Supplemental Notice of Proposed
Rulemaking; Options for PM2.5 and
PM10 Hot-Spot Analyses in theTrans
portation Conformity Rule Amend-
ments for the New PM2.5 and Ex-
isting PM10 National Ambient Air
Quality Standards
EPA is proposing additional options regarding procedures for deter-
mining localized concentrations of particulate matter that could be
caused by transportation projects in certain areas subject to transpor-
tation conformity. Specifically, the options included in this proposal
apply to PM2.5 and PM10 nonattainment areas, which are those areas
that do not meet the national ambient air quality standards for PM2.5
and PM10. These options also apply to PM2.5 and PM10 mainte-
nance areas, which are those areas that previously did not meet the
standard but do so now.
It is possible that concentrations of particulate matter that violate the PM2.5 or
PM10 standards could occur on a local, rather than regional, basis, for example, at
road intersections and truck stops. An analysis of localized pollutant concentrations
from transportation projects is currently part of the transportation conformity re-
quirements in carbon monoxide (CO) and PM10 nonattainment and maintenance
areas.
SEPA
United States
Environmental Protection
Agency
Office of Transportation and Air Quality
EPA-420-F-04-060
December 2004
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Particulate matter, or PM, is a mixture of solid particles and liquid droplets found in the air.
These tiny particles come in many sizes and shapes and can be made up of hundreds of different
chemicals. PM2.5 and PM10 refer to the size of the particles (e.g., PM2.5 refers to particles less
than or equal to 2.5 micrometers — approximately l/30th the size of a human hair). These par-
tides can penetrate the upper regions of the body's respiratory defense mechanisms, and PM2.5
has been associated with premature mortality and other serious health effects.
Transportation conformity is a Clean Air Act requirement that ensures federally supported high-
way and transit project activities are consistent with ("conform to") a state's air quality imple-
mentation plan (SIP). Conformity requires that planned transportation activities do not cause
new violations, worsen existing violations, or delay timely attainment of an air quality standard.
Conformity ensures that potential vehicle emission increases are considered and addressed as
plans are developed for new or expanded highways and transit projects in cities with air quality
challenges.
For PM2.5 nonattainment and maintenance areas, the proposed options range from not requir-
ing a local analysis of pollutant concentrations for any project to establishing requirements that
are similar to those that currently apply in PM10 nonattainment and maintenance areas. For
PM10 nonattainment and maintenance areas, the proposed options range from not requiring
a local analysis of pollutant concentrations for any project, retaining current requirements, or
requiring a local analyses based on either a state air agency or EPA Regional Administrator deci-
sion.
Currently, in PM10 areas, quantitative analyses are required for specific types of transportation
projects, and qualitative reviews are required for all other transportation projects. A quantita-
tive analysis would involve the use of an air quality dispersion model to predict the impact of a
transportation project - for example, the widening of a highway - on air quality in the immedi-
ate vicinity of the project. A qualitative analysis does not involve air quality modeling. Instead,
a qualitative analysis involves comparison of the transportation project to similar projects that
have been approved in the past to determine if there is the potential for the new project to cre-
ate a new violation or worsen an existing violation.
Background and Description of Supplemental Notice of Proposed
Rulemaking
On November 5, 2003, EPA published a proposal to address conformity requirements under the
new ozone and PM2.5 air quality standards (68 FR 62690). The majority of the provisions from
this proposal were finalized in our July 1, 2004, final conformity rule, but EPA decided to publish
a supplemental notice for the provisions related to analyzing the local concentrations of PM
from individual transportation projects. EPA is publishing this supplemental proposal to re-
quest additional comment on options previously proposed as well as new options for PM2.5 and
PM10 nonattainment and maintenance areas. EPA is addressing requirements for local analyses
in both types of PM areas at the same time due to the similarity of the pollutants and possible
analysis requirements.
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EPA is issuing this proposal in the context of the Agency's broader strategies for implementing
the new, more protective, air quality standards. EPA anticipates designating areas for the new
PM2.5 standard in December 2004. Seeking public comment on the full range of options regard'
ing these analyses in PM2.5 and PM10 areas will allow EPA to finalize any requirements for such
analysis in PM2.5 areas shortly after final designations for PM2.5 nonattainment areas.
Key Aspects of the Supplemental Notice of Proposed Rulemaking
• EPA has worked closely with DOT in the development of this proposed rule,
• EPA consulted with state and local transportation and air quality agencies and inter
est groups in its initial development of the conformity options for the new standards,
EPA proposed these options in November 2003. EPA's decision to issue a supplemental
proposal is a direct result of the comment received on the provisions in the Noveiri'
ber 2003 proposal,
• EPA's final decision regarding procedures for determining localized concentrations of
particulate matter that could be caused by transportation projects in PM2.5 and PM10
nonattainment and maintenance areas will depend on the comments we receive on this
supplemental proposal. Comments that provide legal or science-based rationale will be
especially useful.
Health and Environmental Impacts
The Supplemental Notice of Proposed Rulemaking seeks additional information and provides
additional options for considering local analyses of particulate matter concentrations in PM2.5
and PM10 areas. Seeking public comment on the full range of options will allow EPA to finalize
the option(s) that best ensure that conformity is practicably implemented and that conformity
will help achieve the Clean Air Act's public health and environmental goals.
For More Information
You can access the final rule and related documents electronically on the Office of Transporta-
tion and Air Quality Web site at: www.epa.gov/otaq/transp/traqconf.htm
For further information about the final rule, please contact:
Rudy Kapichak
U.S. Environmental Protection Agency
Transportation and Regional Programs Division
2000 Traverwood Drive
Ann Arbor, MI48105
(734) 214-4574
E-mail: kapichak.rudolph@epa.gov
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or
Laura Berry
U.S. Environmental Protection Agency
Transportation and Regional Programs Division
2000 Traverwood Drive
Ann Arbor, MI48105
(734) 214-4858
E-mail: berry.laura@epa.gov
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