Sandra L. Bahr; David Matusow, Petitioners,
U.S. Environmental Protection Agency; Gina McCarthy, Administrator, United States Environmental Protection Agency; Jared Blumenfeld, Regional Administrator, EPA Region IX, Respondents, State of Arizona, Respondent-Intervenor.
and Submitted June 17, 2016 San Francisco, California
Petition for Review of an Order of the Environmental
Herr-Cardillo (argued) and Timothy M. Hogan, Arizona Center
for Law in the Public Interest, Tucson, Arizona, for
D. Greenberg (argued), Attorney; Sam Hirsch, Acting Assistant
Attorney General; Environment & Natural Resources
Division, United States Department of Justice, Denver,
Colorado; Geoffrey Wilcox, Office of General Counsel; Kara
Christenson, Office of Regional Counsel, Region 9; United
States Environmental Protection Agency, San Francisco,
California; for Respondents.
Monique Coady, Assistant Attorney General, Office of the
Attorney General, Phoenix, Arizona, for Respondent-
Before: Richard R. Clifton and Sandra S. Ikuta, Circuit
Judges, and William Q. Hayes, [*] District Judge.
panel granted in part and denied in part a petition for
review of an order of the United States Environmental
Protection Agency approving Arizona's Five Percent Plan
for airborne particulate matter around Maricopa County,
promulgated under the Clean Air Act.
submitted a new State Implementation Plan revision on May 25,
2012 - the Five Percent Plan - to achieve a five percent
annual reduction in PM-10, a harmful air pollutant.
alleged that the EPA acted contrary to law by failing to
require that Arizona include an updated analysis of best
available control measures and most stringent measures in the
Five Percent Plan, excluding 135 exceedances from the
monitoring data as "exceptional events, " and
allowing Arizona to satisfy the "contingency
measures" requirement with previously implemented
panel held that it would apply Chevron U.S.A. Inc. v.
Natural Resources Defense Council, Inc., 467 U.S. 837
(1984), deference to the EPA's interpretation of the
Clean Air Act issued in connection with a State
Implementation Plan approval.
panel upheld the EPA's determination that the control
measures in Arizona's Five Percent Plan did not need to
be updated, and that the 135 exceedances were exceptional
events that were excluded from consideration under the
EPA's regulation and guidance documents.
panel did not defer to the EPA's interpretation of the
contingency measures requirement, however, because under the
plain language of 42 U.S.C. § 7502(c)(9) contingency
measures are measures that will be taken in the future, not
measures that have already been implemented. The panel
remanded to the EPA for further consideration of this portion
of the State Implementation Plan, but otherwise denied the
Clifton concurred in sections I-IV of the majority opinion,
and dissented from the majority's conclusion in section V
that EPA's approval of the contingency measures in
Arizona's State Implementation Plan was contrary to the
clear language of the Clean Air Act. In his view, the scope
of the Clean Air Act's contingency measures requirement
was ambiguous and EPA's reasonable interpretation of that
requirement was entitled to deference.
Bahr and David Matusow petition for review of a final rule
issued by the Environmental Protection Agency (EPA) approving
Arizona's Five Percent Plan for airborne particulate
matter around Maricopa County. They argue that the EPA erred
in approving this plan because it did not include best
available control measures (BACM) and most stringent control
measures (MSM) as of 2012. The petitioners also argue that
the EPA failed to follow its own published guidance in
approving Arizona's claim that 135 exceedances of the air
emission standard could be excluded from consideration.
See 42 U.S.C. § 7619(b)(1)(A). Finally, the
petitioners argue that the EPA's approval of the
contingency measures included in Arizona's Five Percent
Plan was contrary to 42 U.S.C. § 7502(c)(9) because the
measures had already been implemented. We uphold the
EPA's determination that the control measures in
Arizona's Five Percent Plan did not need to be updated,
and that the 135 exceedances were exceptional events that are
excluded from consideration under the EPA's regulation
and guidance documents. We do not defer to the EPA's
interpretation of the contingency measures requirement,
however, because under the plain language of §
7502(c)(9) contingency measures are measures that will be
taken in the future, not measures that have already been
begin by briefly describing the statutory framework. The
Clean Air Act (CAA), 42 U.S.C. § 7401 et seq.,
establishes "cooperative Federal, State, regional, and
local programs to prevent and control air pollution, "
id. § 7401(a)(4). Under the CAA, the EPA is
required to "publish . . . a list which includes each
air pollutant . . . emissions of which, in [the EPA's]
judgment, cause or contribute to air pollution which may
reasonably be anticipated to endanger public health or
welfare." Id. § 7408(a)(1). The EPA is
then required to "prescrib[e] a national primary ambient
air quality standard" (NAAQS) for that pollutant.
Id. § 7409(a).
such harmful air pollutant is "PM-10, " defined as
"particulate matter with an aerodynamic diameter less
than or equal to a nominal ten micrometers."
Id. § 7602(t). According to the EPA,
"PM-10 causes adverse health effects by penetrating deep
into the lungs, aggravating the cardiopulmonary system."
Approval and Promulgation of Implementation Plans-Maricopa
County PM-10 Nonattainment Area, 79 Fed. Reg. 7118, 7118
(Feb. 6, 2014). The EPA established a NAAQS for PM-10 of 150
micrograms per cubic meter, averaged over a 24-hour period.
40 C.F.R. § 50.6(a). This standard, which is sometimes
referred to as the "24-hour PM-10 standard, " is
"attained when the expected number of days per calendar
year with a 24-hour average concentration above 150
μg/m³ . . . is equal to or less than one."
provides that "[e]ach State shall have the primary
responsibility for assuring air quality" within the
state "by submitting an implementation plan"
explaining how the state will meet and maintain the NAAQS and
other standards. 42 U.S.C. § 7407(a). An area within a
state that does not meet a NAAQS is designated as a
"nonattainment" area, id. § 7407(d).
Each state's implementation plan (called a State
Implementation Plan or SIP) must provide for the
"implementation, maintenance, and enforcement" of
the NAAQS. Id. § 7410(a)(1). The CAA requires
each SIP for a nonattainment area to contain specified
information, including a requirement for reasonable further
progress, id. § 7502(c)(2), an emissions
inventory, id. § 7502(c)(3), and a list of
"contingency 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 applicable under this part, "
id. § 7502(c)(9).
sets out a series of deadlines for states to meet the NAAQS
for PM-10, with increasingly stringent requirements if a
state misses a deadline. Id. §§
7513-7513b. The sequence is as follows:
nonattainment area is initially designated as a
"moderate" area. Id. § 7513(a). A SIP
for a "moderate" PM-10 nonattainment area must
explain how that area will meet the PM-10 NAAQS by the
"attainment date, " which for nonattainment areas
designated by Congress was no later than December 31, 1994.
Id. § 7513(c)(1). The SIP must "assure
that reasonably available control measures for the control of
PM-10" are implemented. Id. § 7513a(a).
moderate nonattainment area fails to meet the PM-10 NAAQS by
the attainment date, the EPA must reclassify it as a
"Serious PM-10 nonattainment area." Id.
§ 7513(b). After redesignation, the state must submit a
SIP that demonstrates how the area will meet the PM-10 NAAQS
within 10 years of the original nonattainment designation,
or, for areas originally designated as nonattainment by
Congress, no later than December 31, 2001. Id.
§ 7513(c)(2). A SIP for a serious nonattainment area
must also "assure that the best available control
measures [BACM] for the control of PM-10 shall be
implemented." Id. §
state fails to meet the deadline for bringing a Serious Area
into compliance, the EPA may grant the state a single
five-year extension of the deadline to meet the NAAQS for
PM-10, but only if the state submits a SIP that
"includes the most stringent measures [MSM] that are
included in the implementation plan of any State or are
achieved in practice in any State, and can feasibly be
implemented in the area." Id. §
Serious Area fails to achieve compliance by the attainment
date after receiving the one-time five-year extension under
§ 7513(e), the CAA requires the state to "submit
within 12 months after the applicable attainment date, plan
revisions which provide for attainment of the PM-10 air
quality standard." Id. §
7513a(d). The SIP revisions must provide for an
annual five percent reduction in PM-10 within the Serious
Area from the date the SIP revision was submitted to the EPA
until the state attains the NAAQS in that area. Id.
are required to conduct ambient air quality monitoring to
determine whether a geographical region or area in the state
is meeting the NAAQS for PM-10. Id. §
7410(a)(2)(B)(i). State air quality monitoring systems must
use the criteria and methodology established by the EPA.
Id. § 7619(a). Congress recognized that air
quality monitoring data could be affected by exceptional
events that could not reasonably be controlled by the states,
and directed the EPA to promulgate regulations
"governing the review and handling of air quality
monitoring data influenced by exceptional events."
Id. § 7619(b)(2)(A). The statute defines an
"exceptional event" as an event that "(i)
affects air quality; (ii) is not reasonably controllable or
preventable; (iii) is an event caused by human activity that
is unlikely to recur at a particular location or a natural
event; and (iv) is determined by the Administrator through
the process established in the regulations promulgated under
paragraph (2) to be an exceptional event." Id.
to this direction, the EPA promulgated the "Exceptional
Events Rule, " 40 C.F.R. § 50.14. The rule repeats
the statute's definition of "exceptional event,
" id. § 50.1(j),  and allows a state to
"request EPA to exclude data showing exceedances or
violations of the national ambient air quality standard that
are directly due to an exceptional event, " id.
§ 50.14(a)(1). In order to obtain EPA approval to
exclude exceptional event data, a state must provide evidence
that "[t]he event satisfies the criteria set forth in 40
C.F.R 50.1(j)" and meets other criteria. Id.
§ 50.14(c)(3)(iv). If a state makes the required
showing, the "EPA shall exclude [the exceptional event]
data from use in determinations of exceedances and NAAQS
violations." Id. § 50.14(b)(1).
has recognized that PM-10 levels can be affected by natural
events such as dust storms, see id. §
50.1(j)-(k), and has therefore developed guidance for
applying the Exceptional Events Rule to high wind events.
See Treatment of Data Influenced by Exceptional
Events, 72 Fed. Reg. 13560 (Mar. 22, 2007) (Treatment of Data
Guidance). The Treatment of Data Guidance states that
increased particulate matter concentrations "raised by
unusually high winds will be treated as due to uncontrollable
natural events where (1) the dust originated from
nonanthropogenic sources, or (2) the dust originated from
anthropogenic sources within the State, that are determined
to have been reasonably well-controlled at the time
that the event occurred, or from anthropogenic sources
outside the State." Id. at 13576 (emphasis
2013, the EPA published additional "guidance and
interpretation" explaining how the Exceptional Events
Rule and the Treatment of Data Guidance applies to high wind
events. See EPA, Interim Guidance on the Preparation
of Demonstrations in Support of Requests to Exclude Ambient
Air Quality Data Affected by High Winds Under the Exceptional
Events Rule (May 2013) (Interim Guidance).The Interim
Guidance addresses when an anthropogenic source within the
State is "reasonably well-controlled at the time that
the event occurred, " 72 Fed. Reg. at 13576, as required
by the Treatment of Data Guidance.
provide the background of this case. Congress designated
Maricopa County, Arizona, as a "moderate" PM-10
nonattainment area in 1990. 42 U.S.C. § 7407(d)(4)(B);
PM10 Group I and Group II Areas, 52 Fed. Reg. 29383, 29384
(Aug. 7, 1987). The designated nonattainment area, termed the
"Maricopa County PM-10 Nonattainment Area"
(Maricopa Area), covers the eastern portion of Maricopa
County, including the cities of Phoenix, Mesa, Scottsdale,
Tempe, Chandler, and Glendale. 79 Fed. Reg. at 7118. It also
covers unincorporated parts of Maricopa County and portions
of Pinal County. Id.
the Maricopa Area was designated as a nonattainment area by
Congress, Arizona's first deadline for meeting the NAAQS
for PM-10 was December 31, 1994. 42 U.S.C. § 7513(c).
The Maricopa Area was not in attainment by 1994, so the EPA
reclassified the Maricopa Area as a Serious PM-10
nonattainment area. 42 U.S.C. § 7513(b)(2); Clean Air
Act Reclassification; Arizona-Phoenix Nonattainment Area;
PM-10, 61 Fed. Reg. 21372, 21373 (May 10, 1996). This
required Arizona to submit a SIP that would demonstrate how
the Maricopa Area would meet the NAAQS for PM-10 by December
31, 2001, see 42 U.S.C. § 7513(c)(2), and to
explain how it would implement the best available control
measures for PM-10, id. § 7513a(b).
Maricopa Area did not meet the NAAQS for PM-10 by the end of
2001. Rather, in 2000 Arizona preemptively applied for a
five-year extension (until December 2006) under §
7513(e) and at the same time submitted a SIP for the Maricopa
Area (the 2000 SIP). The 2000 SIP proposed to implement over
70 best available control measures for major dust sources,
Approval and Promulgation of Implementation Plans;
Arizona-Maricopa County PM-10 Nonattainment Area; Serious
Area Plan for Attainment of the Annual PM-10 Standard, 65
Fed. Reg. 19964, 19972-83 (Apr. 13, 2000), and stated that
its measures were "the most stringent measures that are
included in the implementation plan of any State, or are
achieved in practice in any State, " id. at
19984. In 2002, the EPA issued a final rule approving the
2000 SIP and granting the requested extension. Approval and
Promulgation of Implementation Plans; Arizona-Maricopa County
PM-10 Nonattainment Area; Serious Area Plan for Attainment of
the PM-10 Standards, 67 Fed. Reg. 48718, 48718-19 (July 25,
2002) (the 2002 Final Rule). The 2002 Final Rule stated that
the control measures in the 2000 SIP met the BACM and MSM
December 2006, the Maricopa Area had still failed to meet the
NAAQS for PM-10. See Findings of Failure To Attain;
State of Arizona, Phoenix Nonattainment Area; State of
California, Owens Valley Nonattainment Area; Particulate
Matter of 10 Microns or Less, 72 Fed. Reg. 31183, 31184-85
(June 6, 2007). At that point, the CAA gave Arizona 12 months
to submit revisions to the SIP that would achieve attainment
of the NAAQS for PM-10, provide for an annual five percent
reduction in PM-10 in the Maricopa Area, 42 U.S.C. §
7513a(d), and contain appropriate contingency measures,
id. § 7502(c)(9).
submitted revisions to the Maricopa Area SIP in December 2007
(the 2007 SIP). In addition to proposing 53 control measures,
the 2007 SIP proposed revising a previously approved
agricultural control measure, namely an agricultural general
permit specifying best management practices for reducing
PM-10 from agricultural activities. See Approval and
Promulgation of Implementation Plans- Maricopa County
(Phoenix) PM-10 Nonattainment Area; Serious Area Plan for
Attainment of the 24-Hour PM-10 Standard; Clean Air Act
Section 189(d), 75 Fed. Reg. 54806, 54810, 54812-13 (Sept. 9,
2010) (the 2010 Proposed Rule). The 2010 Proposed Rule stated
that the EPA would disapprove this revision to the
agricultural general permit rule on the ground that other
states and local agencies had "acquired additional
expertise about how to control emissions from these sources,
" and as a result the EPA no longer believed that the
requirements in the agricultural general permit rule in the
2000 SIP were best available control measures. Id.
To avoid a partial disapproval, Arizona withdrew the plan in
2011. 79 Fed. Reg. at 7119. As a result of this withdrawal of
the 2007 SIP, the EPA found that Arizona had failed to make a