oEPA
United states Office of Transportation EPA420-F-05-005
Environmental Protection ^ A;..^..,. .. «««,-
Agency and Air Quality May2005
Regulatory
Announcement
Final Rule to Add PM2.5
Precursors to the
Transportation Conformity Rule
This final rule is part of EPA's overall strategy for assisting state and
local governments in implementing the new ozone and PM25 national
ambient air quality standards. Specifically, this final rule provides new
PM2 5 nonattainment areas with the requirements for considering PM2 5
precursor emissions when making determinations that transportation
activities will not interfere with the area's air quality goals. EPA's
designations for the new PM2 5 standard were effective April 5, 2005, at
which point a one-year conformity grace period began. The grace
period allows time for the newly designated PM2 5 nonattainment areas
to prepare their first conformity determinations.
Background
Transportation conformity is a Clean Air Act requirement that ensures
that federally supported highway and transit projects are consistent with
("conform to") a state air quality implementation plan (SIP). Confor-
mity ensures that public health is protected by early consideration of
transportation decisions in cities with air quality challenges.
On November 5, 2003, EPA published a proposal to address conformity
requirements under the new ambient air quality standards (68 FR
62690), including proposals to address PM25 precursor emissions in
conformity. The majority of the provisions from the November 2003
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proposal were finalized in our July 1, 2004, final conformity rule.
Subsequently, Environmental Defense, the Natural Resources Defense
Council, Sierra Club and TRANSDEF filed suit against portions of the
July 1, 2004 rule. This suit specifically challenges the omission of PM25
precursor requirements from that rule.
EPA did not include PM25 precursor requirements in the July 1, 2004,
final rule because, at that time, EPA had not yet proposed a broader
PM2 5 implementation rule to seek comment on options for addressing
PM2 5 precursors in the New Source Review program and in other SIP
planning activities. However, several facts now lead us to believe it is
necessary and appropriate to issue this final rule addressing precursor
emissions in transportation conformity determinations:
• EPAs designations for the new PM25 standard were effective April
5, 2005, at which point a one-year conformity grace period began.
It is important that transportation conformity implementers know
the requirements during the grace period, as it takes time to prepare
a conformity determination. Conformity determinations for the
PM25 standard will be due at the end of the one-year grace period:
April 5, 2006.
• This final rule has been developed in coordination with the PM2 5
implementation rule proposal that is currently being prepared. This
final rule will not prejudge the outcome of the PM25 implementa-
tion rule.
Description of Final Rule
This final rule adds NOx, VOCs, SOx, and ammonia to the transporta-
tion conformity regulations and specifies when each of these precursors
must be considered in conformity determinations in PM25 nonattainment
and maintenance areas, before and after PM25 SIPs are submitted.
Specifically, once a PM25 SIP is submitted, a PM25 precursor must be
considered in an area's conformity determinations if the SIP determines
that emissions for that precursor are a significant contributor to the
area's PM25 air quality problem.
Prior to the submission of a SIP, NOx emissions must be considered in
PM2 5 conformity determinations, unless both the state air agency and
the EPA Regional Administrator make a finding that NOx is not a
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significant contributor to the PM25 air quality problem. Conversely,
VOC, SOx and ammonia emissions do not have to be considered in
conformity, unless either the state air agency or EPA Regional Adminis-
trator makes a finding that on-road emissions of any of these precursors
is a significant contributor to the area's PM air quality issue.
Key Elements of the Final Rule
• This final rule balances the need to protect air quality with the need
to conserve the limited resources of state and local transportation
and air quality agencies. NOx is the only PM25 precursor that must
be examined in conformity analyses (unless a finding is made),
because data indicate that NOx contributes to the air quality prob-
lem in most PM25 nonattainment areas. However, VOC, SOx and
ammonia precursor emissions only need to be examined if they are
found to be significant for a particular area. EPA believes this final
rule is consistent with existing statutory requirements and scientific
information that supports the consideration of PM25 precursor
emissions in transportation conformity.
• This final rule provides new PM25 nonattainment areas with the
requirements for considering PM25 precursor emissions in transpor-
tation conformity determinations. Transportation conformity for the
PM2 5 air quality standard will apply in new nonattainment areas on
April 5, 2006 - that is, one year after the effective date of their
designation.
• This final rule is consistent with EPAs PM2 5 implementation
strategy proposal currently being prepared. However, this rule
should not be seen as prejudging our decision on the PM25 imple-
mentation rulemaking. While EPA's final decisions on PM25 precur-
sors must be legally consistent, EPA could take differing positions
with respect to various precursors in other programs as appropriate
to the programmatic needs, legal requirements and pollution
sources relevant to the differing programs.
• EPA has worked closely with the U. S. Department of Transporta-
tion in the development of this final rule.
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This rule is based on the November 2003 proposal and the public
comments that were received in response to that proposal. EPA
consulted with state and local transportation and air quality agen-
cies and interest groups in its initial development of the conformity
options for the new standards that were proposed in November
2003.
Health and Environmental Impacts
By providing new PM2 5 nonattainment areas with the requirements for
considering PM25 precursor emissions in conformity determinations,
EPA believes this final rule will support the Clean Air Act's air quality
standards to protect the public and environmental health.
For More Information
You can access the final rule and related documents electronically on
EPAs Web site at:
www.epa.gov/otaq/transp/traqconf.htm
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