.C. § 7602(g).
8
68 Fed. Reg. 52,922 (September 8, 2003).

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of the petition was appealed to the federal appeals court in Washington, DC, which upheld the
agency’s decision 2-1.9
In 2007, the Supreme Court in Massachusetts v. EPA reversed the appeals court 5-4, finding for
Massachusetts.10 The Court held that for CAA purposes, GHGs are “air pollutants” and hence that
EPA has the power under the act to regulate GHG emissions from new motor vehicles. Moreover,
said the Court, the phrase “in his judgment” in section 202(a) does not permit EPA to avoid
regulation of air pollutants such as GHGs based on policy considerations. That is, an EPA
decision not to grant a section 202 petition must relate not to administration policy, but to whether
an air pollutant causes, or contributes to, air pollution which may reasonably be anticipated to
endanger public health or welfare.11 That being so, the EPA can avoid regulating GHGs under
202(a) only if it finds that GHGs “do not contribute to climate change or if it provides some
reasonable explanation as to why it cannot or will not exercise its discretion to determine whether
they do.”12 The Supreme Court decision did not order EPA to make a positive endangerment
finding, only to resolve the petition asking it to regulate vehicle GHGs on a correct understanding
of the CAA.
In response to Massachusetts v. EPA, the EPA under the Bush Administration moved toward an
endangerment determination in 2007 but ultimately backed off. On April 24, 2009, under the
newly arrived Obama Administration, EPA issued a proposed positive endangerment
determination for GHGs from new motor vehicles.13 In response, it received 380,000 comments.
On September 28, 2009, EPA also proposed the aforementioned emission standards for GHGs
from new light-duty motor vehicles—the standards required by CAA section 202(a) and referred
to in this report’s title. 14 (September 2009 was a busy month for EPA on the climate change front.
Besides proposing vehicle emission standards, the agency went final with its GHG monitoring
rule for large stationary sources,15 and proposed a “tailoring rule” discussed in Part Four of this
report.) Most recently, EPA published its final endangerment determination for GHGs from new
motor vehicles on December 15, 2009.
Actually, EPA’s endangerment determination consists of two findings, one addressing each
component of the section 202(a) endangerment provision. First, EPA found that current
atmospheric levels of the six major GHGs—from all emission sources—constitute in combination
“air pollution which may reasonably be anticipated to endanger public health and welfare.” This
is a generic determination, not tied to any particular source category. Second, EPA found that
emissions of GHGs by new motor vehicles (comprising four of the aforementioned six GHGs)
will in combination “cause or contribute to” those atmospheric levels. In contrast to the generic
determination, this finding is plainly linked to one source category. This bifurcation of the 202(a)
endangerment language is important in Part Three of this report. In Part Three, a reference to a
CAA endangerment provision being satisfied or simply to a “positive endangerment finding”

9

415 F.3d 50 (D.C. Cir. 2005).
549 U.S. 497 (2007).
11
Id. at 532-533 (quotations marks and brackets omitted).
12
Id. at 533.
13
74 Fed. Reg. 18,886 (April 24, 2009).
14
74 Fed. Reg. 49,454 (September 28, 2009).
15
Though announced on September 22, 2009, this rule was not published until many weeks later: 74 Fed. Reg. 56,260
(October 30, 2009).
10

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means that both the “may reasonably be anticipated to endanger” component finding and the
“contributes to” component finding are satisfied.

Part Three: CAA Sections with Endangerment
Triggers Other Than Section 202(a)
To what extent will the endangerment finding under section 202(a) narrow EPA’s discretion to
deal, or not deal, with GHGs under other CAA provisions with endangerment preconditions? The
CAA contains about a dozen such “endangerment” preconditions. Each one, like section 202(a),
establishes a precondition for EPA action against an air pollutant: EPA first must find that
emissions of that air pollutant (or group of pollutants) from a particular source category “cause or
contribute to air pollution which may reasonably be anticipated to endanger public health or
welfare.” Some endangerment provisions, not section 202(a), add the qualifier “significantly”
after “contribute,” and there are slight variations in singular/plural and punctuation; otherwise the
quoted language repeats throughout the statute. Depending on the CAA section, if EPA finds an
endangerment, it is required or at least authorized, usually without other preconditions, to take
action addressing the endangerment by the source category.
At the outset, an administrative law question arises. Since this report’s topic is whether EPA
might be forced to regulate GHG emissions under CAA provisions outside 202(a), one must ask:
Does EPA have to respond at all to petitions it receives for endangerment findings and standard
setting under those provisions? (At least 10 such petitions seeking EPA control of GHG emissions
from this or that source category have been filed with the agency since Massachusetts v. EPA.16)
Can the agency simply ignore requests to regulate GHG emissions, or inform a petitioner that
EPA is studying the matter without ever reaching a decision? None of the CAA endangerment
provisions expressly authorizes petitions to the agency, in contrast with other provisions in the
CAA and elsewhere that do establish petition mechanisms with agency deadlines for response.17

16
A summary of seven of these petitions is in the ANPR mentioned on page 1 of this report. 73 Fed. Reg. at 44,45844,462. Of the seven petitions, three address GHGs from ocean-going vessels, two from aircraft, and two from nonroad
engines and vehicles. On July 29, 2009, the Institute for Policy Integrity at the New York University School of Law
submitted a petition addressing fuels used in motor and nonroad vehicles and engines, and aircraft. On September 21,
2009, a coalition of environmental, animal welfare, and environmental justice groups submitted a petition requesting
EPA to promulgate new source performance standards for several air pollutants, including greenhouse gases, from new
concentrated animal feeding operations. Finally, on December 2, 2009, the Center for Biological Diversity and 350.org
submitted a petition requesting EPA to issue national ambient air quality standards for seven GHGs.
Each of these petitions asks EPA to make the requisite endangerment finding under the appropriate CAA section—
section 108, 111, 211, 213, or 231. These provisions are discussed further on in this part of the report. To date, EPA has
not responded to any of the petitions. Finally, EPA has received petitions under section 115, dealing with
endangerments in Canada owing to emissions in the United States. Because EPA does not recognize a petition process
under section 115, it has characterized these self-described petitions as “submittals.” The petitions/submittals under
section 115 of which CRS is aware have been rejected.
17
See, e.g., CAA § 126(b), 42 U.S.C. § 7426(b). The text paragraph restates a point made by Justice Scalia in his fourjustice dissent in Massachusetts. As he put it: “Where does the CAA say that the EPA Administrator is required to
[make a ‘judgment’ under 202(a)] whenever a rulemaking petition is filed? The Court points to no such provision
because none exists.” 549 U.S. at 550. The majority does not address the question, probably because EPA did in fact
render a formal decision on the petition in Massachusetts, denying it.

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The answer is that while courts afford federal agencies wide discretion as to whether to initiate a
rulemaking,18 the discretion is not without limit. The Administrative Procedure Act is the
touchstone: under section 553(e), each agency must give interested persons “the right to petition
for the issuance … of a rule,”19 which petition is subject to section 555(b)’s command that an
agency “within a reasonable time … proceed to conclude a matter presented to it.”20 If an agency
fails to heed these directives, section 706(1) empowers courts to “compel agency action
unlawfully withheld or unreasonably delayed.”21 The Supreme Court recently explained that an
APA section 706(1) claim can proceed only when an agency failed to take a discrete agency
action that it is required to take22—but petitions seeking EPA regulation of GHG emissions would
presumably argue that this is exactly what they are alleging. Moreover, these APA provisions
have been applied not only where an agency responds to a rulemaking petition by denying it, but
to instances such as those hypothesized here, where the agency refuses to respond at all.23 In sum,
a reviewing court likely would require EPA to respond—up or down—to a well-supported
petition for GHG regulation within a generous, but finite, period of time.
Given that EPA responds to the petition (or acts without petition), one issue that arises under
every non-202(a) endangerment provision is the effect of the generic component of the agency’s
202(a) finding. Recall that the generic component declared that GHGs already in the atmosphere
from all sources may, in combination, reasonably be anticipated to endanger public health or
welfare. Because non-202(a) endangerment provisions use identical language, arguably at least
the generic component of those provisions also must be deemed satisfied. This is an important
preliminary step in understanding the legal relevance of EPA’s 202(a) endangerment finding to
other endangerment-triggered sections of the CAA—but it is only a preliminary step. Beyond
this, as the following discussion shows, there are differences in the language surrounding the
endangerment provisions, and lower levels of GHG emissions from most non-section-202 source
categories. These differences, it would appear, generally give EPA leeway in deciding whether to
regulate GHGs from sources other than new motor vehicles, notwithstanding the 202(a) finding.
Following are the CAA endangerment provisions being debated as possibly authorizing, or even
mandating, EPA regulation of GHG emissions now that EPA has issued its 202(a) endangerment
determination.

Fuels and Fuel Additives
CAA section 211(c)(1)24 empowers EPA to regulate the manufacture, sale, or offering for sale, of
fuels and fuel additives for use in motor vehicles or nonroad engines or vehicles. The authority
comes into being when, in EPA’s judgment, any emission product of such fuel or fuel additive
triggers an endangerment provision identical to that in 202(a). Unlike section 202, which
18
As a leading commentator observes: “… courts have traditionally applied a highly deferential standard of review in
reviewing cases of agency inaction.” Jeffrey S. Lubbers, A GUIDE TO FEDERAL AGENCY RULEMAKING 542 (4th ed.
2006).
19
5 U.S.C. § 553(e).
20
Id. at § 555(b).
21
Id. at § 706(1).
22
Norton v. Southern Utah Wilderness Alliance, 542 U.S. 55, 63 (2004).
23
See, e.g., In re: American Rivers and Idaho Rivers United, 372 F.3d 413, 418 (D.C. Cir. 2004).
24
42 U.S.C. § 7545(c)(1).

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authorizes standards for emissions, section 211 speaks of standards for the composition of the fuel
that produces the emissions. Presumably because section 202 specifies only a final result, rather
than dictating how manufacturers are to achieve that result, it is “the preferred—although not the
mandatory—alternative under the statutory scheme.”25
Section 211(c)(1) arguably allows EPA to implement low-carbon fuel standards.26 However,
section 211(c)(1) states only that EPA “may” regulate if an endangerment finding is made—
unlike section 202(a), which directs that EPA “shall” regulate on such a finding. 27 Assuming that
“may” is used in the traditional sense of allowing full discretion, a 211(c)(1) endangerment
finding would not compel agency action against fuels and fuel additives. That being so, it is
unnecessary to address whether a “contributes to” component finding under 211(c)(1) would be
compelled by a comparable finding under 202(a).

National Ambient Air Quality Standards
CAA section 108(a)(1)28 contains endangerment language identical to that of 202(a) and might
provide a basis for regulating stationary sources of GHGs through national ambient air quality
standards (NAAQSs).
By way of background, NAAQSs are nationwide standards set by EPA that fix the maximum
concentration of a pollutant (or group of pollutants) allowed in ambient air.29 There are two types
of NAAQSs: primary NAAQSs to protect public health, and secondary NAAQSs to protect
public welfare. 30 Under the CAA, the path to establishing primary and secondary NAAQSs for an
air pollutant consists of three steps: (1) listing of the pollutant by EPA, which requires (2)
issuance by the agency of “air quality criteria” (documents summarizing the scientific
information about a pollutant’s effects—not, as “criteria” implies, standards), which, in turn,
requires (3) promulgation of the NAAQSs. States then are required to submit “implementation
plans” to EPA within three years to achieve and/or maintain the NAAQSs. 31 As a practical matter,
any concern that EPA may be forced by the 202(a) endangerment finding to promulgate NAAQSs
arises chiefly from primary, not secondary, NAAQSs. The reason: areas designated nonattainment
for a primary NAAQS must attain the NAAQS within five years from such designation; in
contrast, no fixed deadline is set for attainment of secondary NAAQSs.32

25

Ethyl Corp. v. EPA, 541 F.2d 1, 11 (D.C. Cir. 1976) (en banc).
Jameel Alsalam, Ctr. For Clean Air Policy, A Pragmatic Approach to Regulating Greenhouse Gases Under the
Clean Air Act 14 (2009), http://www.ccap.org/docs/resources/614/
Clean%20Air%20Act%20and%20GHGs_CCAP_March%202009.pdf.
27
Generally, unless the context indicates otherwise, the words “shall” and “may” in statutes are to be read in their
everyday sense of mandatory and permissive, respectively. See, e.g., Rastelli v. Warden, Metro. Correctional Center,
782 F.2d 17, 23 (2d Cir. 1986) (“The use of a permissive verb—‘may review’ instead of ‘shall review’—suggests a
discretionary rather than mandatory review process.”).
28
42 U.S.C. § 7408(a)(1).
29
Id. at § 7409(a). “Ambient air” is “that portion of the atmosphere external to buildings, to which the general public
has access.” 40 C.F.R. § 50.1(e).
30
See footnote 3 supra.
31
42 U.S.C. § 7410(a)(1).
32
Id. at § 7502(a)(2)(A)-(B).
26

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As the above shows, listing the pollutant is the critical first step—listing compels criteria, which
compel NAAQSs. So when is listing required? Section 108(a)(1) states that “for the purpose of
establishing NAAQSs,” the EPA Administrator “shall” publish a list of air pollutants (A) which
“cause or contribute to air pollution which may reasonably be anticipated to endanger public
health or welfare”; (B) which are emitted from “numerous or diverse mobile or stationary
sources”; and (C) “for which air quality criteria had not been issued before the date of enactment
of the Clean Air amendments of 1970, but for which he plans to issue air quality criteria under
this section.”33 The endangerment finding under section 202(a) arguably forces EPA at some point
to find condition (A) satisfied—the precise phrase “cause or contribute to air pollution which may
reasonably be anticipated to endanger public health or welfare” is found in both 108(a)(1) and
202(a), and 108(a)(1)’s reference to “contribute to air pollution” presumably includes the same
new motor vehicle emissions EPA just found to do so under 202(a). As for condition (B), that CO2
is emitted by “numerous and diverse mobile or stationary sources” seems hard to deny. But based
on the literal language, EPA could be expected to argue that condition (C) gives it discretion
whether to “plan[] to issue air quality criteria”—hence discretion not to promulgate a NAAQS.34
There is contrary authority denying such discretion, however. In NRDC v. Train,35 the Second
Circuit held that EPA could not use condition (C) to avoid setting a NAAQS for lead, once the
agency had recognized lead as satisfying conditions (A) and (B). To hold otherwise, said the
court, would render the 108(a)(1) language that EPA “shall” publish a list “mere surplusage,” and
allow EPA to bypass the rigid CAA deadlines for attaining air quality standards.36 Moreover, said
the court, “it is to the initial list alone [the one required to be published soon after enactment of
the 1970 CAA amendments] that the phrase ‘but for which he plans to issue air quality criteria’ is
directed.”37 Plainly, Train might be invoked by any party seeking to compel EPA to set NAAQSs
for GHGs following a positive endangerment finding for GHGs under section 202(a).
But Train does not settle the matter. Most significantly, the consequences of listing GHGs under
section 108(a), leading to NAAQSs for GHGs, are so awkward—some would say absurd—that
an argument arises that Congress could not have intended this result (assuming NAAQSs for
GHGs were set below current atmospheric concentrations38). For one thing, the state
implementation plans (SIPs) that would be required to achieve these NAAQSs would have an
impossible goal, since even a substantial reduction of GHG emissions in an air quality control
region likely would have little effect on ambient concentrations of GHGs. For this reason, a court
might well take seriously an argument that an endangerment finding under section 202(a) does
not force EPA to promulgate NAAQSs for GHGs. Courts tend to resist interpretations of statutes
that lead to impractical or absurd results.39

33

Emphasis added.
See ANPR, 73 Fed. Reg. at 44, 477.
35
545 F.2d 320 (2d Cir. 1976).
36
Id. at 325.
37
Id. at 325.
34

38

In particular, CAA section 109(b)(2) requires the “secondary” NAAQS to be set at a level that “protect[s] the public
welfare from any known or anticipated adverse effects.” (Emphasis added.) Since current atmospheric levels of GHGs
are already believed to be producing welfare effects, it would seem that the plain meaning of the CAA language
requires that a secondary NAAQS for GHGs be set lower than current concentrations. Under Whitman v. American
Trucking Ass’n, 531 U.S. 457 (2001), EPA may not consider costs of compliance in setting a NAAQS.
39
See, e.g., United States v. Turkette, 452 U.S. 576, 580 (1981) (in construing a statute, “absurd results are to be
avoided”). In Public Citizen v. U.S. Dep’t of Justice, 491 U.S. 440, 470 (1989), Justice Kennedy, writing in
(continued...)

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Other arguments undermining the present-day viability of NRDC v. Train can be conceived,
though each is debatable. First, Train dealt specifically with lead, which the Senate committee
report for the 1970 CAA explicitly expected would be the subject of a NAAQS.40 The Second
Circuit twice noted this explicit mention of lead in the Senate report. In contrast, there is no
legislative history indicating a congressional expectation of a NAAQS for GHGs, suggesting that
Train would have less force in this context.
Second, EPA notes in the ANPR that NRDC v. Train was decided before the Supreme Court’s
decision in Chevron U.S.A. Inc. v. NRDC.41 Chevron sets out the canonical statement of a key
judicial review principle: courts should defer to an agency’s interpretation of a statute it is
charged with administering.42 According to Chevron, if the statute is ambiguous or silent on a
point, a court is to ask only whether the agency’s interpretation is a “permissible” construction
thereof. 43 The reviewing court is not to substitute its own judgment for a permissible agency
construction, even if the agency’s interpretation is not the only reasonable one. EPA’s argument in
the ANPR, it appears, is that the Second Circuit might have deferred to EPA’s we-have-discretion
argument had the court written its decision post-Chevron. However, this argument overlooks the
fact that the deference principle was well established long before Chevron, and certainly by the
time of NRDC v. Train.44
Finally, one might ask why, if Congress always intended NAAQSs to be required once conditions
(A) and (B) are met, no new NAAQSs for a new criteria pollutant have been set since the 1970s.45

New or Modified Stationary Sources
CAA section 111(b)(1) commands EPA to issue new source performance standards (NSPSs) for
new or newly modified stationary sources of air pollution (principally, factories and power plants)
once it determines that a stationary source category “causes, or contributes significantly to, air
pollution which may reasonably be anticipated to endanger public health or welfare.” After EPA
establishes an NSPS for a pollutant from a new-source category, section 111(d) then requires each
state to submit to EPA a plan establishing standards of performance for existing sources of that
pollutant within the same source category—a major air pollution program in its own right. Note,

(...continued)
concurrence for himself and two other justices, noted that “[w]here the plain language of the statute would lead to
patently absurd consequences, that Congress could not possibly have intended, we need not apply the language in such
a fashion. When used in a proper manner, this narrow exception to our normal rule of statutory construction does not
intrude upon the lawmaking powers of Congress, but rather demonstrates a respect for the coequal Legislative Branch,
which we assume would not act in an absurd way.” (citations omitted; emphasis in original)
40
S Rep. No. 91-1196, at 11 (1970).
41
467 U.S. 837 (1984). See ANPR, 73 Fed. Reg. at 44,477 n.229.
42
Such deference has been held to be particularly appropriate in the case of “a statutory scheme as unwieldy and
science-driven as the Clean Air Act.” Appalachian Power Co. v. EPA, 135 F.3d 791, 801-802 (D.C. Cir. 1998).
43
467 U.S. at 843.
44
Indeed, in the same year as NRDC v. Train, the Supreme Court explicitly deferred to EPA’s interpretation of another
one of its statutes, the Clean Water Act. EPA v. California, 426 U.S. 200, 227 (1976).
45
The wording of the text sentence—“no new NAAQSs for a new criteria pollutant”—is meant to exclude revisions of
existing NAAQSs (see CAA § 109(d)(1)), the replacement of the “total suspended particulates” NAAQS with a PM10
NAAQS in 1987, and the promulgation of the PM2.5 NAAQS as a companion to the PM10 NAAQS in 1997.

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however, that section 111(d) state plans are not required for pollutants listed under section 108 for
eventual development of NAAQSs (see previous section).
Immediately plain is one reason why a 202(a) endangerment finding may not force EPA to
promulgate a GHG NSPS for most new source categories: the term “significantly” in 111(b)(1)
distinguishes that provision from 202(a). “Significantly” is not defined in the CAA, so EPA likely
has broad discretion to define it to exclude many stationary source categories. But while such
discretion is broad, it is not unlimited. EPA’s discussion accompanying its 202(a) endangerment
finding extensively documents the harm GHGs may have on the environment, and notes that even
GHG source categories that appear too small to matter in fact could be very significant
contributors in terms of both absolute emissions or in comparison to other similar source
categories. Such statements may limit EPA’s ability to define “significantly” so as to eliminate
entirely any obligation to deal with GHGs through NSPSs, especially for the higher-emitting
source categories. In particular, coal-fired power plants emitted 27.6% of total U.S. GHG
emissions in 200846—by most any measure a “significant” contribution. Thus, the generic
component of EPA’s 202(a) endangerment finding, in combination with a new source category
that is a “significant” contributor of GHGs, would seem to trigger an EPA duty to promulgate
NSPSs for that source category.
In the case of section 111, however, the bare duty to promulgate an NSPS for a new source
category’s GHGs is the minor part of the story. More important is the considerable discretion EPA
would have as to the precise content and applicability of that NSPS. For this reason, the agency is
likely to favor NSPSs for dealing with GHGs—that is, as long as it has to address GHGs under
the existing CAA. The discretion inheres first in the definition of NSPS, which directs EPA to
factor in the feasibility of reducing emissions with current technology, and the cost.47 In the
statute’s words, NSPSs must reflect the degree of emission reduction achievable through
the best system of emission reduction which (taking into account the costs of achieving such
reduction and any nonair quality health and environmental impact and energy requirements),
the [EPA] Administrator determines has been adequately demonstrated.48

The D.C. Circuit has interpreted this standard to mean that EPA should “identify the emission
levels that are ‘achievable’ with ‘adequately demonstrated technology’” (an undefined phrase
allowing EPA broad discretion) and then use its discretion “to choose an achievable emission
level which represents the best balance of economic, environmental, and energy
considerations.”49 Also, section 111(b)(2) allows EPA to “distinguish among classes, types, and
sizes within categories of new sources” in setting NSPSs, adding yet another layer of agency
discretion. In sum, even if the 202(a) endangerment finding leads to an NSPS being required for
GHGs emitted by some new source category, EPA’s latitude in formulating that standard makes it
unlikely the standard will be overly burdensome.

46

U.S. Energy Information Admin. (Department of Energy), EMISSIONS OF GREENHOUSE GASES IN THE UNITED STATES
2008 (2009). The 27.6% figure in the text was calculated by CRS from 2008 figures in Table 1 of the report, showing
total U.S. GHG emissions as 5,839.3 million metric tons of CO2 equivalent, and Table 11, showing coal-fired power
plant emissions as 1,945.9 million metric tons of CO2.
47
42 U.S.C. §§ 7411(a)(1) and (h).
48
Id. at § 7411(a)(1).
49
Sierra Club v. Costle, 657 F.2d 298, 330 (D.C. Cir 1981).

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At present, there are several active suits seeking to compel EPA promulgation of NSPSs for GHG
emissions from one or another stationary source category.50 Petitioners’ prospects in such suits
likely will be improved by EPA’s 202(a) endangerment finding.

Non-202(a) Mobile Sources of Air Pollution
Non-road Engines and Non-road Vehicles
CAA section 21351 applies to non-road engines and non-road vehicles, which include ocean-going
vessels, construction equipment, farm tractors, forklifts, and lawn and garden equipment. Under
213(a)(4), if EPA determines that any emissions from new non-road engines or vehicles
“significantly contribute to air pollution which may reasonably be anticipated to endanger public
health or welfare, the Administrator may promulgate ... such regulations as the Administrator
deems appropriate ... taking into account costs, noise, safety, and energy factors.” This contrasts
in three ways with section 202(a), which (1) requires, rather than merely allows,52 EPA to issue
regulations for (2) emissions that merely “contribute,” rather than “significantly contribute,” to air
pollution, and (3) lacks the discretion-enhancing phrase “as the Administrator deems
appropriate.” Thus EPA has great discretion in responding (or not responding) to GHG emissions
from the non-road category.

Aircraft Engines
CAA section 23153 authorizes EPA to establish emissions standards for aircraft engines. The
agency “shall, from time to time” propose such standards, once a 202(a)-identical endangerment
provision is satisfied. Plainly, a “contributes to” finding for new motor vehicles under 202(a) has
limited relevance to whether EPA must make a counterpart finding for a different source category,
like aircraft, that emits far less GHGs. The pivotal question is whether a “contributes to”
component finding may have to be made for aircraft anyway, independent of section 202(a), in
that whatever the quantity of GHG emissions from aircraft, it is not insignificant. A “contributes
to” component finding for aircraft GHGs combined with a “may reasonably be anticipated to
endanger” component finding carried over from section 202(a) will force EPA to make an overall
endangerment finding for aircraft. This argument may turn on the breadth of EPA’s authority to
set a de minimis threshold for the quantity of aircraft GHG emissions that is deemed to
“contribute to.”
What if an endangerment finding is made for aircraft GHG emissions? Unlike with 202(a), such a
finding under 231 does not automatically require regulations. Section 231(a)(2)(B)(ii) states that
EPA “shall not change the aircraft engine emissions standards” if doing so would “significantly
increase noise and adversely affect safety.”54 Section 231(c) states further that no regulation shall
apply if disapproved by the President following the Secretary of Transportation’s finding that EPA

50

See generally CRS Report RL32764, Climate Change Litigation: A Survey, by (name redacted).
42 U.S.C. § 7547.
52
See supra footnote 27 and accompanying text.
53
42 U.S.C. § 7571.
54
Id. at § 7571(a)(2)(B).
51

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regulations would create a hazard to aircraft safety.55 Also, “any regulation prescribed under
[section 231] ... shall take effect after such period as the Administrator finds necessary ... to
permit the development and application of the requisite technology, giving appropriate
consideration to the cost of compliance within such period.”56 Finally, even should standards be
compelled, section 231 is silent as to their form and stringency level (as under section 202(a)).
Noting these features, the D.C. Circuit has held that EPA enjoys broad discretion under section
231 in determining appropriate regulations for aircraft emissions in light of cost, technology, and
safety, and can subordinate emissions reduction to these other concerns. 57

Air Pollutants from the Loading and Unloading of Tank Vessels
CAA section 183(f)(1)(A)58 requires EPA to regulate “the emission of [volatile organic
compounds] and any other air pollutant from the loading and unloading of tank vessels”59 that
EPA finds “causes, or contributes to, air pollution that may be reasonably anticipated to endanger
public health or welfare.”60 Volatile organic compounds are not GHGs, but the phrase “any other
air pollutant” presumably includes methane, which is a GHG and may be released during the
loading and unloading of tank vessels. The same point made above under section 231 applies
here. To reiterate, a key question is whether a “may reasonably be anticipated to endanger”
component finding under 202(a) will force EPA to make an endangerment finding for loading and
unloading tank vessels given the argument that, however low relative to motor vehicles the GHG
emissions from such operations, they nonetheless demand a “contributes to” component finding.
The answer to this question, to reiterate, may turn on EPA’s discretion in setting a de minimis
threshold for the loading and unloading of tank vessels. Query whether the absence of the phrase
“in his judgment” in 183(f)(1)(A), if contrasted with the presence of the same phrase in section
202(a), may be read by a court to constrain the agency’s discretion under 183(f)(1)(A).
Even when promulgation of standards is compelled, EPA has discretion in other regards: section
183(f)(1)(A) does not explicitly specify the form and stringency of the required standards, and the
standards are to reflect broad parameters (reasonably available technology, environmental
impacts, energy requirements, and safety), as to which latitude of interpretation is inevitable.

Stratospheric Ozone Protection
CAA section 61561 chiefly seeks to protect stratospheric ozone, but its broad language extends to
all threats to the stratosphere. The section is included here because there are several scenarios
under which GHGs might affect the stratosphere.62
55

Id. at § 7571(3)(c).
Id. at § 7571(2)(b).
57
National Association of Clean Air Agencies v. EPA, 489 F.3d 1221, 1230 (D.C. Cir. 2007).
58
42 U.S.C. § 7511b(f)(1)(A).
56

59

CAA section 183(f)(1)(A) incorporates the definition of “tank vessel” in 46 U.S.C. § 2101(39). A tank vessel is a
vessel that carries hazardous material or oil in bulk, or is adapted to do so, and is (A) a vessel of the United States, (B)
operates in U.S. waters, or (C) transfers its good in a U.S. port or any other place subject to U.S. jurisdiction.
60
This endangerment provision lacks the “in his judgment” phrase found in CAA section 202(a).
61
42 U.S.C. § 7671n.
62
See CRS Report R40585, Climate Change: Potential Regulation of Stationary Greenhouse Gas Sources Under the
Clean Air Act, supra page 1, at 14.

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The wording of section 615 is a bit different from the foregoing endangerment provisions:
If, in the Administrator’s judgment, any substance, process, practice, or activity may
reasonably be anticipated to affect the stratosphere, especially ozone in the stratosphere, and
such effect may reasonably be anticipated to endanger public health or welfare, the
Administrator shall promptly promulgate regulations respecting the control of such
substance, process, practice, or activity.

This language presents several distinctions from section 202(a), indicating that a positive
endangerment finding under 202(a) would almost certainly not be found to compel EPA action
under section 615. In particular, section 615 speaks of an effect on the stratosphere that may
endanger public health or welfare, not, as does section 202(a), “air pollution” in the atmosphere
generally that may do so. Thus, the generic component finding under section 202(a) does not
dictate the comparable component finding here. For another thing, section 615 demands that the
“substance” may itself be expected to affect the stratosphere in a way that endangers public health
or welfare; section 202(a) sets a lower threshold, insisting only that the emissions “contribute to”
existing air pollution levels that, without regard to the contributing source, may be expected to
endanger. And as with some other endangerment provisions discussed in this memorandum,
section 615, should it be deemed to require regulations, says nothing explicit as to their form or
stringency.

Pollution in a Foreign Country Caused by Emission Sources in the
United States
Under CAA section 115, “[w]henever the [EPA] Administrator, upon receipt of reports … from
any duly constituted international agency has reason to believe that any air pollutant or pollutants
emitted in the United States cause or contribute to air pollution which may reasonably be
anticipated to endanger public health or welfare in a foreign country,” it must notify the
governors of the states where the emission originates.63 The same result, EPA notification of
states, is required when the U.S. Secretary of State “alleges” such an endangerment and requests
EPA to so notify. The notified states must then revise their state implementation plans “to prevent
or eliminate” the endangerment being caused in the foreign country, but only if EPA finds that the
same rights are granted to the United States by the country affected. 64
Unlike other CAA provisions, section 115’s endangerment provision imposes no requirement that
EPA determine whether the air pollutant endangers public health or welfare in the United States.
At first blush, therefore, one might conclude that a section 202(a) endangerment finding, based on
effects in the United States, has no relevance to section 115, based on foreign effects. However,
given the near uniformity of worldwide atmospheric concentrations of GHGs,65 a positive 202(a)
finding for the United States, which necessarily includes a “may reasonably be anticipated to
endanger” finding for the United States, seems to compel the same component finding for any
foreign country. As for the “contributes to” component finding, the question arises whether such
63

42 U.S.C. § 7415(a) (emphasis added). A comparable provision for abatement of water pollution in the United States
causing endangerment in a foreign country is found at Clean Water Act section 310, 33 U.S.C. § 1320.
64
See Peter Tsirigotis, Discussion of Clean Air Act Authorities and GHGs, available at http://www.epa.gov/air/caaac/
pdfs/2008_01tsirigotis.pdf (Jan. 31, 2008).
65
With respect to the principal GHG, CO2, see Japan Meteorological Society, Carbon dioxide (CO2) distribution
(updated May 20, 2009), available at http://ds.data.jma.go.jp/ghg/kanshi/info_kanshi_e.html.

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finding is to be made for the United States overall, or for individual states. The former seems the
better reading of section 115, given that the section speaks of pollutants emitted “in the United
States” and refers to supporting studies by a “duly constituted international agency.” In either
event, EPA, upon making an endangerment finding and reciprocity finding respecting a foreign
country, would be required to notify and demand implementation plan revisions from many,
probably most, states.
As with setting NAAQSs for GHGs, the consequences of a section 115 endangerment finding
(assuming reciprocity) are extremely awkward, and for the same reason. Again, the compelled
EPA action would be a demand that many or even most state implementation plans be revised “to
prevent or eliminate” the foreign endangerment. As discussed under the NAAQSs section of this
report, such an ambitious result is likely unattainable, even assuming substantial reductions of
GHG emissions in every plan-revising state, owing to the staggering number of GHG sources
worldwide that contribute to the endangerment in the foreign country. Thus, with section 115 as
with the CAA’s NAAQS sections, EPA may search for a plausible interpretation of the statutory
language that could avoid such consequences and the courts may be receptive.
Several such interpretations may be noted, though it must be stressed that they are of varying
degrees of legal persuasiveness and have mostly not been tested in court. The first, noted by EPA
in its ANPR, is that section 115 can only be used to require states to incorporate into their
implementation plans measures related to attainment and maintenance of NAAQSs.66 EPA’s
argument appears to be founded on section 115’s statement that following an endangerment
finding, EPA’s notice to a state “shall be deemed to be a finding under section 110(a)(2)(H)(ii) …
which requires a plan revision with respect to so much of the applicable implementation plan as is
inadequate to prevent or eliminate the endangerment.”67 Implementation plans are required to be
prepared by states under section 110 to achieve and maintain NAAQSs,68 and 110(a)(2)(H)(ii)
states one of the required elements in such plans. Thus, EPA apparently concludes, section 115,
being dependent on 110(a)(2)(H)(ii) for effectuation, likewise must be confined to measures
related to attainment and maintenance of NAAQSs. If this argument is upheld, EPA might be able
to avoid using section 115 if it can avoid setting a NAAQS for GHGs under section 110.
The vulnerability of EPA’s argument, however, is that contrary to EPA’s position, the text of
section 110(a)(2)(H)(ii) appears to reach beyond measures related to attainment and maintenance
of NAAQSs. Section 110(a)(2)(H)(ii) explicitly requires that implementation plans provide for
plan revision when EPA finds that “the plan is substantially inadequate to attain the [NAAQS]
which it implements or to otherwise comply with any additional requirements established under
this Act.”69 Section 115’s command that an EPA-notified state revise its plan to eliminate the
endangerment would seem to be precisely such an “additional requirement[].” Moreover, that
requirement applies under 115(a) to “any” air pollutant emitted in the United States, not just those
that affect attainment and maintenance of NAAQSs.
66

73 Fed. Reg. at 44,482-44,483. See also Letter from Brian J. McLean, Director of EPA Office of Atmospheric
Programs, to Albert Koehl, Ecojustice Canada, dated February 29, 2008 (rejecting petition for section 115
endangerment finding based on, among other U.S.-emitted pollutants, CO2).
67
42 U.S.C. § 7410(a)(2)(H)(ii). The complementary CAA provision is section 110(k)(5): “Whenever the
Administrator finds that the applicable implementation plan for an area is substantially inadequate to attain or maintain
the relevant [NAAQS] … or to otherwise comply with any requirement of this Act, the Administrator shall require the
state to revise the plan as necessary to correct such inadequacies.” (Emphasis added.)
68
Id. at § 110(a)(1).
69
Emphasis added.

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A corollary to EPA’s argument that 110(a)(2)(H)(ii) is limited to NAAQS-related measures is its
stance that owing to the unavailability for GHGs of state notification and plan revision under
110(a)(2)(H)(ii), it is inappropriate for EPA to make the endangerment finding that sets that
process in motion. This argument stems from the EPA view, endorsed by the D.C. Circuit, that
section 115 establishes a single, unitary procedure. 70 That is, either both endangerment finding
and notification/plan-revision occur, or neither does.
Still other arguments that would thwart judicial coercion of EPA action under section 115 are (1)
that in contrast with the CAA section on interstate pollution, section 115 says nothing about
allowing petitions and so they should be assumed unavailable, 71 and (2) that the text of section
115 (“Whenever” the Administrator “has reason to believe”) implies a degree of discretion as to
the endangerment finding.72

Part Four: CAA Sections Having No Endangerment
Trigger
New Source Review in PSD Areas
Possibly the strongest arguments that a positive endangerment finding for new motor vehicle
GHG emissions, and resulting standards, will compel EPA to act against other GHG sources is
based on new source review in Prevention of Significant Deterioration (PSD) areas and on Title V
permitting (discussed in the following section). EPA fully accepts this argument:
EPA expects soon to promulgate regulations under the CAA to control GHG emissions
[from new motor vehicles] and, as a result, trigger PSD and Title V applicability
requirements for GHG emissions.73

As background, an area of the country is PSD for a pollutant if that area is either attaining the
health-based NAAQS for that pollutant or there is insufficient information to determine whether
the area is attaining that standard (“unclassifiable areas”).74 The PSD portion of the CAA seeks to
ensure that air quality in such areas—air that is or may be “cleaner than clean”—not be allowed
to deteriorate down to the minimum acceptable level in the NAAQSs. To ensure this does not
happen, the PSD program acts preventively; it requires EPA or states with approved PSD
programs to review in advance of construction any new major emitting facilities, or major
modifications of existing facilities, proposed for the PSD area.75 This is termed “new source
review.” As part of this review, the owner or operator of the proposed facility must show, for
70

Her Majesty the Queen in Right of Ontario v. U.S. EPA, 912 F.2d 1525 (D.C. Cir. 1990).

71

EPA makes this argument in the McLean letter, supra footnote 66, where the agency pointedly referred to the section
115 petition as a “submittal.” The argument, however, seems to overlook the Administrative Procedure Act sections
noted earlier in this report. See text accompanying notes 19-21 supra. Presumably EPA thinks of submittals as not
triggering a duty to respond.
72
Ontario, 912 F.2d at 1533.
73
Prevention of Significant Deterioration and Title V Greenhouse Gas Tailoring Rule, 74 Fed. Reg. 55,292, 55,292
(October 27, 2009) (proposed rule). Emphasis added.
74
CAA § 161; 42 U.S.C. § 7471.
75
CAA§ 165; 42 U.S.C.§ 7475.

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example, that emissions from the facility will not cause or contribute to more than one
exceedance per year of the maximum allowable increase in concentration for any pollutant.76
“Major emitting facility” is statutorily defined as any facility on a long statutory list (including
large fossil-fuel-fired power plants) that has the potential to emit 100 tons/year of any air
pollutant, and any stationary source in an unlisted category with the potential to emit 250
tons/year of any air pollutant.77
Since the PSD program is triggered by an area’s being cleaner than a NAAQS requires, one might
suppose it has no relevance to any pollutant for which there is no NAAQS—such as, so far,
GHGs. But the CAA’s PSD provisions cast a wider net. To be sure, an area can be designated
PSD only in connection with a NAAQS air pollutant. But once so designated, the statute
stipulates that “the proposed facility is subject to the best available control technology for each
pollutant subject to regulation under this Act emitted from … such facility.”78 The Supreme Court
has held that GHGs are “air pollutants” under the CAA, but what does “subject to regulation
under this act” mean? Did CO2 become “subject to regulation” when EPA promulgated
regulations in 1993 to require monitoring and reporting of CO2 emissions,79 as required by section
821 of the 1990 CAA amendments? Or later, in 2007, when the Supreme Court held that GHGs
are “air pollutants”? Or still later, only when EPA promulgates an emission standard actually
regulating CO2 emissions from some source—such as the expected section 202 standard? In
short, what event triggers the requirement of best available control technology (BACT) in PSD
areas?
Much ink has been spilled over the meaning of “subject to regulation under this Act.” Indeed, the
phrase has been the topic of at least two EPA Environmental Appeals Board decisions and one
EPA Administrator memorandum. 80 While the appeals board decisions have remanded the
question to EPA regional offices for further consideration, the Administrator’s memorandum
adopts the narrowest possible reading of “subject to regulation.” According to the memorandum,
issued at the end of the Bush Administration, the phrase excludes pollutants for which EPA
regulations only require monitoring and reporting, and includes only pollutants covered by an
“actual control of emissions” of the pollutant under the CAA or its regulations. In 2009, EPA
granted reconsideration of the Administrator’s memorandum and has recently sought comment on
the memorandum’s interpretation and other interpretations of “subject to regulation.”81 But the
dispute is likely to be moot soon, at least as to GHGs. Even under the narrow EPA interpretation,
the agency’s expected GHG standard for new motor vehicles in early 2010 will make certain
GHGs “subject to regulation under this Act,” and so trigger PSD/BACT for significant new
sources of those pollutants.
A PSD/BACT requirement for CO2 raises a problem, however, owing to the low 100/250
tons/year thresholds for applicability of the PSD program—recall the definition of “major
76

CAA § 165(a)(3); 42 U.S.C. § 7475(a)(3).
CAA§ 169(1); 42 U.S.C. § 7479(1).
78
CAA § 165(a)(4); 42 U.S.C. § 7475(a)(4). Emphasis added. See also CAA § 169(3); 42 U.S.C. § 7479(3).
79
40 C.F.R. Part 75.
80
Memorandum from Stephen L. Johnson, EPA Administrator, to EPA Regional Administrators, regarding “EPA’s
Interpretation of Regulations that [sic] Determine Pollutants Covered By Federal Prevention of Significant
Deterioration (PSD) Permit Program,” Dec. 18, 2008.
81
74 Fed. Reg. 51,535 (October 7, 2009). EPA identifies the current interpretation of “subject to regulation,” from the
Bush Administration, as the “current and preferred interpretation.” 74 Fed. Reg. at 51,535.
77

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emitting facility” in the second paragraph of this section. Carbon dioxide is emitted in far greater
amounts than any other air pollutant, so based on the statutory 250 tons/year threshold, hospitals,
churches, schools, and other relatively minor sources may be covered. Besides the considerable
pollution-control costs for small entities, coverage of such a vast number of sources, with a caseby-case determination of BACT for each source,82 also raises questions of administrative
practicality for state permitting authorities. To alleviate these problems, EPA has recently
proposed a “tailoring rule” to tailor the tons/year thresholds of PSD new source review to federal
and state administrative realities—in particular, to raise them substantially and thereby greatly
reduce the number of covered sources.83 The rule would depart, at least temporarily, from the
explicit 100 or 250 tons/year threshold in the CAA. As described by EPA—
The first phase, which would last 6 years, would establish a temporary level for the PSD and
Title V applicability thresholds at 25,000 tons per year (tpy) on a “carbon dioxide
equivalent” (CO2e) basis, and a temporary PSD significance level for GHG emissions of
between 10,000 and 25,000 tpy CO2e. EPA would also take other streamlining actions during
this time. … EPA would conduct another rulemaking, to be completed by the end of the sixth
year, that would promulgate, as the second phase, revised applicability and significance level
thresholds and other streamlining techniques.84

Of course, an agency’s departure from the express and unequivocal language of a statute, as EPA
proposes here, is something courts do not condone lightly—though it is another question entirely
whether any group would want to file suit against the tailoring rule, and who would have standing
to sue. 85 In any event, EPA goes to some effort in the preamble to the proposed tailoring rule to
provide legal justification—citing two related, but independent, lines of analysis it terms the
doctrines of “absurd results” and “administrative necessity.” These lines of analysis apply both to
PSD/new source review and Title V permitting, and so are discussed in a separate section of this
report following the upcoming section on Title V.
BACT is defined in the CAA, but in a manner that leaves the permitting authority (EPA or the
state) wide latitude in applying the requirement to a specific emission source.86 That latitude is

82
The CAA requires that BACT for a source be determined by the permit-issuing authority (the state or EPA) on a
“case-by-case basis.” CAA § 169(3); 42 U.S.C. § 7479(3).
83
Prevention of Significant Deterioration and Title V Greenhouse Tailoring Rule, 74 Fed. Reg. 55,292 (October 27,
2009).
84
Id. at 55,292. The threshold of 25,000 tpy relates solely to new major emitting facilities. “PSD significance level,” on
the other hand, relates solely to modifications of existing sources. As noted, only those modifications that are “major”
trigger EPA new source review. (The qualifier “major” is not in the CAA; it was added by EPA regulation—see 40
C.F.R. § 52.21(a)(2)(ii)). To be major, a modification must increase the emissions from a source by at least an EPAdefined “PSD significance level.” 40 C.F.R. §§ 52.21(b)(2)(i), 52.21(b)(40), 52.21(b)(23).
85
It is likely that the additional GHGs emitted by virtue of the temporarily raised tons/year threshold in the tailoring
rule would be insufficient to constitute the “injury in fact” required for standing to sue in federal courts. Speculating,
however, it may be imagined that an environmental group might claim standing by arguing that its members were
injured by the non-GHG emissions that would not have occurred had the statutory 100/250 tons/year threshold been
applied. This argument is based on the fact that BACT for GHGs will also, at many sources, reduce non-GHGs as well.
A second group that might have standing are industries that emit more than the 25,000 tons/year threshold in the
tailoring rule, who could conceivably argue they are at an economic disadvantage to their competitors below the 25,000
tons/year threshold in the rule.
86
CAA § 169(3); 42 U.S.C. § 7479(3).

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less, however, if EPA has an NSPS for the pollutant in question, since BACT can never result in
emissions greater than allowed under an NSPS, if one exists.87

Title V Permitting
CAA title V, added by amendment in 1990, creates an operating permit program applicable to
every “major” stationary source (existing and new), and certain other stationary sources, of air
pollution. 88 However, the Title V permit program imposes no substantive requirements of its own.
Rather, the purpose of a Title V permit is to consolidate in one place the requirements imposed on
the source elsewhere in the CAA, thus simplifying the regulation of each source and the
enforcement of such regulations by EPA, states, and citizen suits.
While imposing no new emission controls, Title V does impose costs on the applicant. For
example, as part of the application process, covered facilities must identify all federally
enforceable emission regulations (plus monitoring and recordkeeping requirements), including
those in state implementation plans, and develop a compliance plan. Once the permit is received,
the facility must monitor compliance and report the results to federal and state authorities at least
every six months. Certain changes in facility operations require a formal Title V permit
modification, at times a burdensome process. Finally, payment of permit fees is required, such
fees to be not less than $25 per ton of regulated pollutant, with exceptions.89 On the other hand,
the act does seek to ameliorate these costs. For example, Title V authorizes states to issue
“general permits” covering “numerous similar sources.”90 Facilities can then submit a simple
application seeking coverage under the general permit.
The general threshold for coverage by Title V is that the facility directly emits, or has the
potential to emit, 100 tons per year or more of any air pollutant. Such a low threshold would
extend Title V permitting requirements to many stationary sources of GHGs that in addition fall
under CAA emission requirements. In particular, a BACT requirement for GHG emissions in
PSD areas, discussed above under New Source Review in PSD Areas, would require new major
emitting facilities and major modifications in such areas to seek Title V permits.
As noted in the preceding section, the arguments made by EPA as to absurd results and
administrative necessity are invoked as well by the agency for narrowing the application of Title
V permitting. However, if the only CAA restrictions on stationary source GHGs are those under
PSD new source review, the thresholds under that program will completely set the scope of Title
V permitting.

87
88

Id.
CAA §§ 501-507; 42 U.S.C. §§ 7661-7661f.

89

CAA § 502(b)(3)(B)(i); 42 U.S.C. § 7661a(b)(3)(B)(i). As pertinent to GHGs, “regulated pollutant” is defined to
include each pollutant regulated under section 111 (NSPSs) and each pollutant for which a primary NAAQS has been
promulgated.
90
CAA § 504(d); 42 U.S.C. § 7661c(d).

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“Absurd Results” and “Administrative Necessity”
EPA has sought to legally justify its departure from the tons/year thresholds stated by the CAA for
PSD/new source review and Title V permitting by what it terms the “doctrines” of “absurd
results” and “administrative necessity.” These doctrines are discussed in detail in the preamble to
the proposed tailoring rule, noted in the New Source Review in PSD Areas section of this
report.91
The “absurd results” doctrine, supported by many court decisions, holds that even clear and
explicit statutory directives may on rare occasion have to be departed from when rigid adherence
would be inconsistent with other provisions of the statute or unambiguous legislative history, or
produce a result so contrary to sensible policy as to permit the inference that Congress could not
have intended that result. EPA asserts in the preamble to the proposed tailoring rule that
adherence to the 100/250 tons/year threshold for new source review in PSD areas would have
precisely this result:
the extraordinary increases in PSD and Title V permit applications that would result from a
literal application of the 100/250 tpy threshold requirements would, at least during the near
term—until EPA and the permitting authorities can develop streamlining methods and ramp
up resources—extensively disrupt the two permitting programs and impose undue regulatory
burdens in the aggregate on the sources newly subject to PSD and Title V permit
requirements.

As a concrete example, EPA asserts that during the initial period of literally applying the 100/250
tons/year threshold, permit applications would increase by 150-fold, “render[ing] it impossible
for permitting authorities to meet the requirement in CAA section 165(c) to process permit
applications within 12 months.”92
From EPA’s early years comes another example of courts endorsing an EPA effort to avoid a
seemingly senseless consequence of a literal statutory reading. During the 1970s, EPA adopted
the position that the National Environmental Policy Act (NEPA) does not require EPA to do
environmental impact statements, despite the fact that the act unequivocally makes its impactstatement directive applicable to “all agencies of the Federal Government.”93 The courts agreed
with EPA, affirming the agency’s rationale that it would be senseless to do environmental impact
statements per NEPA command when the decision-making processes followed by EPA under its
program statutes incorporate the very same environmental considerations and public participation
as NEPA.94 This may be regarded as an early and successful use of something akin to an absurd
results principle.
In sum, if courts agree with EPA that the burdens imposed by a literal reading of the PSD and
Title V thresholds would be crushing, it is quite plausible they would accept an EPA “absurd
results” defense in any litigation attacking the tailoring rule. This is particularly so because EPA is
91

74 Fed. Reg. at 53,303-53,311 (absurd results doctrine); 74 Fed. Reg. at 53,311-53,318 (administrative necessity
doctrine).
92
42 U.S.C. § 7475(c).
93
42 U.S.C. § 4332(2) (emphasis added).
94

See, e.g., State of Wyoming v. Hathaway, 525 F.2d 66, 71-72 (10th Cir. 1975). The question of NEPA’s application
to EPA was resolved, to some extent, by amendments to the Clean Air Act and Clean Water Act expressly exempting
the agency from NEPA’s impact statement requirement.

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not proposing a permanent exemption from the PSD and Title V thresholds, but rather a
temporary phase-in period (though courts may want to revisit the EPA threshold when the agency
makes its six-year adjustment in the threshold, as it promises to do). On the other hand, it must be
noted that in the sheer magnitude of its consequences, the statutory departure in the proposed
tailoring rule is greater than that in any of the “absurd results” cases with which CRS is familiar.95
The second, independent legal justification offered by EPA for its tailoring rule is the “doctrine”
of “administrative necessity.” This principle also has some support in the case law. As its name
suggests, it authorizes an agency to depart from statutory commands when literal compliance is
administratively impossible, or nearly so. To a considerable extent, administrative necessity and
absurd results overlap. EPA strenuously argues in the proposed tailoring rule’s preamble that the
statutory PSD threshold (together with a “zero” significance level threshold for modifications to
existing sources) “would result in a volume of permit applications that is so high that the PSD …
program[] would become impossible for State and Federal authorities to administer.” Only if EPA
can convince a court of such daunting burdens will the tailoring rule survive judicial review
(again, if review is sought).
In the leading case on administrative necessity, Alabama Power Co. v. Costle,96 the D.C. Circuit
was also dealing with EPA, and, by coincidence, the PSD requirements of the CAA. While
rejecting EPA’s expansion of a statutory exemption, the court conceded that
limited grounds for the creation of exemptions are inherent in the administrative process, and
their unavailability under a statutory scheme should not be presumed save in the face of the
most unambiguous demonstration of congressional intent to foreclose them.97

The court stressed, unsurprisingly, that “[c]ategorical exemptions from the clear commands of a
regulatory statute, though sometimes permitted, are not favored.”98 Yet, it added, “[t]his broad
principle that frowns upon categorical administrative exemptions is strict, but not absolute.”99 It is
possible that here, where EPA would have to apply the PSD program to a pollutant (CO2) emitted
in far larger quantities than the pollutants for which the CAA was designed, EPA may be able to
meet the demanding judicial prerequisites for invoking administrative necessity.
Finally, EPA has proposed that its phased approach to reaching the statutory thresholds may be
justified by case law for the proposition that agencies may proceed in an incremental fashion in
implementing a statutory mandate. EPA concedes that these cases are grounded on facts that are
distinguishable from the tailoring rule situation, and solicits comment as to whether the case law
is truly supportive of the proposed tailoring rule. 100

95

Some industry groups have argued that EPA should defer promulgating section 202 GHG emissions standards so as
to postpone triggering PSD/BACT for GHG emissions. This, of course, would avoid the problem of unrealistic
statutory thresholds entirely.
96
636 F.2d 323 (D.C. Cir. 1979).
97
Id. at 357.
98
Id. at 358.
99
Id. at 358.
100
74 Fed. Reg. at 55,319.

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Part Five: Final Thoughts
EPA’s endangerment finding for new motor vehicle GHG emissions, or the emission standards
that must follow, appears to force certain regulatory actions by EPA, leave the agency free to
resist certain other regulatory actions if it chooses, and leave two additional regulatory authorities
in a gray area in between.
Into the first category—forced regulatory action—appears to fall new source review of major
emitting facilities and major modifications of existing facilities in PSD areas. Final motor vehicle
GHG standards, expected by March, 2010, will necessarily mean that GHGs from new stationary
sources that emit more than some threshold amount of any pollutant (100 or 250 tons/year under
the CAA; 25,000 tons/year if the proposed tailoring rule is finalized), and GHGs from major
modifications of existing facilities, will be subject to BACT in such areas. BACT, however, is
loosely defined, particularly if there is no NSPS for the pollutant to set a floor on BACT. Title V
permitting requirements likely will be triggered as well. Further, stationary source categories that
emit large quantities of GHGs may have to be regulated by NSPSs, though the CAA gives EPA
wide latitude in shaping such regulations.
The second category—EPA retains discretionary latitude—appears to include almost all the
endangerment-triggered action authorities under the CAA. These can be distinguished in varying
degrees from section 202(a) on the grounds that, unlike section 202(a), some of them use the
discretionary “may,” some demand that the source category contribute “significantly” to the
endangerment, and some add additional preconditions. Most of these non-202(a) CAA authorities
involve source categories whose GHG emission levels are lower than from new motor vehicles,
meaning that a “contribute to” finding under section 202(a) may not dictate the same finding
under that other authority. Stationary source categories that do not emit large amounts of GHGs
will not have to be covered by NSPSs if EPA defines “significantly” at a high tons/year level.
The third category—the gray area between EPA being forced to act and not being forced to do
so—appears to comprise promulgation of NAAQSs for GHGs under section 108 and international
pollution abatement under section 115. These sections can be read to force EPA action, but there
would appear to be wiggle room for agency interpretation given the awkward consequences and
unattainable pollution-control goals such a reading could entail. The administrative necessity and
absurd results arguments presented so vigorously by EPA in connection with PSD new source
review and Title V permitting may be available to the agency here as well.
Ultimately whether EPA acts against GHG emissions under CAA provisions in the second and
third categories is likely to be a function of the agency’s (and Administration’s) political desires
more than anything else. The EPA under the Obama Administration has repeatedly stated that it is
willing to take on GHG emissions through CAA regulation if Congress does not soon enact
comprehensive climate change legislation reducing such emissions. There are several possible
motivations for the agency’s saying this: CAA regulation by the agency in the near future (1)
ensures that time is not lost in abating the causes of climate change while Congress debates; (2)
buttresses our credibility in international climate change negotiations (such as Copenhagen) by
showing that the United States is “serious” about tackling climate change; and (3) puts pressure
on Congress to enact climate change legislation.

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Author Contact Information
(name redacted)
Legislative Attorney
[redacted]@crs.loc.gov, 7-....

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/crs%3AR40984. Public record. Not legal advice.