online and will be published later this year in the 2012 JMS
Proceedings (http://www.scientificintegrityinstitute.org/ASAS092812.pdf).''
---------------------------------------------------------------------------

    With regard to the suggestion that PM2.5 from diesel
combustion does not present a public health risk, EPA received comment
stating that ``the claimed toxic effects of diesel particulate matter
are hundreds of times smaller than, for example, the increased risk of
lung cancer caused by cigarette smoking. This commenter asserts that
these possible effects are smaller than any previously discovered in
medical history, the actual exposure levels are so difficult to
estimate, and there are so many confounding health factors (smoking and
lifestyle) that are impossible to control, that the entire scientific
basis of the regulatory policy needs to be broadly re-assessed before
allowing CARB any kind of waiver in PM2.5 enforcement.''
\93\
---------------------------------------------------------------------------

    \93\ See Dr. Malken.
---------------------------------------------------------------------------

    EPA also received comment questioning whether PM2.5 from
diesel exhaust is causing cancer, premature death, or other health
effects in

California. For example, one commenter stated that ``we don't know
yet'' and we ``can't rule out'' that exposure to diesel PM might
statistically be related to zero premature deaths.\94\ This commenter
suggests that the toxic effects of diesel particulate matter are so
small that the scientific basis for concerns about PM2.5
impacts on health needs to be re-assessed before EPA authorizes
California's regulation. This commenter maintains that science does not
know yet if fine particulate matter is causing cancer and the premature
death of a measurable number of Californians, and that other factors
like smoking and lifestyle may confound any effects.\95\ EPA also
received comment suggesting that the scientific evidence on the health
effects of particulate air pollution (specifically PM2.5) in
California does not support its further control or regulation at this
time. This commenter maintains that ``[o]ur PM2.5 is
different in composition and is less toxic than that in many Eastern
regions of the U.S.'' \96\ In addition, two commenters stated that
strong epidemiologic evidence shows ambient PM2.5 and diesel
PM is not related to total mortality in California.\97\ The commenters
also note studies published in 2005 and 2011 for support.\98\ One
commenter notes the 2011 study for California-specific evidence
regarding PM2.5 and diesel PM and mortality and claims it
demonstrates no current relationship between PM2.5 and
mortality in California and may show no scientific or public health
justification for this regulation.\99\
---------------------------------------------------------------------------

    \94\ See Dr. Malken. This commenter also suggests that the
PM2.5 from diesel exhaust in California might be
inherently different than the PM studied in the eastern half of the
United States.
    \95\ Id. at 2.
    \96\ See Dr. Phalen.
    \97\ See Delta and Dr. Enstrom. Delta also comments that the
least healthy county in California has low diesel PM air
concentrations, but high poverty and unemployment levels. Delta
states that California is the fourth healthiest state as measured by
premature death rates. EPA notes that Delta makes no attempt to
connect these general views on health with the specific issue of
whether emissions of PM2.5 have any effect on health.
    \98\ See Dr. Enstrom and Dr. Malken. Dr. Malken claims that the
CARB-funded Jerrett et al. (2011) study of the LA subset of ACS data
was the only one which utilized data from particle monitors and
``they found no significant correlation between PM2.5 and
`premature deaths.' '' This commenter also states that weighing all
of the studies that CARB has considered is more a matter of
subjective taste than a scientific process and that CARB has
``cherry-picked'' the few results that have supported their
position.
    \99\ Dr. Enstrom. This commenter maintains that EPA's June 2012
``Regulatory Impact Analysis related to the Proposed Revisions to
the National Ambient Air Quality Standards for Particulate Matter''
erroneously concluded that ``most of the cohort studies conducted in
California report central effect estimates similar to the (nation-
wide) all-cause mortality risk estimate'' but EPA's Table 5 B-10 was
inaccurate or misleading, including the hazard ratio used from his
2005 paper. EPA notes that the proper place to contest the
methodology and findings of the Agency in its NAAQS review process
is in that federal context. This commenter also claims that ``[a]
glaring omission was the detailed evidence from the October 28, 2011
CARB-funded Report, ``Spatiotemporal Analysis of Air Pollution and
Mortality in California Based on the American Cancer Society Cohort:
Final Report,'' by Drs. Michael Jerrett, Richard T. Burnett, C.
Arden Pope III, Daniel Krewski, Michael Thun, and nine others http://www.scientificintegrityinstitute.org/JerrettCriticism102811.pdf).''
This commenter also claims that his September 28, 2012 paper
summarizes the epidemiologic evidence that PM2.5 and
diesel PM are not related to total mortality in California.
---------------------------------------------------------------------------

    Separately, the commenter also takes issue with EPA's Regulatory
Impact Analysis for its proposed PM NAAQS rule (which has since been
finalized), claiming the Regulatory Impact Analysis is misleading and
contains omissions.\100\
---------------------------------------------------------------------------

    \100\ Id.
---------------------------------------------------------------------------

    Lastly, we received comment from CCTA that references a paper
titled ``Mortality Among Members of a Truck Driver Trade Association''
(Truck Driver study) suggesting that any research on exposure to diesel
exhaust should necessarily include truck drivers. CCTA maintains that
the study results indicate that those in closest proximity and duration
of high levels of exposure to diesel exhaust don't seem to share the
same deleterious effects to exposure claimed in other studies.
    In response to claims that the Fleet Requirements are not needed
because there is no causal connection existing between PM2.5
exposure and premature mortality and other health effects, CARB states:

    Staff carefully reviewed all peer-reviewed studies that have
been performed in the United States on the relationship between
long-term PM2.5 exposure and mortality, as has the U.S.
EPA in its recent review of the National Ambient Air Quality
Standard for particulate matter. U.S. EPA's 2009 science assessment
states ``Collectively, the evidence is sufficient to conclude that
the relationship between long-term PM2.5 exposures and
mortality is causal.'' U.S. EPA and ARB have critically evaluated
the methods used in each study so that we can place the most weight
on the studies that have used the strongest methodologies . . ..
ARB's conclusions about the relationship between long-term exposure
to PM2.5 and mortality are aligned with the findings of
the U.S. EPA, the World Health Organization, Health Canada, and the
British government. Those findings have been publicly peer reviewed
by multiple independent bodies worldwide.\101\
---------------------------------------------------------------------------

    \101\ See CARB Written Comments.

    With respect to the questions about the health effects associated
---------------------------------------------------------------------------
with exposure to diesel exhaust PM, CARB notes:

    Staff agrees that ambient PM2.5 arises from many
different sources, including diesel exhaust, and there are no
established methods for routinely measuring the concentration of
PM2.5 in ambient air from any specific source. Diesel PM
is primarily less than 2.5 microns in diameter, and consequently
falls into the PM2.5 size category. As discussed above,
exposure to PM in this size fraction is strongly associated with
premature death. Also, the results of animal exposure studies
suggest that diesel PM is at least as toxic as other species within
this size range.\102\
---------------------------------------------------------------------------

    \102\ Id.

    Further, with respect to questions about the specific health
effects of diesel exhaust PM in California, CARB cites, in its
responsive comments during the waiver proceeding, the large body of
peer-reviewed scientific studies evaluated by CARB and EPA that have
identified a broad range of health effects associated with
PM2.5 exposures.\103\ CARB states that ``[t]he national
studies reviewed by the U.S. EPA for the NAAQS assessment apply to
California. In fact, as part of the federal standards review process,
U.S. EPA estimated the premature deaths associated with
PM2.5 in two California cities--Los Angeles and
Fresno.''\104\ CARB also cites EPA's Quantitative Health Risk
Assessment, which estimates that, based on 2005 ambient mean levels of
PM2.5, approximately 63,000 to 80,000 premature deaths each
year are related to PM2.5 exposures in the United States.
CARB also conducted its own California-focused study, which estimated
that in California, exposure to PM2.5 results in
approximately 9,200 deaths each year.\105\ In further comments, CARB
states that the pre-2010 studies cited by Drs. Enstrom and Malkan in
their comments were reviewed by CARB, as well as by the EPA in the
development of the PM Integrated Science Assessment (ISA).
---------------------------------------------------------------------------

    \103\ Id. at 12, citing attachments 1-3.
    \104\ Id.
    \105\ CARB Written Comments at 12, citing attachments 1 and 2 of
its October 19, 2012 submissions to EPA, including the ``Estimate of
Premature Deaths Associated with Fine Particle Pollution
(PM2.5) in California Using a U.S. Environmental
Protection Agency Methodology,'' August 31, 2010.
---------------------------------------------------------------------------

    Separately, CARB also reviewed the 2011 Jerrett et al. study,
referenced by commenters.106 107 CARB notes that the

study found that ``[c]ardiovascular disease (CVD) deaths, particularly
those from ischemic heart disease (IHD), are consistently and robustly
associated with fine particulate and traffic-related air pollution. The
effects on CVD and IHD in California are virtually identical to those
of the national . . . study.'' The study also found that ``[a]ll-cause
mortality is significantly associated with PM2.5 exposure,
but the results are sensitive to statistical model specification and to
the exposure model used to generate the estimates.'' \108\
---------------------------------------------------------------------------

    \106\ CARB Supplemental Comments.
    \107\ The Jerrett et al., 2011 report was not included in EPA's
PM ISA because it was completed after the ISA was published. It was
also not included in the Provisional Science Assessment because it
was not a peer-reviewed publication at the time. However, the work
conducted by Jerrett et al. was recently published and can now be
found in the peer-reviewed literature [http://www.atsjournals.org/doi/pdf/10.1164/rccm.201303-0609OC]. EPA will consider this study in
the next round of NAAQS reviews that include PM. We note, however,
that the inclusion or exclusion of one report such as Jerrett would
not materially change the large body of scientific evidence
indicating an effect of PM2.5 exposure on human health.
    \108\ CARB Supplemental Comments at 13, citing ``Spatiotemporal
Analysis of Air Pollution and Mortality in California Based on the
American Cancer Society Cohort: Final Report,'' Michael Jerrett,
Ph.D., 2011, at 6-7.
---------------------------------------------------------------------------

    CARB also included a copy of the 2011 Jerrett et al. study in its
comments and indicated the study reached the following conclusion:

    Taken together, the results from this investigation indicate
consistent and robust effects of PM2.5--and other
pollutants commonly found in the combustion-source mixture with
PM2.5--on deaths from CVD and IHD. We also found
significant associations between PM2.5 and all causes of
death, although these findings were sensitive to model
specification. In Los Angeles, where the monitoring network is
capable of detecting intra urban variations in PM2.5, we
observed large effects on death from all causes, CVD, IHD, and
respiratory disease. These results were consistent with past ACS
[American Cancer Society cohort] analyses and with findings from
other national or international studies reviewed in this report. Our
strongest results were from a land use regression estimate of
NO2, which is generally thought to represent traffic
sources, where significant elevated effects were found on deaths
from all causes, CVD, IHD, and lung cancer. We therefore concluded
that combustion-source air pollution as significantly associated
with premature death in this large cohort of Californians.\109\
---------------------------------------------------------------------------

    \109\ Id.

    EPA will address in turn: (1) Suggestions that PM2.5
does not present a public health risk in general; (2) suggestions that
PM2.5 from diesel combustion does not present a public
health risk; and (3) suggestions that PM2.5 from diesel
combustion located in California does not present a public health risk.
    EPA disagrees with the commenters regarding the evidence associated
with PM exposure in the context of all three suggestions noted above.
    Regarding the claim that there is no link between health effects,
including mortality, and exposure to PM2.5, EPA disagrees
with this comment and notes the large body of scientific literature
that was thoroughly evaluated during the NAAQS review process is
discussed in detail in EPA's Integrated Science Assessment (ISA) for
Particulate Matter.\110\ The ISA characterizes the weight of evidence
for different health effects and makes causal determinations for both
short-term (i.e., hours to days) and long-term (i.e., months to years)
exposures to PM2.5, PM10-2.5, and ultrafine
particles. Specifically in the ISA, the EPA carefully evaluated and
integrated the scientific evidence from across epidemiological,
toxicological and controlled human exposure studies to make inferences
about causality. The PM ISA considered and assessed an extensive body
of scientific information, all of which had undergone peer-review prior
to being published.\111\
---------------------------------------------------------------------------

    \110\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-08/139F. Docket entry EPA-HQ-OAR-
2008-0691-0318-attachments 2.1 through 2.5
    \111\ Id. at 1-22. See http://www.epa.gov/ttn/naaqs/standards/pm/data/20121214rtc.pdf at II-9 to II-12 for discussion of EPA's
application of its framework for causal determinations and
recognition of the distinction between evaluating the relative
scientific quality of individual study results and the evaluation of
the pattern of results within the broader body of scientific
evidence. This discussion also addresses allegations of cherry-
picking studies and ignoring studies that reported no association
with PM2.5.
---------------------------------------------------------------------------

    Overall, the PM ISA provides a concise evaluation and integration
of the policy-relevant science. This includes key science judgments
upon which EPA based its Quantitative Health Risk Assessment for
Particulate Matter (PM RA, U.S. EPA, 2010), and the Policy Assessment
for the Review of Particulate Matter National Ambient Air Quality
Standards (PM PA, U.S. EPA, 2011).\112\ These documents informed EPA's
2012 rule completing review of the PM NAAQS.\113\
---------------------------------------------------------------------------

    \112\ See EPA-HQ-OAR-2008-0691-0318-attachment 3 and http://yosemite.epa.gov/sab/sabproduct.nsf/368203f97a15308a852574ba005bbd01/8bee96ad3228eabe8525760400702786!OpenDocument.
    \113\ EPA incorporates by reference our 2012 PM NAAQS review and
associated rulemaking documents. EPA also notes that the reasoning
and conclusions reached in the PM NAAQS review are not being
revisited in the context of this authorization decision but are
cited for the purposes of demonstrating the vast body of peer
reviewed evidence and findings that is not contravened by the few
studies submitted by commenters to the authorization docket. EPA
also states that to the extent the comments take issue with the
determinations made in the context of the PM NAAQS rulemaking, the
proper place to bring challenges to those decisions would be in the
context of that rule.
---------------------------------------------------------------------------

    After a thorough evaluation and integration of the evidence across
scientific disciplines, the PM ISA made causal determinations for the
health effects associated with both short- and long-term exposures to
PM2.5.\114\ For short-term exposures, the PM ISA concludes
that cardiovascular effects (e.g., emergency department (ED) visits and
hospital admissions for ischemic heart disease (IHD) and congestive
heart failure (CHF), changes in cardiovascular function, and myocardial
ischemia), and premature mortality are causally associated with short-
term exposure to PM2.5. It also concludes that respiratory
effects (e.g., ED visits and hospital admissions for chronic
obstructive pulmonary disease (COPD), respiratory infections, and
asthma; and exacerbation of respiratory symptoms in asthmatic children)
are likely to be causally associated with short-term exposure to
PM2.5. For long-term exposures, the PM ISA concludes that
there are causal associations between long-term exposure to
PM2.5 and cardiovascular effects, such as the development/
progression of cardiovascular disease (CVD), and premature mortality,
particularly from cardiovascular causes. It also concludes that long-
term exposure to PM2.5 is likely to be causally associated
with respiratory effects, such as reduced lung function growth,
increased respiratory symptoms, and asthma development. The ISA
characterizes the evidence as suggestive of a causal relationship for
associations between long-term PM2.5 exposure and
reproductive and developmental outcomes, such as low birth weight and
infant mortality. It also characterizes the evidence as suggestive of a
causal relationship between PM2.5 and cancer incidence,
mutagenicity, and genotoxicity.\115\ EPA's evaluation of the

studies presented in the ISA, as well as the causal framework and
determinations upon which the Assessment is based, have undergone
extensive critical review by the EPA, CASAC, and the public during its
development. The rigor of the review makes the ISA the most reliable
source of scientific information on the subject of PM and health and
welfare effects.
---------------------------------------------------------------------------

    \114\ Id. EPA also noted in this Response to Significant
Comments document that ``The EPA's evaluation of the scientific
evidence and its application of the causal framework used in the
current PM NAAQS review was the subject of exhaustive and detailed
review by CASAC and the public. Prior to finalizing the ISA, two
drafts were released for CASAC and public review to evaluate the
scientific integrity of the documents. Evidence related to the
substantive issues raised by CASAC and public commenters with regard
to the content of the first and second draft ISAs were discussed at
length during these public CASAC meetings and considered in
developing the final ISA. CASAC supported the development of the
EPA's causality framework and its use in the current PM NAAQS review
and concluded: The five-level classification of strength of evidence
for causal inference has been systematically applied; this approach
has provided transparency and a clear statement of the level of
confidence with regard to causation, and we recommend its continued
use in future Integrated Science Assessments (Samet 2009f, p. 1).''
(At II-9).
    \115\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report) (ISA). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-08/139F. Section 2.3.5
and Table 2-6. EPA also notes that the ISA assessed the body of
scientific evidence regarding particles available through mid-2009,
which included over two thousand new studies. The ISA received two
rigorous rounds of peer review by the independent Clean Air
Scientific Advisory Committee (CASAC) and two draft PM ISAs were
made available for public review and comment.
---------------------------------------------------------------------------

    Additionally, new health studies published since the completion of
the ISA were discussed in EPA's Provisional Science Assessment (U.S.
EPA, 2012), which was used to ensure-the Administrator was fully aware
of the ``new'' science that developed since 2009 before making final
decisions on whether to retain or revise the ambient PM standards.
Overall, the new health studies were found not to materially change the
conclusions of the 2009 ISA. As in prior NAAQS reviews, the EPA based
its final decisions on the studies and related information included in
the ISA, RA, and PA which had undergone CASAC and public review. To the
extent that the commenters attempt to introduce new arguments or new
studies that have not been peer-reviewed, including the 2011 Jerrett
study, EPA believes the new science published after the ISA does not
materially change the conclusions found within the ISA.\116\ As noted
above, EPA has recently concluded its PM NAAQS review. No comments
submitted in the context of this authorization proceeding lead the
Agency to reassess (for purposes of this authorization) the findings
related to PM exposure and health effects. EPA notes that the study
referenced by Mr. Milloy in his comments was never provided to EPA nor
has EPA found it in the peer-reviewed literature. Therefore EPA has no
basis to review the technical methods used or the summary results.\117\
---------------------------------------------------------------------------

    \116\ Id. EPA is only reviewing the comments submitted to the
EPA-HQ-OAR-008-0691 public docket for CARB's authorization request
and EPA the responses to such comments are not intended to imply
that EPA is engaged in a reexamination of the issues thoroughly
examined in the recent PM NAAQS review.
    \117\ EPA is only reviewing the comments submitted to the EPA-
HQ-OAR-2008-0691 public docket for CARB's authorization request and
EPA's responses to such comments are not intended to imply that EPA
is engaged in a reexamination of the issues thoroughly examined in
the recent PM NAAQS review.
---------------------------------------------------------------------------

    With regard to suggestions that PM2.5 from diesel
combustion does not present a public health risk or assertions that
PM2.5 composition is determinative to risk, EPA believes
that the available scientific evidence linking mortality and morbidity
effects with long-and short-term exposures to fine particles continue
to be largely indexed by PM2.5 mass. In the PM NAAQS review
completed in 2012, EPA concluded that it was appropriate to retain
PM2.5 as the indicator for fine particles due to the
inability to differentiate those components or sources that are more
closely related to specific health outcomes nor to exclude any
component or group of components from the mix of fine particles
included in the PM2.5 indicator. As EPA previously stated in
the ISA ``overall, the results indicate that many constituents of PM
can be linked with differing health effects and the evidence is not yet
sufficient to allow differentiation of those constituents or sources
that are more closely related to specific health outcomes.'' \118\
---------------------------------------------------------------------------

    \118\ See ISA at 2-26.
---------------------------------------------------------------------------

    With regard to suggestions that EPA did not properly consider prior
reports (including the 2005 Dr. Enstrom study), EPA notes the Enstrom
study was included in summary figures depicting the totality of the
evidence for long-term PM2.5 exposure and mortality.\119\ It
is important to note that Dr. Enstrom based his comments solely on
statistical significance. Another commenter also asserts that studies
looking at associations between PM and premature mortality do not have
statistically significant results.\120\ EPA responded in the NAAQS
rulemaking to the issue of relying on statistical significance and why
it is not appropriate to only focus on it when evaluating a body of
evidence.\121\ Specifically, EPA stated:
---------------------------------------------------------------------------

    \119\ EPA noted that an association was reported for long-term
PM2.5 exposure with all-cause deaths from 1973-1982.
However, no significant associations were reported with deaths in
later time periods when PM2.5 levels had decreased in the
most polluted counties (1983-2002). The PM2.5 data were
obtained from the EPA's Inhalation Particle Network (collected 1979-
1983), and the locations represented a subset of data used in the
50-city ACS study (Pope et al., 1995, 045159). However, the use of
average values for California counties as exposure surrogates likely
leads to significant exposure error, as many California counties are
large and quite topographically variable. ISA, at 7-85.
    \120\ See Dr.Malkan.
    \121\ See ``Responses to Significant Comments on the 2012
Proposed Rule on the National Ambient Air Quality Standards for
Particulate Matter (June 29, 2012; 77 FR 38890). http://www.epa.gov/ttn/naaqs/standards/pm/data/20121214rtc.pdf at II-9 to II-12 for
discussion of EPA's application of its framework for causal
determinations and recognition of the distinction between evaluating
the relative scientific quality of individual study results and the
evaluation of the pattern of results within the broader body of
scientific evidence.

    Statistical significance is an indicator of the precision of a
study's results, which is influenced by a variety of factors
including, but not limited to, the size of the study, exposure and
measurement error, and statistical model specifications. Statistical
significance is just one of the means of evaluating the validity of
the relationships determined with epidemiological studies. The EPA
can reasonably look to other indicia of reliability such as the
consistency and coherence of a body of studies as well as other
confirming data to justify reliance on the results of a body of
epidemiological studies, even if individual studies may lack
statistical significance. American Trucking Association v. EPA, 283
F. 3d 355, 371 (D.C. Cir. 2002). As a result, in developing an
integrated assessment of the health effects evidence for PM, the EPA
has emphasized the importance of examining the pattern of results
across various studies and their coherence and consistency, and has
not focused solely on statistical significance as a criterion of
study reliability.
    It has been clearly articulated throughout the epidemiological
and causal inference literature that it is important not to focus on
results of statistical tests to the exclusion of other information.
For example, Rothman (1998) stated: ``Many data analysts appear to
remain oblivious to the qualitative nature of significance testing
[and that] . . . statistical significance is itself only a
dichotomous indicator. As it has only two values, significant or not
significant.'' As a result, Rothman recommended that P-values be
omitted as long as point and interval estimates are available.
    The concepts underlying the EPA's approach to evaluating
statistical associations reported for the health effects on
PM2.5 have been discussed in numerous publications,
including a report by the U.S. Surgeon General on the health
consequences of smoking (Centers for Disease Control and Prevention,
2004). This report cautions against overreliance on statistical
significance in evaluating the overall evidence for an exposure-
response relationship: Hill made a point of commenting on the value,
or lack thereof, of statistical testing in the determination of
cause: ``No formal tests of significance can answer those [causal]
questions. Such tests can, and should, remind us of the effects the
play of chance can create, and they will instruct us in the likely
magnitude of those effects. Beyond that, they contribute nothing to
the `proof' of our hypothesis'' (Hill 1965, p. 299). Hill's warning
was in some ways prescient, as the reliance on statistically
significant testing as a substitute for judgment in a causal
inference remains today (Savitz et al., 1994; Holman et al., 2001;
Poole 2001). To understand the basis for this warning, it is
critical to recognize the difference between inductive inferences
about the truth of underlying hypotheses, and deductive statistical
calculations that are relevant to those inferences, but that are not
inductive statements themselves. The latter include p values,
confidence intervals, and hypothesis tests (Greenland 1998; Goodman
1999). The dominant approach to statistical inference today, which
employs those

statistical measures, obscures this important distinction between
deductive and inductive inferences (Royall 1997), and has produced
the mistaken view that inferences flow directly and inevitably from
data. There is no mathematical formula that can transform data into
a probabilistic statement about the truth of an association without
introducing some formal quantification of external knowledge, such
as in Bayesian approaches to inference (Goodman 1993; Howson and
Urbach, 1993). Significance testing and the complementary estimation
of confidence intervals remain useful for characterizing the role of
chance in producing the association in hand (CDC, 2003, pp. 23 to
24).
    Accordingly, the statistical significance of findings from an
individual study has played an important role in the EPA's
evaluation of the study's results and overall the EPA has placed
greater emphasis on studies reporting statistically significant
results in making determinations as to the elements of the standard.
In particular, as noted in section III.E.4.b.i of the preamble to
the final rule, the EPA identified long- and short-term exposure
studies considered ``key'' multi-city studies for consideration for
informing the decisions on the appropriate standard levels and
included those studies observing effects for which the evidence
supported a causal or likely causal association. Figure 4 in the
preamble to the final rule (also Figure 4 in the proposal, 77 FR
38933) represents the subset of multi-city studies included in
Figures 1 through 3 of the preamble to the final rule (also Figures
1 through 3 in the proposal, 77 FR 38929 to 38931) that provided
evidence of positive and generally statistically significant effects
associated in whole, or in part, with more recent air quality data,
generally representing health effects associated with lower
PM2.5 concentrations than had previously been considered
in the last review.
    The EPA notes that many of these studies evaluated multiple
health endpoints, and not all of the effects evaluated provided
evidence of positive and statistically significant effects. For
purposes of informing the Administrator's decision on the
appropriate standard levels, the Agency considers the full body of
scientific evidence and focuses on those aspects of the key studies
that provided evidence of positive and generally statistically
significant effects. However, in the broader evaluation of the
evidence from many epidemiological studies, and subsequently during
the process of forming causality determinations, the EPA has
emphasized the pattern of results across epidemiological studies for
drawing conclusions on the relationship between PM2.5 and
health outcomes, and whether the effects observed are coherent
across the scientific disciplines. Thus, in making causality
determinations, the EPA did not limit its focus or consideration to
just studies that reported positive associations or where the
results were statistically significant.\122\
---------------------------------------------------------------------------

    \122\ Id.

    In addition, EPA has previously addressed the issue of what one
commenter calls ``confounding health factors.'' In the case of short-
term exposure studies, a confounder would need to vary on a day-to-day
basis with both air pollution and with the specific health outcome
being evaluated (e.g., mortality or hospital admissions or emergency
department visits). The confounders that fit these criteria for short-
term exposure studies are related to weather (e.g., temperature, dew
point, relative humidity). The short-term exposure studies,
specifically time-series studies, evaluated in the ISA all included
weather covariates in their models to account for their potential
---------------------------------------------------------------------------
confounding effects (U.S. EPA, 2009a, Chapter 6).

    With regard to long-term exposure studies, a number of
multilevel cohort studies (Naess et al. 2007; Jerrett et al. 2003;
Jerrett et al. 2005) have evaluated individual-level and contextual,
or ecologic-level variables as potential confounders. As reported in
Jerrett et al. (2005), ``Contextual effects occur when individual
differences in health outcomes are associated with the grouped
variables that represent the social, economic, and environmental
settings where the individuals live, work, or spend time (e.g.,
poverty or crime rate in a neighborhood). These contextual effects
often operate independently from (or interactively with) the
individual-level variables such as smoking.'' These studies found
that the inclusion of contextual variables tended to attenuate the
risk estimates for the association between long-term exposure to
PM2.5 and mortality, but that an independent effect of
PM2.5 on mortality remains. For example, Jerrett et al.
(2005) found that for PM2.5 (controlling for age, sex,
and race), the relative risk was 1.24 (95% CI 1.11, 1.37) for a 10
[micro]g/m3 exposure contrast. In a parsimonious model that
controlled for 44 different individual covariates and ecological
confounder variables that both reduced the pollution coefficient and
had associations with mortality, the relative risk was 1.11 (95% CI
0.99, 1.25) for the same exposure contrast. The EPA believes that
the results of these studies provide confidence that more recent
reports with updated datasets are showing independent effects of
PM2.5.\123\
---------------------------------------------------------------------------

    \123\ Id.

    One commenter's assertion that the risk from PM is hundreds of
times smaller than the increased risk of lung cancer caused by
cigarette smoking, and difficult to estimate, has been previously
addressed during the PM NAAQS review. The ``Responses to Significant
Comments on the 2012 Proposed Rule on the National Ambient Air Quality
---------------------------------------------------------------------------
Standards for Particulate Matter'' stated:

    The comparison of smoking and ambient PM-related effect
estimates was not considered relevant for the PM NAAQS review, and
thus, was not considered in the ISA. This issue was not raised
during the CASAC and public review of the drafts of the ISA. In
order to address the comments submitted, the EPA conducted a
provisional review of the ``new'' literature published since the
close of the ISA including studies cited by commenters, and
identified several relevant studies that compared and evaluated
effect estimates determined for relationships between specific
health outcomes and ambient particulate matter and active smoking
(Pope et al. 2009; Pope et al. 2011). These authors analyzed data
from the American Cancer Society cohort in order to evaluate the
shape of the exposure-response relationship for PM2.5 and
both lung cancer mortality (Pope et al. 2011) and cardiovascular
disease (CVD) mortality (Pope et al. 2009; Pope et al. 2011). In
these studies, the authors evaluated three sources of exposure to
PM2.5: active smoking, passive smoking, and ambient air
pollution.
    For lung cancer mortality, the authors observed ``a monotonic,
nearly linear exposure response relationship with fairly constant
marginal increases in RR [relative risk] with increasing exposure''
across the full range of observed exposures (Pope et al. 2011). When
the authors evaluated CVD mortality, they observed ``an exposure-
response relationship that is substantially non-linear, that is,
much steeper at the very low levels of exposure compared with higher
levels of exposure'' (Pope et al. 2011). In fact, the study authors
noted that ``For lung cancer mortality, the RRs steadily increase to
nearly 40 at the highest increment of cigarette smoking (>42
cigarettes per day), whereas for CVD mortality, the RRs level off at
approximately 2.0-2.5.''
    Because of the much steeper exposure-response relationship for
long-term exposure to PM2.5 and CVD mortality at low
PM2.5 concentrations, which flattens out at higher
PM2.5 concentrations (i.e., those associated with passive
and active cigarette smoking), it is biologically plausible that the
risk estimates for CVD mortality due to exposure to ambient
concentrations of PM2.5 would be similar to risk
estimates for CVD mortality due to active cigarette smoking. These
results are consistent with the results observed in epidemiological
studies of long-term exposure to PM2.5 and mortality, and
with the conclusions drawn in the ISA. For example, Dockery et al.
(1993) found essentially the same risk estimates for CVD mortality
associated with both ambient PM2.5 concentrations and
active cigarette smoking in an area with relatively high levels of
ambient PM2.5concentration.
    Additionally, there could be non-traditional confounders have
not been accounted for in epidemiological studies of short- and
long-term exposure to air pollution. These confounders include
physical and psychological population stress factors. The EPA
disagrees with these commenters because: (1) There is very limited
evidence of stress affecting the air pollution-health effect
relationship upon which to base the commenters assertion; (2) in
order for stress to be a true confounder it would need to vary
temporally (for short-term exposure studies) and spatially (for
long-term exposure studies) with both air pollution concentrations
and the health effect of interest, which has not been demonstrated;

and (3) rather than stress acting as a true confounder, more than
likely stress is on the causal pathway to the health effects that
have been observed to be associated with air pollution. The EPA
acknowledges that stress may contribute bias to epidemiological
studies; however, stress more than likely would influence the
magnitude of individual effect estimates in a single-city or multi-
city study and not the trends of positive associations observed
across studies conducted in multiple locations.'' \124\
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    \124\ EPA's Response to Comments: http://www.epa.gov/ttn/naaqs/standards/pm/data/20121214rtc.pdf at II 23-25.

    With regard to the third set of PM2.5 health effect
comments noted above (suggestions that PM2.5 from diesel
combustion located in California does not present a public health
risk), we note that the isolated studies noted by the commenters are
either consistent with past peer-reviewed studies supportive of
PM2.5-related health effects, or have been considered
previously by EPA and were considered as part of the weight of evidence
used to make conclusions in the ISA.
    Some of the commenters asserted that the composition of PM in
California is less toxic than the PM in other areas of the country. One
commenter asserted that ``[t]he scientific evidence on the health
effect of particulate matter air pollution in CA does not support its
further control or regulation at this time. Our PM2.5 is
different in composition and is less toxic than that in many Eastern
regions of the U.S.'' \125\ Another commenter states that ``[t]he
composition of what CARB defines as PM2.5 has changed over
time, and is not the same as what has been studied in the Eastern half
of the United States.'' \126\ EPA responded to questions about
heterogeneity in risk estimates in the PM NAAQS Review and that
response is included here. EPA finds that no new evidence has been
submitted in the context of the authorization proceeding to change this
conclusion.
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    \125\ See Dr. Phalen comment.
    \126\ See Dr. Malkan comment.
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    EPA responded in the PM NAAQS review that with respect to
understanding the nature and magnitude of PM2.5-related
risks:

    [T]he EPA agrees that epidemiological studies evaluating health
effects associated with long- and short-term PM2.5
exposures have reported heterogeneity in responses between cities
and effect estimates across geographic regions of the U.S. (U.S.
EPA, 2009a, sections <IP_ADDRESS>, <IP_ADDRESS>, 6.5.2, and 7.6.1; U.S. EPA,
2011a, p. 2-25). For example, when focusing on short-term
PM2.5 exposure, the ISA found that multi-city studies
that examined associations with mortality and cardiovascular and
respiratory hospital admissions and emergency department visits
demonstrated greater cardiovascular effects in the eastern versus
the western U.S. (Dominici, et al., 2006a; Bell et al., 2008;
Franklin et al. (2007, 2008)). However, the rationale that
heterogeneity in risk estimates presents a potential bias as posed
by the commenters is simplistic and does not account for a number of
factors that have been shown to influence city-specific risk
estimates in epidemiologic studies. As discussed in the ISA, the EPA
recognizes that there are compositional differences in
PM2.5 across the country and that the county-level air
quality data used in epidemiological studies may result in exposure
error, which could in part account for variability in city-specific
risk estimates (U.S. EPA, 2009a, section 2.3.2).
    There are a limited number of studies that evaluated regional
heterogeneity in the association between long-term exposure to
PM2.5 and mortality. Krewski et al. (2009a) conducted
subset analyses of the ACS cohort in Los Angeles, CA and New York
City, NY, and observed a relative risk in Los Angeles that was
greater in magnitude than what was observed in the full ACS cohort,
while the relative risk in New York City was less than what was
observed in the full ACS cohort. These observations are likely due
to the greater spatial heterogeneity in PM2.5
concentrations observed in Los Angeles, and the overall spatial
homogeneity of PM2.5 concentrations in New York City.
    In another retrospective cohort, Zeger et al. (2008) observed
associations between long term exposure to PM2.5 and
mortality for the eastern and central ZIP codes that were similar to
those reported in the ACS and Harvard Six Cities studies, though no
association was observed in the western region. The lack of the
association in the western region is ``largely because the Los
Angeles basin counties (California) have higher PM levels than other
West Coast urban centers, but not higher adjusted mortality rates''
(Zeger et al. 2008). The ISA also evaluated studies that provided
some evidence for seasonal differences in PM2.5 risk
estimates, specifically in the northeast. The ISA found evidence
indicating that individuals may be at greater risk of dying from
higher exposures to PM2.5 in the warmer months, and at
greater risk of PM2.5 associated hospitalization for
cardiovascular and respiratory diseases during colder months of the
year. The limited influence of seasonality on PM risk estimates in
other regions of the U.S. may be due to a number of factors
including varying PM composition by season, exposure
misclassification due to regional tendencies to spend more or less
time outdoors and air conditioning usage, and the prevalence of
infectious diseases during the winter months (U.S. EPA, 2009a, p. 3-
182).
    Overall, the EPA recognizes that uncertainties still remain
regarding various factors that contribute to heterogeneity observed
in epidemiological studies (77 FR 38909/3). Nonetheless, the EPA
recognizes that this heterogeneity could be attributed, at least in
part, to differences in PM2.5 composition across the
U.S., as well as to exposure differences that vary regionally such
as personal activity patterns, microenvironmental characteristics,
and the spatial variability of PM2.5 concentrations in
urban areas (U.S. EPA, 2009a, section 2.3.2; 77 FR 38910).
    As recognized in the PA, the current epidemiological evidence
and the limited amount of city-specific speciated PM2.5
data does not allow conclusions to be drawn that specifically
differentiate effects of PM in different locations (U.S. EPA, 2011a,
p. 2-25). Furthermore, as discussed in section III.E.1 of the
preamble to the final rule, the ISA concluded, ``that many
constituents of PM2.5 can be linked with multiple health
effects, and the evidence is not yet sufficient to allow
differentiation of those constituents or sources that are more
closely related to specific health outcomes'' (U.S. EPA, 2009a, p.
2-17). CASAC thoroughly reviewed the EPA's presentation of the
scientific evidence indicating heterogeneity in PM2.5
effect estimates in epidemiological studies and concurred with the
overall conclusions presented in the ISA (Pages 6-179-180, Figure 6-
25, Figure 6-26).\127\
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    \127\ See ``Responses to Significant Comments on the 2012
Proposed Rule on the National Ambient Air Quality Standards for
Particulate Matter (June 29, 2012; 77 FR 38890). http://www.epa.gov/ttn/naaqs/standards/pm/data/20121214rtc.pdf at II-37-II-38.

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In the PM ISA EPA has also stated:

    Additionally it is important to point out that there are a few
CA-specific time-series studies conducted by Ostro et al. that did
find associations with PM2.5. These are discussed in the
ISA PM2.5-Mortality Associations on a Regional Scale:
California. Ostro et al. (2006, 087991) examined associations
between PM2.5 and daily mortality in nine heavily
populated California counties (Contra Costa, Fresno, Kern, Los
Angeles, Orange, Riverside, Sacramento, San Diego, and Santa Clara)
using data from 1999 through 2002. The authors used a two-stage
model to examine all-cause, respiratory, cardiovascular, ischemic
heart disease, and diabetes mortality individually and by potential
effect modifier (i.e., age, gender, race, ethnicity, and education
level). The a priori exposure periods examined included the average
of 0- and 1-day lags (lag 0-1) and the 2-day lag (lag 2). The
authors selected these non-overlapping lags (i.e., rather than
selecting lag 1 as the single-day lag) because previous studies have
reported stronger associations at lags of 1 or 2 days or with
cumulative exposure over three days. It is unclear why the
investigators chose these non-overlapping lags (i.e., single-day lag
of 2 instead of 1) even though they state they based the selection
of their lag days on results presented in previous studies, which
found the strongest association for PM lagged 1 or 2 days. Using the
average of 0- and 1-day lags Ostro et al. (2006, 087991) reported
combined estimates of: 0.6% (95% CI: 0.2-1.0), 0.6% (95% CI: 0.0-
1.1), 0.3% (95% CI: -0.5 to 1.0), 2.2% (95% CI: 0.6-3.9), and 2.4%
(95% CI: 0.6-4.2) for all-cause, cardiovascular, ischemic heart
disease, respiratory, and diabetes deaths, respectively, per 10
[micro]g/m\3\.

    . . . Five of the nine counties examined in the Ostro et al.
(2006, 087991) analysis contain cities that are among the 2 cities
examined in the Franklin et al. (2007, 091257) analysis for the same
period, 1999-2002. While the lags used were different between these
two studies, both presented PM2.5 risk estimates in
individual cities or counties (graphically in the Franklin et al.
study (2007, 091257); in a table in the Ostro et al. study (2006,
087991)), which allowed for a cursory evaluation of consistency
between the two analyses. In Franklin et al. (2007, 091257),
PM2.5 risk estimates at lag 1 day for the cities Los
Angeles and Riverside were slightly negative, whereas Fresno,
Sacramento, and San Diego showed positive values above 1% per 10
[micro]g/m3 increase in PM2.5. The 2-day lag result
presented in Ostro et al. (2006, 087991) is qualitatively
consistent, with Los Angeles and Riverside, both of which show
slightly negative estimates, while the other 3 locations all show
positive, but somewhat smaller estimates, than those reported by
Franklin et al. (2007, 091257). The estimates for the average of 0-
and 1-day lags for these five counties in Ostro et al. (2006,
087991), which contain cities examined in Franklin et al. (2007,
091257), were all positive. Thus, these two PM2.5 studies
showed some consistencies in risk estimates even though they used
different lag periods and a different definition for the study areas
of interest (i.e., counties vs. cities).\128\
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    \128\ See EPA-HQ-OAR-2008-0691-0318-attachment 3 and http://yosemite.epa.gov/sab/sabproduct.nsf/368203f97a15308a852574ba005bbd01/8bee96ad3228eabe8525760400702786!OpenDocument at 6-179.

    Thus, as noted in EPA's PM NAAQS review and the Response to
Comments document referenced above, EPA has stated it agrees that
epidemiological studies evaluating health effects associated with long-
and short-term PM2.5 exposures have reported heterogeneity
in responses between cities and effect estimates across geographic
regions of the United States. However, EPA believes it critical to
understand the issue in context and EPA's overall approach in
concluding as it did in the ISA, ``that many constituents of
PM2.5 can be linked with multiple health effects, and the
evidence is not yet sufficient to allow differentiation of those
constituents or sources that are more closely related to specific
health outcomes.'' EPA finds that no new evidence has been submitted in
the context of the authorization proceeding to change this conclusion.
    With regard to the claims made by Dr. Phalen in comments on this
authorization proceeding, Dr. Phalen does not provide any evidence or
studies to support the proposition that PM2.5 is not only
different in composition in California but as a result is less toxic,
or present evidence as to the level of reduced toxicity. With regard to
Dr. Enstrom's comments regarding differences in PM health risk in
California compared to other locations, as discussed above, EPA has
previously reviewed Dr. Enstrom's studies and has responded to his
comments, as well as others, on this issue. As explained above, EPA has
examined the issue of whether PM2.5 composition is
determinative and found that the scientific evidence is not yet
sufficient to allow differentiation of those components or sources that
are more closely related to specific health outcomes nor to exclude any
component or group of components from the mix of fine particles
included in the PM2.5 indicator. EPA similarly concluded
that current evidence does not allow conclusions to be drawn that
differentiate effects of PM in different locations.
    With regard to the claims of omissions in EPA's Regulatory Impact
Analysis (RIA) for its proposed PM air quality standards, it is
necessary to understand that only the peer-reviewed studies cited in
the PM ISA (2009) or PM Provisional Science Assessment (2012) were
listed in the RIA table. Furthermore, the inclusion or exclusion of a
study published after the Provisional Science Assessment would not
materially change the large body of scientific evidence indicating an
effect of PM2.5 exposure on human health.
    With regard to the claims based on the Trucker Study noted above,
the study does not attempt to examine air pollution-related health
effects or provide any measure of air pollution exposure in the cohort
examined. The study looked only at mortality rates for certain deaths
within the population studied. EPA notes that the Truck Driver study
contains a research abstract that plainly states ``[t]he absence of
disease mortality deserves careful interpretation, and may be due to
both a strong healthy worker effect and a short monitoring period.''
\129\ We note that this study did not include an actual close study of
air quality and PM exposure levels and otherwise is not of scientific
significance. This type of study as well as the other few studies
submitted in isolation does not overcome the significant evidence and
scientific evidence that has been peer reviewed and found PM to be
associated with health effects.
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    \129\ CCTA; ``Mortality Among Members of a Truck Driver Trade
Associations'' AAOHN Journal Vol. 58. No. 11, 2010 at 473.
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    The comments provided do not provide sufficient evidence to meet
the authorization opponents' burden of showing that PM emissions in
California do not create any risk to public health, particularly given
the substantial body of evidence suggesting such a risk. Therefore,
even if EPA were to apply the alternative interpretation of section
209(e)(2)((A)(ii) and examine whether CARB has a specific need for its
Fleet Requirements, the opponents of the authorization have not met
their burden of proof to demonstrate that California no longer
continues to have serious air quality issues related to PM and
NOX, that are created by California's underlying compelling
and extraordinary conditions. The evidence submitted to the record, in
addition to EPA's own PM NAAQS review and the multitude of studies
reviewed therein and conclusions of EPA that were peer reviewed by
CASAC, continue to demonstrate requisite health effects due to PM
exposure and therefore the authorization cannot be denied on this
basis.
    Finally, EPA notes that CARB's Fleet Requirements are designed not
only to reduce PM emissions and public health consequences, as
discussed above, but also to address the harmful effects of ozone by
reducing emissions of NOX, as an ozone precursor, from the
in-use fleet.\130\ There is no evidence in the record to suggest that
ozone pollution is not harmful to public health or that CARB's Fleet
Requirements are not needed in that context.
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    \130\ See CARB Authorization Request at 4 (``Even as amended to
provide immediate short-term relief to fleets adversely impacted by
the recession, the In-Use Off-Road Regulation is expected to achieve
a 17 percent reduction in NOX emissions and a 21 percent
reduction in PM2.5 emissions in 2023 from forecasted
emissions that would exist without a regulation in place.'').
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    In conclusion, even if EPA were to use the alternative approach
outlined above--that of reviewing the need for the Fleet Requirements
per se to meet compelling and extraordinary conditions in California--
EPA finds that the opponents of the authorization have not met their
burden of proof. Therefore, even if EPA were to use this alternative
approach, we could not deny the authorization on this basis.
c. Additional PM Comments
    EPA also received comment from the PLF focused on the recent
decision issued by the United States Court of Appeals for the District
of Columbia Circuit in Natural Resources Defense Counsel v. EPA, No 08-
1250, January 4, 2013, (NRDC v. EPA) concerning implementation
regulations applicable to the 1997 PM2.5 NAAQS. PLF
characterizes the court's decision as requiring EPA itself to adopt
stringent

federal implementation standards for PM2.5 throughout the
nation, including California. Because California asserted that it
``needs'' nonroad diesel PM standards that are more stringent than
federal nonroad PM standards, and because (in PLF's view) EPA is now
required to use the ``stringent, action-forcing provisions'' of section
188-188(b) of the Clean Air Act as a result of the Decision, PLF
maintains that it is appropriate to complete EPA's administrative
proceedings on remand (from the decision) for implementation
regulations before EPA is able to determine the extent to which there
is a ``need'' for California to have its own PM2.5 nonroad
diesel standard for engines and vehicles based on ``compelling and
extraordinary conditions'' in California. In addition, PLF highlights
EPA's most recent revision of the primary annual NAAQS for
PM2.5, which lowered the prior standard from 15.0 micrograms
per cubic meter to 12.0 micrograms per cubic meter, and the concomitant
revision to the Air Quality Index for PM2.5. PLF asserts
that these events provide additional reasons to question California's
``need'' for its own PM2.5 nonroad diesel standard.
    PLF's reliance on NRDC v. EPA is misplaced. That decision pertains
only to EPA's regulations governing how states should address the
statutory requirements for attainment plans. It does not require EPA
``to move ahead in implementing strict federal PM2.5
controls,'' through its own regulations as opposed to state regulation
of PM2.5 and PM2.5 precursors. The Clean Air Act
generally requires states to have state implementation plans (SIPs)
that provide for attainment and maintenance of the NAAQS, and nothing
in the Court's opinion obviates or supplants that statutory
requirement. Further, the NRDC v. EPA decision will not result in EPA
itself issuing new regulatory controls that impose any specific
emission reductions requirements on mobile sources. To the extent that
PLF is suggesting that EPA itself is now required to regulate any
particular sources more stringently, through national standards, such
suggestion is incorrect.
    To the extent EPA imposes the ``more stringent'' NAAQS
implementation requirements of sections 188 through 190 of the Act on
the state (rather than the ``less stringent'' implementation
requirements of sections 171 through 179B of the Act), then the state
will still be required to adopt its own regulations (e.g. Fleet
Requirements) to get necessary emission reductions to attain and
maintain the applicable NAAQS. While this may create somewhat lesser
flexibility for states in developing attainment plan measures in the
future, it by no means negates their SIP obligations today. The
emission reductions from the Fleet Requirements take effect at the
beginning of 2014, and California has shown that it needs these
reductions as part of the suite of control measures that are necessary
for purposes of attaining and maintaining the PM2.5 and
ozone NAAQS expeditiously. Moreover, states still have a great deal of
flexibility in designing their emission control program to achieve
needed emission reductions, and nothing in the court's opinion in NRDC
v. EPA indicates any attempt by the court to preclude California from
using the specific flexibility provided by section 209(e)(2)(A) to
reduce emissions through regulation of nonroad engines. Such emission
reductions have been instrumental in California's strategy to meet its
NAAQS requirements.
    With respect to the revisions to the primary annual
PM2.5 NAAQS issued in December of 2012, the revisions have
increased the stringency of the standard. Thus, if anything, the new
PM2.5 standard will increase California's need to find
reductions in emissions of PM2.5 and PM2.5
precursors from regulated sources, which should only increase the need
for such regulations such as the Fleet Requirements.
    For the reasons set forth above, EPA believes that under the
alternative interpretation of the compelling need criterion discussed
above, opponents of authorization have not meet their burden of
demonstrating that California's Fleet Requirements do not have a
rational relationship to contributing to amelioration of serious air
quality problems in California, including its PM2.5 and
ozone. Accordingly, commenters' assertions to the contrary provide no
basis for denying authorization.
4. Section 209(e)(2)(A)(ii) Conclusion
    With respect to the need for California's standards to meet
compelling and extraordinary conditions, after an examination of the
text of section 209 and the legislative history, EPA again concludes
that the best way to interpret this provision is to apply the
traditional interpretation. Under this interpretation, EPA can deny
authorization under section 209(e)(2)(A)(ii) only if it finds that
opponents of authorization have demonstrated that California does not
need a separate nonroad program to address compelling and extraordinary
conditions. Under this traditional interpretation, EPA cannot find that
opponents of the authorization have demonstrated that California does
not need its state standards to meet compelling and extraordinary
conditions. The opponents of the waiver have not adequately
demonstrated that California no longer has a need for its nonroad
emissions program.
    Even if EPA were to apply the alternative interpretation advocated
by commenters--that EPA is required to review, on a case by case basis,
whether the specific standard submitted by CARB is needed to meet
compelling and extraordinary conditions--EPA cannot find that the
opponents of the waiver have demonstrated that California does not need
its Fleet Requirements to meet compelling and extraordinary conditions.
    Accordingly, EPA has determined that it cannot deny the
authorization request under section 209(e)(2)(A)(ii).

C. Consistency with Section 209 of the Clean Air Act

    Section 209(e)(2)(A)(iii) of the Act instructs that EPA cannot
grant an authorization if California's standards and enforcement
procedures are not consistent with ``this section.'' As described
above, EPA's section 209(e) rule states that the Administrator shall
not grant authorization to California if she finds (among other tests)
that the ``California standards and accompanying enforcement procedures
are not consistent with section 209.'' EPA has interpreted the
requirement to mean that California standards and accompanying
enforcement procedures must be consistent with at least section 209(a),
section 209(e)(1), and section 209(b)(1)(C), as EPA has interpreted
this last subsection in the context of motor vehicle waivers.\131\
Thus, this can be viewed as a three-pronged test.
1. Consistency with Section 209(a)
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    \131\ See 59 FR 36969 (July 20, 1994).
---------------------------------------------------------------------------

    Section 209(a) of the Clean Air Act prohibits states or any
political subdivisions of states from setting emission standards for
new motor vehicles or new motor vehicle engines. Section 209(a) is
modified in turn by section 209(b) which allows California to set such
standards if other statutory requirements are met. To find a standard
to be inconsistent with section 209(a) for purposes of section
209(e)(2)(A)(iii), EPA must find that the standard in question actually
regulates new motor vehicles or new motor vehicle engines.
    In its authorization request, CARB stated that by definition, the
section

209(a) preemption does not apply to vehicles covered by the Fleet
Requirements because the regulation only applies to non-new, in-use
vehicles and engines and not to new motor vehicles and engines. CARB
also stated that with a few limited exceptions--workover rigs, two-
engine cranes, and certain other two-engine vehicles--vehicles covered
under the Fleets Requirements are not motor vehicles under the Clean
Air Act definition of motor vehicles.\132\ No commenter argued the
contrary or otherwise asserted that the Fleet Requirements are not
consistent with section 209(a).
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    \132\ CARB Authorization Request. CARB noted that these limited
exceptions are provided to afford fleet operators of such vehicles
additional flexibility to address both the in-use on-highway
requirements associated with the engines designed to propel the
equipment and the nonroad engines on the vehicles designed to
perform other functions. Since the regulation of such non-new (in
use) on-highway vehicles (and the engines designed to propel such
vehicles) is not preempted under section 209(a) CARB did not seek a
waiver under section 209(b) and instead only sought an authorization
under section 209(e) for the in use nonroad engines associated with
such on-highway vehicles.
---------------------------------------------------------------------------

    Therefore, EPA cannot deny California's request on the basis that
California's Fleet Requirements are not consistent with section 209(a).
2. Consistency with Section 209(e)(1)
    To be consistent with section 209(e)(1) of the Clean Air Act,
California's standards or other requirements relating to the control of
emissions must not relate to new engines which are used in farm or
construction equipment or vehicles and which are smaller than 175
horsepower (hp), and new locomotives or new engines used in
locomotives.
    In its Authorization Request, CARB stated that the Fleet
Requirements specifically ``do not apply to locomotives and do not
apply to new farm and construction vehicles and equipment less than 175
hp.'' \133\ CARB notes that ``implements of husbandry, regardless of
engine size, are expressly excluded from coverage.'' While CARB
acknowledged that nonroad construction vehicles and engines used in
such vehicles are covered by the Fleets Requirements, CARB stated that
the regulation does not apply to new construction vehicles or engines.
---------------------------------------------------------------------------

    \133\ Id at 20.
---------------------------------------------------------------------------

    CARB stated that the Fleet Requirements do not attempt to regulate
new construction sources covered by the section 209(e)(1) preemption.
New, as it applies to nonroad engines and equipment other than
locomotives and engine used in locomotives, means engines and equipment
whose legal title has not been transferred to an ultimate purchaser, or
in certain cases, to engines or vehicles that have been placed into
service.\134\ The Fleet Requirements do not regulate engines and
vehicles immediately after their titles are transferred or they enter
service; instead, the regulation exempts any vehicle that is less than
ten years old from the BACT requirements. CARB states that while a
fleet owner may elect to comply with the fleet average or BACT
requirements by purchasing or repowering a vehicle primarily used in
construction with a new nonroad engine under 175 hp, that outcome also
does not run afoul of the 209(e)(1) preemption. CARB notes that this
new engine is only required to be certified to the existing federal
nonroad emission standards.\135\ Therefore, the Fleet Requirements do
not establish standards for such new engines.
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    \134\ See 40 CFR Sec.  1074.5.
    \135\ CARB's regulations establishing new emission standards for
engines less than 175 hp specifically do not cover engines that are
primarily used in farm and construction vehicles and equipment.
---------------------------------------------------------------------------

    EPA received comment from ARTBA suggesting that CARB's regulations
run afoul of section 209(e)(1)'s preemption for ``new engines which are
used in construction equipment or vehicles or farm equipment or
vehicles and which are smaller than 175 horsepower.'' ARTBA argues that
section 209(e)(1)'s limitation on state standards or emission-related
requirements for these engine/equipment categories lasts throughout the
useful life of the equipment.\136\ ARTBA stated in comment that under
this interpretation, California's authorization request should be
denied because the Fleet Requirements apply to all in-use off-road
diesel construction equipment greater than 25 HP, including equipment
in the permanently preempted power range. ARTBA did not provide any
further explanation in its written comments or at the public hearing as
to why this permanent preemption of certain types of ``new'' vehicles
should be interpreted as extending throughout the useful life of the
vehicles.
---------------------------------------------------------------------------

    \136\ See Hearing Transcript at 51-52, and ARTBA at 2.
---------------------------------------------------------------------------

    CARB, in response to comments made by ARTBA at EPA's public
hearing, noted that the contention that the preemption under section
209(e)(1) extends throughout the useful life of the new engine is
simply wrong. CARB noted that EPA considered and rejected this extended
definition of ``new'' in section 209(e)(1) during the 209(e) rulemaking
process.\137\ CARB also noted in its Authorization Request that the
Court of Appeals in Engine Manufacturers Association v. EPA (EMA),
affirmed EPA's definition of ``new'' as it is applied to off-road
sources other than locomotives.\138\ In EMA, the court discussed the
issue of whether EPA's definition of new nonroad engines would
effectively undermine the section 209(e)(1) preemption that states are
prohibited from adopting emission standards for new farm and
construction vehicles with less than 175 hp. CARB noted that the court
concluded that EPA's definition of new did not undermine the preemption
in 209(e)(1).\139\
---------------------------------------------------------------------------

    \137\ 59 FR 31306, 31328-31 (June 17, 1994).
    \138\ EMA 88 F3d 1075, 1082-1086 (D.C. Cir. 1996).
    \139\ A more recent opinion in the Court of Appeals for the
Ninth Circuit agreed with the D.C. Circuit's decision on this issue.
National Association of Home Builders v. San Joaquin UAPCD, 627 F.
3d 730 (9th Cir. 2010).
---------------------------------------------------------------------------

    CARB also notes the more recent history on this issue. In a 2002
petition to EPA, ARTBA requested that EPA revise its regulations such
that nonroad engines in the categories covered under section 209(e)(1)
are preempted for their useful lives. EPA denied ARTBA's request,\140\
and subsequently the United States Court of Appeals for the District of
Columbia dismissed ARTBA's petition for review of that denial.\141\
---------------------------------------------------------------------------

    \140\ 73 FR 59034, 59130 (October 8, 2008).
    \141\ ARTBA v. EPA, 558 F.3d 1109 (D.C. Cir. 2009), certiorari
denied 131 S.Ct. 338, 178 L.Ed.2d 38. A more recent opinion from the
Court of Appeals for the D.C. Circuit came to the same conclusion.
ARTBA v. EPA, 705 F.3d 453 (D.C. Cir. 2013)
---------------------------------------------------------------------------

    At the outset, we note that no commenter disputes CARB's assertion
that its regulations do not violate section 209(e)(1) as EPA's current
regulations implement that provision. Rather, ARTBA's comments appear
to go to the validity of EPA's longstanding regulations, as opposed to
the validity of California standards currently being reviewed under
those regulations. As such, EPA believes ARTBA's comments are
peripheral to this proceeding. EPA is not reviewing its authorization
regulations in this proceeding, but is instead reviewing the validity
of California's Fleet Requirements under those regulations.
    In any event, EPA fully considered the scope of preemption issue
(the definition of ``new'') during its 1994 rulemaking which
implemented the provisions of section 209(e). The rationale contained
in that rulemaking was affirmed by the Court of Appeals in EMA.\142\ As
CARB notes, EPA fully reviewed its rationale regarding the definition
of ``new'' in the context of ARTBA's earlier petition to reconsider its
regulations and EPA denied the petition. No information or argument

has been submitted to the record of this proceeding to rebut EPA's
interpretation. ARTBA provides no new information or argument in the
record of this proceeding to suggest that EPA should change its
longstanding interpretation of ``new'' in section 209(e), \143\ and as
stated above, EPA is not in any case reviewing its regulations in the
context of this proceeding. Moreover, ARTBA does not make any factual
argument regarding the consistency with section 209(e)(1) of the
particular regulations for which CARB is requesting authorization, even
under ARTBA's own definition.
---------------------------------------------------------------------------

    \142\ EMA, 88 F3d 1075, (D.C. Cir. 1996).
    \143\ ARTBA had previously, though not in this proceeding,
provided a fuller explanation of its view regarding the
interpretation of 209(e)(1) and we have previously responded that
ARTBA's arguments were not persuasive. See 73 FR 59034, 59130
(October 8, 2008). The U.S. Court of Appeals for the District of
Columbia subsequently dismissed ARTBA's petition for review of EPA's
response. ARTBA v. EPA (2009 D.C. Cir. (588 F.3d 1109, rehearing en
banc denied (March 5, 2010), certiorari denied 131 S.Ct. 388, 178
L.Ed2d 38. ARTBA has not made similar or other arguments in this
proceeding beyond an unsupported statement regarding how it
interprets the length of the preemption, and we do not address that
issue in depth here, except to say that ARTBA makes no attempt to
support its assertion.
---------------------------------------------------------------------------

    In light of the lack of information in the record, and giving due
consideration to the burden of proof being on the opponents of the
waiver, EPA cannot make a finding that CARB's Fleet Requirements are
inconsistent with section 209(e)(1)(i). Therefore, EPA cannot deny
CARB's authorization request on this basis.
3. Consistency With Section 209(b)(1)(C)
    The requirement that California's standards be consistent with
section 209(b)(1)(C) of the Clean Air Act effectively requires
consistency with section 202(a) of the Act. To determine this
consistency, EPA has applied to California nonroad standards the same
test it has used previously for California motor vehicle standards;
namely, state standards are inconsistent with section 202(a) of the Act
if there is inadequate lead-time to permit the development of
technology necessary to meet those requirements, giving appropriate
consideration to the cost of compliance within that timeframe.
California's accompanying enforcement procedures would also be
inconsistent with section 202(a) if federal and California test
procedures conflicted. The scope of EPA's review of whether
California's action is consistent with section 202(a) is narrow. The
determination is limited to whether those opposed to the authorization
or waiver have met their burden of establishing that California's
standards are technologically infeasible, or that California's test
procedures impose requirements inconsistent with the federal test
procedures.\144\
---------------------------------------------------------------------------

    \144\ MEMA I, 627 F.2d at 1126.
---------------------------------------------------------------------------

    EPA does not believe that there is any reason to review these
criteria any differently for EPA's evaluation of California's Fleet
Requirements. There is nothing inherently different about how the Fleet
Requirement control technologies should be reviewed when making a
determination about technological feasibility or consistency of text
procedures.
a. Technological Feasibility
    The legislative history of section 209 (including the ``consistency
with section 202(a) requirement in 209(b)((1)(C)) indicates that this
provision is intended to relate to technological feasibility.\145\
Section 202(a)(2) states, in relevant part, that any regulation
promulgated under its authority ``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.'' Section
202(a) thus requires the Administrator to first determine whether
adequate technology already exists; or if it does not, whether there is
adequate time to develop and apply the technology before the standards
go into effect. The latter scenario also requires the Administrator to
decide whether the cost of developing and applying the technology
within that time is feasible. Previous EPA waivers are in accord with
this position.\146\ For example, EPA in a 1976 waiver decision
considered California's standards and enforcement procedures to be
consistent with section 202(a) because adequate technology existed as
well as adequate lead-time to implement that technology.\147\ The
legislative history of the 1977 amendments to the Clean Air Act
indicates Congress' view that, generally, EPA's construction of the
waiver provision had been consistent with congressional intent.\148\
---------------------------------------------------------------------------

    \145\ H.R. Rep. No. 95-294, 95th Cong., 1st Sess. 301 (1977).
    \146\ See, e.g., 49 FR 1887, 1895 (May 3, 1984); 43 FR 32182,
32183 (July 25, 1978); 41 FR 44209, 44213 (October 7, 1976).
    \147\ 41 FR 44209 (October 7, 1976).
    \148\ H.R. Rep. No. 95-294, 95th Cong., 1st Sess. 301 (1977).
---------------------------------------------------------------------------

    EPA also evaluates CARB's request in light of congressional intent
regarding the waiver program generally. This is consistent with the
motivation behind section 209(b)--to foster California's role as a
laboratory for motor vehicle emission control, in order ``to continue
the national benefits that might flow from allowing California to
continue to act as a pioneer in this field.'' \149\ For these reasons,
EPA believes that California must be given substantial deference to
adopt not only new motor vehicle emission standards, but to adopt new
and in-use nonroad emission standards which may require new and/or
improved technology. This deference was discussed in an early waiver
decision when EPA approved the waiver request for California's 1977
model year standards:
---------------------------------------------------------------------------

    \149\ 40 FR 23102, 23103 (waiver decision citing views of
Congressman Moss and Senator Murphy) (May 28, 1975).

    Even on this issue of technological feasibility I would feel
constrained to approve a California approach to the problem which I
might feel unable to adopt at the Federal level in my own capacity
as a regulator. The whole approach to the Clean Air Act is to force
the development of new types of emission control technology where
that is needed by compelling the industry to `catch up' to some
degree with newly promulgated standards. Such an approach to
automotive emission control might be attended with costs, in the
shape of reduced product offering, or price and fuel economy
penalties, and by risks that a wider number of vehicle classes may
not be able to complete their development work in time. Since a
balancing of these risks and costs against the potential benefits
from reduced emissions is a central policy decision for any
regulatory agency, under the statutory scheme outlined above I
believe I am required to give very substantial deference to
California's judgment on that score.\150\
---------------------------------------------------------------------------

    \150\ Id. at 23103.

    In MEMA I, the court addressed the cost of compliance relative to
technological feasibility issue at some length in reviewing a waiver
---------------------------------------------------------------------------
decision. According to the court:

    Section 202's cost of compliance concern, juxtaposed as it is
with the requirement that the Administrator provide the requisite
lead time to allow technological developments, refers to the
economic costs of motor vehicle emission standards and accompanying
enforcement procedures. See S. Rep. No. 192, 89th Cong., 1st Sass.
5-8 (1965); H.R. Rep. No. 728 90th Cong., 1st Sass. 23 (1967),
reprinted in U.S. Code Cong. & Admin. News 1967, p. 1938. It relates
to the timing of a particular emission control regulation rather
than to its social implications. Congress wanted to avoid undue
economic disruption in the automotive manufacturing industry and
also sought to avoid doubling or tripling the cost of motor vehicles
to purchasers. It, therefore, requires that the emission control
regulations be technologically feasible within economic parameters.
Therein lies the intent of the cost of compliance requirement
(emphasis added).\151\
---------------------------------------------------------------------------

    \151\ MEMA I at 1118 (emphasis added). See also id. at 1114 n.
40 ([T])he `cost of compliance' criterion relates to the timing of
standards and procedures.

---------------------------------------------------------------------------

    Previous waiver decisions are fully consistent with MEMA I, which
indicates that the cost of compliance must reach a very high level
before the EPA can deny a waiver. Therefore, past decisions indicate
that the costs must be excessive to find that California's standards
are inconsistent with section 202(a).\152\ It should be noted that, as
with other issues related to the determination of consistency with
section 202(a), the burden of proof regarding the cost issue falls upon
the opponents of the grant of the waiver.
---------------------------------------------------------------------------

    \152\ See, e.g. 47FR 7306, 7309 (Feb. 18, 1982), 43 FR 25735
(June 14, 1978), and 78 FR 2112, 2134 (Jan. 9, 2013).
---------------------------------------------------------------------------

    Consistent with MEMA I, the Agency has evaluated costs in the
waiver and authorization context by looking at the actual cost of
compliance in the time provided by the regulation, not the regulation's
cost-effectiveness. The appropriate level of cost-effectiveness for any
given California regulation is a policy decision that state regulators
must consider in adopting the regulation. EPA, historically, has
deferred to these policy decisions. EPA has stated in this regard,
``the law makes it clear that the waiver request cannot be denied
unless the specific findings designated in the statute can be made. The
issue of whether a proposed California requirement is likely to result
in only marginal improvement in air quality not commensurate with its
cost or is otherwise an arguably unwise exercise of regulatory power is
not legally pertinent to my decision under section 209 * * *.'' \153\
Thus, although EPA may evaluate whether compliance costs to
manufacturers (or in this case, fleet operators) are so excessive as to
implicate the regulation's technological feasibility, EPA does not look
at cost-effectiveness when making a waiver decision.
---------------------------------------------------------------------------

    \153\ 36 FR 17158 (August 31, 1971). See also 40 FR 23102,
23104; 58 FR 4166 (January 7, 1993), LEV Waiver Decision Document at
20.
---------------------------------------------------------------------------

    In evaluating the Fleet Requirements' consistency with section
202(a), EPA finds that CARB provided a series of flexibilities in order
to address concerns expressed by some about cost and cost-
effectiveness. CARB, in its Authorization Request, notes that section
2449.1 of its 2010 amendments, requires all fleets to comply with
annual fleet average emission targets or, alternatively, meet the
annual BACT requirements for specified percentages of the fleet. The
fleet average targets, CARB states, have been set to progressively
become more stringent over the years to ensure that fleets modernize to
achieve the necessary emission reductions for California to meet the
federal NAAQS for NOX and PM2.5 and to meet its
2020 goal set forth in CARB's 2000 Diesel Risk Reduction Plan.\154\
---------------------------------------------------------------------------

    \154\ CARB Authorization Request at 21. CARB notes that meeting
the 2020 target would reduce diesel PM from all diesel sources by 85
percent from the 2000 baseline and would prevent thousands of
premature deaths and medical infirmities.
---------------------------------------------------------------------------

    CARB notes that to meet the fleet average targets or the
alternative BACT requirements, a large or medium fleet may comply by
using a variety of different strategies, including: replacing the
engines in existing vehicles with cleaner engines, purchasing newer
vehicles with cleaner engines to replace older, higher emitting
vehicles, retiring vehicles from service, designating vehicles as
permanent low use, or retrofitting engines with verified diesel
emission control strategies (VDECS). Compliance with the amended
regulation will require most large and medium fleets to phase-out use
of Tier 0 and Tier 1 engines through replacement or repowering of
vehicles, but CARB also notes that fleets will be able to meet the
fleet average targets by replacing such vehicles and engines with a
combination of higher-tiered engines. Therefore, it is not until 2018
that the regulation actually requires large and medium fleets to
replace vehicles and engines with only Tier 3 and 4 engines.
    CARB states that by 2018, Tier 3 engines will have been available
for at least ten years, Interim Tier 4 engines for at least seven
years, and Tier 4 engines for at least three years. In addition, CARB
notes that the Fleet Requirements provide relief to fleets if there is
a delay in the availability of vehicles that would be required to use
Tier 3, Tier 4 interim, or final Tier 4 emission standards. Therefore,
CARB notes, it is anticipated that large and medium fleet owners with
high natural turnover of vehicles will be able to meet the fleet
average targets through normal replacement and repowering of vehicles.
Fleets may also choose to meet the BACT fleet average requirements by
either installing retrofits, or by modernizing the fleet by turning
over older, dirtier engines and vehicles to newer (not necessarily new)
and cleaner models; by retiring older vehicles or designating them as
low use; or by using the other exemptions, compliance extensions, and
credit provisions. Additionally, CARB explains that the 2010 amendments
provide even further flexibility and relief for the smaller fleets,
including, but not limited to, an additional five year delay in the
implementation date (2019) of the fleet average targets beyond that
applicable to large fleets, a variety of exemptions from the BACT
requirements including an exemption if the vehicle is less than ten
years old, or if the vehicle has already been retrofitted with a level
2 or 3 VDECS that was the highest level PM VDECS at the time of
installation, etc. The 2010 amendments also included a new compliance
path for small fleets whereby such fleets could comply by phasing out
their Tier 0 and Tier 1 vehicles between 2019 and 2029--and if they
meet such compliance targets for a specific year then no other
compliance requirements would apply.
    EPA received multiple comments regarding the cost of the CARB Fleet
Requirements. The comments address both the cost to fleet operators and
cost-effectiveness of the regulations. Almost all of the comments argue
that authorization should be denied because of the high compliance
costs for fleet operators. The comments claim that these costs are
excessive for an industry characterized by small, independent
companies, and they claim that many will be forced out of business by
the cost of compliance with the Fleet Requirements. EPA also received
comments on other aspects of technological feasibility including
technology availability and safety issues. A detailed discussion of
these comments is presented below.
    EPA received comment from a variety of contractors and associations
claiming that while the nation and California continue to experience a
sluggish economic recovery, employment in the construction sector has
continued to decline. As a result, these commenters argue, the market
is less prepared to handle the Fleet Requirements than even before the
2010 amendments.
    EPA also received a variety of comments stating that the Fleet
Requirements require the use of new equipment that might not be
available for purchase until 2014 or later. In this context, one
commenter noted that, where technology is available, a sudden increase
in demand could cause supplies to be exhausted and that contractors may
be barred from their work if they are not able to make necessary
purchases. As such, the commenter argues that CARB must allow
technology to catch up to the point that compliant equipment is broadly
available. The comment states that without a period for technology to
catch up, contractors will be unable to meet the Fleet Requirements,
triggering negative impacts on California's infrastructure rebuilding
efforts, the health of the state's construction industry, and its
overall economy.

    Similarly, EPA received comment that the eventual elimination of
Tier 0 and Tier 1 equipment has significantly diminished the resale
value of such equipment and, combined with the recession in California,
has forced the sale of this older equipment to out-of-state
contractors. The commenter claims that this has caused a reduction in
the size of the fleet and has probably eliminated up to 15,000 jobs in
California and has also diminished the bonding capacity of contractors
(equipment is used as collateral) and severely limited the size and
number of construction projects which a contractor could undertake.
    EPA also received a number of comments suggesting that the larger
fleet companies may fare better than the smaller companies in terms of
compliance with the Fleet Requirements. One commenter noted that larger
companies have already begun the process of repowering or retrofitting
their equipment: however the smaller companies (less than 10 employees)
will be severely hampered by the costs of repowering or retrofitting
equipment that, in some cases, is the sole asset of their family-owned
businesses. Commenters asserted that many of these smaller companies do
not have the resources or access to capital to repower or retrofit
their engines and may be forced to park the equipment. Due to the
annual emission reduction targets required by the Fleet Requirements,
these commenters argue, many contractors will be required to first
repower or retrofit an engine, only to have to turn around a few years
later and replace the entire piece of equipment when the technology to
do the job right finally hits the marketplace.
    Another commenter maintains that the ongoing economic recession in
conjunction with CARB's ``draconian set of diesel regulations that
denies normal industry replacement cycles'' has placed many businesses
in a ``catch-22'' situation.\155\ Many businesses face having to
replace and/or modify both on-road and off-road diesel powered
equipment, yet the net effect of CARB's regulations has been to devalue
their current equipment to the point they have lost equity necessary to
secure financing. To the extent they may secure financing, the comment
states, many could not secure enough work to satisfy a mortgage
obligation.
---------------------------------------------------------------------------

    \155\ California Construction Trucking Association (CCTA).
---------------------------------------------------------------------------

    EPA also received comment stating that regardless of whether EPA
reconsiders its ``case-by-case'' implementation of section 209 waivers
by revisiting what it means for California to need this regulation to
meet its air quality goals,\156\ the Fleet Requirements still suffer
from gross inefficiencies, amortized over a smaller-than-expected
market, for smaller-than-expected gains which should defeat the
authorization as inconsistent with section 202(a), including
technological feasibility, the cost of compliance, safety, and lead
time.
---------------------------------------------------------------------------

    \156\ To the extent that the ``need'' for the Fleet Requirements
to meet California's air quality goals is relevant to EPA's
consideration of CARB's authorization request we examine this under
the second authorization criterion of section 209(e)(2)(ii) above.
---------------------------------------------------------------------------

    EPA received a variety of comments concerning the reliability and
safety of diesel retrofits. One commenter noted that the California
Occupational Health and Safety Board has established safety standards
for installation and operation of the retrofits.\157\ Another commenter
noted that attempts to meet emission levels by using filtering
equipment have failed--to the extent that the 2010 amendments
eliminated the retrofit requirement altogether and made diesel
particulate filters (DPFs) voluntary only, due to limitations in
safety, reliability, and functionality.\158\
---------------------------------------------------------------------------

    \157\ ARTBA and Allfishch Contractors.
    \158\ United Contractors.
---------------------------------------------------------------------------

    In addition to the concerns about retrofits noted above, EPA also
received comment questioning whether EPA's regulation for replacement
engines has eliminated fleets' ability to choose engine replacement or
repower compliance strategies, which the commenter claimed to be the
only cost effective means to achieve the fleet average emission
standards. This commenter noted that one compliance option is to
replace equipment with the newest equipment available but that this is
impractical for most contractors due to the cost of new equipment. For
example, a new scraper or bulldozer can cost over $1,000,000. The
second option is to repower an older machine with a new engine
(replacing a Tier 0 engine with a Tier 3 engine with a cost of $150,000
or more). The commenter suggested this second option is far more
practical as the equipment is designed to last for 30 years or more.
The commenter contends that EPA's replacement engine regulation at 40
CFR 1068.240 prohibits the repowering of a machine unless the engine
has ``prematurely failed.'' This roadblock makes compliance impossible
according to the commenter.\159\
---------------------------------------------------------------------------

    \159\ See CIACQ.
---------------------------------------------------------------------------

    EPA also received comment stating that attempts to repower or
replace existing older engines with newer, cleaner technology have
encountered the practical issue of compatibility. ``The new engines
either don't fit the old chassis, or require additional alterations or
replacement of other systems (such as cooling units) in the old unit.
Thus, cost-effectiveness of modifying such older units becomes
problematical.'' \160\ This commenter does not note the availability of
retrofit, but instead noted that the alternative to repower is
retirement and replacement.
---------------------------------------------------------------------------

    \160\ See United Contractors.
---------------------------------------------------------------------------

    Finally, EPA received a number of comments suggesting that the
Fleet Requirements are generally not cost-effective, given the makeup
of the current fleet.
    EPA received comment in favor of CARB's Authorization Request from
the Manufacturers of Emission Control Association (MECA), which
supported CARB's original 2007 rule, and continues to support the
current rule while requesting that EPA grant this authorization. MECA
contends that a number of advanced emission control technologies
already exist with the capability to significantly reduce PM and
NOX emissions from the engines subject to CARB's regulation,
and that over 250,000 systems (retrofits) have been installed on off-
road engines worldwide. MECA also disputes safety concerns surrounding
these systems, citing statistics that 35,000 diesel particulate filters
have been installed in California, with fewer than 15 safety-related
issues, all of which ``were shown to be attributed to poor engine or
device maintenance, misapplication of devices, or the ignoring of
warning alarms by the operator.'' MECA does not support the
implementation delays built into the CARB's 2010 amendments, but
nonetheless asks EPA to grant the request.
    In response to comments from opponents of the authorization, CARB
states that the opponents have not met their burden of showing that the
regulation is inconsistent with section 209(b)(1)(C). CARB continues to
rely upon the information presented in its Authorization Request and
earlier submissions and maintains that California has amply
demonstrated that the performance standards of the regulation are
technologically feasible in the lead time provided, giving appropriate
consideration to costs. CARB states that its position that the
feasibility of the performance standards of the regulation are amply
demonstrated is consistent with past EPA authorizations for in-use
vehicles

and equipment, in which EPA has stated:

    [S]ection 202(a) consistency calls for a limited review of
technological feasibility, including analysis of the cost of new
technology, if technology does not currently exist. Section 202(a)
does not allow EPA to conduct a more searching review of whether the
costs are outweighed by the overall benefits of the California
regulations.

    CARB notes that the costs of the regulation, which was amended for
the express purpose of providing fleets with significant economic
relief during the recovery from the nation's economic downturn, cannot
be characterized as so prohibitive as to render the regulation
infeasible. In fact, CARB notes the 2010 amendments have significantly
reduced the costs of compliance for all fleets by reducing the number
of specific compliance actions that a fleet must undertake:

    By delaying initial implementation of the regulation, revising
target and BACT compliance rates downward, and by providing fleets
with greater compliance flexibility (vehicle exemptions, compliance
extensions, and special credits), between 2010 and 2015, the costs
for large fleets will be reduced by approximately 97 percent, from
over $1 billion to approximately $33 million (2010 dollars). Total
costs over the life of the off-road regulation would be reduced by
approximately 72 percent, which represents a cost savings of over
$1.5 billion (2010 dollars). Peak year costs would be postponed from
2013 to 2019 and reduced almost 73 percent, from $542 million to
$146 million (2010 dollars).

    With the amendments, CARB maintains fleets are in a better position
today to effectively pass on the reduced amortized costs of the
regulation to their customers.
    CARB references the testimony of AGC at EPA's public hearing which
characterized the regulation's cost as reasonable.\161\
---------------------------------------------------------------------------

    \161\ CARB Written Comments at 15, citing to the Hearing
Transcript at p. 87. AGC noted that California's construction
contractors invested enormous sums in the equipment in the
reasonable expectation that they could lawfully operate and use it
for the duration of its useful life. AGC also noted, anecdotally,
that contractor defaults in 2012 will be higher than in any of the
previous three years and thus EPA's review of CARB's most recent
amendments is of interest and concern to AGC's members. AGC had
requested EPA to delay prior proceedings on California's Fleet
Requirements given ongoing announced plans by CARB to revisit at
least portions of CARB's rule. AGC had been deeply concerned about
the costs and other estimates CARB had made, about the technology
that contractors would require to comply, and the lead time
provided. AGC noted at EPA's authorization hearing that ``reasonable
people may disagree about whether the rule merits federal approval,
but AGC is not prepared to dispute a resolution that goes either
way.'' ``At the time [of the 2010 amendments], from our members in
California [AGC members], . . ., the costs of the amended rule were
considered reasonable. We would not have agreed to that package of
amendments . . . if they were not considered to be reasonable.''
---------------------------------------------------------------------------

    CARB also notes, that to the extent that some companies may be more
adversely impacted than others, CARB had previously stated in its
authorization request:

    The costs to fleets for compliance varies dramatically,
depending upon the size of the fleet, the type of vehicles and
equipment used by the fleet, the age of the vehicles in the fleet,
the fleet's normal fleet replacement practices, and the compliance
pathway chosen. Regarding the last variable, fleets have wide
discretion on how they choose to comply; which vehicles should be
controlled first, should a [verified diesel emission control
strategy] VDECS be installed, or should the vehicle or engine be
turned over. If turnover is selected, does the fleet choose to
rebuild a vehicle's existing engine, report the engine with a newer,
cleaner engine, replace the older vehicle with a newer vehicle with
a cleaner engine, etc; does the fleet elect to designate a vehicle
as low use. Each of these decisions will determine the actual
compliance costs for the fleet.

    In the context of responding to fleet contractors who may have the
financial inability to meet the compliance costs, CARB states that EPA
has previously addressed this general issue in a separate proceeding:

    Regarding small businesses, the Owner-Operator Independent
Drivers Association (OOIDA) commented that the transport
refrigeration units (TRU) air toxic control measure (ATCM) places a
``particularly onerous financial burden on small business truckers''
with small fleets (20 or fewer trucks) making up 95% of the industry
. . .. EPA believes that the CARB regulations are feasible with
respect to cost objectively; i.e., all fleet operators face the same
cost per unit to comply. While this cost may have different impacts
on fleets of varying sizes, EPA recognizes that it is up to CARB to
choose who it will regulate under its standards. Because these TRU
engines do emit significant amount of pollution and the cost of
compliance are not so large as to render the compliance options
objectively out-of-reach, the fact that some operators may have
difficulties with the cost of the program does not make the Program
infeasible.

    CARB notes that EPA's previous statements regarding feasibility
with regard to analyzing cost objectively and CARB's discretion to
choose who and how it may regulate under its standards also holds true
for its Fleet Requirements. CARB notes that in the context of the Fleet
Requirements the technology itself is feasible and has not been
questioned; and that the objective costs of the regulation--as conceded
by some members of industry--are reasonable.
    With regard to ARTBA and other commenters' contention that small
companies will be severely affected by the Fleet Requirements because
of the costs of repowering and retrofitting vehicles and that these
companies do not have the resources to comply, CARB states that this
overlooks the fact that the amended regulations have significantly
reduced the costs of compliance and have extended the date of
compliance along with a variety of compliance options. CARB notes that
the total costs of compliance of the regulation have been reduced by
approximately 72 percent. In addition, the compliance costs for smaller
fleets are lower than the costs for larger fleets in that small fleets
are exempted from having to turnover vehicles to meet the regulation's
BACT requirements.\162\
---------------------------------------------------------------------------

    \162\ Title 13, CCR, section 2449.1(b)(3)(C).
---------------------------------------------------------------------------

    CARB also addressed the issue of whether its new engine replacement
provisions are inconsistent with EPA's regulations and therefore not a
feasible compliance path for fleet operators in California. As CARB
notes, and CIAQC's comments maintain, repowering under CARB's existing
regulatory authority pertaining to new nonroad CI engine regulations
is, in many instances, technologically feasible at a significantly
lower cost than replacing an older vehicle with a new one. CARB
acknowledges that repowering is not possible in all circumstances but
nevertheless is often a cost-effective option for older equipment and
vehicles. CARB references comment from Altfillisch, as one example,
that it has been able to repower at least 71 nonroad vehicles and
equipment between 2001 and 2005, years before the Fleet Requirements
went into effect.
    With respect to whether EPA's replacement engine regulations are
inconsistent with CARB's replacement engine regulations, CARB notes
that EPA has previously authorized the CARB nonroad CI emission
standards applicable to new engines and equipment which included CARB's
replacement engine regulations.\163\ Therefore California fleet
operators are subject to CARB's replacement engine regulations which
substitute for EPA's replacement engine provisions in California.\164\
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    \163\ See 75 FR 8056, 8060 (February 23, 2010).
    \164\ See CARB Mail Out  MSC 13-07 (March 11, 2013),
see also CARB Supplemental Comments.
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    In response to concerns that the Fleet Requirements are not
technically feasible due to the unavailability of Tier 4 engines, CARB
references its March 1, 2012 Authorization Request wherein it states:

    It is not until 2018 that the regulation requires large and
medium fleets to replace vehicles and engines with only Tier 3 and
Tier 4 engines. By 2018, Tier 3 engines will have been available for
at least ten years, Interim Tier 4 engines for at least 7 years, and
Tier 4 engines for at least 3 years. Additionally, the regulation
provides relief to fleets if there is a delay in availability of
vehicles that would be required to use Tier 3 or Tier 4 interim of
final Tier 4 emission standards.

    CARB noted that there is no basis to ARTBA's conjecture regarding
Tier 4 engine unavailability during the applicable time frame.\165\
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    \165\ CARB Written Comments at 17.
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    Finally, with respect to the compliance option of VDECS or
retrofits, CARB's supplemental comments clarify that the regulation
never required unsafe retrofits to be installed, and retrofit safety is
even less of a concern since the regulation, as amended, removes all
mandatory installation of VDECS. CARB explains that the regulation, as
initially adopted, only required retrofit of a specified percentage of
vehicles if the fleet operator could not meet the PM fleet average
targets. The amendments have since removed this requirement and, in
addition, the California Occupational Health Standards Safety Board
(OSHSB) has adopted amendments to its construction safety orders (after
working with CARB) to ensure that any retrofit will not affect the
capacity, structural integrity, or safe performance of the vehicle in
which it is installed nor create a risk of fire or operator contact
with the exhaust system or impair the vision of the operator. CARB's
2010 amendments to the Fleet Requirements continue to provide that no
VDECS are required to be installed if in violation of the amended OSHSB
safety order and, as noted above, there is no longer a mandate that a
specified percentage of vehicles be retrofitted if the fleet average is
not met.\166\
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    \166\ Id. at 17-18.
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    As explained below, EPA agrees with CARB's presentation of how
technological feasibility should be evaluated, for purposes of
authorization review by EPA, and that CARB has provided ample evidence
of the feasibility of the Fleet Requirements overall, and the
feasibility with respect to individual compliance options. CARB has
presented appropriate evidence of the feasibility and availability of
new nonroad CI engines along with appropriate replacement engines and
retrofits.
    CARB has also properly set forth the role of EPA in reviewing
California in-use performance standards which require legacy fleets to
achieve challenging emission reductions. EPA is not setting its own
standards under section 202(a) of the Clean Air Act, rather EPA's role
within its authorization review is more limited and takes place in the
context of deference that Congress envisioned for California. This
deference was discussed in an early waiver decision when EPA approved
the waiver request for California's 1977 model year standards:

    Even on this issue of technological feasibility I would feel
constrained to approve a California approach to the problem which I
might also feel unable to adopt at the Federal level in my own
capacity as a regulator. The whole approach to the Clean Air Act is
to force the development of new types of emission control technology
where that is needed by compelling the industry to `catch up' to
some degree with newly promulgated standards. Such an approach to
automotive emission control might be attended with costs, in the
shape of a reduced product offering, or price or fuel economy
penalties, and by risks that a wider number of vehicle classes may
not be able to complete their development work in time. Since a
balancing of these risks and costs against the potential benefits
from reduced emissions is a central policy decision for any
regulatory agency, under the statutory scheme outlined above I
believe I am required to give very substantial deference to
California's judgement on that score.\167\
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    \167\ 40 FR 23102, 23103 (May 28, 1975); see also 78 FR 2112
(January 9, 2013).

    CARB has set forth a series of compliance options to address
emissions from its legacy fleet of NR CI engines. Fleet operators may
choose from these compliance options. As explained below, EPA does not
believe those opposing these regulations have met their burden of
showing that the regulations are not technologically feasible.
    Further, while EPA acknowledges the comments it has received that
claim that the Fleet Requirements may have significant adverse economic
affect on individual fleet operators, the Agency finds no factual basis
for determining that the Fleet Requirements are objectively cost
prohibitive. To the extent that a balancing of risks attendant with
adverse effect on some fleet operators against the benefits of
addressing the emission inventory associated with the legacy fleet in
California, EPA gives that the same substantial deference (as with past
waivers) to California's judgment regarding the balancing of the risks
and costs of regulation against the potential benefits from reduced
emissions. CARB has gone through several significant rounds of
amendments to address in part the economic cost associated with the
Fleet Requirements and has afforded the fleet operators a significant
number of compliance options and delays in initial compliance in order
to objectively address the risks associated with costs.
    At the outset, EPA believes it important to note that we agree with
CARB's assessment that the Fleet Requirements will be feasible given
the technology available today along with the technologies that CARB
projects to be available in the lead time provided.
    First, several commenters noted their concern that one of the more
cost effective compliance options, the replacement of engines or
repowering, is precluded as it conflicts with EPA's engine replacement
policy at 40 CFR 1068.240. EPA has previously authorized CARB's
emission standards applicable to new NR CI engines and the regulations
in that authorization included CARB's replacement engine provisions.
Therefore, CARB's replacement engine provisions, not EPA's provisions,
are the applicable provisions for the purposes of these Fleet
Requirements. In addition, EPA has recently published a direct final
rule and accompanying notice of proposed rulemaking that adopts
modifications to the Agency's replacement engine provisions to allow,
on a limited basis, the practice of replacing engines with engines that
are cleaner, but not certified to the most stringent standards, even
where the original engines have not failed prematurely.\168\ Therefore,
EPA's replacement engine provisions do not prevent use of repowering as
a method of complying with CARB's regulations.
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    \168\ See http://www.epa.gov/otaq/climate/documents/420f13001.pdf, and http://www.gpo.gov/fdsys/pkg/FR-2013-06-17/pdf/2013-11980.pdf. The EPA received adverse comment on a portion of the
Direct Final Rule, but no commenter objected to the provision
allowing repowering using engines that are not certified to the most
stringent standards.
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    Second, with respect to fleet operators choosing to replace their
equipment with new cleaner vehicles and commenters questioning the
availability of such vehicles (e.g., Tier 3, interim Tier 4, and Tier
4), EPA notes that these standards have already been reviewed by EPA in
the context of its own rulemakings, and EPA has found these standards
to be feasible in a timeframe allowing even less lead time than that
provided by California. EPA annually certifies new NR CI engines and
the certification data to date strongly suggest that engine
manufacturers are certifying to meet the newest applicable standards,
and that these standards are

feasible.\169\ EPA believes CARB is reasonable in its depiction of
currently available emission control technology and with its projection
of sufficient lead time being available to ensure that a sufficient
supply of newer emission control technologies (meeting newer Tier 3,
and interim and final Tier 4 emission standards) is in place to meet
the demands of fleet operators. As CARB notes, the comments contending
otherwise have not provided any evidence that in 2018 large and medium-
sized fleet operators will not be able to replace vehicles and engines
with Tier 3 and Tier 4 engines. In addition, to the extent a fleet
operator replaces such vehicles and engines, CARB's Fleet Requirements
also provide relief to fleets if there is a delay in availability of
vehicles that would be required to use Tier 3 or Tier 4 interim or
final Tier 4 emission standards. Finally, there is no evidence in the
record indicating a shortage of certified engines during the time frame
for which they will be needed for this rule, given the flexibilities
provided by the amendments. The opponents of the waiver have not met
their burden of proof to demonstrate the lack of commercial
availability of appropriate engines to the extent that the regulations
would be infeasible.
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    \169\ http://www.epa.gov/otaq/certdata.htm#nrci.
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    Third, with respect to the technical feasibility of exhaust
retrofits (VDECS) and the safety-related and compatibility concerns
expressed by commenters, EPA believes that CARB's 2010 amendments add
both the needed flexibility, with respect to not mandating retrofits,
and sufficiently clarify when a NR CI vehicle is exempted due to
expressed safety concerns. The Fleet Requirements never required unsafe
retrofits be installed, and retrofit safety is even less of a concern
now that the regulation has been amended to remove all mandatory
installation of VDECS, even if fleet average targets are not met.\170\
EPA believes that CARB has also appropriately addressed expressed
concerns regarding retrofit safety, including referencing the
amendments adopted by OSHSB. These amendments, adopted in March 2012,
state that a safety order will be provided in order to ensure that a
retrofitted VDECS shall not affect the capacity, structural integrity,
and safe performance of the vehicle in which it is installed nor create
a fire or safety risk or impair the operators' vision.\171\ EPA also
notes that the CARB staff reviewed retrofit field experience since
2002. Of the 35,000 diesel particulate filters (DPFs) deployed in the
state, less than 15 safety-related issues were identified and all of
these were shown to be attributed to poor engine or device maintenance,
misapplication of devices, or the ignoring of warning alarms by the
operator.\172\ With regard to the availability of VDECS in general,
there is no evidence in the record to refute CARB's view that the Fleet
Requirements are likely to continue to increase the demand for
retrofits and that CARB's anticipation that an increase in supply will
occur as compliance deadlines approach is reasonable. CARB has
identified a number of verified Level 3 VDECS and the commenters have
not shown that this option does not provide a feasible alternative in
many cases to meeting the Fleet Requirements.\173\
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    \170\ CARB Supplemental Comments at 17-18.
    \171\ Id.
    \172\ MECA at 4. ``Regarding the safe installation of retrofit
devices, retrofit manufacturers have shown that off-road retrofits
can be installed to comply with the Cal/OSHA retrofit visibility/
safety requirements finalized last year. Retrofit manufacturers are
using the best engineering judgment and installation practices to
ensure the safe installation of devices. In general, retrofit
installations in California have had an excellent safety record.
    \173\ Authorization Request at 24. See also EPA's list of
currently verified technologies at: http://www.epa.gov/cleandiesel/verification/verif-list.htm, and generally: http://www.epa.gov/cleandiesel/technologies/.
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    EPA also believes it important to note that CARB's fleet average
targets have been set so that they progressively become more stringent
over the years in order that CARB's emission reductions goals are met
while affording fleet operators with necessary flexibility and
compliance options. In addition, CARB's four-year delay in compliance
(from 2010 to 2014) helps ensure the feasibility of the regulation
along with built-in provisions that ensure against noncompliance with
the Fleet Requirements due to the unavailability of the highest tiered
engines or VDECS. In addition, CARB's BACT credits compliance path
includes a number of accommodations (e.g. accrual of credits earned
prior to March 1, 2010 may in certain circumstances be applied toward a
large fleets' January 1, 2014 compliance deadline; double credits for
early installation of VDECS; credit for reduced horsepower of the
fleet, etc). There are also a number of exemptions under the BACT
requirements applicable to large and medium fleets, and separately for
small fleets. For example, vehicles in any size fleet are exempt from
the BACT credit requirement calculation if on any given annual
compliance date the vehicle is less than ten years old from the date of
manufacture, and specialty vehicles are exempt if the fleet has applied
BACT to all other vehicles in the fleet and no engine is available to
repower the specialty vehicle and instead has the highest level VDECS
available installed. In addition, for large and medium fleets, a
vehicle is exempt if it had a Level 2 or 3 p.m. VDECS installed within
the last six years and for small fleets the vehicle is exempt if has
already been retrofitted with a Level 2 or 3 VDECS that was the highest
level PM VDECS available at the time of installation. Regarding the
claim that the regulations require an initial repower or retrofit and
then a replacement of an entire piece of equipment shortly thereafter,
CARB's 2010 amendments also provide an exemption for vehicles that have
had a level 2 or 3 p.m. VDECS installed within the last six years and
an exemption for original equipment manufacturer diesel PM equipped
vehicles and, with certain limitations, to vehicles that installed
highest level VDECS prior to 2013. These further accommodations help
assure the feasibility of the Fleet Requirements.
    Although certain fleet operators contend that their business will
either be severely or irreparably harmed (as reviewed further below),
the commenters opposing the authorization have not provided any factual
evidence in the record to demonstrate that a mix of available
compliance options and flexibilities is not feasible.
    EPA believes that CARB has afforded a variety of compliance options
(and initial delays of the phase-in periods for compliance) that
individual fleet operators can employ in a variety of ways depending on
the nature of their business and the composition of their fleets.
Accordingly, with regard to the consideration of cost of the Fleet
Requirements (including comments that the regulation will diminish the
net value of certain fleet operators which will further impair their
ability to finance the upgrades necessary to comply with the regulation
or to obtain construction bonds), we note at the outset that many
factors affect the ability of certain fleet operators to meet the Fleet
Requirements. While it is possible that some diminishment in value of
certain fleet operator equipment will occur as a result of the Fleet
Requirements (while recognizing that CARB has significantly delayed the
requirement that such engines be replaced), there is no evidence or
data in the record to demonstrate that the loss in value to the fleet
operator is the proximate cause of such operations going out of
business or that such

economic results render the Fleet Requirements infeasible for the
broader regulated community. EPA believes that CARB has reasonably
responded to concerns expressed about the costs of the Fleet
Requirements, including the availability of engine replacements and
retrofits. EPA notes that even some commenters otherwise opposed to the
authorization have recognized the feasibility of early engine
replacement. In addition, there is no evidence in the record to reflect
a widespread or significant economic disruption to regulated fleet
operators that is proximately caused by the Fleet Requirements.\174\
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    \174\ Regarding comments that these regulations would stop
valuable work to be performed by this industry in California, there
is no evidence that this rule has led to the widespread cancelation
of projects.
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    More importantly, EPA believes that the CARB regulations are
feasible with respect to cost objectively; i.e., although fleets are
likely to be comprised differently, all fleet operators are
nevertheless facing the same cost per unit to comply. While this cost
may have different impacts on fleets of varying sizes, EPA recognizes
that it is up to CARB to choose who it will regulate under its
standards.\175\ The fact that some operators may have difficulties with
the cost of the program does not make the program infeasible.\176\
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    \175\ CARB notes that the increased costs, due to the Fleet
Requirements, to small fleet operators is on the magnitude of
$38,000 for the youngest fleets to $173,000 for the oldest fleets
(cite) and such costs have not been countered by opponents of the
authorization.
    \176\ EPA has previously stated that it is up to CARB to choose
who it will regulate under its standards, even though such costs may
have differing impacts for different fleets. See 74 FR 3030 (January
16, 2009), TRU Decision Document at 63.
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    In addition, under the guidelines of MEMA I, EPA believes that it
should evaluate costs in authorization requests by looking at the
actual costs of compliance in terms of the lead time provided by the
regulations, and not at the regulation's cost-effectiveness. It is
CARB's responsibility to determine the best way to reduce emissions in