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MEMORANDUM
SUBJECT: Interim Implementation of New Source Review Requirements
for PM2.5
FROM: John S. Seitz, Director Office of Air Quality Planning &
Standards (MD-10)
TO: See Addressees
This memorandum addresses the interim use of PM10 as a surrogate
for PM2.5 in meeting new source review (NSR) requirements under
the Clean Air Act (Act), including the permit programs for prevention
of significant deterioration of air quality (PSD). The revised national
ambient air quality standards (NAAQS) for particulate matter, which
include the revised NAAQS for PM10 and new NAAQS for PM2.5, became
effective on September 16, 1997. In view of the significant technical
difficulties that now exist with respect to PM2.5 monitoring, emissions
estimation, and modeling (described below), EPA believes that PM10
may properly be used as a surrogate for PM2.5 in meeting NSR requirements
until these difficulties are resolved. The EPA's views on implementing
the ozone and PM10 NAAQS during the interim period following the
effective date of the new 8-hour ozone and revised PM10 NAAQS will
be set forth in a separate EPA memorandum.
Section 165(a)(1) of the Act provides that no new or modified
major source may be constructed without a PSD permit. Moreover,
section 165(a)(3) provides that the emissions from any such source
may not cause or contribute to a violation of any NAAQS. Also, section
165(a)(4) requires best available control technology for each pollutant
subject to regulation under the Act. The EPA's recent promulgation
of the primary and secondary standards for PM2.5 marks the first
time that EPA has specifically regulated fine particles--less than
2.5 microns in diameter--as a discrete indicator for particulate
matter. Hence, this memorandum addresses how to implement PSD for
PM2.5 in light of significant technical difficulties which presently
exist.
Of specific concern is the lack of necessary tools to calculate
emissions of PM2.5 and related precursors and project ambient air
quality impacts so that sources and permitting authorities can adequately
meet the NSR requirements for PM2.5. Any comprehensive system for
regulating PM2.5 must take into account not only the fine particles
emitted directly by stationary sources but also the various precursors,
emitted by certain sources, which result in secondarily- formed
fine particles through chemical reactions in the atmosphere. Recent
studies suggest that secondary particulate matter may account for
over half of total ambient PM2.5 nationwide. Emissions factors for
the fine particles emitted directly by stationary sources, and for
some important precursors (e.g., ammonia), are largely unavailable
at the present time.
The EPA is in the process of developing a comprehensive modeling
system which will be designed to include precursor emissions and
account for secondary fine particle formation. The modeling system
will also incorporate a method for nesting small local impacts from
individual point sources within a greater modeling domain. Before
this can be completed, it will be necessary to collect sufficient
monitoring data to verify and validate protocol modeling results.
Ambient monitoring for PSD purposes must be collected from appropriately
designed monitors. Sufficient quantities of such monitors will not
be available specifically for PSD monitoring purposes in the near
future. Initially, as these monitors become available, they will
be needed to establish the new monitoring stations for the national
network of PM2.5 sites, including the required core PM2.5 State
and local air monitoring stations. A high priority has been placed
on the establishment of the necessary PM2.5 monitoring sites nationwide
so that the information from these sites can be analyzed and evaluated
in order to establish plans and priorities for implementing the
PM2.5 NAAQS, including the promulgation of section 107 designations.
For the reasons stated above, EPA believes that it is administratively
impracticable at this time to require sources and State permitting
authorities to attempt to implement PSD permitting for PM2.5 . The
EPA has projects underway that will address the current technical
and informational deficiencies, but it will take 3-5 years to complete
these projects. Until these deficiencies are corrected, EPA believes
that sources should continue to meet PSD and NSR program requirements
for controlling PM10 emissions (and, in the case of PM10 nonattainment
areas, offsetting emissions) and for analyzing impacts on PM10 air
quality. Meeting these measures in the interim will serve as a surrogate
approach for reducing PM2.5 emissions and protecting air quality.
This memorandum presents EPA's views on the issues associated
with implementation of the new PM2.5 NAAQS under Federal, State
and local NSR programs. The statements do not bind State and local
governments and the public as a matter of law. When the technical
difficulties are resolved, EPA will amend the PSD regulations under
40 CFR 51.166 and 52.21 to establish a PM2.5 significant emissions
rate, and EPA will also promulgate other appropriate regulatory
measures pertinent to PM2.5 and its precursors. Because the earliest
date on which PM2.5 nonattainment areas will be designated is in
2002, and nonattainment NSR does not apply until after nonattainment
designations are made, implementation of the nonattainment NSR requirements
under part D of title I of the Act need not be addressed at this
time.
If you have any questions concerning this memorandum or wish to
address any issues raised herein, please contact Dan deRoeck at
(919) 541-5593.
Addressees:
Director, Office of Ecosystem Protection, Region I
Director, Division of Environmental Planning and Protection, Region
II
Director, Air, Radiation, and Toxics Division, Region III
Director, Air, Pesticides, and Toxics Management Division, Region
IV
Director, Air and Radiation Division, Region V
Director, Multimedia Planning and Permitting Division, Region VI
Director, Air, RCRA, and Toxics Division, Region VII
Assistant Regional Administrator, Office of Pollution Prevention,
State and Tribal Assistance, Region VIII
Director, Air and Toxics Division, Region IX
Director, Office of Air Quality, Region X
cc:
New Source Review Contacts
Greg Foote (2344)
Mark Kataoka (2344)
Lydia Wegman (MD-10)
bcc:
Karen Blanchard (MD-12)
Tom Curran (MD-12)
Dan deRoeck (MD-12)
Bill Hamilton (MD-15)
Sally Shaver (MD-15)
USEPA:OAQPS:ITPID:IIG:DDEROECK:PJSMITH:CBaines:NCMU:RM700:MD-12:10-21-97
FILENAME: A:\pmmemo.021
revised: 10/21/97
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