                  FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

ASSOCIATION OF IRRITATED                
RESIDENTS,
                          Petitioner,
                  v.
UNITED STATES ENVIRONMENTAL
PROTECTION AGENCY; MICHAEL
LEAVITT, in his official capacity as
Administrator of the U.S.
Environmental Protection Agency,
WAYNE NASTRI, in his official               No. 04-72650
capacity as Regional Administrator
for Region IX of the U.S.                    EPA No.
                                            Fed. Reg. 69
Environmental Protection Agency,
and DEBORAH JORDAN, in her
official capacity as Acting
Regional Administrator Region IX
of the U.S. Environmental
Protection Agency,
                        Respondents,
SAN JOAQUIN VALLEY UNIFIED AIR
POLLUTION CONTROL DISTRICT;
CALIFORNIA AIR RESOURCES BOARD,
           Intervenors-Respondents.
                                        




                            12383
12384      ASSOCIATION OF IRRITATED RESIDENTS v. EPA



MEDICAL ADVOCATES FOR HEALTHY            
AIR; LATINO ISSUES FORUM; SIERRA
CLUB,
                        Petitioners,
                 v.
UNITED STATES ENVIRONMENTAL
PROTECTION AGENCY; MICHAEL                      No. 04-72736
LEAVITT, Administrator, U.S.
Environmental Protection Agency                  EPA No.
                                              Clean Air 40 CFR
and WAYNE NASTRI, Regional
Administrator, Region IX, U.S.                    OPINION
Environmental Protection Agency,
                      Respondents,
SAN JOAQUIN VALLEY UNIFIED AIR
POLLUTION CONTROL DISTRICT;
CALIFORNIA AIR RESOURCES BOARD,
          Intervenors-Respondents.
                                         
          On Petition for Review of an Order of the
             Environmental Protection Agency

                   Argued and Submitted
          June 15, 2005—San Francisco, California

                    Filed September 6, 2005

          Before: Mary M. Schroeder, Chief Judge,
          William C. Canby, Jr., Circuit Judge, and
           Kevin Thomas Duffy,* Senior Judge.

              Opinion by Chief Judge Schroeder

  *The Honorable Kevin Thomas Duffy, Senior United States District
Judge for the Southern District of New York, sitting by designation.
          ASSOCIATION OF IRRITATED RESIDENTS v. EPA       12387


                         COUNSEL

Susan Britton, Earth Justice, Oakland, California and Brent J.
Newell, Center on Race, Poverty & Environment, San Fran-
cisco, California, for the petitioners.

David A. Carson, United States Department of Justice, Den-
ver, Colorado, Philip M. Jay, Fresno, California, and Gavin G.
McCabe, San Francisco, California, for the respondents.


                          OPINION

SCHROEDER, Chief Judge:

   This is an expedited review of the Environmental Protec-
tion Agency’s May 26, 2004 final approval of the San Joaquin
Valley’s 2003 PM-10 Implementation Plan (Plan). 69 Fed.
Reg. 30,006. In approving the Plan, the EPA has set a new
deadline for the Valley to attain the national ambient air qual-
ity standard for PM-10 pollutants, which are various airborne
fine particles of less than ten microns in diameter. The new
deadline is 2010.

   The petitioners, whose challenges have been consolidated,
are the following groups and non-profit organizations: Asso-
12388      ASSOCIATION OF IRRITATED RESIDENTS v. EPA
ciation of Irritated Residents (AIR), Latino Issues Forum,
Medical Advocates for Healthy Air, and the Sierra Club. They
maintain that under the Clean Air Act, the absolute outside
deadline for PM-10 areas to attain the air quality standard is
2006.

   Petitioners raise a number of issues, but the most signifi-
cant is the EPA’s authority to set a deadline that extends past
2006. We deny the petitions for review because we hold that
the 2010 deadline was authorized within the structure of the
Act, and that petitioners’ other challenges to the Plan do not
warrant judicial intervention.

                          Background

   The Act establishes a comprehensive program requiring
cooperation between states and the federal government to
improve the nation’s air quality. 42 U.S.C. §§ 7401-7671q.
The Act also sets up a scheme under which the public is given
significant opportunities to offer input and criticism at various
stages of each state’s efforts to achieve better air quality. See,
e.g., 69 Fed. Reg. 30,006. States carry most of the burden of
furthering the Act’s purposes by developing implementation
plans after extensive public involvement. These petitioners
have participated throughout this process for the Valley at
each opportunity for notice and comment. The Valley’s
efforts to control PM-10 pollution over the past decade illus-
trate the flexible, cooperative and incremental nature of the
Act. See, e.g., 42 U.S.C. § 7410(a)(2)(A).

   California’s San Joaquin Valley is the heart of the state’s
top agricultural region, producing a wide variety of fruits and
vegetables. It is bordered on the west by the coastal mountain
ranges, and on the east by the Sierra Nevada mountains
including Yosemite, Kings Canyon and Sequoia National
Parks. Unfortunately, the same fertile soil that has led the
region to be known as the state’s “salad bowl” has also con-
tributed to high population growth and industry which,
           ASSOCIATION OF IRRITATED RESIDENTS v. EPA       12389
together with the region’s topography, have resulted in severe
air quality difficulties.

  PM-10 pollution results largely from agricultural operations
and dust kicked up on roads. It is a serious problem in the
Valley. The EPA has recognized that this pollutant can cause
damage to lung tissue, chronic illness and premature death. 63
Fed. Reg. 41,326 (August 3, 1998); 62 Fed. Reg. 38652 (July
18, 1997); see also Vigil v. Leavitt, 381 F.3d 826, 830 (9th
Cir. 2004). Congress addressed this problem in 1990 when it
amended the Act to include specific provisions dealing with
PM-10 pollution, and set an attainment deadline of December
31, 2001 for seriously deficient areas. 42 U.S.C. § 7513(c)(2).

   Pursuant to the 1990 amendments to the Act, the Valley
was designated a “moderate” PM-10 area by operation of law.
See 56 Fed. Reg. 11101, 11103 (March 15, 1991). California
subsequently directed the San Joaquin Valley Unified Air Pol-
lution Control District (District), a state regulatory agency, to
develop and adopt a comprehensive air pollution control strat-
egy calling for the implementation, maintenance and enforce-
ment of PM-10 air quality standards in the Valley. The
District’s plans and plan revisions were eventually forwarded
to the California Air Resources Board (CARB) for review and
inclusion in the state’s air pollution plans. Every state plan or
plan revision must be adopted by the state after reasonable
notice and hearing. See 42 U.S.C. § 7410(a)(1). Ultimately,
the state adopts the plans and forwards them to the EPA for
approval.

   In 1993, after various exchanges between the District and
the EPA, the EPA found that the Valley could not practicably
attain the PM-10 standard by the statutory deadline for “mod-
erate areas,” which was December 31, 1994. The EPA thus
reclassified the Valley as a “serious area.” 58 Fed. Reg. 3334,
3337 (Jan. 8, 1993). This reclassification meant that the Val-
ley’s attainment deadline was changed to December 31, 2001.
42 U.S.C. § 7513(c)(2); 58 Fed. Reg. at 3340.
12390     ASSOCIATION OF IRRITATED RESIDENTS v. EPA
   California submitted a “serious area” plan to the EPA in
July 1997. See 69 Fed. Reg. 5412, 5413 (Feb. 4, 2004). That
plan included a request for a five year extension of the attain-
ment date under § 188(e) of the Act.

   In early 2002, the EPA indicated that it would disapprove
the 1997 Plan for the Valley, so the state withdrew it. In July
2002, the EPA found that the Valley had failed to attain the
required standards by the December 31, 2001 deadline. 67
Fed. Reg. 48,039 (July 23, 2002). The state was then required
to submit plan revisions under § 189(d). The revisions had to
provide for attainment, as well as for five percent annual
reductions of PM-10 pollutants. Following the required notice
and hearing, California adopted and submitted still another
plan in August 2003.

   In May 2004, after another notice and comment period dur-
ing which petitioners, among others, raised most of the con-
cerns at issue here, as well as many others, the EPA approved
the 2003 Plan. That Plan established a new attainment goal of
December 2010. The EPA’s approval of the 2003 Plan effec-
tively certified that the new 2010 deadline complied with the
Act’s general provisions for changing attainment deadlines
that have passed. That approval is the subject of this petition
for review, in which the petitioners claim, inter alia, that the
EPA could not, as a matter of law, have approved the new
deadline using those general provisions. There has been
extensive briefing by all parties, including the District and
CARB, who have intervened in support of the EPA’s plan
approval.

              The PM-10 Attainment Deadline

   [1] Under the Act, there are essentially two statutory path-
ways through which PM-10 attainment deadlines may be
changed. The first applies generally to all pollutants, and is
the one that the EPA relied on here in setting the 2010 dead-
line. The second applies only to PM-10 pollutants. The peti-
          ASSOCIATION OF IRRITATED RESIDENTS v. EPA       12391
tioners argue that the existence of the second pathway
forecloses use of the first for PM-10 pollutants, and creates an
outside attainment date of December 2006.

   Under the Administrative Procedure Act, the EPA’s final
action in this case may be set aside only if it is “arbitrary,
capricious, an abuse of discretion, or otherwise not in accor-
dance with law.” 5 U.S.C. § 706(2)(A); see, e.g., Vigil v.
Leavitt, 381 F.3d 826, 833 (9th Cir. 2004). We deal with an
issue of law. We conclude that the EPA properly relied on the
Act’s general provisions in approving the 2010 deadline. We
turn to the relevant provisions.

   [2] Serious PM-10 areas, such as the Valley, that missed
the December 31, 2001 deadline, were required to submit fur-
ther plan revisions to bring about annual PM-10 or PM-10
precursor reductions of five percent. 42 U.S.C. § 7513a(d).
The section reads:

    Failure to attain — In the case of a Serious PM-10
    nonattainment area in which the PM-10 standard is
    not attained by the applicable attainment date, the
    State in which such area is located shall, after notice
    and opportunity for public comment, submit within
    12 months after the applicable attainment date
    [December 31, 2001], plan revisions which provide
    for attainment of the PM-10 air quality standard and,
    from the date of such submission until attainment,
    for an annual reduction in PM-10 or PM-10 precur-
    sor emissions within the area of not less than 5 per-
    cent of the amount of such emissions as reported in
    the most recent inventory prepared for such area.

42 U.S.C. § 7513a(d). This section does not itself, however,
establish any new attainment deadline dates. The EPA thus
looked to the method of deadline change generally set forth
in § 179(d). That section reads:
12392      ASSOCIATION OF IRRITATED RESIDENTS v. EPA
    (d) Consequences for failure to attain — (1) Within
    one year after the Administrator publishes the notice
    under subsection (c)(2) of this section (relating to
    failure to attain), each State containing a nonattain-
    ment area shall submit a revision to the applicable
    implementation plan meeting the requirements of
    paragraph (2) of this subsection.

42 U.S.C. § 7509(d)(1). Section 179(d)(3) then provides for a
new attainment date five years from the date of the EPA’s
notice that an area has failed to attain any pollutant’s applica-
ble standard. That section also provides that the five year
period can be extended five additional years as follows:

    (2) Attainment dates for nonattainment areas — (A)
    The attainment date for an area designated nonattain-
    ment with respect to a national primary ambient air
    quality standard shall be the date by which attain-
    ment can be achieved as expeditiously as practicable,
    but no later than 5 years from the date of the notice
    under section [179(c)(2)], except that the administra-
    tor may extend the attainment date to the extent the
    administrator determines appropriate, for a period no
    greater than 10 years from the date of the notice
    under section [179(c)(2)], considering the severity of
    nonattainment and the availability and feasibility of
    pollution control measures.

42 U.S.C. § 7502(a)(2)(A)(with substitutions per 42 U.S.C.
§ 7509(d)(3)). In sum, § 179(d) authorizes the EPA to
approve of plan revisions which set forth a new attainment
date up to ten years from the time that the EPA has found that
the area failed to attain the applicable air quality standard.
Since the EPA published notice of the Valley’s failure to
attain the PM-10 standard in July 2002, the new, and here
challenged, 2010 deadline would be authorized under these
provisions.
           ASSOCIATION OF IRRITATED RESIDENTS v. EPA       12393
   [3] The petitioners, nevertheless, argue that the existence of
a statutory provision specifically enabling a state to request a
five year extension of the PM-10 deadline forecloses the
EPA’s application of the general method of changing any
attainment deadline that has already passed. Petitioners rely
on § 188(e), which is under Subpart 4 of the Act dealing spe-
cifically with PM-10 plans. That section sets out the require-
ments for a state to request a one time only, five year
extension of the PM-10 deadline. It reads:

    Upon application by any State, the Administrator
    may extend the attainment date for a Serious Area
    beyond the date specified under subsection (c) of this
    section, if [1] attainment by the date established
    under subsection (c) of this section would be imprac-
    ticable, [2] the State has complied with all require-
    ments and commitments pertaining to that area in the
    implementation plan, and [3] the State demonstrates
    to the satisfaction of the Administrator that the plan
    for that area includes the most stringent measures
    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. . . . The
    Administrator may grant at most one such extension
    for an area, of no more than 5 years.

42 U.S.C. § 7513(e). No language in Subpart 4 prohibits the
EPA’s application of the general provisions to change attain-
ment deadlines. To support their position that the PM-10 spe-
cific provisions under Subpart 4 are exclusive, petitioners
argue that allowing the EPA to look beyond those provisions
to use the more general provisions in this case would allow
a state to circumvent the 2001 deadline by waiting for the date
to pass, rather than asking for an extension. The petitioners
also claim that the EPA’s interpretation would allow for
countless ten year extensions without any repercussions.

  [4] Petitioners’ position is not, however, supported by the
overall statutory scheme. There are repercussions for failing
12394     ASSOCIATION OF IRRITATED RESIDENTS v. EPA
to attain the standard by the applicable deadline. An area that
simply waits for the deadline to pass without requesting a
deadline extension suffers an additional consequence of hav-
ing to reduce its emissions by five percent annually. 42 U.S.C.
§ 7513a(d). This consequence imposes a significant burden on
the nonattaining area. The quota also helps ensure that the
area will eventually be forced to achieve attainment. More-
over, if a state neglects to implement such a newly approved
revised plan, that state eventually faces very severe sanctions
including loss of highway funding. 42 U.S.C. § 7509(b).
Indeed, the petitioners’ interpretation would leave the EPA
with no ability to set a new date at all once a PM-10 area has
missed its deadline. Their position must be rejected. We
therefore conclude that the statutory scheme authorizes the
EPA to look to § 179(d) in order to set a new attainment dead-
line once the EPA has determined that a PM-10 area has
failed to attain the standard. The EPA’s interpretation of the
Act, looking to the general provisions to provide an alterna-
tive path for setting a new PM-10 attainment deadline, is the
correct interpretation of the statutory provisions that, when
viewed in the full statutory context, are not ambiguous. See
Chevron, USA v. NRDC, 467 U.S. 837, 842-45 (1984).

                      Other Contentions

  A. Methods Required to Achieve Additional Five Percent
  Reductions

   The petitioners’ next argument relates to the precise meth-
ods used to achieve the five percent reductions mandated by
§ 189(d) and discussed in the previous section. 42 U.S.C.
§ 7513a(d). The petitioners claim that to meet the five percent
requirement for a given year, the Valley cannot plan to use
reductions from previously required or implemented emis-
sions control measures. In environmental language, the peti-
tioners claim that Congress intended to exclude reductions
resulting from “best available control measures” (BACM) in
          ASSOCIATION OF IRRITATED RESIDENTS v. EPA      12395
determining whether the five percent reductions required
under § 189(d) have been achieved.

   “Serious” areas such as the Valley must implement BACM
as opposed to the “reasonably available control measures”
required of “moderate” areas. 42 U.S.C. § 7513a(a)1, (b)(1).
BACM measures must be implemented within four years of
reclassification. 42 U.S.C. § 7513a(b)(1)(B). The Valley was
required to implement BACM by 1997, well before the area’s
original attainment deadline. Section 189(d), requiring the
additional five percent reductions, however, takes effect only
after an area has missed its attainment deadline. By allowing
the state to use BACM to meet that five percent requirement,
the petitioners claim that the EPA is eviscerating the “tighten
the screws” purpose of § 189(d).

   [5] The language of § 189(d), however, does not specifi-
cally require that an area use any particular method to achieve
reductions. Although the Valley was supposed to implement
BACM before the Valley missed the deadline and thereby
triggered the additional five percent reduction requirement,
emissions reductions from BACM are presumably intended to
continue as long as they are effective, and late implementation
is better than none. The Plan is therefore sound as a matter of
statutory policy, and the language of the Act does not in any
way prohibit or limit the use of particular emissions-reducing
measures, including BACM, in calculating whether the addi-
tional reductions have been achieved.

   A review of other similar provisions in the Act further sup-
ports this result. For example, Congress knew how to provide
that certain control measures would not be counted towards
percentage reduction requirements, for it expressly did so in
provisions dealing with ozone attainment. 42 U.S.C.
§ 7511a(b)(1)(D) (excluding emissions reductions from vari-
ous measures, including those related to motor vehicle
exhaust, from counting towards an additional 15% reduction
requirement). Congress similarly must have known that
12396      ASSOCIATION OF IRRITATED RESIDENTS v. EPA
reductions from BACM would continue to occur even after
attainment dates, and yet did not include any similar language
in § 189(d) to preclude crediting such reductions toward an
area’s five percent requirement. The Act permits crediting
BACM reductions. The EPA interpreted the Act correctly
when it approved this portion of the Valley’s plan.

  B. Crediting Excess Reductions to Meet Requirement in
  Later Years

   The petitioners’ next argument also relates to the Act’s
requirement that the Plan accounts for an annual five percent
reduction in emissions. The petitioners argue that the EPA
violated § 189(d) by allowing the Plan to credit excess emis-
sions reductions in one year towards later, possibly deficient,
years, instead of insisting on a five percent reduction per year.

   [6] Section 189(d) requires “an annual reduction in PM-10
or PM-10 precursor emissions within the area of not less than
5 percent.” 42 U.S.C. § 7513a(d). The petitioners argue that
the word “annual” precludes the Plan’s allowance for “bank-
ing” or crediting earlier emissions reductions to later years.
For illustration, the petitioners argue that if an area achieves
an eight percent emissions reduction in one year, it should not
be able to credit the excess three percent towards the next
year’s five percent requirement. The EPA counters that Con-
gress intended to provide incentives for the use of the most
effective measures as early as possible, and that petitioners’
interpretation would encourage areas to delay early, sizable
emissions reductions in order to be able to meet the five per-
cent requirement in subsequent years.

   We agree with the EPA that prohibiting any credit for past
emissions reductions under § 189(d) would discourage early
reductions and conflict with the larger goals of the Act. By
allowing such crediting, the EPA provides a material incen-
tive for implementing the most effective measures as quickly
          ASSOCIATION OF IRRITATED RESIDENTS v. EPA       12397
as possible. The EPA thus properly approved this portion of
the Plan.

  C.   Ammonia Emissions

   The petitioners’ next argument concerns the Plan’s rejec-
tion of control measures for major stationary sources of
ammonia. The petitioners argue that the EPA improperly
approved of the portion of the Plan which requires control
measures for oxides of nitrogen as precursors to PM-10 pollu-
tion, but not for ammonia. The EPA found that ammonia does
not contribute significantly to PM-10 levels in the Valley and
that the Valley’s decision to control only oxides of nitrogen
was therefore reasonable.

   [7] Ammonium nitrate, formed by a reaction between
ammonia gas and oxides of nitrogen, is the largest component
of PM-10 during the Valley’s worst PM-10 episodes. Ammo-
nia and oxides of nitrogen are thus precursors to PM-10 pollu-
tion. Section 189(d)’s control requirements apply to:

    major stationary sources of PM-10 precursors,
    except where the Administrator determines that such
    sources do not contribute significantly to PM-10
    levels which exceed the standard in the area.

42 U.S.C. § 7513a(e). Petitioners contend that ammonia “con-
tributes significantly” and must be subject to control mea-
sures. The EPA, however, decided to allow the District to
regulate only oxides of nitrogen. According to both the EPA
and the District, because “controlling ammonia in addition to
[oxides of nitrogen] will not accelerate the attainment date for
PM-10 in the [Valley],” ammonia does not “contribute signif-
icantly” to the Valley’s PM-10 pollution. 69 Fed. Reg. at
30,007. Indeed, as the EPA pointed out, because concentra-
tions of ammonia in the Valley are high relative to concentra-
tions of oxides of nitrogen, controlling ammonia would not
accelerate the attainment date for PM-10 in the Valley at all.
12398      ASSOCIATION OF IRRITATED RESIDENTS v. EPA
This is a determination that is scientific in nature and is enti-
tled to the most deference on review. Baltimore Gas & Elec.
Co. v. NRDC, 462 U.S. 87, 103 (1983); Central Arizona
Water Cons. Dist. v. EPA, 990 F.2d 1531, 1539-40 (9th Cir.
1993). There is no basis for this court to second guess the
EPA’s approval of that portion of the plan, particularly given
the discretion vested in the EPA to consider various factors in
determining whether a precursor “contributes significantly” to
PM-10 levels. See 42 U.S.C. § 7513a(e).

  D.    Contingency Measures

  The EPA did not act on that portion of the plan dealing
with contingency measures in the event of future nonattain-
ment of the new deadline. The petitioners contend that the
EPA was required to take action on the state’s contingency
measures before it approved the remainder of the Plan. The
petitioners claim that the EPA can either approve or disap-
prove various parts of a plan, but that the agency cannot sim-
ply refuse to take any action on a required plan element. The
EPA responds that the Act authorizes piecemeal approvals
and that it was therefore not required to take any action on the
contingency measures when it approved the rest of the plan.

   [8] Section 172(c)(9) requires that nonattainment areas’
plans include contingency measures that will go into effect “if
the area fails to make reasonable further progress, or to attain
the [air quality standards] by the [applicable] attainment
date.” 42 U.S.C. § 7502(c)(9). The EPA acknowledges that
contingency measures are a required element of the Valley’s
revised plan, but points out that the Act does not require the
EPA to take action on all of the plan’s elements at the same
time. Different aspects of plan revisions are submitted at vari-
ous times under the statute. A plan is thus not necessarily a
single document that is prepared as a unit, and reviewed and
approved in a single administrative action. This court has held
that the Act permits partial or piecemeal approvals. Hall v.
EPA, 273 F.3d 1146, 1159 (9th Cir. 2001). Such approvals
          ASSOCIATION OF IRRITATED RESIDENTS v. EPA    12399
ensure that earlier-approved provisions will become federally
enforceable as soon as possible. The EPA’s ability to post-
pone action on the contingency measures is consistent with
the Act’s overarching goal that nonattainment areas achieve
the standards as expeditiously as practicable. See 42 U.S.C.
§§ 7502(c)(1); 7513(c)(2).

                        Conclusion

   In sum, the EPA has properly approved of the San Joaquin
Valley’s PM-10 attainment plan. The approval came after
extensive public comments, and comports with the overall
structure and purpose of the Clean Air Act. The petitions for
review must be denied.

  Petitions DENIED.
