Document ID: EPA-HQ-OAR-2003-0062-0227
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-04-25T04:00Z

6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 51 and 52

[EPA-HQ-OAR-2003-0062; FRL-7969-1]

RIN 2060-AK74

CLEAN AIR FINE PARTICLE IMPLEMENTATION RULE

AGENCY:	Environmental Protection Agency (EPA).

ACTION:	Final rule.  

SUMMARY:	This final action provides rules and guidance on the minimum
Clean Air Act (CAA) requirements for State and Tribal plans to implement
the 1997 fine particle (PM2.5) national ambient air quality standards
(NAAQS).  Fine particles and precursor pollutants are emitted by a wide
range of sources, including power plants, cars, trucks, industrial
sources, and other burning or combustion-related activities.  The health
effects associated with exposure to PM2.5 are serious, including
premature death, aggravation of heart and lung disease, and asthma
attacks.  Those particularly sensitive to PM2.5 exposure include older
adults, people with heart and lung disease, and children.  This rule and
preamble describe the requirements that States and Tribes must meet in
their implementation plans for attainment of the 1997 fine particle
NAAQS.   	Air quality designations became effective on April 5, 2005
for 39 areas (with a total population of 90 million) that were not
attaining the 1997 PM2.5 standards became effective on April 5, 2005. 
By April 5, 2008, each State having a nonattainment area must submit to
EPA an attainment demonstration and associated air quality modeling,
adopted State regulations to reduce emissions of PM2.5 and its
precursors, and other supporting information demonstratingensuring that
the area will attain the standards as expeditiously as practicable. 
Section I of the , but no later than 2015.  This rule and preamble
provides background information on this rulemaking.  Section II
describes the various core elements of the PM2.5 describe the
requirements that States and Tribes must meet in their implementation
program, based primarily on the subpart 1 requirements of section 172 of
the CAA.  Important topics discussed in section II include policiesplans
for addressing PM2.5 precursors, attainment dates, attainment
demonstrations and modeling, local emission reduction measures
[reasonably available control technology (RACT) and reasonably available
control measures (RACM)], and reasonable further progress (RFP). 
Section III addresses the various statutory requirements and executive
orders applicable to this rule.  The final section contains the final
regulatory text for implementation of the PM2.5 NAAQS, in the form of
subpart Y amending 40 CFR part 51.  Final revisions to the new source
review program to address the fine particle standards will be set forth
in a separate rulemaking.  of the 1997 fine particle NAAQS.  (Note that
this rule does not include final PM2.5 requirements for the new source
review (NSR) program; the final NSR rule will be issued at a later
date.)

DATES:   This rule is effective on [INSERT DATE 60 DAYS FROM DATE OF
SIGNATURE].  

ADDRESSES:  The EPA has established a docket for this action under
Docket ID EPA-HQ-OAR-2003-0062.  All documents relevant to this action
are listed in the Federal docket management system at   HYPERLINK
"http://www.regulations.gov"  www.regulations.gov .  Although listed in
the index, some information is not publicly available (e.g. Confidential
Business Information or other information whose disclosure is restricted
by statute).   Certain other material, such as copyrighted material, is
not placed on the Internet and will be publicly available only in hard
copy form.  Publicly available docket materials are available either
electronically through www.regulations.gov or in hard copy format at the
EPA Docket Center, EPA/DC, EPA West, Room B1023334, 1301 Constitution
Avenue, NW, Washington, DC.  The Public Reading Room is open from 8:30
a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays.  The
telephone number for the Public Reading Room is (202) 566-1744, and the
telephone number for the Office of Air and Radiation Docket and
Information Center is (202) 566-1742. A variety of information and
materials related to the fine particle NAAQS and implementation program
are also available on EPA’s web site:    HYPERLINK
"https://www.epa.gov/pmdesignations"  https://www.epa.gov/pmdesignations
. http://www.epa.gov/air/particles. 

NOTE:  The EPA Docket Center suffered damage due to flooding during the
last week of June 2006.  The Docket Center is continuing to operate. 
However, during the cleanup, there will be temporary changes to Docket
Center telephone numbers, addresses, and hours of operation for people
who wish to make hand deliveries or visit the Public Reading Room to
view documents.  For current information on docket operations, locations
and telephone numbers, consult EPA’s Federal Register notice at 71 FR
38147 (July 5, 2006) or the EPA website at   HYPERLINK
"http://www.epa.gov/epahome/dockets.htm" 
www.epa.gov/epahome/dockets.htm .  The Docket Center’s mailing address
for U.S. mail and the procedure for submitting comments to   HYPERLINK
"http://www.regulations.gov"  www.regulations.gov  are not affected by
the flooding and will remain the same.

FOR FURTHER INFORMATION CONTACT:  For general information, contact Mr.
Richard Damberg, U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Mail Code C539-01, Research Triangle
Park, NC 27711, phone number (919) 54l-5592 or by e-mail at:   
HYPERLINK "mailto:damberg.rich@epa.gov"  damberg.rich@epa.gov ; or Ms.
Julie McClintock, U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Mail Code C539-01, Research Triangle
Park, NC 27711, phone number (919) 54l-5339 or by e-mail at:   
HYPERLINK "mailto:mcclintock.julie@epa.gov"  mcclintock.julie@epa.gov . 

SUPPLEMENTARY INFORMATION: 

 General Information

Does this Action Apply to Me?

[ADD REGULATED/AFFECTED ENTITIES DISCUSSION]

	Entities potentially regulated by this action are State and local air
quality agencies.  

B.  Where can I get a copy of this document and other related
information?

	In addition to being available in the docket, an electronic copy of
this final rule will also be available on the WWW.internet.  Following
signature by the EPA Administrator, a copy of this final rule will be
posted in the regulations and standards section of our NSR home page
located at [insert location].http://www.epa.gov/particles/actions.html. 

C.	How is the preamble organized?

I.	Background

II.	Elements of the Clean Air Fine Particle Implementation Rule

A. 	Precursors and pollutants contributing to fine particle formation

B.  	No classification system

C.  	Due dates and basic requirements for attainment demonstrations

D.  	Attainment dates

E.	Modeling and attainment demonstrations

F.	Reasonably available control technology and reasonably available
control measures

G.	Reasonable further progress

H.  	Contingency measures

I.	Transportation conformity

J. 	General conformity

K.	Emission inventory requirements

L. 	Condensable particulate matter test methods and related data issues

M.	Improving source monitoring 

N. 	Guidance specific to Tribes

	O.	Are there any additional requirements related to
enforcementEnforcement and compliance?

	P.	What requirements should apply to emergencyEmergency episodes?

	Q.	What ambientAmbient monitoring requirements will apply under the
PM2.5 NAAQS?

III.	Statutory and Executive Order Reviews

	

A.	Executive Order 12866: Regulatory Planning and Review

	B.	Paperwork Reduction Act

	C. 	Regulatory Flexibility Act

	D.	Unfunded Mandates Reform Act

	E.	Executive Order 13132: Federalism

	F.	Executive Order 13175: Consultation and Coordination with Indian
Tribal Governments

	G.	Executive Order 13045: Protection of Children from Environmental
Health and Safety Risks

	H.	Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use

	I.	National Technology Transfer Advancement Act

	J.	Executive Order 12898: Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations

K.	Petitions for Judicial Review tc \l2 "L.  Petitions for Judicial
Review 

L.	Determination Under Section 307(d)

M.	Congressional Review Act

I.	Background

Fine particles in the atmosphere are comprised of a complex mixture of
components.  Common constituents include:  sulfate (SO4); nitrate (NO3);
ammonium; elemental carbon; a great variety of organic compounds; and
inorganic material (including metals, dust, sea salt, and other trace
elements) generally referred to as (crustal( material, although it may
contain material from other sources.  Airborne particulate matter (PM)
with a nominal aerodynamic diameter of 2.5 micrometers or less (a
micrometer is one-millionth of a meter, and 2.5 micrometers is less than
one-seventh the average width of a human hair) are considered to be
(fine particles,( and are also known as PM2.5. (Primary( particles are
emitted directly into the air as a solid or liquid particle (e.g.,
elemental carbon from diesel engines or fire activities, or condensable
organic particles from gasoline engines).  (Secondary( particles (e.g.,
sulfate and nitrate) form in the atmosphere as a result of various
chemical reactions.  (Section II of the proposed rule included detailed
technical discussion on PM2.5, its precursors, formation processes, and
emissions sources.)  

The health effects associated with exposure to PM2.5 are significant. 
Epidemiological studies have shown a significant correlation between
elevated PM2.5 levels and premature mortality.  Other important effects
associated with PM2.5 exposure include aggravation of respiratory and
cardiovascular disease (as indicated by increased hospital admissions,
emergency room visits, absences from school or work, and restricted
activity days), lung disease, decreased lung function, asthma attacks,
and certain cardiovascular problems.  Individuals particularly sensitive
to PM2.5 exposure include older adults, people with heart and lung
disease, and children.  	

On July 18, 1997, we revised the NAAQS for particulate matter to add new
standards for fine particles, using PM2.5 as the indicator.  We
established health-based (primary) annual and 24-hour standards for
PM2.5 (62 FR 38652).  The annual standard is a level of 15 micrograms
per cubic meter, based on the 3-year average of annual mean PM2.5
concentrations.  The 24-hour standard is a level of 65 micrograms per
cubic meter, based on the 3-year average of the 98th percentile of
24-hour concentrations.  The EPA established the standards based on
evidence and numerous health studies demonstrating that serious health
effects are associated with exposures to elevated levels of PM2.5. 
Estimates show that attainment of the PM2.5 standards would be likely to
result in tens of thousands fewer premature deaths each year, tens of
thousands fewer hospital admissions each year, and hundreds of thousands
fewer doctor visits, absences from work and school, and respiratory
illnesses in children annually.  The research on which EPA based the
1997 standards did not identify a specific threshold concentration below
which individuals have no PM-related health effects, meaning that
emissions reductions resulting in reduced concentrations below the level
of the standards may continue to provide additional health benefits to
the local population.  

At the time we established the primary standards in 1997, we also
established welfare-based (secondary) standards identical to the primary
standards.  The secondary standards are designed to protect against
major environmental effects of PM2.5 such as visibility impairment,
soiling, and materials damage.  The EPA also established the regional
haze regulations in 1999 for the improvement of visual air quality in
national parks and wilderness areas across the country.  Because
regional haze is caused primarily by light scattering and light
absorption by fine particles in the atmosphere, EPA is encouraging the
States to integrate their efforts to attain the PM2.5 standards with
those efforts to establish reasonable progress goals and associated
emission reduction strategies for the purposes of improving air quality
in our treasured natural areas under the regional haze program. 

The scientific assessment that resulted in the establishment of the
PM2.5 standards included a scientific peer review and public comment
process.  We developed scientific background documents based on the
review of hundreds of peer-reviewed scientific studies.  The Clean Air
Scientific Advisory Committee, a congressionally mandated group of
independent scientific and technical experts, provided extensive review
of these assessments, and found that EPA(s review of the science
provided an adequate basis for the EPA Administrator to make a decision.
 More detailed information on health effects of PM2.5 can be found on
EPA(s website at:  http://www.epa.gov/air/urbanair/pm/index.html. 
Additional information on EPA(s scientific assessment documents
supporting the 1997 standards is available at:
http://www.epa.gov/ttn/oarpg (see headings for (Staff Papers( and
(Criteria Documents().

EPA issued final PM2.5 designations on December 17, 2004.  They were
published in the Federal Register on January 5, 2005 (70 FR 944).  On
April 5, 2005, EPA issued a supplemental notice which changed the
designation status of eight areas from nonattainment to attainment based
on newly updated 2002-2004 air quality data (70 FR 19844; published in
the Federal Register on April 14, 2005).   A total of 39 areas were
designated as nonattainment for the PM2.5 standards.  The population of
these areas is significant - about 90 million, or more than 30% of the
U.S. population.  Most areas violate only the annual standard, but a few
violate both the annual and 24-hour standards.

The nonattainment designation for an area starts the process whereby a
State or Tribe must develop an implementation plan that includes, among
other things, a demonstration showing how it will attain the ambient
standards by the attainment dates required in the CAA.  Under section
172(b), States have up to 3 years after EPA(s final designations to
submit their SIPs to EPA.  These SIPs will be due in April 2008, three
years from the effective date of the designations. 

Section 172(a)(2) of the Act requires States to attain the standards as
expeditiously as practicable but within five years of designation (i.e.
attainment date of April 2010 based on air quality data for 2007-2009),
or within up to ten years of designation (i.e. to 2015) if the EPA
Administrator extends an area(s attainment date by 1-5 years based upon
the severity of the nonattainment problem or the feasibility of
implementing control measures.  

Virtually all nonattainment problems appear to result from a combination
of local emissions and transported emissions from upwind areas.  The
structure of the CAA requires EPA to develop national rules for certain
types of sources which are also significant contributors to local air
quality problems, including motor vehicles and fuels.  It also provides
for States to address emissions sources on an area-specific basis
through such requirements as RACT, RACM, and RFP. 

We believe that to attain the PM2.5 standards, it is important to pursue
emissions reductions simultaneously on the local, regional, and national
levels.  EPA issued the Clean Air Interstate Rule (CAIR) on March 10,
2005 to address the interstate transport of sulfur dioxide and nitrogen
oxide emissions primarily from power plants.  Section 110 gives EPA the
authority to require SIPs to (prohibit ... any source or other type of
emission activity within the State from emitting any air pollutant in
amounts which will contribute significantly to nonattainment in, or
interfere with maintenance by, any other State with respect to( any
NAAQS, and to prohibit sources or emission activities from emitting
pollutants in amounts which will interfere with measures required to be
included in State plans to prevent significant deterioration of air
quality or to protect visibility (such as the protection of 156
mandatory Federal class I areas under the regional haze rule).  CAIR
employs the same emissions trading approach used to achieve
cost-effective emission reductions under the acid rain program.  It
outlines a two-phase program with declining power plant emissions caps
for 28 eastern states and the District of Columbia: SO2 caps of 3.6
million tons in 2010, and 2.5 million in 2015; NOx caps of 1.5 in 2009
and 1.3 in 2015; and NOx ozone season caps of 580,000 tons in 2009 and
480,000 tons in 2015.  Emission caps are divided into State SO2 and NOx
budgets.  By the year 2015, the Clean Air Interstate Rule will result
in:

-- $85 to $100 billion in annual health benefits, annually preventing
17,000 premature deaths, millions of lost work and school days, and tens
of thousands of non-fatal heart attacks and hospital admissions.

-- nearly $2 billion in annual visibility benefits in southeastern
national parks, such as Great Smoky and Shenandoah.

-- significant regional reductions in sulfur and nitrogen deposition,
reducing the number of acidic lakes and streams in the eastern U.S.

Over the past several years, EPA has also issued a number of regulations
addressing emissions standards for new cars, trucks and buses.  These
standards are providing reductions in motor vehicle emissions of
volatile organic compounds (VOCs, also referred to as hydrocarbons),
NOx, and direct PM emissions (such as elemental carbon) as older
vehicles are retired and replaced.  Other existing rules are reducing
emissions from several categories of nonroad engines.  The Tier 2 motor
vehicle emission standards, together with the associated requirements to
reduce sulfur in gasoline, will provide additional benefits nationally
beginning in 2004.  When the new tailpipe and sulfur standards are fully
implemented, Americans will benefit from the clean-air equivalent of
removing 164 million cars from the road.  These new standards require
passenger vehicles to have emissions 77 to 95 percent cleaner than those
on the road today and require fuel manufacturers to reduce the sulfur
content of gasoline by up to 90 percent.  In addition, the 2001
heavy-duty diesel engine regulations will lead to continued emissions
reductions as older vehicles in that engine class are retired and fleets
turn over.  New emission standards will begin to take effect in model
year 2007 and will apply to heavy-duty highway engines and vehicles. 
These standards are based on the use of high-efficiency catalytic
exhaust emission control devices or comparably effective advanced
technologies.  Because these devices are damaged by sulfur, the level of
sulfur in highway diesel fuel will be reduced by 97 percent by mid-2006.
 We project a 2.6 million ton reduction of NOx emissions in 2030 when
the current heavy-duty vehicle fleet is completely replaced with newer
heavy-duty vehicles that comply with these emission standards.  By 2030,
we estimate that this program will reduce annual emissions of
hydrocarbons by 115,000 tons and PM by 109,000 tons.  These emissions
reductions are on par with those that we anticipate from new passenger
vehicles and low sulfur gasoline under the Tier 2 program. 

EPA also finalized national rules in May 2004 to reduce significantly
PM2.5 and NOx emissions from nonroad diesel-powered equipment.  These
nonroad sources include construction, agricultural, and industrial
equipment, and their emissions constitute an important fraction of the
inventory for direct PM2.5 emissions (such as elemental carbon and
organic carbon), and NOx.  The EPA estimates that affected nonroad
diesel engines currently account for about 44 percent of total diesel PM
emissions and about 12 percent of total NOx emissions from mobile
sources nationwide.  These proportions are even higher in some urban
areas.  The diesel emission standards will reduce emissions from this
category by more than 90 percent, and are similar to the onroad engine
requirements implemented for highway trucks and buses.  Because the
emission control devices can be damaged by sulfur, EPA also established
requirements to reduce the allowable level of sulfur in nonroad diesel
fuel by more than 99 percent by 2010.  In 2030, when the full inventory
of older nonroad engines has been replaced, the nonroad diesel program
will annually prevent up to 12,000 premature deaths, one million lost
work days, 15,000 heart attacks and 6,000 children's asthma-related
emergency room visits. 

EPA expects the implementation of regional and national emission
reduction programs such as CAIR and the suite of mobile source rules
described above to provide significant air quality improvements for
PM2.5 nonattainment areas.  At the same time, analyses for the final
CAIR rule indicate that without implementation of local measures, a
number of PM2.5 areas are projected to remain in nonattainment status in
the 2010-2015 timeframe.  Thus, EPA believes that local and State
emission reduction efforts will need to play an important role in
addressing the PM2.5 problem as well.  EPA will work closely with
States, Tribes, and local governments to develop appropriate in-state
pollution reduction measures to complement regional and national
strategies to meet the standards expeditiously and in a cost-effective
manner.  States will need to evaluate technically and economically
feasible emission reduction opportunities and determine which measures
can be reasonably implemented in the near term.  Local and regional
emission reduction efforts should proceed concurrently and
expeditiously.

	The public health benefits of reducing PM2.5 are significant.  Even
small reductions in PM2.5 levels may have substantial health benefits on
a population level.  For example, in a moderate-sized metropolitan area
with a design value of 15.5 ug/m3, efforts to improve annual average air
quality down to the level of the standard (15.0 ug/m3) may be expected
to result in as many as 25-50 fewer mortalities per year due to air
pollution exposure.  In a smaller city, the same air quality improvement
from 15.5 to 15.0 ug/m3 still may be expected to result in a number of
avoided mortalities per year.  These estimates are based on EPA(s
standard methodology for calculating health benefits as used in recent
rulemakings.  In addition, because many different precursors contribute
to the formation of fine particles, reductions in pollutants that
contribute to PM2.5 also can provide concurrent benefits in addressing a
number of other air quality problems - such as ground-level ozone,
regional haze, toxic air pollutants, and urban visibility impairment.  

	In order to assist States in developing effective plans to address the
local component of the PM2.5 nonattainment problem, EPA is issuing this
final fine particle implementation rule.  EPA is issuing this rule to
implement the PM2.5 NAAQS in accordance with the statutory requirements
of the Act set forth in Subpart 1 of Part D of Title 1, i.e., sections
171 – 179B of the Act.  EPA believes that the Act directs the Agency
to implement new or revised NAAQS in nonattainment areas solely in
accordance with Subpart 1, unless another Subpart of the Act also
applies to the particular NAAQS at issue.  In this case, EPA has
concluded that Congress did not intend the Agency to implement
particulate matter NAAQS other than those using PM 10 as the indicator
in accordance with Subpart 4 of Part D of Title 1, i.e., sections 188
– 190 of the Act.  Moreover, EPA believes that implementation of the
PM2.5 NAAQS under the provisions of Subpart 1 is more appropriate, given
the inherent nature of the PM2.5 nonattainment problem.  In contrast to
PM 10, EPA anticipates that achieving the NAAQS for PM2.5 will generally
require States to evaluate different sources for controls, to consider
controls of one or more precursors in addition to direct PM emissions,
and to adopt different control strategies.  As a result, EPA has
concluded that the provisions of Subpart 1 will allow States and EPA to
tailor nonattainment area plans so that they can be based more
specifically upon the facts and circumstances of each nonattainment
area.   

	The proposed clean air fine particle implementation rule was issued on
November 1, 2005 (70 FR 65984).  About 100 comments were received from
private citizens and parties representing industry, state and local
governments, environmental groups, and federal agencies.  Section II of
this notice describes the primary elements of the fine particle
implementation program.  Each section summarizes the relevant policies
and options discussed in the proposed rule, discusses the final policy
set forth by EPA in the final rule, and provides responses to the major
comments received on each issue.  

II.	Elements of the Clean Air Fine Particle Implementation Rule

A.	Precursors and Pollutants Contributing to Fine 

	Particle Formation

1.	Introduction.

	The main precursor gases associated with fine particle formation are
sulfur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds
(VOC), and ammonia.  This section provides technical background on each
precursor, discusses the policy approach for addressing each precursor
under the PM2.5 implementation program, and responds to key issues
raised in the public comment process.  A subsection is also included on
direct PM2.5 emissions to address key comments received on this issue as
well.  

	Gas-phase precursors SO2, NOx, VOC, and ammonia undergo chemical
reactions in the atmosphere to form secondary particulate matter. 
Formation of secondary PM depends on numerous factors including the
concentrations of precursors; the concentrations of other gaseous
reactive species; atmospheric conditions including solar radiation,
temperature, and relative humidity (RH); and the interactions of
precursors with preexisting particles and with cloud or fog droplets.
Several atmospheric aerosol species, such as ammonium nitrate and
certain organic compounds, are semivolatile and are found in both gas
and particle phases. Given the complexity of PM formation processes, new
information from the scientific community continues to emerge to improve
our understanding of the relationship between sources of PM precursors
and secondary particle formation.

	As an initial matter, it is helpful to clarify the terminology we use
throughout this notice to discuss precursors.  We recognize NOX, SO2,
VOCs, and ammonia as precursors of PM2.5 in the scientific sense because
these pollutants can contribute to the formation of PM2.5 in the ambient
air.  However, interactions among these pollutants are complex and
variable.In section II.K on emission inventory issues, we make the point
that because of the complex and variable interaction of multiple
pollutants and precursors in the formation of fine particles, it is
important for States and EPA to continue to characterize and improve the
emissions inventories for all PM2.5 precursors.  The States and EPA need
to use the best available information available in conducting air
quality modeling and other assessments.  At the same time, the level of
our understanding about the emissions inventories, the efficacy of
relevant control measures, and the overall contribution of thesefine
particle precursors to PM2.5 formation varies by location.  This
requires that we further consider in this action how States should
address these PM2.5 precursors in their PM2.5 nonattainment plan
programs.  Thus, we require emission inventories to include the best
available information on all pollutants and precursors that contribute
to PM2.5 concentrations, and at same time we use the term “PM2.5
nonattainment plan precursor” to describe only those precursors that
are required to be addressedevaluated for control strategies in a
specific PM2.5 nonattainment area or maintenance area plan. 

	In this rule, EPA has not made a finding that all precursors should be
addressedevaluated for possible controls in each specific nonattainment
area.  The policy approach in the rule instead requires sulfur dioxide
to be addressedevaluated for control measures in all areas, and
describes general presumptive policies for NOx, ammonia, and VOC for all
nonattainment areas.  The rule provides a mechanism by which the State
and/or EPA can make an area-specific demonstration to reverse the
general presumption for these three precursors.  States must also
consider any relevant information brought forward by interested parties
in the SIP planning and development process.  (See section II.A.8 for
additional discussion on these issues.)

	In the following sections, we discuss how States must addressevaluate
PM2.5 precursors for nonattainment program issues in PM2.5
implementation plans, including issues such as RACT, RACM, and
reasonable further progress.  This discussion in the final rule is
linked to precursor policies for the implementation of the new source
review program, the transportation conformity program, the general
conformity program, and the regional haze program.  All of these
programs take effect prior to approval of SIPs for attaining the PM2.5
NAAQS.  In the case of NSR, the program applies on the effective date of
the nonattainment area designation.  In the case of transportation
conformity and general conformity, the program takes effect 1 year from
the effective date of designation of the nonattainment area (i.e., April
5, 2006 for areas designated nonattainment effective April 5, 2005). 
Thus, for each of these programs there is an interim period between the
date the program becomes applicable to a given nonattainment area and
the date the State receives EPA approval of its overall PM2.5
implementation plan.  

2.  Legal Authority to Regulate Precursors

a.  Background.

	The CAA authorizes the Agency to regulate criteria pollutant
precursors.  The term “air pollutant” is defined in section 302(g)
to include “any precursors to the formation of any air pollutant, to
the extent the Administrator has identified such precursor or precursors
for the particular purpose for which the term ‘air pollutant’ is
used.”  The first clause of this second sentence in section 302(g)
explicitly authorizes the Administrator to identify and regulate
precursors as air pollutants under other parts of the CAA.  In addition,
the second clause of the sentence indicates that the Administrator has
discretion to identify which pollutants should be classified as
precursors for particular regulatory purposes.  Thus, we do not
necessarily construe the CAA to require that EPA identify a particular
precursor as an air pollutant for all regulatory purposes where it can
be demonstrated that various CAA programs address different aspects of
the air pollutant problem.  Likewise, we do not interpret the CAA to
require that EPA treat all precursors of a particular pollutant the same
under any one program when there is a basis to distinguish between such
precursors.  For example, in a recent rule addressing PM2.5 precursors
for purposes of the transportation conformity program, we chose to adopt
a different approach for one precursor based on the limited emissions of
that precursor from onroad mobile sources and the degree to which it
contributes to PM2.5 concentrations.  (70 FR 24280; May 6, 2005).   

  	Other provisions of the CAA reinforce our reading of section 302(g)
that Congress intended precursors to NAAQS pollutants to be subject to
the air quality planning and control requirements of the CAA, but also
recognized that there may be circumstances where it is not appropriate
to subject precursors to certain requirements of the CAA.  Section 182
of the CAA provides for the regulation of NOx and VOCs as precursors to
ozone in ozone nonattainment areas, but also provides in section 182(f)
that major stationary sources of NOx (an ozone precursor) are not
subject to emission reductions controls for ozone where the State shows
through modeling that NOx reductions do not decrease ozone.  Section
189(e) provides for the regulation of PM10 precursors in PM10
nonattainment areas, but also recognizes that there may be certain
circumstances (e.g. if  precursor emission sources do not significantly
contribute to PM10 levels) where it is not appropriate to apply control
requirements to PM10 precursors.  The legislative history of Section
189(e) recognized the complexity behind the science of precursor
transformation into PM10 ambient concentrations and the need to
harmonize the regulation of PM10 precursors with other provisions of the
CAA:

The Committee notes that some of these precursors may well be controlled
under other provisions of the CAA.  The Committee intends that . . .the
Administrator will develop models, mechanisms, and other methodology to
assess the significance of the PM10 precursors in improving air quality
and reducing PM10.  Additionally, the Administrator should consider the
impact on ozone levels of PM10 precursor controls.  The Committee
expects the Administrator to harmonize the PM10 reduction objective of
this section with other applicable regulations of this CAA regarding
PM10 precursors, such as NOx.  See H. Rpt. 101-490, Pt. 1, at 268 (May
17, 1990), reprinted in S. Prt. 103-38, Vol. II, at 3292. 

	In summary, section 302(g) of the CAA clearly calls for the regulation
of precursor pollutants, but the CAA also identifies circumstances when
it may not be appropriate to regulate precursors and gives the
Administrator discretion to determine how to address particular
precursors under various programs required by the CAA.  Due to the
complexities associated with precursor emissions and their variability
from location to location, we believe that in certain situations it may
not be effective or appropriate to control a certain precursor under a
particular regulatory program or for EPA to require similar control of a
particular precursor in all areas of the country.

b.  Final rule.

	The final rule maintains the same legal basis for regulating precursors
as was described in the proposal and in the background section above. 
We also include a clarification of the term "significant contributor."

	In the proposal, when considering the impacts of the precursors NOx,
VOC and ammonia on ambient concentrations of particulate matter, we
referred to the possibility of reversing the presumed approach for
regulating or not regulating a precursor if it can be shown that the
precursor in question is or is not a “significant contributor” to
PM2.5 concentrations within the specific nonattainment area. 
“Significant contribution” in this context is a different concept
than that in Section 110(a)(2)(D).  Section 110(a)(2)(D) prohibits
States from emitting air pollutants in amounts which significantly
contribute to nonattainment or other air quality problems in other
states.  Consistent with the discussion of sections 189(e) and 302(g)
above, we are clarifying that the use in this implementation rule of the
term “significant contribution” to the nonattainment area’s PM2.5
concentration means that a significant change in emissions of the
precursor from sources in the state would be projected to provide a
significant change in PM2.5 concentrations in the nonattainment area. 
For example, if modeling indicates that a reduction in a state’s NOx
emissions would reduce ambient PM2.5 levels in the nonattainment area,
but that a reduction in ammonia emissions would result in virtually no
change in ambient PM2.5 levels, this would suggest that NOx is a
significant contributor but that ammonia is not.  EPA in this rule is
not establishing a quantitative test for determining whether PM2.5
levels in a nonattainment area change significantly in response to
reductions in precursor emissions from sources in a state.  However, in
considering this question, it is relevant to consider that relatively
small reductions in PM2.5 levels are estimated to result in worthwhile
public health benefits.

	This approach to identifying a precursor for regulation reflects
atmospheric chemistry conditions in the area and the magnitude of
emissions of the precursor in the area or State.  Assessments of which
source categories are more cost effective or technically feasible to
control should be part of the later RACT and RACM assessment, to occur
after the basic assessment of which precursors are to be regulated is
completed.

	In the proposed regulatory text, the provisions for reversing
presumptions for NOx, VOC and ammonia included consideration of whether
the precursor would significantly contribute to “other downwind air
quality concerns.” In the final rule we have removed that language to
clarify that identification of nonattainment plan precursors involves
evaluation of the impact on PM2.5 levels in a nonattainment area of
precursor emissions from sources within the state(s) where the
nonattainment area is located. Other parts of the Act, notably section
110(a)(2)(D) and section 126, focus on interstate transport of
pollutants. 

c.  Comments and responses

	Comment:  The EPA received several comments supporting EPA’s
interpretation of 302(g) to determine the appropriate regulatory status
of each precursor pollutant.

Response:  The EPA agrees with the commenters.  In establishing section
302(g), Congress intended that precursors to NAAQS pollutants be subject
to the air quality planning and control requirements of the CAA. 
However, the CAA also recognizes that there may be circumstances where
it is not appropriate to subject precursors to certain requirements of
the CAA.   

	Comment:  The EPA received several comments regarding the applicability
of section 189(e), noting that it requires states to presumptively
control sources of PM10 precursors except where the EPA “determines
that such sources [of precursors] do not significantly contribute to
PM-10 levels which exceed the standard in the area.”  Several
commenters stated that EPA does not have the legal authority to regulate
PM2.5 precursors in a different manner.  Several commenters maintained
that all PM2.5 precursors presumptively should be subject to regulation
unless demonstrated by the State as not a significant contributor to
PM2.5 concentrations in a specific area.

	Response:  As stated above, EPA believes that section 302(g) allows the
Administrator to presumptively not require certain precursors to be
addressed in PM2.5 implementation plans generally, while allowing the
State or EPA to make a finding for a specific area to override the
general presumption.  In the following pollutant-specific sections of
this preamble, EPA finds that at this time there is sufficient
uncertainty regarding whether certain precursors significantly
contribute to PM2.5 concentrations in all nonattainment areas such that
the policy set forth in this rule does not presumptively require certain
precursors (ammonia, VOC) to be controlled in each area.  However, the
State or EPA may reverse the presumption and regulate a precursor if it
provides a demonstration showing that the precursor is a significant
contributor to PM2.5 concentrations in the area.  In addition, if in the
State’s SIP planning and adoption process a commenter provides
additional information suggesting an alternative policy for regulating a
particular precursor, the State will need to respond to this information
in its rulemaking action.  

3.  Policy for ammonia

[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999); sec
51.1002 in draft and final regulatory text.]

a. Background 

	Ammonia (NH3) is a gaseous pollutant that is emitted by natural and
anthropogenic sources. Emissions inventories for ammonia are considered
to be among the most uncertain of any species related to PM.  Ammonia
serves an important role in neutralizing acids in clouds, precipitation
and particles.  In particular, ammonia neutralizes sulfuric acid and
nitric acid, the two key contributors to acid deposition (acid rain). 
Deposited ammonia also can contribute to problems of eutrophication in
water bodies, and deposition of ammonium particles may effectively
result in acidification of soil as ammonia is taken up by plants.  The
NARSTO Fine Particle Assessment indicates that reducing ammonia
emissions where sulfate concentrations are high may reduce PM2.5 mass
concentrations, but may also increase the acidity of particles and
precipitation. An increase in particle acidity is suspected to be linked
with human health effects and with an increase in the formation of
secondary organic compounds.  Based on the above information and further
insights gained from the NARSTO Fine Particle Assessment, it is apparent
that the formation of particles related to ammonia emissions is a
complex, nonlinear process.

	Though recent studies have improved our understanding of the role of
ammonia in aerosol formation, ongoing research is required to better
describe the relationships between ammonia emissions, particulate matter
concentrations, and related impacts.  The control techniques for ammonia
and the analytical tools to quantify the impacts of reducing ammonia
emissions on atmospheric aerosol formation are both evolving.  Also,
area-specific data are needed to evaluate the effectiveness of reducing
ammonia emissions on reducing PM2.5 concentrations in different areas,
and to determine where ammonia decreases may increase the acidity of
particles and precipitation.  

	The proposal showed consideration for the uncertainties about ammonia
emissions inventories and about the potential efficacy of ammonia
control measures by providing for a case-by-case approach.  It was
recommended that each State should evaluate whether reducing ammonia
emissions would lead to PM2.5 reductions in their specific PM2.5
nonattainment areas.  The proposed policy did not require States to
address ammonia as a PM2.5 nonattainment plan precursor, unless a
technical demonstration by the State or EPA showed that ammonia
emissions from sources in the State significantly contribute to the
PM2.5 problem in a given nonattainment area or to other downwind air
quality concerns. Where the State or EPA has determined that ammonia is
a significant contributor to PM2.5 formation in a nonattainment area,
the State would be required to addressevaluate control measures for
ammonia emissions in its nonattainment SIP due in 2008, in the
implementation of the PM program, and in other associated programs in
that area.

b. Final rule

	In the final rule, ammonia is presumed not to be a PM2.5 nonattainment
plan precursor, meaning that the State is not required to address
ammonia in its nonattainment plan or evaluate sources of ammonia
emissions for reduction measures.  This presumption can be reversed
based on an acceptable technical demonstration for a particular area by
the State or EPA.  If a technical demonstration by the State or EPA
shows that ammonia emissions from sources in the State significantly
contribute to the PM2.5 problem in a given nonattainment area, the State
must then evaluate and consider control strategies for reducing ammonia
emissions in its nonattainment SIP due in 2008, in the implementation of
the PM2.5 program.  Technical demonstrations on ammonia should also
consider the potential for atmospheric and particle acidity to increase
with ammonia reductions. Further discussion about technical
demonstrations to support reversing a PM2.5 precursor presumption is
included in section II.A.8 below.

	This approach was retained from the proposal because of continued
uncertainties regarding ammonia emission inventories and the effects of
ammonia emission reductions.  Ammonia emission inventories are presently
very uncertain in most areas, complicating the task of assessing
potential impacts of ammonia emissions reductions. In addition, data
necessary to understand the atmospheric composition and balance of
ammonia and nitric acid in an area are not widely available across PM2.5
nonattainment areas, making it difficult to predict the results of
potential ammonia emission reductions.  Ammonia reductions may be
effective and appropriate for reducing PM2.5 concentrations in selected
locations, but in other locations such reductions may lead to minimal
reductions in PM2.5 concentrations and increased atmospheric acidity. 
Research projects continue to expand our collective understanding of
these issues, but at this time EPA believes this case-by-case policy
approach is appropriate given that there is sufficient uncertainty
regarding the impact of ammonia emission reductions on PM2.5
concentrations in all nonattainment areas.  In light of these
uncertainties, we encourage States to continue efforts to better
understand the role of ammonia in its fine particle problem areas.  

	c.  Comments and Responses

	Comment: One commenter stated that scientific understanding of the
complexities of PM formation from ammonia is limited. The commenter
claimed that the reduction of ammonia will not reduce PM in many areas,
and speciated PM data to investigate the potential decrease in PM from
ammonia emissions reductions is not available in all areas.

	Response:  The final rule takes these uncertainties into consideration
by allowing ammonia to be addressed on a case-by-case basis.  For any
area about which enough information is available to determine that
ammonia emission reductions would lead to a beneficial reduction in
PM2.5, the State can develop a technical demonstration justifying the
control of ammonia.  If the State chooses to develop such a
demonstration, preferably it should be completed as part of the SIP
development process and prior to the adoption of control measures, in
consultation with the appropriate EPA regional office.  

	Comment: Some commenters claimed that requiring no action on some
precursors is counter to the requirement in sections 172(a)(2) and 188
to attain the NAAQS as expeditiously as practicable.  They also asserted
that presuming that ammonia is not a PM2.5 nonattainment plan precursor
violates 302(g) by improperly delegating authority to the States.

	Response:  In many areas, reducing ammonia emissions could have little
effect on PM2.5 concentrations and could lead to the potentially harmful
effect of increased atmospheric acidity.  While States are not required
to take action on ammonia sources under this policy, States would be
required to address information on ammonia brought to their attention
during the planning and rule adoption process.  Under this approach,
States should assess whether ammonia reductions would lead to reduced
PM2.5 concentrations in specific nonattainment areas.  If the State
decides that ammonia reductions could yield beneficial reductions in
PM2.5, the State should complete a technical demonstration supporting a
reversal of the presumption.  The EPA does not believe that this
approach improperly delegates authority to the States.  It establishes a
general presumption for all areas through this rulemaking process, and
allows for the presumption to be modified by the State or EPA on a
case-by-case basis.  EPA still retains the ability to make a technical
demonstration for any area if appropriate to reverse the presumption and
require ammonia to be addressed in its nonattainment area plan.  

	Comment: Some commenters stated that the results of a large study on
air emissions from concentrated animal feeding operations (CAFOs) should
be evaluated before requiring control of ammonia in areas where
agriculture is alleged to be a major source.

	Response:  The $15 million national CAFO consent agreement study
coordinated by Purdue University will greatly improve ammonia and VOC
emissions inventories and our understanding of the impacts of
agricultural emissions on particle formation.  EPA recognizes that the
agricultural emissions study is expected to provide data for future
planning purposes, and we expect that some of the results of the study
will not be available in time to be considered in the development of
PM2.5 State Implementation Plans dues in April 2008.  However, if a
State believes it has sufficient technical information to warrant
regulation of ammonia emissions in their 2008 implementation plans, it
may include in its plan a demonstration to reverse the presumption as
well as emission reduction measures.  EPA will review each submittal on
a case-by-case basis.  

	Comment: A presumption to not address ammonia will impede certain
states (i.e. those that have provisions requiring their regulations to
be “no stricter than Federal” provisions) from regulating ammonia.

	Response: This presumptive approach to ammonia will not restrict States
from addressing ammonia in their PM2.5 nonattainment plans.  If a State
has information indicating that reductions in ammonia emissions would
cause beneficial reductions in PM2.5 concentrations, the State can make
a technical demonstration to reverse the presumption.  In such cases,
inclusion of ammonia as a PM2.5 nonattainment plan precursor would not
be considered stricter than Federal requirements.  Under the policy in
the final rule, the Federal government or the State may assess the
impact of ammonia in a particular area and determine whether the
presumption of insignificance is appropriate or whether ammonia is in
fact a significant contributor to the PM2.5 problem in the area.

4.  Policy for VOC

[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999); sec
51.1002 in draft and final regulatory text.]

a. Background 

	The VOC policy in today’s rule addresses volatile and semivolatile
organic compounds, generally up to 24 carbon atoms. High molecular
weight organic compounds (typically 25 carbon atoms or more) are emitted
directly as primary organic particles and exist primarily in the
condensed phase at ambient temperatures.  Accordingly, high molecular
weight organic compounds are to be regulated as primary PM2.5 emissions
for the purposes of the PM2.5 implementation program.

	The organic component of ambient particles is a complex mixture of
hundreds or even thousands of organic compounds. These organic compounds
are either emitted directly from sources (i.e. primary organic aerosol)
or can be formed by reactions in the ambient air (i.e. secondary organic
aerosol, or SOA). Volatile organic compounds are key precursors in the
formation processes for both SOA and ozone. The relative importance of
organic compounds in the formation of secondary organic particles varies
from area to area, depending upon local emissions sources, atmospheric
chemistry, and season of the year. 

	The lightest organic molecules (i.e., molecules with six or fewer
carbon atoms) occur in the atmosphere mainly as vapors and typically do
not directly form organic particles at ambient temperatures due to the
high vapor pressure of their products. However, they participate in
atmospheric chemistry processes resulting in the formation of ozone and
certain free radical compounds (such as the hydroxyl radical [OH]) which
in turn participate in oxidation reactions to form secondary organic
aerosols, sulfates, and nitrates. These VOCs include all alkanes with up
to six carbon atoms (from methane to hexane isomers), all alkenes with
up to six carbon atoms (from ethene to hexene isomers), benzene and many
low-molecular weight carbonyls, chlorinated compounds, and oxygenated
solvents. 

	Intermediate weight organic molecules (i.e., compounds with 7 to 24
carbon atoms) often exhibit a range of volatilities and can exist in
both the gas and aerosol phase at ambient conditions. For this reason
they are also referred to as semivolatile compounds.  Semivolatile
compounds react in the atmosphere to form secondary organic aerosols. 
These chemical reactions are accelerated in warmer temperatures, and
studies show that SOA typically comprises a higher percentage of
carbonaceous PM in the summer as opposed to the winter.  The production
of SOA from the atmospheric oxidation of a specific VOC depends on four
factors: its atmospheric abundance, its chemical reactivity, the
availability of oxidants (O3, OH, HNO3), and the volatility of its
products.  In addition, recent work suggests that the presence of acidic
aerosols may lead to an increased rate of SOA formation. Aromatic
compounds such as toluene, xylene, and trimethyl benzene are considered
to be the most significant anthropogenic SOA precursors and have been
estimated to be responsible for 50 to 70 percent of total SOA in some
airsheds.  Man-made sources of aromatics gases include mobile sources,
petrochemical manufacturing and solvents.  Some of the biogenic
hydrocarbons emitted by trees are also   considered to be important
precursors of secondary organic particulate matter.  Terpenes (and
b-pinene, limonene, carene, etc.) and the sesquiterpenes are expected to
be major contributors to SOA in areas with significant   vegetation
cover, but isoprene is not.  Terpenes are very prevalent in areas with
pine forests, especially in the southeastern U.S.  The rest of the
anthropogenic hydrocarbons (higher alkanes, paraffins, etc.) have been
estimated to contribute 5–20 percent to the SOA concentration
depending on the area. 

	The contribution of the primary and secondary components of organic
aerosol to the measured organic aerosol concentrations remains a
controversialcomplex issue.  Most of the research performed to date has
been done in southern California, and more recently in central
California, while fewer studies have been completed on other parts of
North America.  Many studies suggest that the primary and secondary
contributions to total organic aerosol concentrations are highly
variable, even on short time scales.  Studies of pollution episodes
indicate that the contribution of SOA to the organic particulate matter
can vary from 20 percent to 80 percent during the same day.

	Despite significant advances in understanding the origins and
properties of SOA, it remains probably the least understood component of
PM2.5.  The reactions forming secondary organics are complex, and the
number of intermediate and final compounds formed is voluminous.  Some
of the best efforts to unravel the chemical composition of ambient
organic aerosol matter have been able to quantify the concentrations of
hundreds of organic compounds representing only 10–20 percent of the
total organic aerosol mass. For this reason, SOA continues to be a
significant topic of research and investigation.

	Current scientific and technical information clearly shows that
carbonaceous material is a significant fraction of total PM2.5 mass in
most areas, that certain VOC emissions are precursors to the formation
of secondary organic aerosol, and that a considerable fraction of the
total carbonaceous material is likely from local as opposed to regional
sources.  However, while significant progress has been made in
understanding the role of gaseous organic material in the formation of
organic PM, this relationship remains complex.  We recognize that
further research and technical tools are needed to better characterize
emissions inventories for specific VOC compounds, and to determine the
extent of the contribution of specific VOC compounds to organic PM mass.

	In light of these factors, the proposed rule did not require States to
address VOC’s as PM2.5 nonattainment plan precursors and evaluate them
for control measures, unless the State or EPA makes a finding that
VOC’s significantly contribute to a PM2.5 nonattainment problem in the
State or to other downwind air quality concerns.  Many PM2.5
nonattainment areas are also nonattainment areas for the 8-hour ozone
standard; control measures for VOCs will be implemented in some of these
areas, potentially providing a co-benefit for PM2.5 concentrations.

b. Final rule

	The final rule maintains the same policy as proposed..  States are not
required to address VOC in PM2.5 implementation plans and evaluate
control measures for such pollutants unless the State or EPA makes a
technical demonstration that emissions of VOCs from sources in the State
significantly contribute to a PM2.5 problem in a given nonattainment
area.  Technical demonstrations are discussed in section II.A.8 below. 
If a State chooses to make technical demonstration, it should be
developed in advance of the attainment demonstration.  

c. Comments and Responsesresponses

	Comment:  One commenter stated that our understanding of the
complexities of PM2.5 formation from VOCs is limited, that speciated PM
data are not available in all areas, and that VOC reductions will not
reduce PM2.5 in many areas.  

	Response:  The EPA acknowledges the uncertainties regarding the role of
VOC in secondary organic aerosol formation.  For this reason the final
rule does not presumptively include VOC as a regulated pollutant for PM
planning.  However, if available data demonstrates that control of VOC
would reduce PM2.5 concentrations in an area, the State or EPA may
include VOC as a nonattainment plan precursor.

	Comment:  One commenter stated that the rationale that VOC should not
be “out” considered a PM2.5 nonattainment plan precursor because
most PM areas are also ozone areas is not appropriate because many ozone
areas will attain soon and VOC reductions will still be needed for PM.

	Response:  The primary rationale for not including VOC as a regulated
PM2.5 nonattainment plan precursor in every nonattainment area is the
uncertainty regarding the contribution of anthropogenic VOCs to the
formation of the organic carbon portion of fine particles.  In certain
areas, EPA expects that VOC control measures will have some co-benefits
in the reduction of fine particulates.  However, this reason should not
be considered the principle reason for the policy in the final rule that
VOCs presumptively should not be considered PM2.5 nonattainment plan
precursors.  If a State or EPA determines that VOCs do contribute
significantly to PM2.5 concentrations in an area, the State will be
required to address evaluate control measures for VOC as a
regulatedPM2.5 nonattainment plan precursor for that area.  This
approach will provide for regulation of VOCs in locations where it is
most appropriate.  

	Comment:  One commenter suggested that EPA wait for the results of the
pending agricultural emissions study before requiring control of VOCs in
agricultural areas.  	Response:  The $15 million national CAFO consent
agreement study coordinated by Purdue University will greatly improve
ammonia and VOC emissions inventories and our understanding of the
impacts of agricultural emissions on particle formation.  EPA recognizes
that the agricultural emissions study is expected to provide data for
future planning purposes, and we expect that some of the results of the
study will not be available in time to be considered in the development
of PM2.5 State Implementation Plans dues in April 2008.  However, if a
State believes it has sufficient technical information to warrant
regulation of VOC emissions in their 2008 implementation plans, it may
include in its plan a demonstration to reverse the presumption as well
as emission reduction measures.  EPA will review each submittal on a
case-by-case basis.  

5.  Policy for NOx

[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999); sec
51.1002 in draft and final regulatory text.]

a. Background 

	The sources of NOx are numerous and widespread.  The combustion of
fossil fuel in boilers for commercial and industrial power generation
and in mobile source engines each account for approximately 30 percent
of NOx emissions in PM2.5 nonattainment areas (based on 2001 emission
inventory information).  Nitrates are formed from the oxidation of
oxides of nitrogen into nitric acid either during the daytime (reaction
with OH) or during the night (reactions with ozone and water).  Nitric
acid continuously transfers between the gas and the condensed phases
through condensation and evaporation processes in the atmosphere. 
However, unless it reacts with other species (such as ammonia, sea salt,
or dust) to form a neutralized salt, it will volatilize and not be
measured using standard PM2.5 measurement techniques.  The formation of
aerosol ammonium nitrate is favored by the availability of ammonia, low
temperatures, and high relative humidity.  Because ammonium nitrate is
semivolatile and not stable in higher temperatures, nitrate levels are
typically lower in the summer months and higher in the winter months. 
The resulting ammonium nitrate is usually in the sub-micrometer particle
size range.  Reactions with sea salt and dust lead to the formation of
nitrates in coarse particles.  Nitric acid may be dissolved in ambient
aerosol particles.

	Based on a review of speciated monitoring data analyses, it is apparent
that nitrate concentrations vary significantly across the country. For
example, in some southeastern locations, annual average nitrate levels
are in the range of 6 to 8 percent of total PM2.5 mass, whereas nitrate
comprises 40 percent or more of PM2.5 mass in certain California
locations.  Nitrate formation is favored by the availability of ammonia,
low temperatures, and high relative humidity.  It is also dependent upon
the relative degree of nearby SO2 emissions because ammonia reacts
preferentially with SO2 over NOx.  NOx reductions are expected to reduce
PM2.5 concentrations in most areas.  However, it has been suggested that
in a limited number of areas, NOx control would result in increased
PM2.5 mass by disrupting the ozone cycle and leading to increased
oxidation of SO2 to form sulfate particles, which are heavier than
nitrate particles.  Because of the above factors, the proposed rule
presumed that States must evaluate and implement reasonable controls on
sources of NOx in all nonattainment areas, but allowed for the State and
EPA to develop a technical demonstration to reverse this presumption. 

b. Final rule

	EPA is retaining the proposed approach in the final rule..  Under this
policy, States are required to address NOx as a PM2.5 nonattainment plan
precursor and considerevaluate  reasonable controls for NOx in PM2.5
nonattainment areaattainment plans, unless the State and EPA makes a
finding that NOx emissions from sources in the State do not
significantly contribute to the PM2.5 problem in a given nonattainment
area.  This policy is consistent with other recent EPA regulations
requiring NOx reductions which will reduce fine particle pollution, such
as the Clean Air Interstate Rule and a number of rules targeting onroad
and nonroad engine emissions.  

	Technical demonstrations that would reverse the presumption should be
developed in advance of the attainment demonstration and are discussed
in section II.A.8 below.  

c. Comments and Responsesresponses

	Comment:  Most commenters generally agreed with the proposed inclusion
of NOx as a presumptive PM2.5 nonattainment plan precursor.  

	Response:  The EPA agrees with these commenters.  

	Comment:  Some commenters requested guidance on what would constitute
an acceptable demonstration to reverse the presumption that NOx is a
PM2.5 nonattainment plan precursor.  

	Response: Guidance on technical demonstrations to reverse the
presumptive inclusion of NOx in all state implementation plans is
discussed in section II.A.8 below.  

	Comment:  One commenter raised concerns that the proposed policy for
NOx would allow a State to find NOx to be an insignificant contributor
to an area’s PM2.5 nonattainment problem and effectively keep the
State from controlling the area’s NOx emissions for other purposes,
such as to address interstate transport under section 110 of the CAA. 
Section 110 requires SIPs to prohibit emissions within the State that
would contribute significantly to another State’s nonattainment
problem or interfere with another State’s maintenance plan. 

	Response:  The identification of precursors for regulation under this
rule is for purposes of PM2.5 nonattainment and maintenance plans under
Part D of the Clean Air Act  The PM2.5 implementation rule does not
prevent a State from regulating NOx sources under any other federal or
state rule, including interstate transport rules under Section 110. 

6.  Policy for SO2

[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999); sec
51.1002 in draft and final regulatory text.]

a. Background 

	Sulfur dioxide is emitted mostly from the combustion of fossil fuels in
boilers operated by electric utilities and other industry.  Less than 20
percent of SO2 emissions nationwide are from other sources, mainly other
industrial processes such as oil refining and pulp and paper production.
 The formation of sulfuric acid from the oxidation of SO2 is an
important process affecting most areas in North America.  There are
three different pathways for this transformation.  

	First, gaseous SO2 can be oxidized by the hydroxyl radical (OH) to
create sulfuric acid.  This gaseous SO2 oxidation reaction occurs slowly
and only in the daytime.  Second, SO2 can dissolve in cloud water (or
fog or rain water), and there it can be oxidized to sulfuric acid by a
variety of oxidants, or through catalysis by transition metals such as
manganese or iron.  If ammonia is present and taken up by the water
droplet, then ammonium sulfate will form as a precipitate in the water
droplet.  After the cloud changes and the droplet evaporates, the
sulfuric acid or ammonium sulfate remains in the atmosphere as a
particle.  This aqueous phase production process involving oxidants can
be very fast; in some cases all the available SO2 can be oxidized in
less than an hour.  Third, SO2 can be oxidized in reactions in the
particle-bound water in the aerosol particles themselves.  This process
takes place continuously, but only produces appreciable sulfate in
alkaline (dust, sea salt) coarse particles.  Oxidation of SO2 has also
been observed on the surfaces of black carbon and metal oxide particles.
 During the last 20 years, much progress has been made in understanding
the first two major pathways, but some important questions still remain
about the smaller third pathway.  Models indicate that more than half of
the sulfuric acid in the eastern United States and in the overall
atmosphere is produced in clouds.

	 The sulfuric acid formed from the above pathways reacts readily with
ammonia to form ammonium sulfate, (NH4)2SO4.  If there is not enough
ammonia present to fully neutralize the produced sulfuric acid (one
molecule of sulfuric acid requires two molecules of ammonia), part of it
exists as ammonium bisulfate, NH4HSO4 (one molecule of sulfuric acid and
one molecule of ammonia) and the particles are more acidic than ammonium
sulfate.  In certain situations (in the absence of sufficient ammonia
for neutralization), sulfate can exist in particles as sulfuric acid,
H2SO4.  Sulfuric acid often exists in the plumes of stacks where SO2,
SO3, and water vapor are in much higher concentrations than in the
ambient atmosphere, but these concentrations become quite small as the
plume is cooled and diluted by mixing.

	Because sulfate is a significant contributor (e.g. ranging from 9
percent to 40 percent) to PM2.5 concentrations in nonattainment areas
and to other air quality problems in all regions of the country, EPA
proposed that States would be required to address sulfur dioxide as a
PM2.5 nonattainment plan precursor in all areas. 

b. Final rule

	The final rule includes the same policy for sulfur dioxide as in the
proposal.  States are required to address sulfur dioxide as a PM2.5
nonattainment plan precursor and evaluate SO2 for possible control
measures in all areas.  Sulfate is an important precursor to PM2.5
formation in all areas, and has a strong regional impact on PM2.5
concentrations.  This policy is consistent with past EPA regulations,
such as the Clean Air Interstate Rule, the Clean Air Visibility Rule,
the Acid Rain rules, and the Regional Haze rule, that require SO2
reductions to address fine particle pollution and related air quality
problems.   

	Under the transportation conformity program, sulfur dioxide is not
required to be addressed in transportation conformity determinations
before a SIP is submitted unless either the state air agency or EPA
regional office makes a finding that on-road emissions of sulfur dioxide
are significant contributors to the area's PM2.5 problem.  Sulfur
dioxide would be addressed after a PM2.5 SIP is submitted if the area's
SIP contains an adequate or approved motor vehicle emissions budget for
sulfur dioxide.  EPA based this decision on the de minimis level of
sulfur dioxide emissions from on-road vehicles currently, and took into
consideration the fact that sulfur dioxide emissions from on-road
sources will decline in the future due to the implementation of
requirements for low sulfur gasoline (which began in 2004) and for low
sulfur diesel fuel (beginning in 2006).  For more information, see the
May 6, 2005 transportation conformity rule on PM2.5 precursors at 70 FR
24283.

c. Comments and Responsesresponses

	Comment:  Most commenters agreed with the proposed policy for SO2.  One
commenter stated, “…requiring states to address sulfur dioxide in
nonattainment planning in all areas is consistent with the science of
PM2.5 formation and essential to effective implementation of the PM2.5
NAAQS.”  Another commenter concluded that EPA’s proposal “…is
justified based on the fact that SO2 has been found to be a significant
contributor to PM2.5 nonattainment in all areas.”

	Response:  The EPA agrees with these comments.  

	Comment:  Some commenters believe States should be able to make a
demonstration that SO2 not be addressed as a nonattainment plan
precursor.  The commenters claim that the urban increment of sulfate is
generally small, and SO2 control will not matter in many areas. 
Commenters also note that a large percentage of the SO2 emission
inventory is being reduced and will be reduced further through existing
programs, and that if attainment can be demonstrated without additional
SO2 controls, a State should be allowed to make that demonstration in
its SIP.  One commenter stated that whether SO2 emissions from a given
source located in a nonattainment area in fact contribute significantly
to ambient concentrations of sulfate and PM2.5 in that nonattainment
area likely will depend on a range of factors, including source type,
stack height, location, and meteorology.  The commenter asserted that
sulfate forms over significant geographic distances from the source of
the SO2 emissions and may not form significant concentrations of PM2.5
in the local nonattainment area.

	Response:  As in the proposal, the final rule requires SO2 to be
considered a PM2.5 nonattainment plan precursor in all cases.  Sulfate
is a significant fraction of PM2.5 mass in all nonattainment areas
currently, and although large SO2 reductions are projected from electric
generating units with the implementation of the CAIR program, sulfate is
still projected to be a key contributor to PM2.5 concentrations in the
future.  SO2 emissions also lead to sulfate formation on both regional
and local scales.  EPA agrees that the extent of the contribution from a
particular source in a nonattainment area to PM2.5 concentrations in the
area will depend on a number of factors, and that at times the reaction
of SO2 emissions in the atmosphere to form sulfate particles may occur
less rapidly and extend over a significant distance.  However, at other
times the conversion of SO2 to sulfate can occur rapidly and local
impacts from a particular source can be more significant.  States are
required to develop plans to attain as expeditiously as practicable
through the identification of technically and economically feasible
control measures from the full range of source categories contributing
to PM2.5 nonattainment areas.  In developing these plans, each State
will need to consider whether controls on local SO2 sources would be
cost-effective and would be needed to attain expeditiously.  

7. Policy for direct PM

 Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999); sec
51.1002 in draft and final regulatory text.]

a. Background 

	This section addresses inorganic and organic forms of directly emitted
PM.  Although these direct emissions are by definition not precursors to
PM2.5, this section is included to provide information on the full range
of components that commonly make up fine particulate matter.  

	The main anthropogenic sources of inorganic (or crustal) particles are:
 entrainment by vehicular traffic on unpaved or paved roads; mechanical
disturbance of soil by highway, commercial, and residential
construction; and agricultural field operations (tilling, planting and
harvesting).  Industrial processes such as quarries, minerals
processing, and agricultural crop processing can also emit crustal
materials.  While much of these emissions are coarse PM, the size
distribution can have a tail of particles smaller than PM2.5.  

	In general, coarse PM is most important close to the source, and not
generally a significant contributor to regional scale PM problems.  Even
so, during certain high wind events, fine crustal PM has been shown to
be transported over very long distances.   

	Emission estimates of mechanically suspended crustal PM from sources
within the US are often quite high.  However, this PM is often released
very close to the ground, and with the exception of windblown dust
events, thermal or turbulent forces sufficient to lift and transport
these particles very far from their source are not usually present. 
Thus, crustal material is only a minor part of PM2.5 annual average
concentrations. 

 	Primary carbonaceous particles are largely the result of incomplete
combustion of fossil or biomass fuels.  This incomplete combustion
usually results in emissions of both black carbon and organic carbon
particles.  High molecular weight organic molecules (i.e., molecules
with 25 or more carbon atoms) are either emitted as solid or liquid
particles, or as gases that rapidly condense into particle form.  These
heavy organic molecules sometimes are referred to as volatile organic
compounds, but because their characteristics are most like direct PM
emissions, they will be considered to be primary emissions for the
purposes of this regulation.  Primary organic carbon also can be formed
by condensation of semi-volatile compounds on the surface of other
particles.  

 	The main combustion sources emitting carbonaceous PM2.5 are certain
industrial processes, managed burning, wildland fires, open burning of
waste, residential wood combustion, coal and oil-burning boilers
(utility, commercial and industrial), and mobile sources (both onroad
and nonroad).  Certain organic particles also come from natural sources
such as decomposition or crushing of plant detritus.  Most combustion
processes emit more organic particles than black carbon particles.  A
notable exception to this is diesel engines, which typically emit more
black carbon particles than organic carbon. Because photochemistry is
typically reduced in the cooler winter months for much of the country,
studies indicate that the carbon fraction of PM mass in the winter
months is likely dominated by direct PM emissions as opposed to
secondarily formed organic aerosol. 

	Particles from the earth’s crust may contain a combination of
metallic oxides and biogenic organic matter.  The combustion of surface
debris will likely entrain some soil.  Additionally, emissions from many
processes and from the combustion of fossil fuels contain elements that
are chemically similar to soil.  Thus, a portion of the emissions from
combustion activities may be classified as crustal in a compositional
analysis of ambient PM2.5.

The proposed rule required that States address the direct emissions of
particulate matter in their PM2.5 nonattainment plans.  During the
comment period, EPA received several comments regarding the definition
of what should be regulated as “direct PM2.5.”

b. Final rule

	This rule defines direct PM2.5 emissions as “air pollutant emissions
of direct fine particulate matter, including organic carbon, elemental
carbon, direct sulfate, direct nitrate, and miscellaneous inorganic
material (i.e crustal material).”   Development of nonattainment plans
will include direct PM2.5 emissions and specific PM2.5 nonattainment
plan precursors.      

c. Comments and Responsesresponses

	Comment:  A few commenters noted that section40 CFR 51.1000 of the
proposed rule includes definitions for both “direct PM2.5 emissions”
and for “PM2.5 direct emissions.”  They recommend including just one
definition in the final rule.  

	Response:  EPA acknowledges this oversight and has included in the
final rule a single definition for “direct PM2.5 emissions.”  It
reads:  “Direct PM2.5 emissions means solid particles emitted directly
from an air emissions source or activity, or gaseous emissions or liquid
droplets from an air emissions source or activity which condense to form
particulate matter at ambient temperatures.  Direct PM2.5 emissions
include elemental carbon, directly emitted organic carbon, directly
emitted sulfate, directly emitted nitrate, and other inorganic particles
(including but not limited to crustal material, metals, and sea
salt).”

8.  Optional technical demonstrations for NOx, VOC, and ammonia

[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999); sec
51.1002 in draft and final regulatory text.]

a. Background 

	The proposed rule required States to evaluate and consider control
strategies for sources of SO2 and direct PM2.5 emissions in all
nonattainment areas.  For the precursors NOx, VOC, and ammonia, the
proposed rule included presumptive policies that could be reversed with
an acceptable technical demonstration by the State or EPA.  (The policy
in the proposal presumptively required that NOx emissions must be
addressed in all areas, and that VOC and ammonia emissions do not need
to be addressed in all areas.)  A number of commenters requested
additional guidance on the criteria for an acceptable technical
demonstration.  

b. Final rule

	The final rule retains provisions for the State or EPA to conduct a
technical demonstration to reverse the presumptive inclusion of NOx or
to reverse the presumptive exclusions of ammonia and VOC as PM2.5
nonattainment plan precursors.  Demonstrations to reverse the
presumptions for ammonia, VOC, or NOx are to be based on the weight of
evidence of available information, and any demonstration by the State
must be approved by EPA.  The State must demonstrate that based on the
sum of available technical and scientific information, it would be
appropriate for a nonattainment area to reverse the presumptive approach
for a particular precursor.  The demonstration should include
information from multiple sources, including results of speciation data
analyses, air quality modeling studies, chemical tracer studies,
emission inventories, or special intensive measurement studies to
evaluate specific atmospheric chemistry in an area.  

	Because of the variation among nonattainment areas in terms of such
factors as local emissions sources, growth patterns, topography, and
severity of the nonattainment problem, EPA believes that it would not be
appropriate to define a prescriptive set of analyses that must be
included in all PM2.5 precursor technical demonstrations.  The key
criterion is that any technical demonstration must fairly represent
available information.  

	In developing the implementation plan for a nonattainment area, the
State should use all relevant information available (from EPA, the
State, or other sources) to determine the scientifically most
appropriate approach to regulating NOx, ammonia, and VOC emissions in
the area.  As required under any State rulemaking process, the State
must consider and provide a response in the record to any information or
evidence brought forward by commenters during the SIP planning,
development and review process which indicates that the presumption for
a precursor should be reversed.  In its review of the forthcoming State
implementation plan submittal, EPA will review the State’s proposed
precursor policies in light of all currently available information.  If
information brought forward by commenters or the State in the SIP
development process shows that the presumption in this rule for ammonia,
VOC or NOx is not technically justified for a particular nonattainment
area, the State must conduct a technical demonstration to reverse the
presumption.  In the case of ammonia or VOC, the State then would
evaluate control measures and implement those measures that are
technically and economically feasible and that will contribute to
expeditious attainment of the standards.	

	In the section below we suggest examples of the types of analyses that
would be appropriate to use in developing such a demonstration.  States
are encouraged to consult with EPA in formulating appropriate technical
demonstrations.

i. Emission inventory information: An analysis might show that a
precursor composes a significant fraction of the emissions inventory in
an area and therefore requires greater consideration.

Example: Several stationary sources emitting particular VOCs known to
contribute to SOA formation make up a significant portion of the
area’s VOC inventory.  This analysis may be useful in conjunction with
other analyses included in a weight of evidence demonstration.  , 

ii. Speciation data information: Analysis of data from speciation
networks might lead a State to determine the relative importance of a
precursor to seasonal or yearly average PM concentrations.  Individual
precursors require different approaches.  Collection of new data could
be used to understand the impacts of precursors in an area.

Example: Nitrate ion is a large portion of winter average PM2.5 mass. 
Nitrate ion is a major portion of PM2.5 mass on the 10 highest PM2.5
days in winter in the past 3 years.  The days with the highest mass
concentrations might be indicative of inversion conditions and/or local
impacts, rather than large-scale transport processes.  For these
reasons, nitrate should be addressed in the PM2.5 nonattainment plan.  

Example: Ammonium ion data combined with total calculated nitrate data
indicates that reductions in ammonia would reduce PM concentrations
without a sharp related increase in particle acidity.  PM speciation
data shows that PM in the area is generally within 10% of calculated
neutralization.  In places for which the needed atmospheric data are
available to determine whether increased acidity is an issue, analysis
showing that increased acidity of particles and precipitation would
likely result from ammonia controls would support the presumption
against ammonia regulation.  Analysis showing that ammonia reductions
would be unlikely to increase the acidity of particles and
precipitation, and that potential reductions in ammonia would
significantly reduce PM2.5 levels, would support a technical
demonstration to reverse the presumption.  

iii. Modeling information: Results of atmospheric modeling may help a
State characterize the impacts of potential precursor emission
reductions on PM2.5 concentrations in an area.

Example: Modeling of SO2, NOx, and VOC emission reductions result in
lower sulfate and nitrate levels but not lower secondary organic aerosol
levels.  This likely indicates that VOC reductions are not as vital as
reductions of the other precursors.  

Example: Modeled reductions of NOx show a potential increase in sulfate
formation through disruption of the ozone cycle.  SO2 reductions may be
a better choice than NOx reductions.

Example:  Modeled ammonia reductions show a projected reduction in PM2.5
concentrations in selected areas.  Although dependant on good quality
inventory data, this type of an analysis would indicate that the area is
ammonia-limited and that ammonia reductions may be beneficial.

Example:  Modeling shows that reductions in SO2 in the absence of NOx
reductions in an area will not result in a significant PM2.5 reduction
because more nitrate particles form when less SO2 is available for
particle formation.  However, PM2.5 reductions are significant when both
SO2 and NOx are reduced concurrently.  This analysis would indicate that
NOx reductions should be included in the PM2.5 nonattainment plan in the
area.

iv. Monitoring, data analysis, or other special studies:  Could include
monitoring of gases and compounds not typically monitored under the
PM2.5 speciation network, receptor modeling analysis, or special
monitoring studies.  

Example:  Data from specialized monitoring studies can provide insights
about concentrations of ammonia gas and nitric acid in an area and
whether the area is ammonia-limited or not.  Ammonia reductions in
ammonia-limited areas typically yield reductions in PM2.5
concentrations.  Specialized monitoring and laboratory studies can also
assess the relative concentrations of organic compounds and provide
insights into the contributions of different anthropogenic and biogenic
VOCs to secondary organic aerosol formation.  

Example:  Receptor modeling and statistical analysis PM2.5 speciation
monitoring data can indicate relative contributions to PM2.5 mass from
sources with different chemical “fingerprints.”

Example:  Additional analysis of organic compounds on filters collected
through speciation monitoring may reveal insights about the relative
degree of carbonaceous material considered to be from fossil fuel
combustion as opposed to combustion of “modern” material (such as
wood or biomass).

	

 c. Comments and Responsesresponses

	Comment: A number of commenters requested that the final rule include
guidance on acceptable technical demonstrations.

	Response: The above section includes examples designed to help States
formulate appropriate demonstrations.  Prescribing specific technical
indicators to be used in all areas would ignore the scientific
uncertainty inherent in the relationships between precursor emissions
and the responses of atmospheric concentrations of PM2.5.  Therefore,
States are encouraged to review available information and consult with
EPA in formulating technical demonstrations appropriate to a particular
area.  

  SEQ CHAPTER \h \r 1 B.	  No classification system for PM2.5
nonattainment areas.  tc "B.	Classification options under consideration
for PM2.5 nonattainment areas. " \l 2 

1.  No classification system or a two-tiered (moderate/serious) system. 

a. Background. 

	Section 172 of subpart 1 contains the general requirements for SIPs for
all nonattainment areas.  Section 172(a)(1) states that on or after the
date of designation, the Administrator may classify an area for the
purpose of applying an attainment date or for some other purpose.  Thus,
a classification system is allowed under section 172 of the CAA, but is
not required for the purposes of implementing a national ambient air
quality standard.  The CAA also states that EPA may consider certain
factors in making a decision concerning classification for areas, such
as the severity of nonattainment in such areas, and the availability and
feasibility of the pollution control measures that may be needed to
achieve attainment.	In the proposed rule, EPA provided  two
implementation approaches for classifying PM2.5 nonattainment areas. 
Under the first approach, there would be no classification system. 
Under the second approach, a two-tiered classification system would
apply, with areas classified as either “moderate” or “serious”
based on specific criteria.  

	For example, the two classification tiers could be based on the
severity of nonattainment (e.g., serious areas would be those with a
design value above a specific threshold), or on the attainment date for
the area (e.g., serious areas would be those with attainment dates after
April 2010).   However, any moderate area that needs an attainment date
longer than 5 years would be reclassified as serious.  This would ensure
that areas with a more persistent PM2.5 problem are subject to more
stringent requirements, even if they are not one of the areas with the
highest current design values.  For such areas, the State would be
required to request reclassification for an area and ensure that the
2008 attainment SIP submission for the area includes all measures needed
to meet the serious area requirements. Under the two tiered
classification approach, we proposed that serious PM2.5 nonattainment
areas would be required to meet the more stringent requirements than
moderate areas that would be defined in this rulemaking action (e.g.,
lower thresholds for RACT, fixed percentage reduction for RFP, etc.). 
For serious areas, the attainment date would be as expeditious as
practicable, but no later than 10 years after designation, depending on
the year in which the area would be projected to attain considering
existing control requirements and the effect of RACM, RACT and RFP.

b. Final rule. 

	 The EPA believes that in the case of PM2.5, the no-classification
approach is the most appropriate approach.  An advantage of this
approach is that it provides a relatively simple implementation
structure for State implementation of the PM2.5 standards, and avoids
the need to define a classification system and determine classifications
for each area.  Without classifications, this rule still requires that
that SIPs include all reasonable measures that contribute to achieving
attainment as expeditiously as practicable.  (Further detail is provided
in sections D. and F. below.)  Because of differences in the nature and
sources of the PM2.5 problem in different parts of the country, EPA did
not find it appropriate to establish a tiered classification system with
increasing control measure requirements.  The no-classifications
approach provides States with greater flexibility to determine the
control strategies that will be most effective and efficient in bringing
specific areas into attainment as expeditiously as practicable.  	In
addition, EPA believes that States requesting additional time to attain
the standard beyond the initial 5 year attainment date, provided for
under Subpart I, will need to adopt additional or more stringent
measures to meet their obligations for RACT, RACM and attainment that is
as expeditious as practicable.   We believe that this addresses the main
concerns of those commenters who contend that a two tiered
classification system should be implemented.

c. Comments and Responsesresponses.  

	Comment:   The majority of the commenters who commented on this issue
stated that they agreed with EPA’s preferred no classification
approach.  These commenters generally stated that they believed that EPA
has the authority not to establish a classification system for PM2.5
nonattainment areas.  Some commenters stated that it would also be
unreasonable, at this point in the process, for EPA to implement a
classification scheme for the PM2.5 standard.  Many commenters support
the no classification approach because it provides for a simple
implementation structure and/or allows greater implementation
flexibility to States, including flexibility to address specific
problems related to individual nonattainment areas in the most
cost-effective and expeditious manner, rather than through a one size
fits all approach.  Other commenters stated that they believe that a
classification system is not needed because  nonattainment areas in the
Eastern United States are likely to attain the standard within a
timeframe that is consistent with the timeframe established under
Subpart 1.  

	Response: The EPA agrees with these commenters.

	Comment:   Several commenters disagreed with EPA’s preferred approach
and agreed with the two tiered classification approach featuring a
“moderate” and a “serious” area classification. These commenters
also stated that the threat of reclassification or “bump up” to a
higher classification was a powerful incentive for areas to attain as
expeditiously as practicable.  Commenters also indicated that areas
needing more time to attain the standard should be required to implement
more stringent measures or mandatory measures. 

	Response:   The EPA agrees that areas with more severe nonattainment
problems will need to implement more stringent measures to attain. 
However, EPA does not believe that a classification system is needed to
ensure that such measures are implemented.  The EPA believes that on
balance the no classification approach is the most appropriate
classification option for the implementation of the PM2.5 standard
because of the difference in contributing sources from area to area.  	

	Comment:  Several commenters stated that under EPA’s preferred
approach, each State would be required to submit an attainment
demonstration proposing an attainment date that is “as expeditious as
practicable” for each area.  They asserted that to allow States to
propose their own attainment dates would invite delay in the process of
cleaning up fine particle pollution.  These commenters further stated
that States would have no incentive to set an attainment date earlier
than the outer limit set by EPA, even if it would be practicable to
attain the NAAQS sooner.

	Response:   Section 172 of the CAA requires SIPs to demonstrate
attainment as expeditiously as practicable regardless of whether there
is a classification system, and under this rule states must justify that
their attainment date is as expeditious as practicable considering all
reasonable measures.  As noted above, EPA believes that States
requesting additional time to attain the standard beyond the initial 5
year attainment date will need to adopt additional or more stringent
measures to meet their obligations for RACT and RACM and to attain as
expeditiously as practicable.  More details on the analytical process
required for an attainment demonstration is included in section II.F.

	Comment:   Several commenters stated that the CAA requires regulation
of the PM2.5 standard under Subpart 4 of Part D.  These commenters State
that EPA takes the position that it must regulate PM2.5 under Subpart 1
of the CAA, which applies to nonattainment areas in general.  The
commenters State that section 7513, in Subpart 4 of Part D of the CAA,
contains specific provisions for classification of particulate matter
nonattainment areas, and that EPA must therefore regulate PM2.5 under
Subpart 4, which requires a moderate and serious area classification
system.  Other commenters argued that implementation of the PM2.5
standard must proceed under Subpart 1 of Part D of Title I of the CAA
and cannot be governed by Subpart 4 of Part D, which addresses the
implementation of the PM10 standard which is a different pollutant than
PM2.5.

	Response:   The EPA finds that the PM2.5 standard should be implemented
under subpart I of the CAA, which is the general provision of the CAA
related to NAAQS implementation.  Part D of Title I of the CAA sets
forth the requirements for SIPs needed to attain the national ambient
air quality standards.  Part D also includes a general provision under
Subpart I which applies to all NAAQS for which a specific subpart does
not exist.  Because the PM2.5 standards were not established until 1997,
the nonattainment plan provisions found in section 172 of subpart 1
apply.  The EPA further agrees with comments stating that subpart 4 on
its face applies only to the PM10 standard.  In general, the emphasis in
subpart 4 on reducing PM10 concentrations from certain sources of direct
PM2.5 emissions can be somewhat effective in certain PM2.5 nonattainment
areas but not in all.  Contributions to PM2.5 concentrations are
typically from a complex mix of sources of primary emissions and sources
of precursor emissions which form particles through reactions in the
atmosphere.  PM2.5 also differs from PM10 in terms of atmospheric
dispersion characteristics, chemical composition, and contribution from
regional transport.

2.  Rural transport classification  tc "2.  Rural transport
classification " \l 4 option

a. Background.	

	The 8-hour ozone implementation program includes a “rural transport
classification” for subpart 1 nonattainment areas.  In the proposal
for this rule we discussed whether an area classification of this type
would be appropriate for the PM2.5 implementation program in light of
the fact that no currently designated PM2.5 nonattainment area met the
criteria similar to those that apply to rural transport areas under the
ozone implementation program.

	As addressed in the proposal, a PM2.5 nonattainment area would qualify
for the “rural transport” classification if it met criteria similar
to those specified for rural transport areas for the 1-hour ozone
standard under section 182(h).  Section 182(h) defines “rural
transport” areas as those areas that do not include, and are not
adjacent to, any part of a Metropolitan Statistical Area (MSA) or, where
one exists, a Consolidated Metropolitan Statistical Area (CMSA). 
Section 182(h) further limits the category to those areas whose own
emissions do not make a significant contribution to pollutant
concentrations in those areas, or in other areas. 

	As discussed in the preamble to the proposed rule, potential criteria
for a State to identify an area for a rural transport classification
under the PM2.5 program could be similar to the criteria used in the
ozone implementation program:  a State with a PM2.5 “rural
transport” area would need to 1) demonstrate that the area meets the
above criteria,  2) demonstrate using EPA approved attainment modeling
that the nonattainment problem in the area is due to the “overwhelming
transport” of emissions from outside the area, and 3) demonstrate that
sources of PM2.5 and its precursor emissions within the boundaries of
the area do not contribute significantly to PM2.5 concentrations that
are measured in the area or in other areas. 

	An area which qualifies for the “rural transport” classification
would only be required to adopt local control measures sufficient to
demonstrate that the area would attain the standard by its attainment
date “but for” the overwhelming transport of emissions emanating
from upwind States.  RFP requirements under subpart 1 would still apply
to these areas.  As with other nonattainment areas, rural transport
nonattainment areas would be subject to NSR, transportation conformity,
and general conformity requirements.  In the proposal we solicited
comments on whether it would be appropriate to establish less burdensome
NSR requirements in the event that a classification for rural transport
areas is adopted in the final rule.  The EPA requested comment on
whether this type of classification option is needed at all under the
PM2.5 implementation program. 

b. Final rule.

	The final rule does not include a rural transport classification.  This
type of classification was included in the CAA for purposes of
implementing the ozone standards because of the phenomenon of the
formation of high ozone levels far downwind in very rural locations,
including on high elevation mountain peaks.  In reviewing the currently
designated PM2.5 nonattainment areas, it appears that all areas but one
are within or adjacent to a metropolitan area (i.e. core-based
statistical area or consolidated statistical area), and thus would not
meet the criteria discussed above.  Although PM2.5 concentrations are
greatly affected by long-range transport of air pollution, it appears
that nonattainment areas typically are located in urban areas and
include significant local pollutant sources. 

c. Comments and responses

	Comment:   Several commenters stated that they do not support the
adoption of a rural transport classification because it is not needed. 
Commenters stated that given the criteria for the rural transport
classification, which greatly limits its applicability, few if any PM2.5
nonattainment areas can qualify for the option. One commenter stated
that EPA modeled the rural transport classification after the “rural
transport areas” provision contained in subpart 2 of the CAA, which
applies only to the ozone standard.  The commenter further states that
neither Subpart 1 nor 4 contain any statutory authority for such a
classification.

	Response:  The EPA believes that it has sufficient statutory authority
under the CAA to establish a rural transport classification, but we do
not believe that such a classification is needed. 

	Comment:   One commenter generally supported the rural transport
concept and the proposed associated requirements, with the addition that
data analysis be included as appropriate in the required technical
demonstrations in addition to modeling.  While no PM2.5 area currently
meets the requirements for the rural transport classification option,
several commenters recommended that it be maintained for potential cases
in which the PM2.5 standards are made more stringent, or measured air
quality in areas change in such a way that areas would qualify for the
rural transport classification at a later date.

	Response: The EPA does not agree that a rural transport classification
is needed.  The EPA will re-evaluate the need for such a classification
as appropriate.  

 When are PM2.5 attainment demonstrations and SIPs due and what
requirements must they address?

C.  Due dates and basic requirements for attainment demonstrations 

a. Background. 

	 Part D of Title I of the CAA sets forth the requirements for SIPs
needed to attain the national ambient air quality standards.  Part D
includes a general subpart 1 which applies to all NAAQS for which a
specific subpart does not exist.  The 1990 CAA Amendments do not include
any subpart for PM2.5 because the PM2.5 standards were not yet
established.  The EPA has determined that for PM2.5, the nonattainment
plan provisions found in section 172 of subpart 1 apply.  

	Section 172(b) of the CAA requires that at the time the Agency
promulgates nonattainment area designations, the EPA must also establish
a schedule for States to submit SIPs meeting the applicable requirements
of section 172(c) and of section 110(a)(2) of the CAA.  Nonattainment
area designations were finalized in December 2004, and a supplemental
notice was issued in April 2005.  Consistent with section 172(b) of the
CAA, section40 CFR 51.1002 of the proposed rule requires the State to
submit its attainment demonstration and SIP revision within 3 years, or
by April 2008.

	Section 51.1006 of the proposed rule addresses the situation in which
an area is initially designated as attainment/unclassifiable but is
later designated as nonattainment based on air quality data after the
2001-2003 period.  Under such circumstances, the SIP submittal date
would be 3 years from the effective date of the redesignation, and the
attainment date would be as expeditiously as practicable but no later
than 5 years from the effective date of the redesignation.  

	The section 172(c) requirements that States are to address under
section 172(c) (including RACT, RACM, RFP, contingency measures,
emission inventory requirements, and NSR) are discussed in later
sections of this notice.  Section 110(a)(2) of the CAA requires all
States to develop and maintain a solid air quality management
infrastructure, including enforceable emission limitations, an ambient
monitoring program, an enforcement program, air quality modeling, and
adequate personnel, resources, and legal authority.  Section
110(a)(2)(D) also requires State plans to prohibit emissions from within
the State which contribute significantly to nonattainment or maintenance
areas in any other State, or which interfere with programs under part C
to prevent significant deterioration of air quality or to achieve
reasonable progress toward the national visibility goal for Federal
class I areas (national parks and wilderness areas).  In order to assist
States in addressing their obligations regarding regionally transported
pollution, EPA has finalized the CAIR to reduce SO2 and nitrogen oxide
emissions from large electric generating units.

	To date, few states have submitted a SIP revision addressing the
section 110(a)(2) requirements for the purposes of implementing the
PM2.5 standards.  The EPA recognizes that this situation is due in part
to the fact that there were a series of legal challenges to the PM
standards which were not resolved until March 2002, at which time the
standards and EPA’s decision process were upheld (see section I.B. for
further discussion of past legal challenges to the standards).  To
address the States’ continuing obligation to address the requirements
of section 110(a), section40 CFR 51.1002 of the proposed rule also
required each State to address the required elements of section
110(a)(2) of the CAA in its nonattainment plan SIP revision, if it has
not already done so. On March 10, 2005, EPA entered into a consent
decree with Environmental Defense and American Lung Association
concerning EPA’s failure to find that States failed to submit SIPs to
address the section 110(a)(2) requirements.  As a part of that consent
decree, by no later than October 8, 2008, EPA is required to publish a
notice in the Federal Register related to its determinations of whether
each State has submitted SIPs for PM2.5 that meet the requirements as
stated under section 110(a)(2) of the CAA.     

b. Final Rule. 

	The final rule maintains the regulatory approach described above.

c. Comments and Responsesresponses.  

	There were no comments on this portion of the proposal.

D.  How will the attainment date for a PM2.5 nonattainment area be
determined? Attainment dates

1. Background on statutory requirements.  

	Establishing attainment dates.  Section 172(a)(2) states that an
area’s attainment date “shall be the date by which attainment can be
achieved as expeditiously as practicable, but no later than 5 years from
the date such area was designated nonattainment …, except that the
Administrator may extend the attainment date to the extent the
Administrator determines appropriate, for a period no greater than 10
years from the date of designation as nonattainment considering the
severity of nonattainment and the availability and feasibility of
pollution control measures.”

	Since PM2.5 designations have an effective date of April 2005, the
initial 5-year attainment date for PM2.5 areas would be no later than
April 2010.  For an area with an attainment date of April 2010, EPA
would determine whether it had attained the standard by evaluating air
quality data from the three previous calendar years (i.e. 2007, 2008,
and 2009).  

	For any areas that are granted the full 5 year attainment date
extension under section 172, the attainment date would be no later than
April 2015.  For such areas, EPA would determine whether they have
attained the standard by evaluating air quality data from 2012, 2013,
and 2014.  Section 51.1004 of the proposed regulations addressed the
attainment date requirement.  Section 51.1004(b) provided that in their
attainment demonstrations, States would propose an attainment date
representing attainment as expeditiously as practicable based upon
implementation of existing Federal and State measures, and all new
reasonable local and intrastate measures.  The EPA would approve a
particular attainment date based on its review of the attainment
demonstration.  

Determining Whether an Area Has Attained.  The EPA has the
responsibility for determining whether a nonattainment area has attained
the standard by its applicable attainment date.  Section 179(c)(1) of
the Act requires EPA to make determinations of attainment no later than
6 months following the attainment date for the area.  Under section
179(c)(2), EPA must publish a notice in the Federal Register identifying
those areas which failed to attain by the applicable attainment date. 
The statute further provides that EPA may revise or supplement its
determination of attainment for the affected areas based upon more
complete information or analysis concerning the air quality for the area
as of the area(s attainment date.

Section 179(c)(1) of the Act provides that the attainment determination
for an area is to be based upon an area(s (air quality data as of the
attainment date.(  The EPA will make the determination of whether an
area(s air quality is meeting the PM2.5 NAAQS by the applicable
attainment date primarily based upon data gathered from the air quality
monitoring sites which have been entered into EPA(s Air Quality System
(AQS) database.  No special or additional SIP submittal will be required
from the State for this determination.  

 μg/m3.  The 24-hour standard for PM2.5 is met when the average of 98th
percentile values for three consecutive calendar years at each
monitoring site is less than or equal to 65.5 μg/m3. 

The EPA will begin processing and analyzing data related to the
attainment of PM2.5 areas immediately after the applicable attainment
date for the affected areas.  Current EPA policy, under 40 CFR part 58,
sets the deadline for submittal of air quality data into the AQS
database for no later than 90 days after the end of the calendar year. 

While EPA may determine that an area(s air quality data indicates that
an area may be meeting the PM2.5 NAAQS for a specified period of time,
this does not eliminate the State(s responsibility under the Act to
adopt and implement an approvable SIP.  If EPA determines that an area
has attained the standard as of its attainment date, the area will
remain classified as nonattainment until the State has requested, and
EPA has approved, redesignation to attainment for the area. 

In order for an area to be redesignated as attainment, the State must
comply with the five requirements listed under section 107(d)(3)(E) of
the Act.  This section requires that :

- EPA has determined that the area has met the PM2.5 NAAQS; 

- EPA has fully approved the state’s implementation plan; 

- the improvement in air quality is due to permanent and enforceable
reductions in emissions;

- EPA has fully approved a maintenance plan for the area; 

- the State(s) containing the area have met all applicable requirements
under section 110 and part D.  

2. Determination ofEstablishing Attainment Dates

a. Background

	The EPA proposed rule language on attainment dates that closely tracks
the statutory language.  In the preamble, EPA noted that the attainment
date that is as expeditious as practicable should reflect the projected
impact of existing national and State programs (e.g. partial
implementation of the CAIR rule, final Acid Rain Program, motor vehicle
tier II standards and heavy-duty diesel engine standards, NOx SIP call,
State legislation such as Clean Smokestacks bill in North Carolina) as
well as additional reasonable measures required for the PM2.5
nonattainment SIP.

	With respect to its authority to extend an area’s date beyond 5
years, EPA stated in the preamble that the State can submit a SIP
demonstrating that it is impracticable to attain by the 5-year
attainment date:

 “As stated previously, under section 172(a)(2)(A), EPA may grant an
area an extension of the initial attainment date for a period of one to
5 years.  States that request an extension of the attainment date under
this provision of the CAA must submit a SIP in 2008 that includes, among
other things, an attainment demonstration showing that attainment within
5 years of the designation date is impracticable.  It must also show
that the area will attain the standard by an alternative date that is as
expeditiously as practicable, but in no case later than 10 years after
the designation date for the area (i.e. by April 2015 for an area with
an effective designation date of April 2005).  An appropriate extension
in some cases may be only 1 or 2 years - a 5-year extension is not
automatic upon request. 

	The attainment demonstration must provide sufficient information to
show that attainment by the initial attainment date is impracticable due
the severity of the nonattainment problem in the area, the lack of
available control measures, and any other pertinent information which
shows that additional time is required for the arearelated to attain the
standardthese statutory criteria.   States requesting an extension of
the attainment date must also demonstrate that all local control
measures that are reasonably available and technically feasible for the
area are currently being implemented to bring about expeditious
attainment of the standard by the alternative attainment date for the
area.  The State(s plan will need to project the emissions reductions
expected due to Federally enforceable national standards, State
regulations, and local measures such as RACT and RACM, and then conduct
modeling to project the level of air quality improvement in accordance
with EPA(s modeling guidance.  The EPA will not grant an extension of
the attainment date beyond the initial five years required by section
172(a)(2)(A) for an area if the State has not considered the
implementation of all RACM and RACT local control measures for the area
(see section III.I for a more detailed discussion of RACT and RACM). 
The EPA also will examine whether the State has adequately considered
measures to address intrastate transport of pollution from sources
within its jurisdiction.  In attainment planning, States have the
obligation and authority to address the transport of pollution from one
area of the State to another.  Any decision made by EPA to extend the
attainment date for an area beyond its original attainment date will be
based on facts specific to the nonattainment area at issue and will only
be made after providing notice in the Federal Register and an
opportunity for the public to comment.” 

b. Summary of finalFinal rule

	We are adopting the approach described above from the proposed rule. 
We also wish to clarify language that was in the preamble to the
proposed rule regarding the criteria for an extension.  The preamble
stated that attainment date extensions would be based on the two
statutory extension criteria – “the severity of nonattainment, and
the availability and feasibility of pollution control measures,” - as
well as “other pertinent information which shows that additional time
is required for the area to attain the standard.”  The Clean Air Act
does not include this third clause and the regulatory text for the final
rule does not include this third clause.  The intent of this language in
the preamble to the proposal was that States could include “other
pertinent information” related to the two statutory criteria.     

c. Comments and responses

	Comment: Some commenters expressed concern that EPA’s preamble
language appeared to assert a new basis for granting extensions not
provided by the statute.  They said EPA has authority to extend the
attainment date under Section 7502(a)(2) based solely on consideration
of  two enumerated factors:  the severity of nonattainment, and the
availability and feasibility of control measures.

	Response:  The EPA agrees that extensions must be based upon the two
factors in the statute, which are quite broad.  A clarification of the
preamble phrase cited by the commenter is provided above. The phrase in
question – “any other pertinent information which shows that
additional time is required for the area to attain the standard” --
refers to information that relates to the two statutory factors.

	Comment:  One commenter stated that an area should qualify for an
extension only if the area will implement stringent local controls, yet
still cannot practicably attain by the five-year deadline.  The
commenter stated that at a minimum, EPA must require states to adopt
RACM for both mobile and stationary sources before granting an
extension.  Another commenter said that given the difficulty many areas
will have in meeting the five-year deadline for attainment of the PM2.5
NAAQS (and especially in light of the fact that the deadline occurs only
2 years after states are to submit attainment SIPs), EPA should provide
maximum flexibility in allowing extensions to the full 10-year period.  

	Response:  The EPA agrees that extensions should be granted only if an
area cannot practicably attain within 5 years despite application of all
reasonable measures, including RACM.  Although some measures can be
implemented within a year or two, many measures require a longer period
for installation of controls or full program implementation.  In light
of the limited time period between the SIP submittal deadline and the
5-year date, EPA believes that a significant number of areas may warrant
extensions ranging from one to 5 years, with the length of extension
depending on the factors described above.

	Comment:  One commenter advocated that EPA include in this final rule a
determination of those areas for which attainment within 5 years is
impracticable.  Another commenter advocated that EPA establish guidance
based on EPA national modeling conducted last year to establish 2015 as
constituting expeditious attainment for certain areas.  

	Response: The EPA is not determining in this rulemaking the areas that
should receive extensions or should receive the maximum 10-year
attainment date, for several reasons.  First, EPA did not propose such
an approach.  Therefore, the public has not had the opportunity to
comment on the approach or on the technical information on which EPA
would make such judgments.  

	Second, EPA believes that modeling being conducted by the states, with
updated inventories and finer grids, will generally provide a more
reliable basis for projecting future PM2.5 base case levels than
national modeling conducted by EPA with older information.  State
modeling of future year PM2.5 levels that has been conducted to date
indicates that some areas will start closer or farther from the standard
than EPA had projected.   

	Third, the SIP process provides a forum for states to identify
reasonable controls and conduct analyses to determine the appropriate
attainment date for an area.  This process provides for input from
expert stakeholders, the general public, other states which may share
the same multi-State nonattainment area, and EPA on decisions regarding
controls and attainment dates.  At this time, EPA does not have the
benefit of this process to inform a judgment as to when areas can
practicably attain.  States are responsible for developing RACM
demonstrations; at this time, EPA lacks the information to conduct a
credible RACM demonstration for all PM2.5 nonattainment areas.

	Fourth, no State commenter advocated that EPA attempt to make these
judgments on attainment dates in advance of the State SIP process.  The
statute gives the states the lead in developing State implementation
plans.

	Comment:  Another commenter recommends that an area should receive an
attainment date extension when collectively the following conditions
have been met:

It is proven through modeling that the region is adversely effected by
transport of PM2.5 emissions from up wind sources beyond that State(s
control; 

A State has submitted and committed to implementing all Federal PM2.5
emission reduction requirements in a timely manner; and,

The extension concept is approved through the State air agency or
through the MPO Interagency Consultation Process at the MPO level if
applicable.

	Response:  This commenter advocates for attainment date extensions
without any consideration of reasonable local measures.  As stated
above, EPA believes that extensions should be granted only if an area
cannot practicably attain within 5 years despite application of all
reasonable measures, including RACM.  Although some measures can be
implemented within a year or two, many measures may require a longer
period for installation of controls or full program implementation.  In
light of the limited time period between the SIP submittal deadline and
the 5-year date, EPA believes that a significant number of areas may
warrant extensions ranging from one to 5 years, with the length of
extension depending on the factors described above.

3.  Attainment dates:  1-year extensions

a.  Background.  

	Subpart 1 provides for States to request two 1-year extensions of the
attainment date for a nonattainment area under limited circumstances. 
Section 172(a)(2)(C) of the CAA provides that EPA initially may extend
an area(s attainment date for 1 year, provided that the State has
complied with all the requirements and commitments pertaining to the
area in the applicable implementation plan, and provided that the area
has had no more than a minimal number of (exceedances( of the relevant
standard in the preceding year.  Because the PM2.5 standards do not have
exceedance-based forms but are based on 3-year averaging periods, we
interpret the air quality test in section 40 CFR 51.1005 to mean that
the area would need to have (clean data( for the third of the 3 years
that are to be evaluated to determine attainment.   By this we mean that
for the third year, the air quality for all monitors in the area as
analyzed in accordance with Appendix N to 40 CFR Part 50 each must have
an annual average of 15.0 μg/m3 or less, and a 98th percentile of
24-hour monitoring values of 65 μg/m3 or less in order to qualify for a
1-year extension.  (Given the rounding provisions specified in 40 CFR
Part 50, Appendix N, these criteria would be satisfied if the
concentrations before final rounding are less than an annual average of
15.05 μg/m3 and a 24-hour value of 65.5 μg/m3.)

	For example, suppose an area in violation of the annual standard has an
attainment date of April 2010, and its annual average for 2007 was 15.8
and for 2008 was 15.6.  If the annual average for the area in 2009 is
14.9, then the 3-year average would be 15.4, and it would not have
attained the standard.  We interpret section 172(a)(2)(C) as allowing
the area to submit a request to EPA for a 1-year extension of its
attainment date to 2011 (provided the State has also complied with its
requirements and commitments) since the 14.9 ambient air quality value
in the third year (2009) met the test of being at or below 15.0. 
Section 51.1005(a) of the proposed regulation addresses the initial
1-year attainment date extension.

	The air quality measured in 2010 in conjunction with prior data will
determine if the area attains the standard, qualifies for a second
1-year extension, or does not attain the standard.  For example, if the
area(s annual average for 2010 is 14.3, then its 3-year average for
2008-2010 would be 14.9 and it would have met the annual standard.  

	If the area(s annual average for 2010 is 14.9, however, then its 3-year
average for 2008-2010 would be 15.1.  In this situation the area would
not have attained the standard, but the area would meet the air quality
test for the second of the 1-year extensions allowed under section
172(a)(2)(C), because the 2010 annual average was at or below 15.0. 
Section 51.1005(b) of the proposed rule addresses the second 1-year
attainment date extension.  After obtaining a second 1-year extension,
the State would evaluate whether the air quality values in 2011, in
conjunction with 2009 and 2010 data, bring the area into attainment. 

	Pursuant to section 172(a)(2)(C), States must submit additional
information to EPA to demonstrate that they have complied with
applicable requirements, commitments, and milestones in the
implementation plan.  This information is needed in order for EPA to
make a decision on whether to grant a 1-year attainment date extension. 
The EPA will not be inclined to grant a 1-year attainment date extension
to an area unless the State can demonstrate that it has met important
requirements contained in the area(s implementation plan.  States must
demonstrate that: (1) control measures have been submitted in the form
of a SIP revision and substantially implemented to satisfy the
requirements of RACT and RACM for the area, (2) the area has made
emissions reductions progress that represents reasonable further
progress (RFP) toward attainment of the NAAQS, and (3) trends related to
recent air quality data for the area indicate that the area is in fact
making progress toward attainment of the standard.  Any decision made by
EPA to extend the attainment date for an area will be based on facts
specific to the nonattainment area at issue, and will only be made after
providing notice in the Federal Register and an opportunity for the
public to comment.

	If an area fails to attain the standard by the attainment date, EPA
would publish a finding to this effect in accordance with section 179 of
the CAA.  The area then would be required, within 1 year of publication
of this finding, to develop a revised SIP containing additional emission
reduction measures needed to attain the standard as expeditiously as
practicable.  

b.  Final ruleRule.  

	The final rule retains the proposed criteria for states to receive a
1-year attainment date extension for a nonattainment area.  

c.  Comments and Responses

	Comment:  A number of commenters supported EPA(s ability to grant a
1-year attainment date extension if monitoring data indicate that the
PM2.5 levels during the most recent year were below 15.05 ug/m3.  

	Response:  The EPA agrees with these comments.

	Comment:  Some commenters recommended that a 1-year extension be
provided if the trend line of the area’s emissions levels or air
quality data projects attainment in the extension year.  

	Response:  The EPA believes that 1-year extensions should be based on
air quality data, which can be assessed quickly after the end of the
year.  Basing such extensions solely on emissions trends would be
impractical due to the longer turnaround time needed to evaluate
emissions changes affecting a monitor. 

	Comment:  One commenter believes the current requirement is overly
stringent and inconsistent with the statute.  The commenter believes
that EPA’s proposed approach incorrectly defines the statutory
language referring to a “minimal number of exceedances” of the
standard in the previous year as “zero” exceedances.  
Alternatively, the commenter suggests EPA could withdraw this provision
and provide more detailed guidance giving the Agency and states some
flexibility to demonstrate that exceedances were minimal in a given case
since nothing in the statute requires the rigid definition of minimal
that EPA proposes.

	Response:  The EPA believes the policy in the final rule is a
reasonable application of the statutory language to a standard not based
on exceedances.  The EPA does not believe it would be appropriate to
provide a 1-year extension to an area with air quality data showing it
violating the standard over the 3 years prior to the attainment year. 

4.  Achieving “Clean Data” Prior to the area’s approved attainment
date

 a.  Background 

	Section III.D of the preamble to the proposed rule describes the
incentives for attaining the standards prior to April 2008, when SIP
submittals are due, or prior to an area’s approved attainment date. 
Areas with design values just over the level of the standard may be able
to achieve reductions in the local area or in the State so that, when
their effect is considered in combination with reductions achieved under
national programs, they may be sufficient to attain the standards before
SIPs are due in 2008.  For example, if monitoring in a nonattainment
area shows that the air quality for 2004-2006 meets the standards, then
the area may be subject to reduced regulatory requirements and be
redesignated as (attainment.(  

	EPA issued a (Clean Data( policy memorandum in December 2004 describing
possible reduced regulatory requirements for areas that attain the
standards early, but have not yet been redesignated as attainment.

b.  Final Rule

	In the proposed rule, EPA indicated that it had issued  this “Clean
Data” policy to apply for purposes of the PM2.5 standards.  In this
action EPA is finalizing as a rule the statutory interpretation that is
embodied in the policy.  Section 51.1004(c).  The text of the final rule
encapsulates the statutory interpretation set forth in the policy. 
Determinations as to whether individual areas have attained the PM2.5
standard and thus qualify for application of the new clean data rule
will be made in the context of rulemakings for those individual areas.

	The preamble to the proposed rule mistakenly stated that if an area
achieved “clean data,” it would be “relieved of the requirements
to implement the nonattainment NSR program otherwise required for
nonattainment areas, and instead would implement the PSD program.”  
EPA wishes to clarify that the   SEQ CHAPTER \h \r 1 Clean Data Policy
does not provide for suspension of the requirements for NSR nor for
RACT.  The provisions at issue in the Clean Data Policy include the
requirements for an attainment demonstration and other related
requirements, reasonable further progress, and contingency measures.

	c.  Comments and Responses

	Comment:  One commenter stated that EPA has absolutely no authority to
waive NSR or any of the Clean Air Act(s other requirements for
nonattainment areas merely because a nonattainment area has 3 years of
clean data, nor does EPA have authority to waive mandatory requirements
of the CAA such as NSR, RACT, and RFP merely because EPA or the State
claims they are not needed for attainment.  The commenter believes that
the only way that a nonattainment area can cease implementing controls
and requirements mandated for such areas is to seek and obtain
redesignation to attainment, and demonstrate in the process that the
controls and requirements are not needed for maintenance of standards. 
The CAA has explicit procedures and prerequisites for redesignating
nonattainment areas to attainment (CAA ((sections 107(d)(3)(E) and
175A).  EPA(s “clean data” proposal would illegally circumvent those
requirements.

	Response:  The Clean Data policy does not waive requirements for NSR
nor for RACT.  However, EPA believes that “clean data” policies for
the ozone and fine particle programs are based on a reasonable
interpretation of the CAA.  The Clean Data Policy is the subject of two
EPA memoranda setting forth our interpretation of the provisions of the
Act as they apply to areas that have attained the relevant NAAQS.  EPA
also finalized the statutory interpretation set forth in the policy in a
final rule, 40 CFR 51.918, as part of its Final Rule to Implement the
8-Hour Ozone National Ambient Air Quality Standard – Phase 2 (Phase 2
Final Rule).  See discussion in the preamble to the rule at 70 FR
71645-71646 (November 29, 2005).  The legal rationale for the Clean Data
policy is explained in our Phase 2 Final Rule, in our December 14, 2004
memorandum from Stephen D. Page entitled “Clean Data Policy for the
Fine Particle National Ambient Air Quality Standards” (Page Memo), and
in our May 10, 1995 memorandum from John S. Seitz, entitled
“Reasonable Further Progress, Attainment Demonstration, and Related
Requirements for Ozone Nonattainment Areas Meeting the Ozone National
Ambient Air Quality Standard” (Seitz memo).    We adopt and reiterate
those explications here.

	EPA has also explained its rationale for applying the Clean Data policy
in rulemaking actions associated with nonattainment areas for the PM-10
and 1-hour ozone standards.  For rulemaking actions applying the Clean
Data policy to the PM-10 standards, see 71 FR 27440 (May 11, 2006)
(Weirton, WVA), 71 FR 13021 (March 14, 2006) (Yuma, AZ), 71 FR 6352
(February 8, 2006) (Ajo, Az).  For a discussion of the legal rationale
supporting rulemaking actions applying the Clean Data policy to the
1-hour ozone standards, see, for example, 67 FR 49600 (July 31, 2002);
65 FR 37879 (June 19, 2000) Cincinnati-Hamilton, Ohio-Kentucky); 61 FR
20458 (May 7, 1996) (Cleveland Akron-Lorain, Ohio); 66 FR 53094 (October
19, 2001) (Pittsburgh-Beaver Valley, Pennsylvania); 61 FR 31832 (June
21, 1996 (Grand Rapids, Michigan); 60 FR 36723 (July 18, 1995) (Salt
Lake and Davis Counties, Utah); 68 FR 25418 (May 12, 2003) (St Louis,
Missouri); 69 FR 21717 (April 22, 2004) (San Francisco Bay Area).  

 	EPA has further elaborated on its legal rationale for the Clean Data
Policy in briefs filed in the 10th, 7th, and 9th Circuits, and hereby
incorporates those briefs insofar as relevant here.  See Sierra Club v.
EPA, No. 95-9541 (10th Cir.), Sierra Club v. EPA, NO. 03-2839, 03-3329
(7th Cir.), Our Children’s Earth Foundation v. EPA, No. 04-73032 (9th
Cir.).  As stated in the policy, the attainment demonstration, RFP
requirements, and contingency measure requirement are designed to bring
an area into attainment.  Once this goal has been achieved, it is
appropriate to suspend the obligation that States submit plans to meet
these goals, so long as the area continues to attain the relevant
standard.  The Tenth, Seventh and Ninth Circuits have all upheld EPA
rulemakings applying the Clean Data Policy.  See Sierra Club v. EPA, 99
F. 3d 1551 (10th Cir. 1996); Sierra Club v. EPA, 375 F. 3d 537 (7th Cir.
2004); Our Children’s Earth Foundation v. EPA, No. 04-73032 (9th Cir. 
June 28, 2005 (Memorandum Opinion).

	EPA has explained in its memoranda on the Clean Data Policy for PM 2.5
and for ozone that it is reasonable to interpret the provisions
regarding RFP and attainment demonstrations, along with certain other
related provisions, as not requiring further submissions to achieve
attainment for so long as the area is in fact attaining the standard. 
Under the policy, EPA is not granting an exemption from any applicable
requirement under Part D.  Rather, EPA has interpreted these
requirements as not applying for so long as the area remains in
attainment with the standard.  This is not a waiver of requirements that
by their terms apply; it is a determination that certain requirements
are written so as to be operative only if the area is not attaining the
standard.  

     CAA section 172(c)(2) provides that SIP provisions in nonattainment
areas must require “reasonable further progress.”  The term
“reasonable further progress” is defined in section 171(1) as
“such annual incremental reductions in emissions of the relevant air
pollutant as are required by this part or may reasonably be required by
the Administrator for the purpose of ensuring attainment of the
applicable NAAQS by the applicable date.”  Thus, by definition, the
“reasonable further progress” provision requires only such
reductions in emissions as are necessary to attain the NAAQS.  If an
area has attained the NAAQS, the purpose of the RFP requirement will
have been fulfilled, and since the area has already attained, showing
that the State will make RFP towards attainment will “have no meaning
at that point.”  EPA’s General Preamble for the Implementation of
Title I of the Clean Air Act Amendments of 1990” (General Preamble) 57
FR 13498 , 13564 (April 16, 1992).  

     CAA section 172(c)(1), the requirement for an attainment
demonstration, provides in relevant part that SIPs “shall provide for
attainment of the [NAAQS].”   EPA has interpreted this requirement as
not applying to areas that have reached attainment.  If an area has
attained the standard, there is no need to submit a plan demonstrating
how the area will reach attainment.  In the General Preamble (57 FR
13564), EPA stated that no other measures to provide for attainment
would be needed by areas seeking redesignation to attainment since
“attainment will have been reached.”  See also Memorandum from John
Calcagni, “Procedures for Processing Requests to Redesignate Areas to
Attainment,” September 4, 1992, at page 6.  

       CAA section 172(c)(9) provides that SIPs in nonattainment areas
“[S]hall provide for the implementation of specific measures to be
undertaken if the area fails to make reasonable further progress, or to
attain the [NAAQS] by the attainment date applicable under this part. 
Such measures shall be included in the plan revision as contingency
measures to take effect in any such case without further action by the
State or [EPA].”  

	This contingency measure requirement is inextricably tied to the
reasonable further progress and attainment demonstration requirements. 
Contingency measures are implemented if reasonable further progress
targets are not achieved, or if attainment is not realized by the
attainment date.  Where an area has already achieved attainment by the
attainment date, it has no need to rely on contingency measures to come
into attainment or to make further progress to attainment.  As EPA
stated in the General Preamble:

“The section 172©(9) requirements for contingency measures are
directed at ensuring RFP and attainment by the applicable date.”   57
FR 13564.  Thus these requirements no longer apply when an area has
attained the standard.

It is important to note that should an area attain the PM2.5 standards
based on three years of data, its obligation to submit an attainment
demonstration is not waived but is only suspended.  If the area then has
air quality concentrations in the following year such that the area
exceeds the standard for years 2 through 4, then the area’s obligation
to submit an attainment demonstration is back in effect.  

     The determination of attainment contemplated by the Clean Data
Policy does not purport to be a redesignation, and thus the requirements
for redesignation under section 107(d) are not applicable.  Nor does the
Clean Data Policy avoid or illegally circumvent the redesignation
requirements of section 107 of the Clean Air Act.  All of the
requirements for redesignation remain in effect and must be satisfied
for an area to be redesignated.  Sierra Club v. EPA, 99 F.3d at
1557-1558.   The Clean Data Policy is simply an interpretation of
certain provisions of the CAA, whose express purpose is to achieve
attainment of the standard, as not requiring SIP revisions to be made by
the State for so long as the area continues to attain the standard.  The
policy does not purport to exempt areas from requirements that are
inapplicable only if an area is redesignated to attainment.  It
interprets certain provisions which are written in such a way as to
impose requirements only upon areas that are not attaining the NAAQS,
regardless of whether they have been redesignated to attainment.  EPA
has not provided for any waiver from statutory requirements that was not
provided by Congress.  The area at issue remains designated
nonattainment, and is subject to the risk that if a violation occurs it
will have to adopt and implement reasonable further progress
requirements, contingency measures, and an attainment demonstration,
unless it is redesignated to attainment.  In order to be redesignated to
attainment, however, the area will have to satisfy all of the
requirements of section 107(d)(3)(E), including the requirement for a
long-term maintenance plan.  

     While a determination of attainment is not equivalent to a
redesignation to attainment, nothing in the Act compels EPA to wait
until an area meets all the requirements for redesignation before EPA
makes a determination that the area is in attainment with the standard,
thereby suspending the requirements for certain provisions related to
attainment.  Indeed, section 179(c) of the Act requires EPA to make an
attainment determination within six months after an area’s applicable
attainment date whether or not EPA has made a finding with respect to
redesignation.  EPA’s interpretation of the Act’s provisions not to
require, once attainment has been reached, certain plan submissions
whose purpose is to assure attainment, is not at odds with the
requirements for redesignation.  Nor does EPA’s construction of the
statute adversely impact planning for maintenance.  An area that is
monitoring attainment, but is still designated as a nonattainment area,
retains strong incentives to seek redesignation to attainment, and
remains subject to the requirement to demonstrate maintenance in order
to be redesignated.  For a detailed discussion of the relationship of
redesignation requirements and attainment determinations, see the
discussions in the EPA briefs in Our Children’s Earth Foundation v.
EPA, supra at pp. 43-60., Sierra Club v. EPA No. 95-9541 (10th Cir.) at
29-43, and Sierra Club v. EPA Nos. 03-2839, 03-3329 (7th Cir.) at 33-44
which are contained in the docket for this rulemaking. 

4.  Determining attainment 

[to be added]

	  SEQ CHAPTER \h \r 1 Comment: A commenter noted that EPA’s proposal
suggested that areas attaining the standard would be subject to reduced
regulatory requirements.  The commenter believed that EPA’s
interpretation should be codified in regulatory form, in order to assure
that areas legally meeting the current PM2.5 standard and those
requesting redesignation be enabled to be redesignated and to benefit
from the interpretation through regulation, rather than by guidance or
policy.

	Response:  EPA has adopted the commenter’s suggested approach of
codifying its Clean Data Policy interpretation for PM 2.5 in regulatory
form.  Section 51.1004(c).  As it did for ozone in its Phase II Ozone
Implementation Rule, EPA is including in this rulemaking a regulation
that encapsulates the statutory interpretation  that is embodied in its
Clean Data Policy for PM2.5 , set forth above.  As noted in the 
response to comment above, determinations as to whether individual areas
have attained the PM2.5 standard and thus qualify for application of the
rule will be made in the context of rulemakings for those individual
areas.  EPA believes, however, that encapsulating its interpretation in
regulatory form will lend clarity and consistency to the process of
applying its interpretation.   

E.  Modeling and Attainment Demonstrations

a.1.  Background

[Section III.F.1 of November 1, 2005 proposed rule (70 FR 66007); sec
51.1007 in draft and final regulatory text]

	As noted in the proposal, Section 172(c) requires States with
nonattainment areas to submit an attainment demonstration.  An
attainment demonstration consists of: (1) technical analyses that
locate, identify, and quantify sources of emissions that are
contributing to violations of the PM2.5 NAAQS; (2) analyses of future
year emissions reductions and air quality improvement resulting from
already-adopted national and local programs, and from potential new
local measures to meet the RACT, RACM, and RFP requirements in the area;
(3) adopted emission reduction measures with schedules for
implementation; and (4) contingency measures required under section
172(c)(9) of the CAA.  

b.a.  Final Rule

	The requirements from the proposal are unchanged.  Each State with a
nonattainment area will be required to submit a SIP with an attainment
demonstration that includes analyses supporting the State(s proposed
attainment date.  States must show that the area will attain the
standards as expeditiously as practicable and it must include an
analysis of whether implementation of reasonably available measures will
advance the attainment date.  

2. Areas that need to conduct modeling

[Section III.F.2 of November 1, 2005 proposed rule (70 FR 66007)]

a.  Background

	All nonattainment areas need to submit an attainment demonstration, but
in some cases, States may not need new, local-scale modeling analyses. 
In the proposed rule, EPA proposed that States may use in a PM2.5
attainment demonstration certain local, regional and/or national
modeling analyses that have been developed to support Federal or local
emission reduction programs, provided the modeling meets the attainment
modeling criteria set forth in EPA(s modeling guidance.  The proposal
also stated that nonattainment areas for which local, regional, or
national scale modeling demonstrates the area will not attain the
standard within 5 years of designation would be required to submit an
attainment demonstration SIP that includes new modeling showing
attainment of the standards as expeditiously as practicable.  

b.  Final Rule

	In the final rule, EPA is reaffirming the potential use of national
and/or regional modeling as part of an attainment demonstration.  We are
also clarifying the types of modeling analyses that may be useful as a
“primary” modeling analysis and as a “supplemental” analysis.  

The proposal suggested that it may be appropriate, in certain
circumstances, for a State to submit regional or national modeling as
the sole (primary) modeling analysis in its attainment demonstration. 
This implies that the State would not need to conduct local modeling
analyses.  

We wish to further define the differences between “national”,
“regional”, and “local” modeling analyses.  In this context,
national analyses are generally those conducted by EPA in support of
national or regional rules.  Regional and local modeling analyses are
generally those conducted by the RPOs and/or States for the purpose of
developing State Implementation Plans (SIPs).  

EPA has conducted national scale modeling for a variety of rules and
analyses.  Additionally, the RPOs and many States are conducting
regional and/or local scale modeling of PM2.5 and regional haze across
the country.  The national scale of the EPA modeling analyses requires
basic assumptions concerning local model inputs.  Compared to regional
or local modeling done by the States and/or RPOs, EPA modeling may, in
some cases, use coarser grid resolution, use inventories that are not as
refined, and model performance may be highly variable from area to area.
 For these reasons, national scale modeling may not always be
appropriate for local area attainment demonstrations.  

While States are encouraged to submit national modeling that supports
their attainment demonstrationTherefore, we believe that this modeling
is best served as a supplemental analysis and/or part of a weight of
evidence demonstration.  Regional regional or local modeling conducted
by the States or RPOs is best suited as the primary modeling analysis
for a modeled attainment demonstration.  The local modeling is more
likely to meet the recommendations contained in EPA’s modeling
guidance.  However, some areas having design values close to the
standard may be projected to come into attainment within five years
based on modeling analyses of national and regional emission control
measures (e.g CAIR) that are scheduled to occur through 2009.  Regional
scale modeling for national rules such as the Tier II motor vehicle
standards, the Heavy-duty Engine standards, the Nonroad Engine
standards, and CAIR indicate major reductions in PM2.5 by 2010.  A
portion of these benefits will occur in the 2006-2009 PM2.5 attainment
timeframe. 

Experience with past ozone attainment demonstrations has shown that the
process of performing detailed photochemical grid modeling to develop an
attainment demonstration can be very resource intensive for States.  The
EPA believes that it would be appropriate for States to leverage
resources by collaborating on modeling analyses to support SIP
submittals, or by making use of recent modeling analyses that are
completed prior to the SIP submittal date.  For this reason, EPA
recognizes that States may use in a PM2.5 attainment demonstration
certain local, regional and/or national modeling analyses that have been
developed to support Federal or local emission reduction programs,
provided the modeling meets the attainment modeling criteria set forth
in EPA(s modeling guidance (described below).  As with all SIPs under
subpart 1, the State must demonstrate that the area will attain the
PM2.5 standards as expeditiously as practicable.  The judgment of
whether the modeling is appropriate for an area should be made by the
State(s) and their respective EPA regional office on a case-by-case
basis. 

c.  Comments and Responses

	Comment:  There were many commenters that agreed that States should be
able to use EPA modeling or other national or regional modeling as a
modeled attainment demonstration.  One commenter recommended that the
final rule require States to show that the existing modeling
incorporates realistic assumptions, accurately reflects local emissions
and trends, and provides adequate model performance for the local
nonattainment area.

	Response:  We agree that national and/regional modeling may be used as
part of an attainment demonstration as long as it is shown to be
applicable to the local area.  This is consistent with the proposal
where we said that existing modeling should “meet the attainment
modeling criteria set forth in EPA(s modeling guidance.”  Part of the
analysis to determine if existing modeling meets the criteria in the
modeling guidance is to assess whether the modeling incorporates
realistic assumptions, accurately reflects local emissions and trends,
and provides adequate model performance for the local nonattainment
area. 

	Comment:  Some commenters thought States should be able to use EPA
modeling in the absence of an analysis of the applicability of the
modeling for a local nonattainment area.  One commenter said that EPA
should determine that States should not have to do any additional
modeling analyses if the CAIR modeling showed they were expected to
attain the NAAQS by 2010.  

	Response:  WeWhile we acknowledge there may be some circumstances in
which national or regional modeling would be appropriate to use without
local modeling and allow for such use, we disagree that national
modeling should be used in support of an attainment demonstration
without further analysis of the modeling assumptions for a particular
area.  National scale modeling may not always be appropriate for local
areas.  Most often, national scale EPA modeling is best suited for use
as a supplemental analysis or as part of a "weight of evidence"
demonstration.  The modeling guidance recommends supplemental analyses
for all attainment demonstrations.  The guidance specifically recommends
the examination of other modeling studies as a supplemental analysis. 
The EPA modeling as well as other “non-local” modeling can be used
for this purpose.  The “weight” of this alternative modeling in an
attainment demonstration should be guided by how well the modeling
system is suited for the local nonattainment area.  States should
consult with their EPA regional offices for further guidance and
recommendations. As such, we do not believe it to be appropriate to
determine a priori that CAIR or any other modeling analyses are
appropriate to use in a local attainment demonstration for any or all
nonattainment areas.  

	Comment:  Several commenters believe that States should be able to use
existing EPA modeling (such as CAIR), as the basis for an extension of
the area’s attainment date, if it shows that the nonattainment area
may not be able to attain the NAAQS by 2010.  They believe that the
State should not have to do additional modeling to show that they need
an attainment date extension. 

	Response:  We disagree with this comment.  The CAIR modeling only
included national controls that are expected to be in place by 2010
(including the CAIR rule itself).  It did not include any additional
local controls that could be implemented under RACT and RACM
requirements that may bring the area into attainment sooner. 
Nonattainment areas are required to attain the NAAQS as expeditiously as
practicable.  Therefore, additional modeling of existing controls as
well as additional local controls is needed before an attainment date
extension can be granted.  Additional information on attainment dates
and extensions is contained in the preamble to the final rule, section
xxxxII.D., and additional information on RACT and RACM requirements is
contained in section III.J.(?)F.

	Comment:  Several commenters noted an apparent inconsistency in the
language concerning who would be required to perform “new”
local-scale modeling.  First, there are potentially conflicting
statements in the proposal when EPA states that areas with an attainment
date of 2010 will need to conduct local-scale modeling to project the
estimated level of air quality improvement in accordance with EPA’s
modeling guidance.  This conflicts with the proposed ability for States
to use existing national or regional modeling as their modeled
attainment demonstration.  Second, a portion of a sentence was removed
from the Federal Register version of the notice which differs from the
pre-Federal Register version.  The published version implies that all
nonattainment areas would be required to submit new modeling.  

	Response:  We agree that there are inconsistencies in the proposal
preamble text.  To clarify, new local-scale modeling is required for
areas that are not expected to come into attainment by 2010.  For other
areas, there may be national or regional modeling which may be
applicable to the area which shows they are likely to come into
attainment.  As noted earlier, national scale modeling is best suited
for use as a supplemental analysis, but in some cases may be acceptable
evidence that an area will attain by 2010.

	Additionally, the preamble language in the Federal Register contained
an error.  A portion of a sentence was mistakenly removed, which led to
some confusion.  The language in the FR notice (FR page 66008) stated
“Nonattainment areas would be required to submit an attainment
demonstration SIP that includes new modeling showing attainment of the
standards as expeditiously as practicable.  The new modeling will need
to include additional emissions controls or measures in order to
demonstrate attainment.”  The language should have read,
“Nonattainment areas for which local, regional, or national scale
modeling demonstrates the area will not be in attainment of the NAAQS
within 5 years of designation would be required to submit an attainment
demonstration SIP that includes new modeling showing attainment of the
standards as expeditiously as practicable.  The new modeling will need
to include additional emissions controls or measures in order to
demonstrate attainment.”  This should clarify that States that cannot
show attainment within 5 years will need to develop new modeling
analyses which contain additional control strategies which show how and
when they expect to attain the PM2.5 NAAQS.    

	Comment:  One commenter maintained that relying on large-scale regional
modeling alone may allow for PM2.5 hot spots (i.e. small unmonitored
areas projected to exceed the standard) to exist past the attainment
date.

	Response:  The EPA’s modeling guidance for PM2.5 generally recommends
that for urban scale PM2.5 modeling, the State performs modeling
analyses at 12 kilometer grid resolution or finer.  The guidance
contains procedures for examining modeled results in areas without
monitors.  The "unmonitored area analysis" procedure recommended in the
guidance is intended to address large scale unmonitored areas (on the
order of 12km resolution) that may be in danger of violating the NAAQS.
These areas may be influenced by a large range of sources including
direct PM2.5 emissions from point sources.  In areas where potential
NAAQS violations are indicated, EPA recommends that the State conduct
further analyses to better understand the sources potentially
contributing to the projected high values.  For example, the State could
run a dispersion model to further evaluate the contributions of sources
of direct PM2.5 emissions.	Response:  We agree that nonattainment areas
with potential hotspot issues (relatively high concentrations and/or
gradients of primary PM2.5) should not rely exclusively on regional
modeling.  EPA's attainment demonstration modeling guidance attempts to
address several aspects of hotspot issues in both monitored and
unmonitored areas.  The modeled attainment tests contained in EPA's
modeling guidance are primarily monitor based tests.  Ambient data is
combined with the model predicted relative change in PM components to
determine if attainment of the standards is likely in the future.  There
are several aspects of the attainment test.  In most cases, States will
run a photochemical grid model to determine the future year predicted
PM2.5 concentrations at monitors.  The modeling guidance generally
recommends that for urban scale PM2.5 modeling, the State performs
modeling analyses at 12 kilometer grid resolution or finer.  There is an
additional component to the attainment test for areas that have measured
relatively high concentrations and/or gradients of primary PM2.5 at
monitors.  In these cases, we recommend running a Gaussian dispersion
model for potential primary PM sources, to determine the local impact of
changes in primary PM emissions (from the modeled sources) on predicted
concentrations at the monitor(s).  

	In addition, we describe an "unmonitored area analysis" which uses
interpolated ambient data combined with gridded model outputs to examine
whether potential violations of the NAAQS may occur in unmonitored
areas.  If potential violations are indicated, we recommend further
analysis of the problem through additional local modeling.  Options for
State action to address such a situation could include imposition of
reasonably available control technology to reduce emissions, or the
deployment of an air quality monitor to further characterize the
problem. 

	We believe that the combination of these model based tests will
adequately determine whether attainment of the standards is likely by
the attainment date.  We also believe that these tests address the issue
of hotspots by recommending a combination of photochemical modeling,
dispersion modeling of local sources, and additional monitoring and/or
emissions controls. 

3. Modeling Guidance

[Section III.F.3 of November 1, 2005 proposed rule (70 FR 66008)]

a.  Background.

	Section 110(a)(2)(K)(i) states that SIPs must contain air quality
modeling as prescribed by the Administrator for the purpose of
predicting the effect of emissions on ambient air quality.  The
procedures for modeling PM2.5 as part of an attainment SIP are contained
in EPA(s (Guidance for Demonstrating Attainment of Air Quality Goals for
PM2.5 and Regional Haze.”  The proposal summarized several of the
chapters in a draft version of the modeling guidance.

b.  Final rule.  

	TheA draft of the PM2.55 attainment demonstration and regional haze
modeling guidance has now been finalizedrevised (September 2006) and is
available at   HYPERLINK "http://www.epa.gov/ttn/scram/xxxxx" 
http://www.epa.gov/ttn/scram/xxxxx
.http://www.epa.gov/ttn/scram/guidance_sip.htm.  The final draft PM2.5
attainment demonstration and regional haze guidance has been
incorporated into the ozone modeling guidance and is now called
“Guidance on the Use of Models and Other Analyses in for Demonstrating
Attainment of Air Quality Goals for the 8-Hour Ozone and PM2.5 NAAQS and
Regional Haze”.  The final version of the modeling guidance will be
available at the same location by the end of the year.  

	The finalrevised draft PM2.5 modeling guidance document is very similar
to the previous draft version, although there were several changes and
updates.  Among them are new methods in treating PM2.5 species
components as part of the PM2.5 attainment test; new methods for
determining potential future year violations in unmonitored areas; new
procedures for handling potential PM2.5 “hotspots”; and an increased
reliance on supplemental analyses, including “weight of evidence”
analyses.  EPA notes that the PM2.5 attainment demonstration modeling
guidance that we have released is separate from the Agency’s future
hot-spot modeling guidance for transportation conformity purposes.     

	The modeling guidance describes how to estimate whether a control
strategy to reduce emissions of particulate matter and its precursors
will lead to attainment of the annual and 24-hour PM2.5 NAAQS.  Part I
of the guidance describes a (modeled attainment test( for the annual and
24-hour PM2.5 NAAQS.  Both tests are similar.  The output of each is an
estimated future design value consistent with the respective forms of
the NAAQS.  If the future design value does not exceed the concentration
of PM2.5 specified in the NAAQS, then the primary modeled test is
passed.  The modeled attainment test applies to locations with monitored
data. 

	A separate test is recommended to examine projected future year PM2.5
concentrations in unmonitored locations.  Interpolated PM2.5 ambient
data, combined with modeling data, is used to predict PM2.5
concentrations in unmonitored areas.  The goal of this analysis is to
identify areas without monitors that may be violating the PM2.5 NAAQS,
often due to high levels of primary PM2.5 (both now and in the future). 
The details of the analysis are contained in the final modeling
guidance.

	The guidance also discusses modeling PM2.5 at monitors where high
concentrations of primary PM2.5 are measured.  In these cases, it may be
beneficial to model the primary component of the PM2.5 with a Gaussian
dispersion model.  Dispersion models are better able to capture the
influence of primary PM sources where large concentration gradients may
exist.  Grid models spread out the PM emissions to the size of the grid
(typically 4 or 12 km). This makes it difficult to judge the benefits of
control strategies that may affect primary PM sources.  The final
modeling guidance recommends procedures for applying dispersion models
in these situations. 

	The guidance also recommends the submittal of supplemental analyses as
part of all attainment demonstrations.  Supplemental analyses are
modeling, emissions, and/or ambient data analyses that are submitted as
part of a SIP, in addition to the primary modeled attainment test.  The
evaluation of supplemental analyses when the predicted concentrations in
the primary attainment test are close to the NAAQS (slightly above or
slightly below) is called a weight-of-evidence (WOE) analysis.  This is
simply a collection of evidence that aims to show that attainment of the
standard is likely.  The final version of the modeling guidance puts
more emphasis on the submittal of supplemental analyses than in previous
versions.  

	Part II of the guidance describes how to apply air quality models to
generate results needed by the modeled tests for attainment. This
includes developing a conceptual description of the problem to be
addressed; developing a modeling/analysis protocol; selecting an
appropriate model to support the demonstration; selecting appropriate
meteorological episodes or time periods to model; choosing an
appropriate area to model with appropriate horizontal/vertical
resolution; generating meteorological and air quality inputs to the air
quality model; generating emissions inputs to the air quality model;
evaluating performance of the air quality model; and performing
diagnostic tests.  After these steps are completed, the model is used to
simulate the effects of candidate control strategies.

	Comment: Several commenters were supportive of the weight of evidence
concept.  They said that PM2.5 modeling is inherently more uncertain
than previous ozone modeling and the modeling guidance should reflect
that.  One commenter noted that weight of evidence demonstrations should
be “unbiased”, meaning that States should use all relevant analyses
and not only information that helps their case. 

	Response:  The EPA agrees with these comments.  The final modeling
guidance recommends supplemental analyses (including weight of evidence)
for all attainment demonstrations.  All States should submit modeling,
ambient data, and emissions analyses in addition to the primary modeling
demonstration.  A weight of evidence analysis is needed if the predicted
future year PM2.5 concentrations are slightly higher or slightly lower
than the NAAQS. 

	We also agree that a weight of evidence demonstration should include
all relevant information, including analyses which support attainment
and those that do not.  The idea of the analysis is to “weigh” the
evidence, both good and bad.  That cannot be fairly done if some
evidence is not presented.    

	Comment:  Several commenters suggested that a modeled attainment
demonstration should not be specifically required.  Instead they suggest
that all demonstrations should be weight of evidence demonstrations. 
This would include different analyses of ambient data, trends, and
modeling.  But due to the uncertainties in the current PM2.5 models and
emissions data, modeling would be but one part of a broader weight of
evidence approach.

Response:  We disagree with this comment.  Model results should be the
primary analysis of an attainment demonstration.  Regardless of current
uncertainties in the PM2.5 models and emissions, models are the only
tool that can predict future concentrations of PM2.5.  The uncertainties
in the model inputs and formulation should be taken into account when
evaluating the results.  We agree that a broad analysis of modeling,
ambient data and emissions trends should be part of the attainment
demonstration.  This is reflected in the final modeling guidance.  

4.  Modeled Attainment test

[Section III.F.4 of November 1, 2005 proposed rule (70 FR 66008)]

a.  Background.

	The proposal described the nature of the attainment tests for the
annual average and 24-hour average PM2.5 NAAQS contained within the
modeling guidance.  Both tests use monitored data to estimate current
air quality.  The attainment test for a given standard is applied at
each monitor location within or near a designated nonattainment area for
that standard.  There is also an additional attainment test to be
performed in unmonitored areas.  Models are used in a relative sense to
estimate the response of measured air quality to future changes in
emissions.  Future air quality is estimated by multiplying current
monitored values times modeled responses to changes in emissions. 
Because PM2.5 is a mixture of chemical components, the guidance
recommends using current observations and modeled responses of major
components of PM2.5 to estimate future concentrations of each component.
 The predicted future concentration of PM2.5 is the sum of the predicted
component concentrations. 

b.  Final Rule.

	The nature of the PM2.5 attainment tests is unchanged.  The final
modeling guidance recommends refinements to the test and discusses the
treatment of individual PM2.5 species.  The speciated modeled attainment
test (SMAT) that was used to estimate future PM2.5 concentrations for
CAIR has been (mostly) implemented in the final guidance.  Among the new
recommendations is to better account for the known differences between
the PM2.5 Federal Reference Method (FRM) measurements and the PM2.5
speciation measurements.  For example, it is recommended to account for
the volatilization of nitrate from the FRM filters and to account for
uncertainties in organic carbon measurements by employing an “organic
carbon by mass balance” technique.  This assumes that all remaining
mass not accounted for by other species is organic carbon mass. 
Additional details are contained in the modeling guidance.

	The guidance also recommends, where necessary, to spatially interpolate
PM2.5 species data to estimate the species concentrations at FRM sites. 
It is necessary to estimate species concentrations when there are no
species measurements at FRM sites.  Several techniques can be used to
estimate species concentrations.  Spatial interpolation techniques may
be useful in many areas.  In other cases, it may be adequate to assume
that data from a speciation monitor may be representative of multiple
FRM monitors.  It is particularly important to develop credible
techniques to estimate species concentrations at the locations of the
highest FRM monitors.  

	The guidance lists several techniques that can be used. The EPA will
provide software which will apply the modeled attainment test, using
ambient data and model outputs.  Additionally, the software will
interpolate the PM2.5 species data to allow application of SMAT for all
FRM monitors.  The software iswill be available at xxxxx.the same
location as the final modeling guidance
(http://www.epa.gov/scram001/guidance_sip.htm).  

	Ultimately, it is up to the States to determine the best method to
represent the PM2.5 species concentrations, subject to EPA’s review
and approval.  These estimates are needed to perform the modeled
attainment test.

c.  Comments and Responses

	Comment:  Several commenters were concerned that interpolation of PM2.5
species concentrations may not be appropriate in certain areas or
situations.  The concentrations can vary significantly between urban and
rural areas and even between nearby urban areas.  One commenter
suggested that it might be useful to use older field study measurements
to derive current species concentrations.  Another commenter suggested
that it might be reasonable to assume that speciation measurements were
representative of nearby FRM sites.

	Response:  We agree that interpolations of species data may not always
be the best way to estimate species concentrations at FRM sites.  The
modeling guidance lists several different possible techniques.  States
should review their data and situation and choose the most reasonable
methodology to estimate species concentrations.  Nonattainment areas
that don’t have speciation measurements at the highest FRM site(s)
need to be especially careful.  The result of the speciated attainment
test can be heavily influenced by the assumed species concentrations at
the highest FRM sites.  The attainment test will be more straightforward
in areas with speciation monitors at the highest FRM sites.  States are
also encouraged to place speciation monitors at the highest FRM sites. 
This will aid in future assessments of attainment and ambient trends. 

5.  Multi-pollutant assessments 

[Section III.F.5 of November 1, 2005 proposed rule (70 FR 66009)]

a.  Background.

	The formation and transport of PM2.5 is in many cases closely related
to the formation of both regional haze and ozone.  There is often a
positive correlation between measured ozone and secondary particulate
matter.  Many of the same factors affecting concentrations of ozone also
affect concentrations of secondary particulate matter.  For example,
similarities exist in sources of precursors for ozone and secondary
particulate matter.  Emissions of NOx may lead to formation of nitrates
as well as ozone.  Sources of VOC may be sources or precursors for both
ozone and organic particles.  Presence of ozone itself may be an
important factor affecting secondary particulate formation.  The
proposal recommended multi-pollutant assessments for PM2.5 attainment
demonstrations.  A multi-pollutant assessment, or one-atmosphere
modeling, is conducted with a single air quality model that is capable
of simulating transport and formation of multiple pollutants
simultaneously.  This type of model simulates the formation and
deposition of PM2.5, ozone, and regional haze components, and it
includes algorithms simulating gas phase chemistry, aqueous phase
chemistry, aerosol formation, and acid deposition.

b.  Final Rule.

	The recommendation to conduct multi-pollutant assessments remains
unchanged.  It is recommended to model the impacts of future year
control strategies on PM2.5, ozone, and regional haze.  It may not
always be possible or convenient to do so, but it can be beneficial to
the strategy development process.  

	PM2.5 control strategies will have an impact on regional haze, and will
possibly impact ozone.  Even if high ozone and high PM2.5 concentrations
don’t typically occur during the same time of the year, controls that
affect precursors to PM2.5 may also affect ozone (e.g. NOx).

The SIP submittal dates for PM2.5, ozone, and regional haze do not
currently line up.  The PM2.5 SIPs are due almost 1 year later than
ozone.  But States can still do modeling analyses that can provide
information for multiple pollutants.  States can use one-atmosphere
models that are capable of simulating both ozone and PM2.5.  They can
also try to use consistent meteorological fields and emissions
inventories so that the same control strategies are relatively easy to
evaluate for both ozone and PM2.5.  Modeling the same future year(s) for
PM2.5 and ozone can also make it easier to evaluate the impacts of
controls on both pollutants.  

	It should be noted that there are no specific modeling requirements
other than the recommendation to try to harmonize the ozone, PM2.5, and
regional haze analyses whenever possible.

c.  Comments and Responses

	Comment: One commenter suggests that multi-pollutant assessments may
not be beneficial because their area experiences winter PM2.5
exceedences and summer ozone exceedences.

	Response:  We disagree with the comment.  Even in situations where high
PM2.5 and ozone don’t occur during the same time of year,
multi-pollutant assessments may be helpful.  NOx controls that may be
needed to reduce nitrates in the winter are likely to have an impact on
ozone in the summer.  As well, changes in VOCs and SO2 may have an
impact on both PM2.5 and ozone.  Running potential control strategies
through the same modeling platform for ozone, PM2.5, and regional haze
may allow the development of optimized strategies.  

6.  Which future years(s) should be modeled?

[Section III.F.6 of November 1, 2005 proposed rule (70 FR 66009)]

a.  Background.  

	Modeling analyses consist of base year modeling and future year
modeling.  The attainment test examines the change in air quality
between the base and future years.  The proposal recommended, where
possible, future modeling years should be coordinated so that a single
year can be used for both PM2.5 and ozone modeling.  This coordination
will help to reduce resources expended for individual modeling
applications for PM2.5 and ozone and will facilitate simultaneous
evaluation of ozone and PM impacts.  

	Although there is some flexibility in choosing the future year modeling
time periods, unless the State believes it cannot attain the standards
within 5 years of the date of designation and must request an attainment
date extension, the choice of modeling years for PM2.5 cannot go beyond
the initial 5 attainment period.  Attainment date extensions will only
be granted under certain circumstances.  Among other things, the State
must submit an attainment demonstration showing that attainment within 5
years of the designation date is impracticable.

b.  Final Rule.  

	Further information is now known concerning the modeling years for
ozone.  Moderate nonattainment areas are presumed to be modeling 2009. 
This is consistent with the last year of the 5 year period allowed under
Subpart I for PM2.5.  Therefore, it is logical to presume that areas
that are able to attain the PM2.5 NAAQS within 5 years will model a
future year of 2009.  Areas that won’t be able to attain the standard
in 5 years will need to request an attainment date extension (of up to 5
additional years).  

	The NAAQS must be attained as expeditiously as practicable.  Therefore,
attainment date extensions must contain modeling analyses to justify the
extension.  Details of the required analyses are contained in the RACT
and RACM sections of the final rule.  See section XX J.F for more
details.  

7.  Mid course reviews

[Section III.F.7 of November 1, 2005 proposed rule (70 FR 66010)]

F.  What requirements apply for RACT and RACM for PM2.5 nonattainment
areas?	Reasonably available control technology and reasonably available
control measures.  

	This section of the preamble discusses the final rule requirements for
RACT and RACM.  In order to explain EPA’s approach in the final rule
more clearly, we first discuss the statutory and regulatory background
for the RACT and RACM requirements, and we then explain the key options
and interpretations upon which we took comment in the proposal. 
Thereafter, we discuss significant comments we received on the proposal
and provide brief responses to those comments. [Additional comments and
responses appear in the RTC for this final rule located in the docket.] 
Most of the comments received on this topic addressed the three options
EPA proposed for the RACT requirement, the relationship between the RACT
requirement and EPA’s Clean Air Interstate Rule (CAIR), and the
control measures to be required or considered for RACT and RACM.

1.  Background on statutory requirements for RACT and RACM tc "General
background " \l 3 	

 Subpart 1 of Part D of the CAA (sections 171 – 179B) applies to all
designated nonattainment areas.  Section 172 of this subpart includes
general requirements for all nonattainment area plans. 

Notably, Congress provided EPA and States a great deal of deference for
determining what measures to include in a nonattainment plan. 
Specifically, Section 172(c)(1) requires that each nonattainment area
plan “provide for the implementation of all reasonably available
control measures as expeditiously as practicable (including such
reductions in emissions from existing sources in the area as may be
obtained through the adoption, at a minimum, of reasonably available
control technology), and shall provide for attainment of the national
primary ambient air quality standards.” In this provision,
“reasonably available control measures” or RACM, are understood to
be controls  By including language in Section 172(c)(1) that only
“reasonably available” measures be considered for RACT/RACM, and
that implementation of these measures need be applied only “as
expeditiously as practicable,” Congress clearly intended that the
RACT/RACM requirement be driven by an overall requirement that the
measure be “reasonable.”   Thus, the rule of “reason” drives the
decisions on what controls to apply, what should be controlled, by when
emissions must be reduced, and finally, the rigor required in a
State’s RACT/RACM analysis.  For example, we previously stated that
the Act “does not require measures that are absurd, unenforceable, or
impractical” or result in “severely disruptive socioeconomic
impacts” 55 FR 38327.  Moreover, we interpret the term “reasonably
available” to allow States to consider both the costs and benefits of
applying the measure, and whether the measure can be readily and
effectively implemented without undue administrative burden.  66 FR
26969. 

We also interpret the “reasonably available control measures” in
these provisions as referring to measures of any type that may be
applicable to a wide range of sources, whereas the parenthetical
reference to “reasonably available control technology” or RACT are
understood to be technology based controlsrefers to measures applicable
primarily to stationary sources. Thus, RACT areis a subsettype of RACM. 
 specifically designed for stationary sources.  As noted above, States
are required to implement RACM and RACT “as expeditiously as
practicable” as part of nonattainment area plans designed to attain
the standards as expeditiously as practicable.  

Section 172 does not include any specific applicability thresholds to
identify the size of sources that States and EPA must  consider in the
RACT and RACM analysis.  However, the RACT requirement applies both to
sources of direct PM2.5 emissions and to sources of PM2.5 precursors in
the given nonattainment area.Nor, does Section 172 specifically indicate
which pollutant(s) or precursor(s) must be subject to RACM or RACT
measures to attain the NAAQS.  Other pollutant-specific provisions of
the CAA do include suchapplicability thresholds pertaining to
nonattainment area plan requirements for thoseNAAQS and precursor
pollutants.  For example, subpart 2 of part D, which establishes
additional requirements for ozone nonattainment areas, establishes
thresholds ranging from 100 to 10 tons per year for requirements
applicable to “major sources” or “major stationary sources,”
depending on the area’s classification or level of nonattainment.  
Subpart 4 of part D, which  provides additional plan requirements for
for PM-10 nonattainment areas, establishes thresholds of 100 and 70 tons
per year for requirements applicable to a “major source” or “major
stationary source.”

SimilarlyMoreover, subpart 1, unlike subparts 2 and 4, does not 
identify specific source categories for which EPA must issue control
technology documents or guidelines, thereby identifyingor  identify
specific source categories for State and EPA evaluation during
nonattainment area  plan development  .  For ozone, subpart 2 contains a
list of specific requirements for control techniques guidelines (CTGs)
and alternative control techniques (ACT) documents. [For PM10, section
190 of the CAA (in subpart 4) places particular emphasis on specific
sources of area emissions, but does not identify specific stationary
source categories for which RACT guidance must be issued.  Section 190
requires EPA to develop RACM guidance documents for residential wood
combustion, prescribed silvacultural and agricultural burning for forest
management and agricultural activities, and for urban fugitive dust
control.] 

2. What is the Overall Approach to Implementing RACT and RACM in the
final rule?

a. Background for RACT. 

	Since the late 1970s, EPA has interpreted RACT to mean “the lowest
emissions limitation that a particular source is capable of meeting by
the application of control technology that is reasonably available,
considering technological and economic feasibility (44 FR 53762;
September 17, 1979).  Because RACT is a control technology requirement
and because modeling techniques were not precise in the past, we have
generally considered RACT to be independent of the need to demonstrate
attainment.  In other words, we have generally required that a
stationary source of the requisite type and size be subject to the
controls that were deemed to be RACT, whether or not such controls were
actually demonstrated to be necessary for the area to attain by its
specified attainment date.  The EPA’s approach to RACT was affirmed in
the 1990 amendments to the CAA, which adopted this approach for purposes
of ozone in the subpart 2 provisions added at that time.  [Thus, for
example, section 182(b)(2) requires the imposition of RACT controls for
all VOC source categories covered by a CTG and for all other major
stationary sources of VOC that are located within certain nonattainment
areas.  The statute thus requires these controls in such an area,
without a specific showing that they are necessary for the area to
attain, and without the possibility of a showing that they are not
necessary to attain as a means to exclude them from the plan.  Extensive
discussion of this issue appeared in the 1992 general preamble (57 FR
13541), in which EPA provided guidance for implementation of the ozone
NAAQS.  ” as well as other considerations. In practice, RACT is
generally described as the “norm achievable” by the source category.

	Significantly, Congress did not amend the generally applicable
provisions for nonattainment areas that appear in subpart 1 in 1990. 
This indicates that the Agency retains the authority to interpret the
generally applicable  nonattainment area plan requirements of section
172(c), including the RACT and RACM requirements, in the way that is
most appropriate for new NAAQS that are subject to subpart 1.  As
discussed below, EPA has determined that a more flexible approach to the
RACT requirement is appropriate for implementation of the PM2.5 NAAQS. 
The EPA believes that the improved ability to model the impacts of
controls allows for this more flexible approach, so long as the analysis
of what controls are necessary to achieve the NAAQS as expeditiously as
practicable in a given area is sufficiently robust.]  

	Section 110 of the 1970 Clean Air Act required States to develop SIPs
providing for attainment of the NAAQS by 1975 or 1977.  A number of
areas were having difficulty with developing attainment plans,
particularly for the ozone standard.  In response to the implementation
needs of this time period, EPA introduced the term “RACT” in a 1976
memorandum from Roger Strelow, Assistant Administrator for Air and Waste
Management to Regional Administrators, “Guidance for Determining
Acceptability of SIP Regulations in Non-attainment Areas” (Dec. 9,
1976).  In this early guidance relating to the acceptability of SIP
regulations, we indicated that our overriding concern in approving SIPs
was attaining the particular NAAQS as expeditiously as practicable
through reasonably available control technology and other reasonably
available control measures.  “The basis for fully approving
state-submitted SIP regulations continues to be demonstrated attainment
and maintenance of all national ambient air quality standards as
expeditiously as practicable,” the memo stated.

The 1977 Clean Air Act amendments added Part D to Title I of the Act,
and for the first time the Act specifically called for EPA to designate
nonattainment areas and for SIPs to require RACT and RACM in those
nonattainment areas.   In a 1979 Federal Register notice, EPA noted its
view that Congress adopted EPA’s pre-existing conception of RACT in
the 1977 amendments. (44 FR 53782, September 17, 1979).  Also during the
late 1970s, EPA developed a number of new control techniques guideline
(CTG) documents as directed in the 1977 amendments.  These CTGs provided
States with information on controls for a number of categories of
sources emitting VOCs, and recommended a “presumptive norm” for
State RACT determinations based on the control levels achievable by
sources in a given industry.   CTGs reduced the burden on States by
eliminating the need for each State to develop its own technical support
for implementing the RACT requirement.   Since the CTG-recommended
controls were based on general capabilities of an industry, EPA in the
1979 guidance (44 FR 53782) urged States in setting RACT to judge the
feasibility of the recommended controls on particular sources, and to
adjust accordingly.  

	As noted above, EPA’s early guidance related to the RACT requirement
indicated that our overriding concern in approving State RACT
requirements was attaining the particular NAAQS.   We initially required
States to apply RACT to qualify for attainment extensions, and in some
cases, for plans that could not demonstrate attainment.    

During the 1980s, EPA implemented the RACT requirements with a number of
CTGs and guidance documents.   These materials were aimed at addressing
the attainment deadlines of 1982 and 1987 under the 1977 Clean Air Act
amendments.   During this time, EPA, for pollutants other than ozone,
considered RACT to be dependent upon reductions needed for attainment as
expeditiously as practicable.  For ozone, where the State performed
photochemical grid modeling, the approach was the same, but where the
State used less sophisticated tools, we considered RACT to be
independent of whether the controls were needed to reach attainment as
expeditiously as practicable. We took this alternate approach because of
concerns related to the precision of modeling techniques.  In other
words, in those cases, we required that a stationary source of the
requisite type and size be subject to RACT, whether or not such controls
were actually demonstrated to be necessary for the area to attain by its
specified date.  (44 FR 20375-20376, April 4, 1979)  

	Congress followed a similar approach in the 1990 amendments to the CAA
for purposes of the ozone NAAQS in the subpart 2 provisions added at
that time.  For example, section 182(b)(2) requires the imposition of
RACT controls for all VOC source categories covered by a CTG and for all
other major stationary sources of VOC located within certain
nonattainment areas.  Thus, Congress required  these controls without
allowing for an area-specific demonstration by the State that the area
needed the controls for attainment as expeditiously as practicable. 
Extensive discussion of this requirement appeared in the 1992 general
preamble (57 FR 13541), in which EPA provided guidance for
implementation of the ozone NAAQS.  

	Notably, Congress did not significantly amend the generally applicable
provisions for nonattainment areas that appear in subpart 1 of Part D in
1990.  This indicates that Congress intended that the Agency retain the
authority to interpret the generally applicable nonattainment area plan
requirements of section 172(c), including the RACT and RACM
requirements, in the way that is most appropriate for new NAAQS that are
subject to subpart 1.  As discussed below, EPA has determined that an
approach to the RACT requirement in which RACT varies in different
nonattainment areas based on the reductions needed for attainment as
expeditiously as practicable, is appropriate for implementation of the
PM2.5 NAAQS.  We believe that the improved ability to model air quality
impacts of emissions controls allows for this approach.

b. Proposed options for RACT.

	The EPA proposed and requested comment on three alternative approaches
for interpretation of the RACT requirement of section 172(c)(1) for
implementation of the PM2.5 NAAQS.  The EPA proposed these approaches in
order to evaluate which method would best ensure that States consider
and adopt RACT measures for stationary sources in a way that is
consistent with the overarching requirement to attain the standards as
expeditiously as practicable, while providing flexibility for States to
focus regulatory resources on those sources of emissions that contribute
most to local PM2.5 nonattainment.  

	Under the first proposed alternative, EPA would require States to
conduct a RACT analysis and to identify and require reasonably available
controls for all affected stationary sources in the nonattainment area,
comparable to the implementation of RACT provided in subpart 2 governing
implementation of the 1-hour ozone NAAQS.  Under this option, covered
sources would be required to apply technicallyreasonable available
controls considering technical and economically feasible
controlseconomic feasibility, and there would be no opportunity for
States to excuse  stationary sources from control on the basis that the
emissions reductions from those controls would not be necessary to meet
RFP requirements or to expeditereach attainment.    Under this
alternative, EPA proposed to limit the universe of sources for which
States must conduct a RACT analysis and impose RACT controls, by
providing an applicability threshold based upon the amount of emissions
potentially emitted by the sources.  Under this first option, EPA
requested comment on a number of alternative emissions applicability
thresholds.  

Under the second proposed alternative, EPA would require States to
conduct a RACT analysis and to identify reasonably available controls
for all affected stationary sources.  Under this  option, however,
States could thereafter  determine that RACT does not include controls
that would not otherwise be necessary to meet RFP requirements or to
attain the PM2.5 NAAQS as expeditiously as practicable.  Under this
approach, RACT would be determined as part of the broader RACM analysis
and identification of all measures - for stationary, mobile, and area
sources - that are technically and economically feasible, and that would
collectively contribute to advancing the attainment date..  Because RACT
and RACM are considered together under this alternative, we did not
propose emissions threshold options for evaluation of stationary source
RACT.  In addition, underconsistent with existing policies, States would
be required to evaluate the second alternative, areas cannot avoid the
impositioncombined effect of eitherreasonably available RACT or RACM
measures without a demonstration that there is no combinationto
determine whether application of such declined RACT and RACM measures
that would could advance the date of attainment date by at least one
year. 

The third proposed alternative, EPA’s preferred option in the
proposal, combined the first two options and is similar to the RACT
approach adopted in the final implementation rule for the 8-hour ozone
program.  Under the third option, EPA would require States to conduct a
RACT analysis and to require reasonably available controls for all
affected stationary sources in nonattainment areas with attainment dates
more than 5 years from the date of designation.  For areas with an
attainment date within 5 years of designation (e.g. by April 2010 for
areas with an effective date for designation of  April 2005), EPA would
require RACT as under the second proposed alternative, in which RACT
would be determined as part of the broader RACM analysis.   For these
areas, States could determine that RACT does not include controls that
would not otherwise be necessary to meet RFP requirements or to attain
the PM2.5 NAAQS as expeditiously as practicable.  The same proposed
suboptions with respect to the size of sources for consideration under
the first alternative were also included under this alternative.  

c. Proposed Approach for RACM  

	The EPA proposed and asked for comment on one  approach  for
interpreting the RACM requirement for PM2.5.  EPA based the proposal on
the approach that it has we adopted for other   NAAQS implementation
programs.  Under this approach, EPA requires the a State to provide
provides a demonstration in its SIP that it has adopted all reasonably
available measures needed to meet RFP requirements and to attain the
standard as expeditiously as practicable.  Reasonable measures are those
measures  and that are technologically and economically feasible for the
area in question.  The required demonstration must show that there are
no reasonably available additional reasonable measures available in the
nonattainment area that would advance the advance the attainment date by
at least 1 year or would be necessary to meet the RFP requirement for
the area.

  	Under section 172(a)(2), the attainment datestate implementation plan
must provide for a nonattainment area isto attain as expeditiously as
practicable, but no later than 5 years after the effective date of
designation of the area (e.g., no later than April 2010 for the final
designations effective April 2005).  The statute thus creates a
presumption for attainment within 5 years of designation unless certain
statutory criteria are met for an extension of the attainment date. 
Under the proposed approach to RACM for PM2.5, EPA each State would
require each State to evaluate all RACM for all available measures for
sources of PM2.5 or its regulatory precursors in the area to determine
if any suchreasonable measures could contributewere needed to meeting
the RFP requirement or  or to achievingto achieve attainment as
expeditiously as practicable.  If this evaluationmodeling of all RACM
findsand other state, regional and federal measures indicates that the
State will not be able to demonstrate attainment within 5 years after 
designation based  upon the severity of   nonattainment in that area or
the availability or feasibility of implementing controls in that area,
then the State may request an attainment date extension.  We proposed
that under these circumstances, the EPA could extend the attainment date
for a period of 1 to 5 years, provided thatwhen the State has presented
an adequate demonstration showing they shows that it will implement all
RACT and RACM as expeditiously as practicable, has met its obligation to
address intrastate pollution transport from sources within its
jurisdiction, and still needneeds additional time to attain.

	 In the proposed rule, the EPA also took comment on the following
overall steps for implementing the statutory requirement for RACM.

(1) Identification of measures.  The State would begin the process of
determining RACM by identifying all available control measures for all
sources of PM2.5 and its precursors in the nonattainment area.  The RACM
can apply to mobile sources, area sources, and stationary sources.  

(2) Evaluation of measures.  After the State identifies the universe of
available measures for the sources in the area, the State would evaluate
them to determine whether implementation of such measures is technically
and economically feasible, and whether the measure will contribute to
advancing the attainment date. 

(3) Adoption of measures.  The State would have the initial
responsibility for demonstrating to EPA that it has has adopted adopt
all reasonably available measures for the area consistent with meeting
the applicable RFP requirements and attaining  the standardsNAAQS as
expeditiously as practicable, in accordance with applicable policy and
guidance for attainment demonstrations.  The EPA notes that it must take
action on State nonattainment plansWe would then approve or disapprove
the State’s plan through notice and comment rulemaking, and failure of
a State to supply adequate reasoning and support for its submission with
respect to RACM measures would be a basis for disapproval of the
submission.   In .  We also noted that in reviewing the State’s
selection of measures for RACM, or determinationdetermining that certain
measures are not RACM, EPA couldmay independently supplement the
rationale of the State or provide an alternative reason for reaching the
same conclusion as the State, but only where EPA deems it appropriate. .

 	In the proposal, EPA also confirmed its past interpretation that the
RACM requirement requires the collective evaluation of measures and the
assessment of whether they will advance the attainment date when taken
together.  Thus, for any measure or measures that would otherwise be
RACM in the area, the State would be required to provide a reasoned
rationale for declining to adopt such measure or measures, and an
analysis to show that adoption of all such measures cumulatively would
not advance the attainment for that area by at least 1 year. 

c. Final rule. 

	The EPA has carefully considered the properour interpretation of
section 172(c) (1) for the PM2.5 NAAQS.   Because of the variable nature
of the PM2.5 problem in different nonattainment areas, which may require
States to develop nonattainment area plans that address widely disparate
circumstances (e.g., different source types and mixes, different
precursors and mixes of precursors, and different meteorological
conditions), EPA haswe determined that the regulations implementing the
PM2.5 NAAQS should provide for a great degree of flexibility with
respect to the RACT and RACM controls.

	Selected approach to RACT and RACM.   The final rule reflects EPA’s
decision to select option 2 for RACT and to require a combined approach
to RACT and RACM (subject to special considerations for electric
generating units participating in CAIR as discussed in section F.6). . 
Under   this approach, RACT and RACM are those measures whichthat a
State finds are both reasonably available considering technical and
economic feasibility, and which contribute to advancing the attainment
date by 1 year or more as expeditiously as practical in the specific
nonattainment area.  

By definition, those measures that are not necessary either to meet the
RFP requirement or to help the area attain the NAAQS as expeditiously as
practicable, are not required RACT or RACM for such area.  The EPA
believes that this approach provides the greatest flexibility to a State
to tailor its SIP control strategy to the needs of a particular PM2.5
nonattainment area.  In exchange for this flexibility, however, States
will need to , but it may require the State to conduct a more rigorous
and systematic analysisdetailed analysis to identify the most effective
RACT/RACM strategy to determine what constitutes  RACT and RACM measures
and what  attainment date  is as expeditious as practicable for each
area.  The final rule requires States to demonstrate that they have
adopted all appropriate RACT and RACM measures attain the attainment
demonstrations that States must submit to EPA in early 2008NAAQS.

The EPA stresses that under the approach in the final rule, it is
inappropriate to reject a single measure under consideration as RACT or
RACM because the emission reduction benefits from that measure alone
would not advance the attainment date by 1 year. For any measure or
measures that would otherwise be RACM in the area, the State is required
to provide a reasoned rationale for declining to adopt such measure or
measures, and an analysis to show that adoption of all such declined
measures cumulatively would not advance the attainment for that area by
at least 1 year.  Th  EPA believes that PM2.5 nonattainment is typically
the result of the cumulative impact of emissions from a large number of
different sources of varying sizes.  Implementation strategies,
therefore, will require consideration of controls on a broad variety of
sources that might not individually cause nonattainment but whose
contribution to nonattainment must nevertheless be reduced in order to
achieve the NAAQS.  Therefore, an approach to RACM that would excuse
control measures that would not singlehandedly bring an area into
attainment would be an inappropriate way to implement the RACM
requirement for PM2.5.

Under the final rule, the State’s analysis must   provide a reasoned
justification for rejecting any available control measures that would
constitute RACT or RACM in such area.  The supporting information must
show why each rejected measure, including any measure raised during  the
State's public hearing or public comment process, is technologically or
economically infeasible or unreasonable, or will not contribute to
advancing attainment by 1 year.  Note that special considerations for
EGUs apply as discussed in section F.6 below.

	Guidance on State analysis to identify RACT, RACM and appropriate
attainment date.  For each nonattainment area, the State must provide a
demonstration showing that the area will attain the standards as
expeditiously as practicable considering implementation of existing
Federal measures, plus implementation of RACT, RACM, and potential
measures to reduce intrastate pollution transport that contributes to
the nonattainment problem. 

All nonattainment areas are subject to RACT and RACM requirements. 
However, EPA believes that areas clearly projected to attain within 5
years of designation as a result of existing national measures (i.e.
projected to have a design value of 14.5 or lower) may be able to
conduct a limited RACT and RACM analysis that does not involve
additional air quality modeling.  A limited analysis of this type would
involve the review of reasonably available measures, the estimation of
potential emissions reductions, and the evaluation of the time needed to
implement these measures.  If the State could not achieve significant
emissions reductions during 2008 due to time needed to implement the
potential measures or other relevant factors, then the State and EPA
could conclude   that reasonably available  measures in the area could
not advance the attainment date relative to the presumptive outer limit
for attainment dates, i.e., 5 years from designation.  In lieu of
conducting air quality modeling to assess the impact of potential RACT
and RACM measures, EPA believes that it would be appropriate for States
to consider existing modeling information  in determining the magnitude
of emissions reductions that could significantly affect air quality and
potentially result in attaining prior to 2010 (e.g. in 2009 based on
2006-8 air quality data).  If the State, in consultation with EPA,
determines from this initial limited RACT and RACM analysis that the
area may be able to advance its attainment date through implementation
of reasonable measures, then the State must conduct a more detailed RACT
and RACM analysis, including appropriate air quality modeling analyses,
to assess whether it can advance the attainment date.  

	In general, the combined approach to RACT and RACM in the final rule
includes the following steps:  (1) identification of potential measures;
(2) modeling to identify the attainment date that is as expeditious as
practicable; and (3) selection of RACT and RACM.

	Identification of potential measures:  As supporting information for
identification of RACT and RACM, the State  must provide data on
technologically feasible control measures:

During the comment period, commenters raised concerns that this approach
may be overly burdensome on States because of the number of potential
control measures a State would need to consider.  Today, we clarify that
although the State must conduct a thorough analysis of reasonably
available measures, States need not analyze every conceivable measure,
as explained in the guidance below.  Instead, “reason” should drive
States identification of potential measures, but States should remain
mindful of the public health risks of PM2.5. As long as a State’s
analysis is sufficiently robust in considering potential measures to
ensure selection of all appropriate RACT and RACM, and the State
provides a reasoned justification for its analytical approach, we will
consider approving that State’s RACT/RACM strategy.  

	Guidance on State analysis to identify RACT, RACM and appropriate
attainment date.  

A State must consider RACT and RACM for all of its nonattainment areas. 
However, EPA believes that if the State projects that an area will
attain the standard within 5 years of designation as a result of
existing national measures (i.e. projected to have a design value of
14.5 or lower), then the State may conduct a limited RACT and RACM
analysis that does not involve additional air quality modeling.  A
limited analysis of this type would involve the review of reasonably
available measures, the estimation of potential emissions reductions,
and the evaluation of the time needed to implement these measures.  If
the State could not achieve significant emissions reductions during 2008
due to time needed to implement the potential measures or other relevant
factors, then the State and EPA could conclude that there are no further
reasonably available control measures for that area that would advance
the attainment date by one year or more relative to the presumptive
outer limit for attainment dates, i.e., 5 years from designation.  In
lieu of conducting air quality modeling to assess the impact of
potential RACT and RACM measures, States may consider existing modeling
information to determine the magnitude of emissions reductions that
could significantly affect air quality and potentially result in
attaining prior to 2010 (e.g. in 2009 based on 2006-8 air quality data).
 If the State, in consultation with EPA, determines from this initial,
limited RACT and RACM analysis that the area may be able to advance its
attainment date through implementation of reasonable measures, then the
State would conduct a more detailed RACT and RACM analysis, including
appropriate air quality modeling analyses, to assess whether it can
advance the attainment date.  

	In general, the combined approach to RACT and RACM in the final rule
includes the following steps:  (1) identification of potential measures
that are reasonable; (2) modeling to identify the attainment date that
is as expeditiously as practicable; and (3) selection of RACT and RACM.

	Identification of potential measures:  The State’s review of
potential measures must be sufficient to identify all appropriate RACT
and RACM.  As stated previously, inherent to RACT/RACM is the basic
requirement that the measure be “reasonable.”  A State need not
evaluate measures in its RACM/RACT analysis that it determines are
unreasonable such as measures that are “absurd, unenforceable, or
impractical” or that would cause “severely disruptive socioeconomic
impacts, (e.g. gas rationing and mandatory source shutdowns); such
measures are not required by the Act.  55 FR 38327  

	As we also stated earlier, a State’s RACT/RACM analysis not only
involves an assessment about what emissions sources to control and to
what level, but also a judgement as to when it is reasonable to require
a sector to comply with a given measure.  Accordingly, if the State or
Federal rules already heavily regulate a given sector, it is reasonable
for the State to first look to unregulated parts of the sector for
RACT/RACM measures, especially, in light of costs already realized by
the regulated sector.  A State may conclude that it is unreasonable to
further regulate the industry, or that it is only reasonable to impose
measures in the latter years of the attainment plan.

	Finally, the State should use reason in the extent of its efforts to
identify potential control measures.  For example, if a review of
monitoring data and modeling studies indicates that reductions in SO2
are much more effective in reducing ambient PM2.5 than reductions in
other pollutants, we expect that the State will more vigorously identify
RACT/RACM measures for SO2 than for other pollutants.  Conversely, if
reductions in a given pollutant, even in large quantities, would have
trivial impacts on PM2.5, less rigor is needed in the State’s
assessment of controls for that pollutant, because such controls could
not contribute to advancing the attainment date.  Likewise, where
reducing emissions of a pollutant is effective in reducing ambient
PM2.5, if the emissions inventory for that pollutant is dominated by a
given type of emissions source, then it would be appropriate to focus
the analysis on measures for that segment of the inventory. No RACT/RACM
analysis is needed for pollutants that are not nonattainment plan
precursors for a particular PM2.5 nonattainment area.

	As supporting information for identification of RACT and RACM, the
State ordinarily provides data on technologically feasible control
measures:

-- A list of all emissions source categories, sources and activities in
the nonattainment area (for multi-State nonattainment areas, this would
include source categories, sources and activities from all states which
make up the area)

-- For each source category, source, or activity, an inventory of direct
PM2.5 and precursor emissions;

-- For each source category, source, or activity, a list of
technologically feasible emission control technologies and/or measures  

-- For each technologically feasible emission control technology or
measure, the State should provide the following information: (1) the
control efficiency by pollutant;  (2) the possible emission reductions
by pollutant; (3) the estimated cost per ton of pollutant reduced; and
(4) the date by which the technology or measure could be reasonably
implemented.

	Based on this and other relevant information, the State  will identify
technically and economically feasiblethe reasonable measures (potential
RACT and RACM) for to be included in air quality modeling.  (At its
option, the State may prefer not to make a judgment on whether certain
measures are technically and economically feasible, if it believes they
will not contribute to earlier attainment.   In that case, the State 
could include those measures in the modeling, and later exclude them
from RACT and RACM by showing that all the excluded measures together
would not advance the attainment date by at least 1 year.)  As
previously mentioned, in determining the attainment date that is as
expeditiousexpeditiously as practicable, the State is also   responsible
for considering should consider impacts on the nonattainment area of
intrastate transport of pollution from sources within its jurisdiction,
and potential reasonable measures to reduce emissions from those
sources.  The State should provide its rationale for including, or not
including, such measures in its SIP (e.g., based on potential emissions
reductions, costs and air quality impacts).

	Modeling to determine the attainment date that is as
expeditiousexpeditiously as practicable:  Second, for purposes of
determining the attainment date that is as expeditiousexpeditiously as
practicable, the State will need to conduct modeling to show the
combined air quality impact of all of the potential measures identified
in the first step with a modeling analysis for the year 2009.  A base
case scenario for the year 2009 would project future air quality given
implementation of existing measures (Federal, State and local).  If this
base case scenario demonstrates attainment by 2010, then the State must
demonstrate why “expeditious” attainment could not be achieved in an
earlier year.   (As noted above, given the April 2008 due date for SIP
submissions, it may be difficult to achieve earlier attainment in many
cases).   

	If the base case scenario does not demonstrate attainment, then a
control case scenario for 2009(described below) is needed.  to examine
whether the reasonable, technically and economically feasible measures
identified by the State would result in attainment in 2009. The control
case scenario would add potential SIP measures – specifically, all
technically and economically feasible nonattainment area measures which
could be implemented by the beginning of calendar year 2009-- e.g.
potential RACT/RACM, plus any candidate intrastate transport measures
that the State has identified and would be feasible to implement by that
year.  States in multi-State nonattainment areas are strongly encouraged
to collaborate on their modeling analyses.   This modeling, along with
other information known as weight of evidence considerations, would
inform a judgment as to whether reasonable measures could lead to
attainment of the standards within 5 years after designation.  If the
analysis does not demonstrate attainment by April 2010 (2009 analysis
year), then the analysis would serve as the technical basis for the
State to seek an extension of the attainment date beyond April 2010 for
that area.  Further analysis would then be necessary and is required to
identify the specific attainment date. 

	The choice of future years to model beyond 2010 may vary from area to
area.  Often, modeling potential controls in two different future years
may be necessary to support a judgment that a projected attainment year 
is as expeditiousexpeditiously as practicable.  If the area is projected
to remain over the standard in the early projection year (e.g., 2009)
despite the emission reductions from the modeled control measures, but
is projected to be well below the standard in the later projection year
(e.g., 2012), interpolation and emission inventory analysis could
identify an intermediate year as the appropriate attainment date.  There
may be cases in which modeling a single year is sufficient because
modeling of all technically and economically feasible controls results
in attainment by a narrow margin in that year.

	For many areas, EPA modeling analysis for CAIR and other modeling
analyses that have been performed suggest a number of nonattainment
areas will have a modest amount (in some cases only a few tenths of a
microgram) of needed reductions in ambient levels after 2010 to reach
attainment.  For any such area, and for areas otherwise expected to
attain relatively soon after 2010 (for example, due to substantial
reductions in a dominentdominant local source), EPA believes that this
analysis should be for a year no later than 2012.  A later date (e.g.,
2014) may be appropriate for areas with very high PM2.5 levels that face
difficulty attaining within 10 years.

The EPA believes that it is not reasonable to require that States
shouldto model each and every year between 2009 and 2014 in order to
determine the appropriate attainment date.  Modeling future year
inventories is a time consuming and resource intensive process. 
Multiple models and pre-processors are needed in order to generate year
specific emissions for the various emissions sectors (e.g. mobile,
non-road, non-EGU point, EGU point, etc.).  Because it is not reasonable
to model every year, a logical compromise is choice often may be to
model a year in the middle of the period.  As such, we recommend
modeling an emissions year no later than 2012 as the initial extension
date (which translates to a 2013 attainment date).  If this modeling
indicates that the area can reach attainment  by 2012, then the State
can futherfurther analyze emissions and strategies to determine if the
attainment date can be advanced to an earlier year.  If the modeling
indicates that the area cannot reach attainment by 2012, then the
modeling will serve as further justification for granting  a longer
attainment date extension (e.g., attainment date of 2015 with modeling
for 2014). In that case, additional modeling of 2014 with further
emissions controls would be required in order to show attainment. Again,
the State should then further analyze emissions and strategies to
determine if the attainment date can be advanced to an earlier year
between 2012 and 2015.

Additionally, in the discussion of air quality modeling issues in
section II.E above, we discuss the benefits of addressing control
strategies for multiple pollutants. Part of the challenge of
multi-pollutant modeling is coordinating the future modeling years for
different pollutants in order to minimize the number of required future
year model runs. As part of the requirements of the 8-hour ozone
implementation rule, States are currently working on modeling analyses
for 2009 and in some cases for 2012 (serious nonattainment areas).  For
an area that cannot attain the PM2.5 NAAQS by 2010, this may be reason
to select 2012 as the year to model, so that the State could conduct the
modeling for both ozone and PM2.5 in tandem.  This would, in some cases,
allow the pooling of resources (e.g., inventories, model runs, etc.) and
provide for faster development of a PM2.5 attainment demonstration. 

It may also be possible for the State to look at 2009 and 2014 only.  In
this instance, the State may find sufficient data to interpolate results
for the years in between based on estimated changes in emissions. 

	We emphasize that when a State models later years, that this analysis
must take into account potential controls that the State may previously
have determined not to be RACT or RACM either because they could not
implement the controls in time to meet an earlier nonattainment date
(e.g., because of technological, economic, or timing reasons) or because
the controls would not sufficiently advance the attainment date.  For
example, some reasonable measures that are impractical to implement by
2009 could be reasonable if implemented by 2010, 2011 or 2012.  Thus,
when the State models later years, the list of potential controls should
be expanded to include technically and economically feasible measures
that can be implemented by the analysis year.  

	Selection of RACT & RACM:  Based on this analysis, the State should
make decisions on RACT, RACM, intrastate measures, and the attainment
date that is as expeditiousexpeditiously as practicable.  Because EPA is
defining RACT and RACM as only those reasonable, technically and
economically feasible measures that are necessary for expeditious
attainment of the NAAQS as expeditiously as practicable, the State need
not adopt all measures that are all technically and economically
feasible measures feasible, reasonable measures.  The State may exclude
those reasonable measures that, considered collectively, would not
advance the attainment date by at least 1 year.  Given the public health
risks of PM2.5, we believe that the State should carefully consider a
decision to forego a measure that would otherwise be RACT or RACM, and
we will require that the State present an adequate rationale and
technical support for exclusion of such measures.  The EPA notes that
States retain the authority under section 116 of the CAA to require more
emission reductions, beyond what is required for RACT and RACM, and
without regard to whether it would advance the attainment date.    . 

d.  Comments and responses.

	Comment:  A number of commenters   generally supported EPA’s second
proposed alternative to RACT (option 2).  Most of these commenters
expressed concern that the other options would require the imposition of
controls whether or not they were needed to attain the PM2.5 standards
as expeditiously as practicable. Some State and local commenters also
urged EPA to select option 2 as the best interpretation of the RACT
requirement for PN PM2.5 because they believe that it will be the most
appropriate approach for designing attainment strategies for their
particular nonattainment area or areas.   

	Response:  The EPA agrees that these two points are important
considerations.  Th  EPA initially believed that option 1 or option 3
would provide advantages, in that they would automatically require RACT
controls on larger sources of emissions in all areas (under option 1) or
on all larger sources of emissions in areas which need longer than five
years from designation to attain (in the case of option 3).  This might
allow States to focus control efforts on such sources, to use their
analytical resources to evaluate other sources, and to simplify and
streamline somewhat the SIP development process.  After further
consideration, however, EPA has concluded that these options have at
least the potential to After carefully considering the options, we
concluded that Option 2 was the most suitable approach for the PM2.5
NAAQS. Options 1 and 3 do not reduce the States’ burden to analyze
potential control measures as the States would still be required to look
beyond the mandated RACT for reasonably available measures.  Moreover,
Options 1 and 3 could require imposition of controls on some sources
that would not strictly be necessary to attain the NAAQS as
expeditiously.  Moreover, even under options 1 or 3, States would have
had an obligation to consider the full range of sources for control
under in the process of conducting a RACM analysis, so either option
would not necessarily have significantly reduced the degree of analysis
that many States would need to conduct under any of the options. as
practicable.  Given the nature of the PM2.5 nonattainment problem, EPA
has concluded that an interpretation that provides the maximum
flexibility, coupled with the requirement of a robust analysis to
justify the resulting nonattainment area plans, is a better approach.

	Comment:   Some commenters recommended that EPA modify proposed option
2 to include a tons-per-year threshold.   Under such an approach, the
States and EPA would only require RACT for sources whose emissions were
above the threshold.  Most of these comments recommended a RACT
threshold of 100 tons per year.  These commenters expressed concern that
if option 2 were implemented without such a threshold, States would be
burdened with conducting RACT analyses for very small sources or source
categories with low emissions. 

	Response:   The EPA believes that under the approach chosen for the
final rule in which RACT is considered to be a part of the overall RACM
process, it would be inappropriatedifficult to define a threshold that
would apply for all types of sources and for all types of control
measures   in all nonattainment areas.  It has not been common practice
under past EPA policy to establish or use an emissions threshold when
considering sources for possible emission reductions as part of a RACM
analysis to show attainment as expeditiously as practicable.  Indeed,
many of the control technique guidelines for VOC RACT do not recommend
an emissions threshold. Also, identification of   A state needing
significant emission reductions to attain the standards in a specific
threshold in this rule would not be consistent with the case-by-case
nature of the RACT and RACM analysis for eachgiven area.  For example,
an area needing significant emission reductions to attain the standards
even by 2015 would likely conclude that controls should be considered on
smaller sources than would be needed for.  In contrast, a
nonattainmentState with an area that exceeds the standard by only a few
tenths of a microgram per cubic meter may not need to consider controls
on smaller source to reach attainment as expeditiously as practicable. 
The EPA has selected option 2 for interpretation of the RACT requirement
for PM2.5, in part, specifically because that approach contemplates that
States will conduct a fullan appropriate analysis of the full spectrum
of source categories and potential controls available.  To cut off such
analysis at a set emissions-based cut point for all sources and all
areas would therefore subvertundermine one of the key benefits of the
approach.  Accordingly, EPA disagrees with comments that option 2 should
include a nationally-defined threshold for the size of sources or source
categories that require RACT analyses. 

	Comment:   A number of commenters supported EPA’s first and third
proposed alternative approaches to RACT (option 1 and option 3). 
Commenters supporting these two options used similar reasoning. 
Commenters cited the statutory language in section 172(c)(1) requiring
that the nonattainment plan provide for “at a minimum” the adoption
of RACT.  Accordingly, these commenters argued that RACT is an
independent, minimum requirement of nonattainment plans irrespective of
the attainment demonstration and that option 2, which would not require
the adoption of RACT for all sources, has no policy or legal
justification.   Other commenters noted that option 1 would be much
easier to implement, because RACT would be defined according to
technical reasonableness and would not hinge on complicated
determinations involving attainment demonstrations.  Some commenters
argued that option 1 provides for greater equity, because similar
measures would be required for similar sources for all nonattainment
areas.   Finally, some commenters believed that it is inherently
inconsistent to assert that plans have met the requirement for
attainment “as expeditiously as practicable” without applying RACT
to all major sources. 

	Response:  The EPA disagrees with these comments.  The EPA believes
that option 2 is fully consistent with section 172(c)(1).  Section
172(c)(1) requires that nonattainment plans must provide for the
implementation of RACM as expeditiously as practicable (including such
reductions in emissions from existing sources in the area as may be
obtained through the adoption, at a minimum, of RACT).  Contrary to the
commentercommenters’ assertions, this language does not demonstrate
that RACT is required for all sources, independent of RACM and
attainment demonstrations.   Moreover, this provision does not require
RACT whether or not imposition of technology would advance the
attainment date.  Instead, section 172(c)(1) explicitly provides that
RACT is included within the definition of RACM, and EPA has previously
determined that the CAA only requires such RACM as will provide for
expeditious attainment as expeditiously as practicable.  (See 57 FR
13498, 13560).   The courts have deferred to this interpretation and
concluded that EPA has reasonably interpreted interprets RACM as a
collection of reasonable measures that would advance the attainment
date.   See Sierra Club v. EPA, 294 F.3d 155, 162 (D.C. Cir. 2002); see
also Sierra Club v. EPA, 314 F.3d 735, 744 (5th Cir. 2002).  The CAA
does not “compel [ ] a State to consider whether any measure is
‘reasonably available’ without regard to whether it would expedite
attainment in the relevant area.”  Sierra Club v. EPA, 294 F.3d at
162.  The EPA concludes that because section 172(c)(1) establishes that
RACT is a part of RACM, EPA is reasonably applying the same
interpretation to the RACT requirement for PM2.5.  The RACT is a part of
the collection of measures that would advance the attainment date. are
necessary to reach attainment as expeditiously as practicable. It is
thus directly related to what a specific area needs to attain the NAAQS,
and States need not implement reasonably available measures that would
not advance the attainment date need not be implemented as part of the
PM2.5 RACT requirement. 

	The EPA also finds that option 2 is consistent with the statutory
language providing that a State must apply RACT to existing sources,
“at a minimum,” to meet its requirement to apply RACM.  Th  EPA
interprets We interpret the “at a minimum” clause to mean that the
states must include, as part of RACM, RACT controls onwhen a State
determines that control of a specified existing stationary source(s) is
necessary to attain, the State must apply RACT to that source.  Further,
EPA believes this requirement for RACT applies to stationary sources as
a group, and not to each stationary source.  While a State may also
chose to impose RACM on other source categories such as mobile sources,
RACT controls are only required for existing stationary sources. 
Section 172(c)(1) requires that RACM include, at a minimum, RACT on
existing stationary sources and the final rule is fully consistent with
that requirement.

The EPA believes that there arefinds sound policy reasons for choosing
option 2.  While an approach that provided for application of the same
controls in all areas would provide for more equity across areas, EPA
emphasizes that equity is only one of many factors considered by EPA
when deciding between options 1, 2 and 3. The EPA believes that it is
also important to ensure that control strategies focus on the most
effective measures with the greatest possibility for significant air
quality improvements.   In addition, while EPA agrees that options 1 and
3 could provide for greater ease of implementation, this is also only
one of the factors EPA considered when deciding between the proposed
options. Under option 2, States have a greater burden and responsibility
to identify the local strategy that is tailored to their particular air
quality problem.   At the same time, the States have the ability to
identify the sources with the greatest impact on nonattainment and to
identify a sound strategy that achieves attainment in the most sensible
manner.  The EPA believes that approaching RACT and RACM in this manner
is consistent with the overall philosophy imbedded in the SIP program
since its inception in the late 1960s and early 1970s.

	Comment:   Some commenters believed that the proposed RACM requirement
was too broad.  These commenters believed that the requirement to
analyze the entire “universe” of possible measures was too
burdensome for States.  Commenters felt this was especially true in
light of the lack of federally issued CTG and ACT documents for PM2.5
and its precursors for all potential source categories.   

	Response:  The EPA recognizesAs explained earlier, States should apply
“reason” in identifying measures to evaluate as potential RACM/RACT.
 We recognize that States are implementing the PM2.5 standard for the
first time, and do not have the long history and experience in
implementing PM2.5 as they have in implementing the PM10 and ozone
standards.  Accordingly, we expect that both the States and EPA will be
required to expend extra effort in developing and evaluating
nonattainment plans that contain appropriate controls.  Given the nature
of PM2.5 and the needA number of resources exist to address emissions of
both direct PM2.5 and its precursors from a variety of sources, however,
EPA cannot artificially curtail the RACM requirement solely to those
sources and potential controls for which the most extensive information
exists.  The EPA believes that there are a number of resources available
to States that provide States with information on potential control
measure costs and emissions reductions.   EPA also intendsWe intend to
facilitate the sharing of information through a control measure website
and other efforts.   In addition, given the provisions allowing
exclusion of a set of measures that collectively would not advance the
attainment date by 1 year, , and expect that States will likely only
need to adopt an appropriate subset of the full “universe” of
measures that have a potential for substantial air quality benefit, and
it is likely thatdevelop screening approaches will be available to
demonstrate that this is the case.    methods to reduce the burden of
analysis.

	Comment:  One commenter asserted that EPA should not require the
analysis for, or implementation of, RACT and RACM for sources throughout
the entire nonattainment area, and should permit States to focus only on
sources located in smaller specific “problem areas” within the
nonattainment area.

	Response:   The EPA has designated areas nonattainment based upon
analysis of the geographic area with sources that “contribute” to
the violation of the NAAQS in the area, in accordance with section
107(d). These designations are based upon, among other things, a network
of monitors that the State and EPA had previously agreed upon as
representative of represented the ambient air concentrations throughout
the area.  Additional analysis of information during the designation
process  indicated those areas that contributed to the violations at the
violating monitor because of, among other things, the amount of
emissions in such adjoining areas.  Accordingly, the State in which a
nonattainment area is located must evaluate the full range of sources of
PM2.5 and its precursors throughout the designated nonattainment area
during the development of the SIP.  The EPA agrees that there are some
nonattainment areas where one or a few large emissions sources may be
causing localized concentrations at a monitor that are much higher than
those within the remainder of the nonattainment area.   For such areas,
the nonattainment strategy will likely not succeed without addressing
those sources.   The EPA does not, however, believe it is acceptable
that the nonattainment strategy focus only on those sources, because
additional reductions within the nonattainment area would still have the
potential to advance the attainment date.  Exempting portions of the
nonattainment area could expose a portion of the public residing
downwind in the area to exposure to levels of PM2.5 that exceed the
NAAQS for longer than necessary, and the health detriments from such
exposure, merely to minimize the impact of having to impose control
strategies on sources upwind.   Moreover, to the extent that monitoring
in one portion of a nonattainment area indicates violations in multiple
portions of the area, a strategy that solely focused upon the sources in
the immediate vicinity of the monitor would subvert the goal of
achieving might fail to assure that the NAAQS is achieved throughout the
area.  Because NAAQS violations generally reflect a combination of
regional scale, metropolitan scale, and local scale impacts, and all
three scales must be addressed, EPA requires RACT/RACM submittals to
address sources throughout the nonattainment area.

Comment:  Some commenters agreed with EPA’s view   that  State’s
RACM analysis must address those measures that a State declines to adopt
and must show  whether the combined measures would cumulatively advance
the attainment date by at least 1 year.  One commenter questioned the
legal basis for EPA’s determination that the only controls necessary
to attain the PM2.5 NAAQS as expeditiously as practicable are those that
would cumulatively advance an area’s projected attainment date by at
least one calendar year.  The commenter suggested that control measures
that would advance attainment by a smaller increment “would meet the
criteria endorsed in Sierra Club [Sierra Club v. EPA, 294 F.3d 155 (D.C.
Cir 2002)] by ‘expedit[ing] attainment in the relevant area.’”

Response:  The EPA has consistently interpreted RACM as a collection of
measures that would advance the attainment date by at least 1 year, and
the courts have determined that the statutory RACM requirement is
ambiguous and deferred to EPA’s interpretation of the requirement. 
See Sierra Club. v. EPA, 314 F.3d 735, 744 (5th Cir. 2002); see also
Sierra Club v. EPA, 294 F.3d, 155 162 (D.C. Cir. 2002).  Contrary to the
commenter’s suggestion, the court in Sierra Club v. EPA, did not
endorse specific criteria for identifying control measures that expedite
attainment, but instead deferred to EPA’s interpretation of an
ambiguous statutory term.  The courts decided to deferdeferred to
EPA’s interpretation after reviewing EPA’s approval of State SIP
submissions.  The EPA conducts such reviews consistent with its
determination that the CAA only requires such RACM as will provide for
expeditious attainment as expeditiously as practicable, and its belief
that it would be unreasonable to require implementation of measures that
would not in fact advance attainment.  See 57 FR 13498, 13560 (April 15,
1992); see also 44 FR 20372, 20374 (April 4, 1979).   In considering
whether a collection of measures would advance the attainment date of an
area, EPA has previously interpreted the phrase “advance the
attainment date” as meaning that the attainment date would be advanced
by at least 1 year.   See e.g., 66 FR 57160, 57182 (Nov. 14, 2001)
(approval of Houston SIP); 66 FR 586 (Jan 3. 2001) (approval of DC area
SIP).  Further, EPA’s use of a one-year increment in determining
whether a collection of measures would advance the attainment date is
reasonable and consistent with the fact that all areas will be designing
attainment demonstrations for the annual PM2.5 standard.  Section
172(a)(2)(C) statute uses 1 year as the increment by which attainment
date extensions can be granted. Thus, requiring evaluation of whether
control measures would advance attainment by an increment of 1 year is a
reasonable approach for the PM2.5 NAAQS.

	Comment:   Some commenters recommended that EPA consider not requiring
a RACM analysis for areas projected to attain the standards within 5
years of designation, i.e., by April 2010 for the areas currently
designated nonattainment.  One commenter suggested that practical
considerations would make it impossible for any State projected to
attain by 2010 to advance the attainment date by a year.  This commenter
noted that because measures to provide for attainment by 2010 must be
implemented by the beginning of 2009, and SIPs are not submitted until
April 2008, it would impossible to advance the implementation of
measures by 1 year (that is, the beginning of 2008). 

	Response:  The EPA generally agrees that given the time constraints it
will be difficult for States with areas currently designated
nonattainment to devise, adopt, and implement RACM measures to advance
the attainment date before 2010.   At the same time, however, we note
that nothing precludes States from taking early action and we encourage
States to take actions to reduce PM2.5 concentrations where feasible
even before the SIPs are submitted.  RACM is required by the CAA and
thus EPA cannot waive the requirement for the analysis and.  At the
expeditious implementation of measuressame time, EPA recognizes that
will advance attainment in the area, although a streamlined analysis may
be appropriate given the short time periods involved.

3.   Observations and considerations in determining RACT and RACM tc
"15.What factors should States consider in determining whether control
measures are reasonably available? " \l 3 

a. Background. 

	The preamble to the proposed rule included a discussion of general
considerations for RACT (70 FR 66020 and 66021, latter part of section
III.I.6) and RACM (70 FR 66028, section III.1.15).   The preamble to the
final rule retains this discussion with some modifications and
restructuring to reflect the combined approach to RACT and RACM

b. Final rule.   

	General considerations.  Once the State has identified measures and
technologies that are available for implementation in the nonattainment
area, then it must evaluate those measures to determine whether
implementation of such measures would be technically and economically
feasibleare reasonable, and would collectively advance attainment.  Many
of the factors that the State should take into consideration in
determining whether a measure is “reasonable” are related to the
measure’s technical and economic feasibility are described in sections
F.4 and F.5 below. . Since RACM applies to area and mobile sources as
well as stationary sources, the State should consider other factors as
well in conducting its RACM analysis.  For example, in many cases
obtaining emissions reductions from area and mobile sources is achieved
not by adding control technology to a specific emissions source, but by
reducing the level of activity of a fleet of vehicles or by modifying a
type of commercial process.  In these situations, the State should also
consider local circumstances such as infrastructure, population, or
workforce and the time needed to implement the measure in light of the
attainment date.

	The EPA believes that while areas projected to attain within 5 years of
designation as a result of existing national measures should still be
required to conduct a RACT and RACM analysis, such areas may be able to
conduct a limited RACT and RACM analysis that does not involve
additional air quality modeling.  A limited analysis of this type could
involve the review of available reasonable measures, the estimation of
potential emissions reductions, and the evaluation of the time needed to
implement these measures.  If the State could not achieve significant
emissions reductions by the beginning of 2008 due to time needed to
implement reasonable measures or other factors, then it could be
concluded that reasonably available local measures would not advance the
attainment date.  In lieu of conducting air quality modeling to assess
the impact of potential RACT and RACM measures, existing modeling
information could be considered in determining the magnitude of
emissions reductions that could significantly affect air quality and
potentially result in earlier attainment.  If the State, in consultation
with EPA, determines from this initial, more limited RACT and RACM
analysis that the area may be able to advance its attainment date
through implementation of reasonable measures, then the State must would
conduct a more detailed RACT and RACM analysis, involving air quality
modeling analyses, to assess whether it can advance the attainment date.
 .

	Observations on control opportunities.  The implementation of the PM2.5
NAAQS is in its initial stages, and many of the designated PM2.5
nonattainment areas are not current or former PM10 nonattainment areas. 
Thus, some existing stationary sources in these areas may currently be
uncontrolled or undercontrolled for PM2.5 or PM2.5 precursors.  Further,
to this point in time, emissions controls for existing sources in these
areas may have focused primarily on particulate matter that is
filterable at stack temperatures and thus may not adequately control
condensable emissions.  In addition, States should bear in mind that the
controlled sources may have installed emission controls 15 years ago or
more, and there may now be cost-effective opportunities available to
reduce emissions further through more comprehensive and improved
emissions control technologies, or through production process changes
that are inherently lower in emissions.  

	Moreover, improved monitoring methods may enhance the ability of
sources to maintain the effectiveness of installed emissions controls
and to reduce emissions by detecting equipment failures more quickly. 
For example, State imposition of requirements for more frequent
monitoring (e.g., continuous opacity monitors, PM continuous emissions
monitors, etc.) may provide greater assurance of source compliance and
quicker correction of inadvertent upset emissions conditions than
existing approaches. 

	Even in former or current PM10 nonattainment areas, existing
requirements for controlling direct PM emissions (e.g., with a baghouse
or electrostatic precipitator) may not have been revised significantly
since the 1970's.  When EPA established the PM10 standards in 1987, we
stated in the  preamble that it was reasonable to assume that control
technology that represented RACT and RACM for total suspended
particulates (TSP) should satisfy the requirement for RACT and RACM for
PM10.  52 FR 24672 (July 1, 1987).   The  basis for EPA’s belief was
that controls for PM10 and TSP would both focus on reducing coarse
particulate matter, and specifically that fraction of particulate matter
that is solid (rather than gaseous or condensable) at typical stack
temperatures.  However, emission controls to capture coarse particles in
some cases may be less effective in controlling PM2.5.  For this reason,
there may be significant opportunities for sources to upgrade existing
control technologies and compliance monitoring methods to address direct
PM emissions contributing to fine particulate matter levels with
technologies that have advanced significantly over the past 15 years.  

	Precursor Controls.  It will be important for States to conduct RACT
and RACM determinations for stationary sources of PM2.5 precursors as
well as direct PM2.5 emissions although, as noted above, the known
atmospheric chemistry of the area may dictate the necessary rigor of
this analysis.  A significant fraction of PM2.5 mass in most areas
violating the standards is attributed to secondarily-formed components
such as sulfate, nitrate, and some organic PM, and EPA believes that
certain stationary sources of precursors of these components in
nonattainment areas currently may be poorly controlled.  Accordingly, to
address these precursors, States should review existing sources for
emission controls or process changes that could be reasonably
implemented to reduce emissions from activities such as fuel combustion,
industrial processes, and solvent usage. 

Multi-State nonattainment areas.  States in multi-State nonattainment
areas will need to consult with each other on appropriate level of RACT
and RACM for that area. We anticipate that States may decide upon RACT
and RACM controls that differ from State to State, based upon the
State’s determination of the most effective strategies given the
relevant mixture of sources and potential controls in the relevant
nonattainment areas.  So long as each State can adequately demonstrate
that its chosen RACT and RACM approach will provide for meeting RFP
requirements and for attainment of the NAAQS as expeditiously as
practicable for the nonattainment area at issue, we anticipate approving
plans that may elect to control a somewhat different mix of sources or
to implement somewhat different controls as RACT and RACM. 
Nevertheless, States should consider and address RACT and RACM measures
developed for other areas or other States as part of a well reasoned
RACT and RACM analysis.  The EPA’s own evaluation of State SIPs for
compliance with the RACT and RACM requirements will include comparison
of measures considered or adopted by other States.. EPA may consider
such measures in assessing the approvability of a State’s SIP. 

c. Comments and Responses

	Comment:  In the proposed rule, EPA indicated that States could
consider the “social acceptability” of measures as a factor in the
determination of what constitutes RACM in a given area.   A number of
commenters recommended that EPA eliminate use of this factor.  Some
commenters questioned whether States or EPA had the legal authority to
exclude measures from consideration based on social acceptability or
popularity, if the measures are technically and economically available ,
and are needed to attain the NAAQS for protection of public health.  
Others expressed concerns that inclusion of such a factor would
inevitably result in the elimination of controls for area and mobile
sources and for this reason would unfairly focus emissions reduction
strategies on industrial sources of PM2.5 and precursors.

	Response:  The EPA believes that in developing RACM measures, it is
important that States not rely unduly on measures that would be very
difficult to achieve enforce in practice.  The EPA’s intent was to We
discourage States from relying on measures that on paper may seem
reasonably available but in practice might fail to achieve benefits due
to resistance to implementing the measures.  However, we recognize that
the CAA does not identify “social acceptability” as a factor in the
definition of what may constitute RACT or RACM, and more generally the
CAA does not establish a preference for measures that affect industrial
sources instead of  the general public and are therefore more likely to
be “socially acceptable.”  Therefore, given the concerns raised by
commenters that establishment of “social acceptability” as a factor
in the RACM analysis is without basis in the CAA and might result in
inappropriate skewing of control strategies, we have removed this term
from the final rule. We reiterate, however, that capability of effective
implementation and enforcement are relevant considerations in the RACM
analysis, even though public “unpopularity” is not.  Moreover, in
assessing the efficacy of measures and the credit they should be given
in the context of attainment demonstrations or RFP calculations, EPA
believes that such considerations are important.  

4.	What factors should States consider in determining whether an
available control technology or measure is technically feasible?

a. Background.

	 In the preamble to the proposed rule, EPA includedThe following
provides guidance for States to consider in determining whether an
available control technology is technologically feasible.  We include
this guidance in this preamble as well.  

b.  Final Rule. 

	The technological feasibility of applying an emission reduction method
to a particular source should consider factors such as the source’s
process and operating procedures, raw materials, physical plant layout,
and any other environmental impacts such as water pollution, waste
disposal, and energy requirements.  For example, the process, operating
procedures, and raw materials used by a source can affect the
feasibility of implementing process changes that reduce emissions and
the selection of add-on emission control equipment.  The operation and
longevity of control equipment can be significantly influenced by the
raw materials used and the process to which it is applied.  The
feasibility of modifying processes or applying control equipment also
can be influenced by the physical layout of the particular plant.  The
space available in which to implement such changes may limit the choices
and will also affect the costs of control.  

	Reducing air emissions may not justify adverseadversely affecting other
resources by increasing the pollution of bodies of water, creating
additional solid waste disposal problems or creating excessive energy
demands.  An otherwise available control technology may not be
reasonable if these other environmental impacts cannot reasonably be
mitigated.  For analytic purposes, a State may consider a PM2.5 control
measure technologically infeasible if, considering the availability (and
cost) of mitigating adverse impacts of that control on other pollution
media, the control would not, in the State's reasoned judgment, provide
a net benefit to public health and the environment.  In However, in many
instances, however,past situations, States and owners of existing
sources have adopted PM2.5 control technologies have with known energy
penalties and some adverse effects on other media, but based on the
reasoned judgment that installation of such effects and the cost of
their mitigation are also knowntechnology would result in a net benefit
to public health and have been borne by owners of existing sources in
numerous cases.  Such well-established adverse effects and their costs
are normal and assumed to be reasonable and should not, in most cases,
justify rejection of the potential PM2.5 control technology.the
environment.  States should consider this in determining technical
feasibility.  The costs of preventing adverse water, solid waste and
energy impacts will also influenceshould be included in assessing the
economic feasibility of the PM2.5 control technology.

	One particular cross-media issue relates to concentrated animal feeding
operations (CAFOs).  Since 2003, EPA and many stakeholders have been
interested in developing a framework to enable CAFOs to pursue superior
environmental performance across all media.  We are aware that today
some CAFOs voluntarily conduct whole-farm audits to evaluate releases of
pollutants to all media through Environmental Management Systems,
self-assessment tools, performance track, ISO 14001 certification, and
State-approved trade offs in meeting regulatory thresholds between air
and water that accomplish the best overall level of environmental
protection given State and local conditions.  The EPA continues to
believe the development of new and emerging technologies offers the
potential to achieve equivalent or greater pollutant reductions than
achieved solely by effluent guidelines and standards.  Many of these are
superior from a multimedia perspective, and EPA would like to encourage
superior multimedia solutions.  SIPs which need to address ammonia may
provide a unique opportunity to encourage multimedia approaches at
CAFOs.  For example, the addition of animal by-products provides a
valuable source of nutrients for crops, improves soil structure which
enhances soil permeability, and adds valuable organic matter that
improves soil health.  However, inappropriate application can lead to
air and water quality concerns or the improvement of one media at the
cost of another.  Optimal application technologies and rates reduce
potential air and water quality standards violations.  The EPA does not
want to discourage approaches that are superior from a cross media
perspective.

	The EPA recommends that States evaluate alternative approaches to
reducing emissions of particulate matter by reviewing existing EPA
guidance and other sources of control technology information.  The
EPA’s 1998 guidance presents information on topics such as  the
design, operation and maintenance of general particulate matter control
systems such as electrostatic precipitators, fabric filters, and wet
scrubbers.  The filterable particulate matter collection efficiency of
each system is discussed as a function of particle size.  The guidance
document also provides informatinoinformation concerning other relevant
considerations such as energy and environmental considerations,
procedures for estimating costs of particulate matter control equipment,
and evaluation of secondary environmental impacts.  Because control
technologies and monitoring approaches are constantly being improved,
the State should also consider more updated or advanced technologies not
referenced in this 1998 guidance when conducting a RACT determination. 
Emissions reductions may also be achieved through the application of
monitoring and maintenance programs that use critical process and
control parameters to verify that emission controls are operated and
maintained so that they more continuously achieve the level of control
that they were designed to achieve.

c. Comments and Responses

	Comment:  One commenter noted that the guidance for “technical
feasibility” implies that States look at individual sources with a
BACT-like case-by-case analysis.  The commenter recommended that source
owners conduct such a site-specific analysis and submit the analysis to
the State through the permitting process.

	Response:    While the analytical analysis to identify RACT is similar
to BACT, as noted above, EPA in the past has issued CTGs that describe
the presumptive norm for RACT controls for a given industry, but that
allow for case-by-case considerations for a given source.  Where States
wished to require source owners to conduct such a site-specific analysis
as part of the control technology review, EPA supports this type of
process.  On the other hand, EPA does not believe it would be
appropriate to require all RACT-eligible sources to conduct such an
analysis, given that States have the primary responsibility for
identifying and analyzing measures for such sources.

5.  What factors should States consider in determining whether an
available control technology or measure is economically feasible? tc
"7.What factors should States consider in determining whether an
available control technology is economically feasible? " \l 3 

a. Background.

	In the preamble to the proposed rule, EPA includedThe follow provides
guidance for States to consider in determining whether an available
control technology is economically feasible for purposes of identifying
reasonably available control measures.  We include this guidance in this
preamble as well, with modificationsThis guidance is slightly modified
from our proposal. 

b.   Final Rule.

	 Economic feasibility considers the cost of reducing emissions and the
difference between the cost of the emissions reduction approach at the
particular source and the costs of emissions reduction approaches that
have been implemented at other similar sources.  Absent other
indications, EPA presumes that it is reasonable for similar sources to
bear similar costs of emissions reduction.  Economic feasibility for
RACT purposes is largely determined by evidence that other sources in a
source category have in fact applied the control technology or process
change in question.   Of course, EPA also encourages the development of
innovative measures not previously employed which may also be
technically and economically feasible.

	The 	 Economic feasibility encompasses considerations such as whether
the cost of a potential measure is reasonable considering attainment
needs of the area and the costs of other measures, and whether the cost
of a measure is reasonable for the regulated entity to bear, in light of
benefits.

	While many States generally establish RACT requirements for a category
of sources, the Act does not require the same level of control on all
sources in a category, nor does the Act require that each source be
controlled individually.  Similar sources may have different marginal
costs, profit margins and abilities to pass costs through to the
consumer.  These factors are appropriate to consider in determining
whether a given level of control is appropriate for an individual source
or category of sources.  Accordingly, there is no presumption that a
given source must bear a cost similar to any other source.  

	States should consider the capital costs, annualized costs, and cost
effectiveness of an emissions reduction technology should be considered,
and effects on the local economy in determining whether a potential
control measure is reasonable for an area or State.  One available
reference for calculating costs is the EPA Air Pollution Control Cost
Manual, which describes the procedures EPA uses for determining these
costs for stationary sources. The above costs should be determined for
all technologically feasible emission reduction options if such measure
is inherently “reasonably available” (e.g., not absurd or clearly
impractical).   States may give substantial weight to cost effectiveness
in evaluating the economic feasibility of an emission reduction
technology.  The cost effectiveness of a technology is its annualized
cost ($/year) divided by the emissions reduced (i.e., tons/year) which
yields a cost per amount of emission reduction ($/ton).  Cost
effectiveness provides a value for each emission reduction option that
is comparable with other options and other facilities.  Where multiple
control options exist for a given source or source category, States
should consider both the cost effectiveness (dollars per ton) of each
option, and the incremental cost effectiveness per ton between the
options (incremental increase in cost between options divided by the
incremental tons reduced).

With respect to In determining whether a given pollutant, a measure is
likely to be reasonable if it has a cost, States may consider costs per
ton similar toof other measures previously employed forto reduce that
pollutant.  In addition, a measure is likely to be reasonable from a
cost effectiveness standpoint if it has a cost per ton similar to that
of other measures needed to achieve expeditious attainment in the area
within the act’s time frames, but similar costs are not conclusive. 
As discussed above, States may evaluate equity considerations in
weighing the economic feasibility of imposing a measure on a given
source or source category.   

The fact that a measure has been adopted or is in the process of being
adopted by other states is an indicator (though not a definitive one)
that the measure may be technically and economically feasible for
another State.  We anticipate that States may decide upon RACT and RACM
controls that differ from State to State, based on the State’s
determination of the most effective strategies given the relevant
mixture of sources and potential controls in the relevant nonattainment
areas, and differences in the difficulty attaining expeditiously. 
Nevertheless, States should consider and address RACT and RACM measures
developed for other areas or other States as part of a well reasoned
RACT and RACM analysis.  The EPA’s own evaluation of State SIPs for
compliance with the RACT and RACM requirements will include comparison
of measures considered or adopted by other States.of reaching
attainment.  

	In considering what level of control is reasonable, EPA is not
proposing a fixed dollar per ton cost threshold for RACT, consistent
with the views of multiple commenters.  Areas with more serious air
quality problems typically will need to obtain greater levels of
emissions reductions from local sources than areas with less serious
problems, and it would be expected that their residents could realize
greater health benefits from attaining the standard.  For these reasons,
we believe that it will be reasonable and appropriate for areas with
more serious air quality problems and higher design values to impose
emission reduction requirements with generally higher costs per ton of
reduced emissions than the cost of emissions reductions in areas with
lower design values.  In addition, where.  Where essential reductions
are more difficult to achieve (e.g., because many sources are already
controlled), the cost per ton of control may necessarily be higher.  

We believe that in determining appropriate emission control levels, the
State should consider the collective health benefits that can be
realized in the area due to projected improvements in air quality.  The
health benefits associated with reducing PM2.5 levels are significant. 
Using estimation techniques reviewed and deemed reasonable by the
National Academy of Sciences, national monetized health benefits
resulting from reductions in PM concentrations are estimated to exceed
emission control costs by a factor of three to thirty times, depending
on the particular controls on sources of PM and precursor emissions.10 
This approach is consistent with EPA’s selection of option 2 for the
interpretation of the RACT requirement for PM2.5, i.e., that RACT is
related to what is needed for attainment.  That is, because EPA
concludes that RACT requirement will be met where the State demonstrates
timely attainment, and areas with more severe air quality problems
typically will need to adopt more stringent controls, RACT level
controls in such areas will require controls at higher cost
effectiveness levels ($/ton) than areas with less severe air quality
problem  

It is not appropriate to assume that the same cost per ton range is
reasonable for direct PM2.5 and different precursors, because an equal
amount of emission reduction in different pollutants has a different
impact on PM2.5 ambient levels.  For example, in a given nonattainment
area, reductions of direct PM2.5 emissions may prove more expensive than
reductions of Nox emissions, but the resulting benefits of reductions of
direct PM2.5 might warrant the higher costs.  A State should consider
this differential impact on ambient PM2.5 in considering the cost per
ton that is reasonable for controlling different pollutants.  During the
SIP process, States and regional planning organizations typically
conduct sensitivity modeling that can provide this information.  Also,
the forthcoming PM NAAQS RIA will provideprovides information on the
differential impact of PM2.5 and PM precursor reductions on ambient
PM2.5 levels in various areas.

In identifying the range of costs per ton that are reasonable,
information on benefits per ton of emission reduction can be useful as
one factor to consider.  The PM NAAQS RIA will provide information on
the estimated benefits per ton of reducing direct PM2.5 and PM
precursors from various sectors in several analyzed areas.  It should be
noted that such benefits estimates are subject to significant
uncertainties, and that benefits per ton vary in different areas. 
Nonetheless this information could be used in a way that recognizes
uncertainties.  If the cost per ton for a measure is significantly less
than the anticipated benefits per ton, this would be a positive
indicator that the cost per ton is reasonable.

One of the factors that could affect estimated compliance costs of an
emission reduction measure is the timing of its implementation. 
Hypothetically, if a short compliance period were contemplated for a set
of sources, and if the short compliance period resulted in high demand
for a limited supply of labor or other resources, compliance costs could
be higher than if the same measure were implemented by a later
compliance date.  Should such a situation arise, in considering the
controls that are reasonable, the state should take into account both
the potential for higher costs and the additional health benefits of
achieving the emission reductions sooner rather than later.In such a
case it may be reasonable for the State to find that the measure is
reasonable only if implemented by the later date. 

	If a source contends that a source-specific RACT level should be
established because it cannot afford the technology that appears to be
RACT for other sources in its source category, the source should can
support its claim with detailed and verifiedsuch information regarding
the impact of imposing RACT onas:

-- fixed and variable production costs ($/unit),

-- product supply and demand elasticity,

-- product prices (cost absorption vs. cost pass-through),

-- expected costs incurred by competitors,

-- company profits, once the technology or measure is in operation
(considering the annualized costs and the marginal costs of alternative
technologies and measures), , 

-- employment costs., and

-- any other unique factor(s) particular to the individual source.

	Finally, the EPA clarifies that if the State demonstrates through
economic analysis that the imposition of the measure would cause
unacceptable economic disruption for the local economy, that is, a plant
shutdown or a severe curtailment in plant employment or output, a State
may reject the measure as not reasonable to reach attainment as
expeditiously as practicable.

c. Comments and Responses. 

	Comment:   Some commenters agreed with EPA’s proposal not to
establish presumptive cost-effectiveness thresholds. 

	Response:  The EPA agrees with the commenters.

	Comment:  A number of commenters expressed concerns over the references
to health benefits as a consideration in whether measures are
technically or economically available.   Some commenters believed this
is a consideration not authorized by the CAA.  Others believed that
consideration of benefits, in combination with EPA’s estimates of
benefits per ton, would have the effect of converting RACT to more
stringent LAER levels.  Some commenters expressed concerns whether
States had the resources or expertise to conduct cost-benefit analyses
for this purpose.  

	Response:   The EPA wishes to clarify that the reference to health
benefits does not mean that a cost-benefit, or a detailed health
benefits assessment, is a necessary part of a control strategy
demonstration.   We also wish to clarify that EPA is not requiring that
the costs of all technologies and measures for PM2.5 and precursors be
deemed acceptable at any dollar/ton levels at or below the calculated
monetized benefits per ton of reduction.   We do, however, continue to
believe that whetherthe significant benefits associated with PM2.5
ambient reductions generally lead to very high monetized benefits is a
relevant consideration in control strategy development.  We believe that
the general level of benefits is something States and the public should
consider when making decisions on whether to pursue control measures and
technologies.   The EPA disagrees that this limited consideration of
benefits would convert the RACT process to the equivalent of LAER.  
This would perhaps be theoretically possible if RACT were an entirely
independent analysis separate from the attainment demonstration, and EPA
took the position that all measures less than a bright-line monetized
benefits cutoff must be selected.     Because RACT, as structured in the
final rule, is inherently linked to the attainment demonstration, and
because as clarified above, the benefits estimates are not to be used as
a “bright line,” we disagree that use of these benefits estimates
could even theoretically convert RACT to LAER. Because RACT is linked to
what is necessary to attain as expeditiously as practicable, we disagree
that any consideration of benefits would convert RACT to LAER.

	Comment:  One commenter objected to EPA’s proposed requirement that
States consider competitive factors such as production costs, demand
elasticity, product prices, and cost incurred by competitors in the
determination of RACT. The commenter believed that this information is
generally not accessible to States or industrial facility owners, and is
not necessary for a RACT determination.  

	Response:   The EPA generally disagrees that this type of information
is unavailable.  For example, EPA calculates or reviews this type of
data on a regular basis as part of our work on MACT, NSPS, and other
emissions standards.   A document that describes these types of analyses
and the data used to prepare them is the OAQPS Economic Resource Manual
found at     HYPERLINK "http://www.epa.gov/ttn/ecas/analguid.html" 
http://www.epa.gov/ttn/ecas/analguid.html .    EPA believes that this
issue is most relevant to category-wide RACT rules where a source seeks
a case-by-case exemption.   Further, EPA believes most RACT
determinations will be developed through case-by-case analyses rather
than rules affecting entire source categories.  Accordingly, this
analysis likely will be requiredrelevant in relatively few cases.   

6.  What specific source categories and control measures should a State
evaluate when determining RACT and RACM for a nonattainment area? tc
"16.What specific source categories and control measures should a State
evaluate when determining RACM for a nonattainment area? " \l 3 

a.  Background.

	 Section 172 does not provide a specific list of source categories and
control measures that must be evaluated for RACT and RACM for PM2.5. 
However, section 172(c)(3) indicates that the nonattainment area plan
must include a “comprehensive, accurate, current, inventory of actual
emissions from all sources of the relevant pollutant.”  This indicates
that States should look broadly at allthe different types of sources in
the nonattainment area.  We recognize that PM2.5 is a new NAAQS without
a long history of implementation as with  ozone.  Therefore, we included
a list of potential RACM measures in the preamble to the proposed rule,
based upon a review of information about the contribution of various
sources to emissions inventories and a review of potential control
measures for such sources.  We requested comment on the specific sources
and potential control measures recommended for RACM analysis on this
list.   Based on comments received and additional information available
to EPA since the proposal, we have made some changes to the list. We
also refer to this list of  potential “RACT and RACM” measures for
the combined approach to RACT and RACM in the final rule.

	In the preamble to the proposed rule, EPA indicated that due to the
short time available, it does not plan  to develop new control
techniques guidance (CTG) or ACT documents specifically for purposes of
PM2.5 implementation.  The EPA indicated that other information was
available on control technologies, and EPA also indicated its intention
to maintain an updated list of references for new PM2.5 control
technology information.  

b. Final rule.

 Emission reduction measures constituting RACM should be determined on
an area-by-area basis.  We believe that a State should consider each of
the measures listed in this section to determine if each measure is
reasonably available in the applicable nonattainment area.  However, we
do not presume that each of these measures is reasonably available in
each nonattainment area. 

	We recommend that each State use the list of source categories in this
section as a starting point for identifying potentially available
control strategies (regulatory and voluntary) for a nonattainment area. 
States are encouraged and expected to add other potentially available
measures to the list based on its knowledge of the particular universe
of emissions sources in the area and comments from the general public. 
We expect that, depending on the potential measure being analyzed, the
State’s degree of evaluation will vary as appropriate.  Detailed
information on emission control technologies is available from a number
of sources.   EPA intends to maintain a website with links to sources of
information for controlling emissions of direct particulate matter and
PM precursors.  

	As discussed in section II.J.5. above, EPA recognizes that control
technology guidance for certain source categories has not been updated
for many years.  Section 183(c) of the CAA, which addresses control
technologies to address ozone nonattainment problems, requires EPA to
“revise and update such documents as the Administrator determines
necessary.”  As new or updated information becomes available States
should consider the new information in their RACT determinations.  A
State should consider the new information in any RACT determinations or
certifications that have not been issued by the State as of the time
such updated information becomes available.

Stationary source measures

- Stationary diesel engine retrofit, rebuild or replacement, with
catalyzed particle filter

- New or upgraded emission control requirements for direct PM2.5
emissions at stationary sources (e.g., installation or improved
performance of control devices such as a baghouse or electrostatic
precipitator; revised opacity standard; improved compliance monitoring
methods)

- Improved capture of particulate emissions to increase the amount of
PM2.5 ducted to control devices, and to minimize the amount of PM2.5
emitted to the atmosphere, for example, through roof monitors

- New or upgraded emission controls for PM2.5 precursors at stationary
sources (e.g., SO2 controls such as wet or dry scrubbers, or reduced
sulfur content in fuel; desulfurization of coke oven gas at coke ovens;
improved sulfur recovery at refineries; increasing the recovery
efficiency at sulfuric acid plants)

- Energy efficiency measures to reduce fuel consumption and associated
pollutant emissions (either from local sources or distant power
providers)

- Measures to reduce fugitive dust from industrial sites

Mobile source measures

- Onroad diesel engine retrofits for school buses,11 trucks and transit
buses using EPA-verified technologies

- Nonroad diesel engine retrofit, rebuild or replacement, with catalyzed
particle filter12

- Diesel idling programs for trucks, locomotive, and other mobile
sources13

- Transportation control measures (including those listed in section
108(f) of the CAA as well as other TCMs), as well as other
transportation demand management and transportation systems management
strategies14

- Programs to reduce emissions or accelerate retirement of high emitting
vehicles, boats, and lawn and garden equipment

- Emissions testing and repair/maintenance programs for onroad vehicles

- Emissions testing and repair/maintenance programs for nonroad
heavy-duty vehicles and equipment15

- Programs to expand use of clean burning fuels

- Prohibitions on the sale and use of diesel fuel that exceeds a high
sulfur content

- Low emissions specifications for equipment or fuel used for large
construction contracts, industrial facilities, ship yards, airports, and
public or private vehicle fleets

- Opacity or other emissions standards for “gross-emitting” diesel
equipment or vessels

- Reduce dust from paved and unpaved roads

Area source measures					

- New open burning regulations and/or measures to improve program
effectiveness such as programs to reduce or eliminate burning of land
clearing vegetation

- Smoke management programs to minimize emissions from forest and
agricultural burning activities

- Programs to reduce emissions from woodstoves and fireplaces including
outreach programs, curtailments during days with expected high ambient
levels of PM2.5, and programs to encourage replacement of woodstoves
when houses are sold

- Controls on emissions from charbroiling or other commercial cooking
operations

- Reduced solvent usage or solvent substitution (particularly for
organic compounds with 7 carbon atoms or more, such as toluene, xylene,
and trimethyl benzene)

- Reduce dust from construction activities and vacant disturbed areas

Category- Specific Guidelines on innovative approaches.  The EPA has
issued a number of category specific guidelines on approaches to taking
into account innovative approaches to emissions reductions for purposes
of SIPs.   Categories currently covered by these guidelines include: (1)
Electric-sector Energy Efficiency and Renewable Energy Measures (2) Long
Duration Switch Yard Locomotive Idling (3) Long Duration Truck Idling
(4) Clean Diesel Combustion Technology (5)  Commuter Choice Programs.  
See http://www.epa.gov/ttn/airinnovations/measure_specific.html

c.  Comments and Responses

Comment:  Some commenters recommended that EPA provide new CTGs or other
control technology review documents for purposes of assisting States to
address PM2.5 and its precursors, because the information in some
current documents is out-dated.

Response: The EPA recognizes that issuance of new or updated CTGs
specifically tailored for PM2.5 would be useful.  Unfortunately,
limitations on time and resources preclude EPA from developing such CTGs
in advance of the SIP submission date.  The EPA cannot delay the
statutorily specified outer date for SIP submission.  However, EPA
believes that there are already many sources of information and guidance
on key source categories.  To the extent that States need to examine
potential control measures for sources never addressed before in any
area or other context for a previous NAAQS, EPA anticipates that it will
work closely with States during the process of plan development and
approval to ensure an appropriate approach.   

Comment:  A number of commenters expressed concerns with references to
the STAPPA and ALAPCO Menu of Options document.  Some commenters
believed that this document must be subject to formal review and comment
to ensure appropriate stakeholder input.     

Response:  The EPA believes that the Menu of Options update contains
control technology information that States may wish to consider in
developing their PM2.5 SIPs.   The purpose of the document was to
develop “opportunities” for control through a “menu of options”
for States to consider.   As the document notesResponse:  The language
in the final preamble has been changed to refer to a website EPA
maintains that provides access to a variety of information sources
regarding control technologies that may be useful to States to consider
in developing their PM2.5 SIPs.  These links include evaluations
developed by government and nongovernment organizations.  One such
source with potentially useful information is the STAPPA and ALAPCO Menu
of Options.  However, EPA is not specifically recommending that States
adhere to this list of available sources of information during their
evaluation nor is EPA endorsing any of the specific evaluations as being
appropriate in any specific situation.  Rather, we think documents such
as the Menu of Options provide potentially useful ideas.  Specifically,
States willwould need to assess which items on the menu are applicable
in their areas, and will have to assess the costs of applying controls
locally.   Accordingly, there shouldwould be ample opportunity for
public review of the State’s analysis of the local cost and air
quality impacts of any measure listed in the document which is included
in a State’s SIP.  The EPA is not requiring that States adhere to the
list of measures in the Menu of Options.  The EPA does not in any way
mean to imply that the measures in the Menu of Options are presumed to
be RACM, merely that they are potential controls for areas to consider. 
 The Menu of Options has no regulatory significance and thus need not be
issued through notice-and-comment rulemaking.  The EPA notes, however,
that the Menu of Options does provide a comprehensive list of potential
sources and measures that should can help inform States in the
development of their plans.  Similarly, our own list of potential
measures is not intended to be a categorical list of measures which
States must adopt, rather it is intended to provide guidance about the
types of sources and measures that States shouldcan consider in
constructing their nonattainment area plans.  The EPA emphasizes that
whether a source category or potential measure is or is not on this list
is simply not dispositiveconclusive as to whether a given measure should
be required to meet is appropriate to consider in the RACT and RACM
requirement.analysis.  That can be determined only through the State’s
development of the nonattainment plan, and EPA’s evaluation of such
plan.

Comment:  A commenter representing the paper industry interpreted the
proposed rule as requiring electrostatic precipitator and tighter
sulfur-in-fuel requirements for the forest products industry.   The
commenter believed that  EPA was creating limits for such without
adequate rulemaking process.

Response:  The EPA disagrees that the listing of control technologies in
the table in the rule creates a “rebuttable presumption.”   Rather,
the table identifies potential opportunities for emissions reductions
which should be reviewed in light of technical and economic feasibility,
and which a State  should consider in a list of possible RACT and RACM
measures for purposes of attaining the standards as expeditiously as
practicable.  The EPA is currently conducting a sector-based approach to
the paper industry.  One of the goals of the sector initiative on pulp
and paper is to work with the industry to identify reductions in SO2 and
PM2.5 that will assist us in meeting the NAAQS, considering facility
locations, magnitude of emissions, emission stream characteristics, and
cost effectiveness of controls.  

Comment:  A number of commenters believed that EPA should develop not
only a list of measures to consider for RACM, but should develop a list
of mandatory measures that States should include, particularly for areas
with attainment dates more than 5 years after designation.

Response:  See discussion in section II.D.3 regarding rule requirements
for attainment date extensions and the issue of whether certain measures
should be mandatory in order for an area to receive an extension. 

Comment:   Some commenters believed that the list of possible measures
was deficient in not including sources of PM2.5 and PM2.5 precursors
from agricultural sources.  One commenter believed the list is
incomplete without identifying the contribution of ammonia emissions
associated with livestock, poultry, and crop fertilizers.   

Response:   The EPA agrees that measures have been identified for
reducing emissions of PM2.5 and other pollutants from agricultural
operations.   Substantial activity is underway to better characterize
emissions and contributions to ambient levels from agricultural
activities.  For example, a number of air quality topics related to
agriculture as discussed on EPA’s website at     HYPERLINK
"http://www.epa.gov/agriculture/tair.html" 
http://www.epa.gov/agriculture/tair.html .   The EPA’s list of
potential measures is not intended to be an exhaustive list of measures
for States to consider, and States should evaluate all measures with
potential for reasonable control of emissions that are significant in
their areas.   

	Since 2003, EPA and many stakeholders have been interested in
developing a framework to enable CAFOs to pursue superior environmental
performance across all media.  We are aware that today some CAFOs
voluntarily conduct whole-farm audits to evaluate releases of pollutants
to all media through Environmental Management Systems, self-assessment
tools, performance track, ISO 14001 certification, and State-approved
trade offs in meeting regulatory thresholds between air and water that
accomplish the best overall level of environmental protection given
State and local conditions.   The EPA continues to believe the
development of new and emerging technologies offers the potential to
achieve equivalent or greater pollutant reductions than achieved by the
solely effluent guidelines and standards.  Many of these are superior
from a multimedia perspective, and EPA would like to encourage superior
multimedia solutions.  SIPs which need to address ammonia may provide a
unique opportunity to encourage multimedia approaches at CAFOs.  For
example, the addition of animal by-products provides a valuable source
of nutrients for crops, improves soil structure which enhances soil
permeability, and adds valuable organic matter that improves soil
health.  However, inappropriate application can lead to air and water
quality concerns or the improvement of one media at the cost of another.
 Optimal application technologies and rates reduce potential air and
water quality standards violations.  The EPA does not want to discourage
approaches that are superior from a cross media perspective.  

	The EPA notes that during the SIP development process at the State
level, members of the public can recommend measures for the State to
consider, and that this will obligate the State to investigate such
controls to determine if they should be RACT or RACM in a given area. 
Through this process, EPA anticipates that States with areas that should
implement such measures will do so.   Further discussion regarding
ammonia is provided in section II.A. above regarding
precursors.Response:   As we indicated in the proposal, we included a
list of potential RACM measures in the preamble to the proposed rule,
based upon a review of information about the contribution of various
sources to the emissions inventories and a review of potential control
measures for such sources.  We did not identify emissions from
agricultural sources in this review.  Because ammonia is not presumed to
be a PM2.5 precursor unless identified for a specific area by the State
or EPA, regulation of ammonia emissions from agricultural sources may
not be necessary. 

We also note that the agricultural industry presents unique challenges
to regulators given the nature of the emissions source. Moreover, we
currently lack good methods to quantify agricultural emissions, and we
do not fully understand their contribution to nonattainment problems. 
We have entered into an agreement with several animal producer sectors
to monitor animal feeding operations to develop better tools to assess
emissions from this industry.  Hopefully, these tools will enhance our
knowledge of agricultural emissions and their contribution to
nonattainment problems, but until emissions from these sources are
better understood, States should apply appropriate deference in
determining whether any specific measure is RACT/RACM for this industry.
 

	Comment:   Some commenters raised concerns about a statement in the
proposal that “[i]n addressing a nonattainment area having military
training, testing and operational activities occurring within it, the
State should not need to target these activities for emission
reductions.”  Some commenters interpreted this statement as an
exemption from any emission reduction requirements for military sources.
 

	Response:  The statement in the proposal was not intended as an
exemption for all military activities.  Emissions potentially
contributing to PM2.5 concentrations at military installations originate
from a variety of sources:  basic operational activities (such as power
generation, other fuel combustion, and transportation to and from
residences, offices, and schools); and from field training and testing
activities (such as personnel training, obscurants used in training,
operation of nonroad vehicles and equipment, and related prescribed
burning operations).  EPA believes that in evaluating emissions for a
specific nonattainment area having military activities occurring within
it, the State should consult with DOD for information on the nature of
these activities and their associated emissions. 

	With regard to military training activities specifically, such
activities are periodic in nature, and when they do occur, the principal
type of emissions generated by these activities is dust (e.g. inorganic
direct PM emissions) from field operations.  Other pollutants may be
emitted to a lesser degree from certain onroad and nonroad motor
vehicles.  While military training activities may contribute some degree
of primary PM2.5 emissions to certain nonattainment area inventories,
the fugitive dust generated from military training activities is
predominantly comprised of coarse PM rather than fine PM.  

	Based on data from the PM2.5 speciation monitoring network operated by
EPA and the States, the contribution of inorganic dust to total PM2.5
mass on an annual average basis is relatively low in most nonattainment
areas, on the order of 0.5 to 1.5 micrograms per cubic meter (generally
10% or less of total PM2.5 mass).  Dust from military training
activities would be a subset of these levels.  Depending on the
available information and specific circumstances for a particular area,
a State could find in its SIP development analyses that direct PM2.5
emissions from military training activities do not significantly
contribute to PM2.5 concentrations in the nonattainment area, and
therefore would not need to target military training activities for
emission reductions in its nonattainment plan.  

  

7.  How should States consider EGU reductions for CAIR in meeting RACT
and /RACM requirements?  

a.  Background.

	 In section III.I.11 of the preamble to the proposed rule, we discussed
the nature of the SO2 and NOx RACT obligations of electric generating
unit (EGU) sources in states subject to the CAIR emission reduction
requirements.  The CAIR rulemaking was finalized in March 2005 and
published at 70 FR 25221 (May 12, 2005).  CAIR requires 28 states and
the District of Columbia to significantly reduce emissions of SO2 and/or
NOx.  The 26 jurisdictions in the CAIR PM2.5 region are required to
reduce annual emissions of SO2 and NOx, and the 26 jurisdictions in the
CAIR ozone region are required to reduce seasonal emissions of NOx.  
These jurisdictions also have the option of participating in
EPA-administered annual SO2, annual NOx, and seasonal NOx cap-and-trade
programs (the CAIR trading programs) to meet these emission reduction
requirements.  In addition, in March 2006, EPA promulgated a Federal
implementation plan (FIP) to implement CAIR in these jurisdictions until
they have EPA approved CAIR SIPs in place (71 FR 25328, April 28, 2006).
 The FIP adopts, as the control measure, the CAIR trading programs
slightly modified to allow for Federal instead of State implementation.
When fully implemented, CAIR will reduce SO2 emissions in these
jurisdictions by over 70 percent and NOx emissions by over 60 percent
from 2003 levels. This will result in $85 to $100 billion in health
benefits and nearly $2 billion in visibility benefits per year by 2015
and will substantially reduce premature mortality in the eastern United
States. The benefits will continue to grow each year with further
implementation.

	Sources subject to cap-and-trade programs such as the CAIR trading
programs generally have the option of installing emissions control
technology, adopting some other strategy to reduce emissions, or
purchasing emissions allowances and thereby effectively paying other
sources covered by the cap to reduce emissions. In the proposal, we
noted that a number of EGUs expected to be covered by the CAIR trading
programs are located in nonattainment areas. Based on emissions
projections for 2010 and 2015 using the Integrated Planning Model (IPM),
some of these EGUs are expected to comply with CAIR by purchasing
allowances under the trading program and some are expected to comply by
installing emission controls.  

	The proposal also described our past experience with the implementation
of the NOx SIP Call and our belief that many power companies will
develop their strategies for complying with CAIR based, in part, on
consultations with State and local air quality officials in order to
address local PM2.5 and ozone attainment planning needs.  The EPA
suggested that consultations on location of CAIR controls would be
timely during State development of the CAIR SIP, which is due in 2006,
prior to the April 2008 deadline for submitting PM2.5 nonattainment area
SIPs.

	The EPA proposed a determination that in states that fulfill their CAIR
SO2 emission reductions entirely through EGU emission reductions (i.e.
without reductions from non-EGU sources or allowing non-EGU sources to
opt-in to the CAIR SO2 trading program), participation in the CAIR SO2
trading program would satisfy the SO2 RACT requirement for the EGU
sources.  The EPA also proposed that in states that fulfill their CAIR
NOx emission reductions entirely through EGU emission reductions, CAIR
would satisfy NOx RACT for the EGU sources, provided that those sources
with existing selective catalytic reduction (SCR) emission control
technology installed on their boilers operate that technology on a
year-round basis beginning in 2009.  Note that direct PM2.5 emissions
are not addressed by the CAIR program, and EPA did not propose any
determination that compliance with CAIR would satisfy RACT for direct
PM2.5 emissions.  The proposal included a discussion of the rationale
for these proposed determinations for SO2 and NOx, and requested
comments on the issue.  

b.  Summary of finalFinal rule.

	Based on consideration of the public comments received, the final rule
maintains the determinations for SO2 and NOx RACT as described in the
proposal, and clarifies that, consistent with the SO2 RACT
determination, the NOx RACT determination for PM2.5 may be relied upon
by states subject to CAIR annual NOx and SO2 emission reduction
requirements (i.e. all states in the CAIR PM2.5 region), that achieve
all annual CAIR NOx reductions from EGUs.  

Section 51.1010 ofAs discussed in section II.F.2 on our overall policy
for RACT and RACM, we consider an area’s obligation to implement RACT
to be part of the area’s overall RACM obligation – to adopt those
reasonably available measures needed to reach PM2.5 attainment as
expeditiously as practicable.  The final rule also reflects this
combined RACT/RACM approach regarding EGU control obligations under CAIR
and the extent to which meeting CAIR also satisfies a source’s RACT
and RACM requirements for attainment.  

Specifically, the final rule providesincludes a presumption that in
States that fulfill their CAIR SO2 emission reduction requirements
entirely through EGU emission reductions (i.e. without reductions from
non-EGU sources or allowing non-EGU sources to opt in to the CAIR SO2
trading program), compliance by EGU sources with an EPA-approved CAIR
SIP or a CAIR FIP would satisfy the SO2 RACT requirement their SO2
RACT/RACM requirements for attaining the sources.fine particle NAAQS. 
This section also providesincludes a presumption that in States that are
subject to CAIR annual NOx emission reduction requirements and fulfill
these requirements entirely through EGU emission reductions (i.e.
without reductions from non-EGU sources or allowing non-EGU sources to
opt in to the CAIR annual NOx trading program), compliance by EGU
sources with an EPA-approved CAIR SIP or a CAIR FIP would satisfy the
NOx RACT/RACM requirement for the sourcesPM2.5 NAAQS, provided that the
sources with existing selective catalytic reduction (SCR) emission
control technology installed on their boilers operate that technology on
a year-round basis beginning in 2009.  This final position is based on a
number of factors identified in the proposal and reviewed discussed
below.  

	As discussed more fully in the CAIR final rulemaking notice, EPA has
set the 2009 and 2010 CAIR caps for SO2 and NOx at a level that will
require EGUs to install emission controls on the maximum total capacity
on which it is feasible to install emission controls by those dates. 
The EPA concluded that the CAIR compliance dates represent an aggressive
schedule that reflects the limitations of the labor pool, and
equipment/vendor availability, and need for electrical generation
reliability for installation of emission controls.

	Although the actual SO2 cap does not become effective until 2010, we
have designed (banking( provisions in CAIR so that covered EGUs will
begin to reduce their SO2 emissions almost immediately after CAIR is
finalized, and will continue steadily to reduce their emissions in
anticipation of the 2010 cap and the more stringent cap that becomes
effective in 2015.  The 2015 SO2 and NOx caps are specifically designed
to eliminate all SO2 and NOx emissions from EGUs that are highly cost
effective to control (the first caps represent an interim step toward
that end).  In general, we expect that due to economic considerations
many of the largest-emitting sources will be the first to install SO2
and NOx control technology and that such control technology will
gradually be installed on progressively smaller-emitting sources until
the ultimate cap is reached.

	Many PM2.5 nonattainment areas are projected to achieve significant SO2
and NOx reductions under the CAIR program.  We do not believe that
requiring source-specific RACT/RACM controls on specified EGUs in
nonattainment areas would reduce total SO2 and NOx emissions from
sources covered by CAIR below the regionwide levels that will be
achieved under CAIR alone.  In fact, if states chose to require
smaller-emitting sources in nonattainment areas to meet source-specific
RACT requirements by 2009, they would likely use labor and other
resources that would otherwise be used for emission controls on larger
sources.  Because of economies of scale, more boiler-makers may be
required per megawatt of power generation for smaller units than larger
units.  In this case, the imposition of source-specific RACT on smaller
emitting sources by 2009 could actually reduce the amount of (banking(
that would otherwise occur and result in higher SO2 emissions in 2009 as
compared to the level that would result from implementation of CAIR
aloneNor do we believe that “beyond CAIR” EGU controls for SO2 and
NOx are “reasonably available” control measures for most areas
within the CAIR Region.  Accordingly, most States need not evaluate
additional control measures on EGUs to satisfy RACT/RACM requirements as
explained above.

In any event, the imposition of source-specific control requirements on
a limited number of sources also covered by a cap-and-trade program
would not reduce the total regionwide emissions from sources subject to
the program.  Under a cap-and-trade program such as CAIR, there is a
given number of allowances that equals a given emission level. 
Source-specific control requirements may affect the temporal
distribution of emissions (by reducing banking and thus delaying early
reductions) or the spatial distribution of emissions (by moving them
around from one place to another), but it does not affect total
emissions.  If source-specific requirements were targeted at the units
that can be controlled most cost-effectively, then the imposition of
source-specific controls would likely achieve the same result as the
cap-and-trade program.  If not, however, the imposition of
source-specific requirements would make any given level of emission
reduction more costly than it would be under the cap-and-trade program
alone.  Thus, the imposition of source-specific RACT on EGUs covered by
CAIR would not reduce total regionwide emissions, but would likely
achieve the same total emission reductions in a more costly way.  

	For the reasons stated above, we are confident that CAIR will provide
substantial and highly cost-effective SO2 and NOx emissions reductions
in most nonattainment areas in the CAIR region, as well as substantial
SO2 and NOx reductions in attainment areas.  Collectively these
regionwide reductions will substantially improve air quality in PM2.5
nonattainment areas in the CAIR region.  

In defining RACT, EPA believes that power generation facilities
participating in CAIR in states that achieve all reductions from EGUs
can be treated differently from other sources because of special
attributes of that group of facilities including the unique interrelated
nature of the power supply network, and their participation in the CAIR
program.  Th  EPA is defining RACT for other sources in a manner that
involves assessment of potential emission reduction options and
attainment needs in individual nonattainment areas.  By contrast, for
EGUs subject to our finding, EPA is defining RACT as a particular level
of control independent of attainment needs of the individual area:  the
level of control that results from implementation of CAIR.  Based on the
collective reductions and air quality improvements projected throughout
the CAIR region, and the other considerations described above in this
section, EPA has determined that compliance by EGUs with EPA-approved
CAIR SIPs or CAIR FIPs meeting the requirements discussed above would
meet the SO2 and NOx RACT requirement for participating EGUs located in
PM2.5 nonattainment areas.  

The States will need to review sources in other emissions categories
independently in making RACT determinations.  Controls on sources
subject to RACT are an important element in plans to ensure attainment
of the standards as expeditiously as practicable.

EGU controls for expeditious attainment.  As discussed in a previous
section of the preamble, in this final rule RACT is interpreted as being
a part of RACM under section 172(c)(1) of the CAA.  The RACM is the
collection of measures from stationary, mobile, and area sources which
ensure attainment of the standards as expeditiously as practicable.  
States need to consider for each area those reasonably available
measures that if adopted would meet the overarching requirement to
attain as expeditiously as practicable.  The controls that would be
considered necessary for expeditious attainment depend to an extent on
the difficulty of attaining the standard in a particular area. 

	The EPA cannot rule out the possibility that through its analytical
process a State designing an attainment plan might determine that a
certain nonattainment area (1) cannot attain within 5 years, (2)
contains EGU units that would be feasible and cost effective to control
but would not expeditiously apply controls as a result of CAIR, and (3)
would advance its projected attainment date by at least 1 year if those
nonattainment area units were controlled in the nonattainment SIP as
part of a suite of reasonable measures.  Under this area-specific
analysis, it could be determined that it would be reasonable for certain
EGUs to reduce emissions and advance the attainment date, and in that
event their control would be needed to satisfy the requirements for RACM
and expeditious attainment.  Th  EPA anticipates that these
circumstances could arise in a few areas (e.g., nonattainment areas
where our models project little or no additional emissions reduction due
to CAIR).  For many other areas, analyses may show attainment by 2010
with existing measures, or show that controls for the particular EGUs in
question would not provide a sufficient improvement in local air quality
to advance the attainment date.  

In conclusion, and in response to a number of commenters, EPA clarifies
that the RACT and CAIR determinations described above do not inhibit
State and local air agencies from taking actions to attain the standards
as expeditiously as practicable by consulting with power companies and
establishing additional “beyond RACT” emission control requirements
on specific sources in nonattainment areas as necessary to provide for
expeditious attainment.As discussed previously, we are not requiring
that States impose RACT on any specific size or type of source. 
Instead, States must conduct a RACT/RACM analysis considering measures
that are “reasonably available” to meet the overarching requirement
to attain the standards as expeditiously as practicable.  Thus,
today’s final rule imposes no specific requirement on States to impose
RACT/RACM on EGUs.  

Nonetheless, in evaluating RACT/RACM for EGUs, EPA believes it is
appropriate for States (states that achieve all reductions from EGUs) to
consider the special attributes of that group of facilities including
the unique interrelated nature of the power supply network, and their
participation in the CAIR program.  For EGUs in the CAIR region, based
upon the presumption explained here, States may define RACT/RACM as the
CAIR level of control on the collective group of sources in the region
rather than impose a specific level of control on an individual source. 
This approach is similar to the Agency’s past “bubble” policy, as
discussed in section (c) addressing comments on the proposal.   

As discussed more fully in the CAIR final rulemaking notice, EPA has set
the 2009 and 2010 CAIR caps for SO2 and NOx at a level that will require
EGUs to install emission controls on the maximum total capacity on which
it is feasible to install emission controls by those dates.  The EPA
concluded that the CAIR compliance dates represent an aggressive
schedule that reflects the limitations of the labor pool, and
equipment/vendor availability, and need for electrical generation
reliability for installation of emission controls. 

	Although the actual SO2 cap does not become effective until 2010, we
designed banking provisions in CAIR so that covered EGUs will begin to
reduce their SO2 emissions almost immediately after CAIR is finalized,
and will continue steadily to reduce their emissions in anticipation of
the 2010 cap and the more stringent cap that becomes effective in 2015. 
The 2015 SO2 and NOx caps are specifically designed to eliminate all SO2
and NOx emissions from EGUs that are highly cost effective to control
(the first caps represent an interim step toward that end).  

Moreover, we predicted that the majority of large coal-fired utilities
will install advanced control technologies under CAIR because the larger
and higher emitting source offer an opportunity to obtain more
cost-effective emissions reductions.  We expect that the
largest-emitting sources will be the first to install SO2 and NOx
control technology and that such control technology will gradually be
installed on progressively smaller-emitting sources until the ultimate
cap is reached.  As a result, few, if any coal-fired units with greater
than 600 MW of operating capacity should operate in PM2.5 nonattainment
areas without advanced control after full implementation of CAIR. Of the
remaining units operating without advanced pollution controls, a great
many of these units will have operating capacities below 300 MW.  We
predict that these units “will be utilized less often,” and
“typically have baghouses and electrostatic precipitators for
particulate control, have combustion controls for NOx control, and burn
low-sulfur coal.”  See “Contributions of CAIR/CAMR/CAVR to NAAQS
Attainment: Focus on Control Technologies and Emission Reductions in the
Electric Power Sector,” Office of Air and Radiation, U.S.
Environmental Protection Agency, April 18, 2006 (available at
http://www.epa.gov/airmarkets/cair/analyses/naaqsattainment.pdf).  In
light of these expected results, we generally believe that the cost to
install additional controls on these smaller units would be
unreasonable. 

We are also concerned that if States require specific EGUs to install
advanced pollution control measures, it could interfere with the
market-based incentives inherent in the cap and trade program.  This
could increase the cost of compliance and shift the location of the
units that would otherwise opt to install advanced emissions controls. 
Such a result may be counterproductive to that State’s attainment
efforts, as the State may forego a larger quantity of more beneficial
reductions in transported pollutants, in exchange for a smaller quantity
and less beneficial reduction in local emissions.  Moreover, it may
reduce the benefits expected in other nonattainment areas as well. 
Accordingly, even if a State found the cost to control an individual
unit acceptable on a cost per ton basis, the potential overall
disbenefit of control may nonetheless make imposition of the control not
“reasonably available.”  

	EPA finds that the control installations projected to result from CAIR
NOx and SO2 caps in 2009 and 2010 are as much as feasible from EGUS
across the CAIR Region by those dates.  In fact, if states chose to
require smaller-emitting sources in nonattainment areas to meet
source-specific RACT requirements by 2009, they would likely use labor
and other resources that would otherwise be used for emission controls
on larger sources.  Because of economies of scale, more boiler-makers
may be required per megawatt of power generation for smaller units than
larger units.  In this case, the imposition of source-specific RACT/RACM
on smaller emitting sources by 2009 could actually reduce the amount of
banking that would otherwise occur and result in higher SO2 emissions in
2009 as compared to the level that would result from implementation of
CAIR alone.

In any event, the imposition of source-specific control requirements on
a limited number of sources also covered by a cap-and-trade program
would not reduce the total regionwide emissions from sources subject to
the program.  Under a cap-and-trade program such as CAIR, a given number
of allowances are issued in order to achieve a given emission level. 
Source-specific control requirements within the CAIR program may affect
the temporal distribution of emissions (by reducing banking and thus
delaying early reductions) or the spatial distribution of emissions (by
moving them around from one place to another), but they would not affect
total regional emissions under the program.  If source-specific
requirements were targeted at the units that could be controlled most
cost-effectively, then the imposition of source-specific controls would
likely achieve the same result as the cap-and-trade program.  If not,
however, the imposition of source-specific requirements would make any
given level of emission reduction more costly than it would be under the
cap-and-trade program alone.  Thus, the imposition of source-specific
RACT on EGUs covered by CAIR would not reduce total regionwide
emissions, but would likely achieve the same total emission reductions
in a more costly way.  

  Given the considerations described above, we think that in many areas
additional controls on EGUs generally would not be “reasonably
available.”  Notwithstanding these conclusions, we recognize that
States are in the best position to determine how best to achieve
attainment with the PM2.5 NAAQS in light of local needs and conditions. 
As we acknowledged in our proposed rule, power plant operators typically
have ongoing relationships with the state and local officials involved
in air quality planning.  We expect that power plants will continue to
collaborate with State officials to determine how best to address
multiple air quality goals, and which plant locations to control under
CAIR, considering local PM2.5 and ozone attainment needs.

EPA expects States and local air agencies to identify reasonably
available control measures that are necessary and reasonable to attain
the standards as expeditiously as practicable; and that after consulting
with power companies, the State may conclude that establishing
additional “beyond CAIR” emission control requirements on specific
sources in nonattainment areas is warranted to provide for attainment as
expeditiously as practicable.  Nevertheless, in preparing the overall
attainment demonstration, States should be aware of the expected
benefits of the market-based incentives of the CAIR program, the cost
effectiveness of control, feasibility of implementation, and any
disbenefits that would result from requiring “beyond CAIR” controls
on any specific EGU before concluding that addition controls on EGUs are
“reasonably available” and necessary to satisfy RACT/RACM
requirements.  

	Year-round NOx controls.  In the CAIR final rulemaking notice, EPA
found that the operation of existing SCRs on a year-round basis, instead
of operating them only during the ozone season, could achieve NOx
reductions at low cost relative to other available NOx controls.  The
EPA projected that power generators would employ this control measure to
comply with CAIR SIPs.  Based on this control opportunity, EPA estimated
the average cost of non-ozone-season NOx control at $500/ton.  These
considerations support a finding that RACT should include year-round
operation of EGUexisting SCRs that are located in PM2.5 nonattainment
areas.  Because all PM2.5 nonattainment areas violate the annual form of
the PM2.5 standard and public health can be affected by high PM2.5
levels in the winter as well as the summer, we believe that year-round
operation of existing SCR that are located in nonattainment areas where
NOx is a nonattainment plan precursor will provide additional health
benefits for relatively low dollar cost per ton of pollutant reduced.

	In the proposal notice, EPA conditioned its proposed CAIR-RACT
determination on year-round operation as RACT for EGU SCRproposed to
define “existing” SCRs as those units that were in place by the date
of the proposed rule, saying that this cutoff date would avoid
disinventives to install SCR.  For the final rule, we have eliminated
the cutoff date because we believe the reasons for year-round operation
of SCR that are located in nonattainment areas apply equally to SCR
installed before and after the cutoff date.  We do not see a basis for
exempting SCR installed after that date from the year-round operation
proviso.  We have concluded that the concern stated in the proposal
notice about potential disincentives for SCR installation was misplaced,
because the CAIR rule annual NOx cap provides generators with financial
incentives to operate in-place SCR year-round.  (November 1, 2005).  We
selected this date rather than the final date to avoid creating an
incentive to delay installation of new SCR.  Today, we finalize our
proposed approach with one clarification.  To avoid confusion over the
proper interpretation of the phrase “in place,” we are clarifying
that an existing SCR is one which is fully installed and capable of
operation by November 1, 2005.

	The CAA requires RACT to be implemented as expeditiously as practicable
(and, in the case of areas without an attainment date extension, no
later than 2009).   Depending on the source, year-round operation of
existing SCR involves either no alteration or relatively minor
alteration (the installation of a bypass duct and dampers) of existing
equipment.  For EGUs where these alterations are needed, we expect, that
most of the work can be done while the unit is operating and that work
that needs to be done while the unit is shut-down can be done during a
normally scheduled maintenance outage.  We also expect that the
materials needed for the modifications are readily available and will
not require significant lead-times for purchase.  Finally, the We also
proposed that these existing SCR begin year-round operations no later
than January 1, 2009 to qualify as RACT/RACM under our presumptive
approach. We noted that year round operation of existing SCR involves
little to no alteration of existing equipment, and that EGUs could
conduct any required work during normal outages.  Today, after taking
these factors into account, we finalize our proposed rule.  The
year-round operation requirement, however, will not be legally
applicablefederally enforceable to individual sources EGUs until EPA
approves a RACTState’s  SIP including the requirement is adopted. We
note that all EGUs in PM2.5 nonattainment areas are on notice from the
date this rule is finalized that SIPs must require year-round operation
of in-place SCRs in order to support a determination that the EGUs in
the area meet RACT.

Taking these factors into account, EPA believes that a January 1, 2009,
implementation date (as proposed) would provide ample lead time to
enable SCRs that currently exist in PM2.5 nonattainment areas to be
operated year-round, including those SCRs for which physical alterations
are necessary.  Also, EPA believes that it is reasonable for EGU SCR
that are installed in PM2.5 nonattainment areas after the date of this
final rule to be operated year-round by January 1, 2009, or the date
they commence operation, whichever is later.  We note that this rule
provides notice of EPA’s NOx RACT determination for nonattainment area
EGU, including the year-round operation proviso for SCR, 27 months in
advance of January 1, 2009.  Therefore, generators installing SCR during
the period between the promulgation date of this final rule and January
1, 2009, should be able either to ensure that the initial design
accommodates year-round operation, or make alterations during an routine
outage, prior to the beginning of 2009.

In summary, EPA is determining that in states that fulfill their CAIR
NOx emission reductions entirely through EGU emission reductions, CAIR
would satisfy NOx RACT for the EGU sources, provided that those
nonattainment-area sources with selective catalytic reduction (SCR)
emission control technology installed on their boilers operate that
technology on a year-round basis by January 1, 2009, or in the case of
SCR installed after that date, the date when SCR operation commences.   

c.  Comments and responses

	Comment:  Some commenters supported the proposed determination
described in section (a) that for EGUs located in states in States that
achievefulfill their CAIR SO2 emission reduction requirements entirely
through EGU emission reductions from EGUs only, compliance with CAIR
would satisfy the source’s obligation to meet SO2 and NOx RACT
requirements.(i.e. without reductions from non-EGU sources or allowing
non-EGU sources to opt in to the CAIR SO2 trading program), compliance
by EGU sources with an EPA-approved CAIR SIP or a CAIR FIP would satisfy
the SO2 RACT requirement for the sources; and in States that are subject
to CAIR annual NOx emission reduction requirements and fulfill these
requirements entirely through EGU emission reductions (i.e. without
reductions from non-EGU sources or allowing non-EGU sources to opt in to
the CAIR annual NOx trading program), compliance by EGU sources with an
EPA-approved CAIR SIP or a CAIR FIP would satisfy the NOx RACT
requirement for the sources, provided that the sources with existing
selective catalytic reduction (SCR) emission control technology
installed on their boilers operate that technology on a year-round basis
beginning in 2009.  One commenter supportssupported EPA’s approach so
long as states may pursue additional reductions from EGUs if needed for
expeditious attainment as expeditiously as practicable.  A number of
other commenters opposed the proposed determination regarding RACT for
EGUs based on a number of issues.

	Response:  The EPA agrees with these comments.

	Comment:  A number of commenters agreed with EPA that CAIR will
satisfyBased on the NOx RACT requirement for any EGU with an
SCRrationale described in place and operated year-round by no later than
the beginning of 2009. sections above, the final rule includes a
presumption that compliance with CAIR satisfies SO2 and NOx RACT/RACM
requirements for EGUs in many areas.  Nonetheless, States can require
“beyond CAIR” EGU controls if a State determines that it is a
necessary and reasonable means to attain the PM2.5 standards.  Comments
opposing this approach are addressed in more detail below.

	Response:  The EPA agrees with these comments. 	

	Comment:  A number of commenters objected to the proposed
determination, arguing that it would result in greater control
requirements and economic burden on non-EGU sources located in
nonattainment areas.  These commenters urged EPA to adopt a final rule
that provides for implementing the most cost-effective controls
necessary to attain the standard.  They assert that with the proposed
finding that compliance with CAIR satisfies RACT for EGUs, the proposed
rule would not provide for the most cost-effective approach to
attainment.  They argue EPA and States should develop cost-effectiveness
guidance that includes all stationary source control measures and they
should develop SIPs based on the most economic means to attain the
standard.  They make several arguments to support this position.  If The
commenters asserted that if an EGU control is more cost-effective than a
non-EGU control, the EGU should be subject to “beyond-CAIR”
controls.  IfThey also asserted that if EPA chooses to callconsider the
CAIR rule equivalent toas satisfying SO2 and NOx RACT for EGUs, then
other sources should not be subjected to control costs greater than
those found reasonable under CAIR (i.e., $800/ton). It  They believe it
would be inequitable to require smaller sources to pay a higher cost for
emissions reductions than larger sources, which are a more significant
contributor to the problem and which may be able to make more
cost-effective emission reductions.  One commenter also suggested that
EPA should authorize a presumption that emissions reductions required on
electric utilities under the CAIR will be equivalent to RACT only if a
particular source in a CAIR State has installed controls that achieve
the average level of control that EPA has projected will occur for the
particular pollutant under the CAIR requirements.

	Response:  The EPA believeshas determined that implementation of the
CAIR trading programs are the mostprogram represents highly
cost-effective methods for achieving controls that will achieve
widespread regional SO2 and NOx emissions reductions from EGUs and for
providingwill provide significant air quality benefits for ozone and
PM2.5 nonattainment areas.  The determination in the final rule that
compliance with a CAIR SIP or FIP may satisfy RACT for EGUs does not
constrain a State from requiring specific sources to install emission
controls in order for an area to attain an air quality standard as
expeditiously as practicable.  In developing attainment SIPs and
identifying RACM, States will need to consider additional cost-effective
and reasonable controls to reach attainment as expeditiously as
practicable.  EPA does not agree with the commenter’s argument that
controls on non-EGUs should be no more than the projected cost of EGU
controls under CAIR.  EPA expects that in order to achieve attainment as
expeditiously as practicable, some states may need to adopt control
measures for some sources which cost more per ton but which still are
considered to be reasonable and cost-effective.

	Comment:  A number of commenters opposed the proposed CAIR=RACT
determination arguing it In addition, States must consider the economic
feasibility of implementing a given control measure.  Because of
facility-specific factors, EPA believes it would be inappropriate to
establish a threshold of control effectiveness (e.g. dollars per ton)
based on control of EGUs and apply this threshold to all source
categories.  The ability of a source to cost-effectively reduce
emissions is dependent on case-specific factors, including the ability
of the given source to sustain the cost of control, and prevailing costs
in the specific geographical location.  A direct correlation between the
size of an emissions source and the economic feasibility of controls for
that source and location does not necessarily exist.

We also disagree with the commenter who suggests that RACT requirements
should only be satisfied if a source achieves an average level of
control that EPA projects to occur under CAIR.  EPA maintains that the
presumption that CAIR satisfies SO2 and NOx RACT/RACM for EGUs in most
areas is an appropriate policy.  As discussed further below, we  have
always recognized that States could determine RACT for a single source
or group of sources.   

Comment:  A number of commenters opposed the proposed determination that
CAIR would satisfy the SO2 and NOx RACT requirement for EGU’s.  The
commenters argued that this determination is unlawful, it does not
comply with section 172(c)(1) of the CAA which requires RACT (i.e.
controls that are technologically and economically feasible) “at a
minimum” for all existing sources in the nonattainment area, it would
allow very large stationary sources to escape cost-effective controls
entirely, and it is largely based on the legally-irrelevant contention
that CAIR will reduce emissions more cost-effectively than RACT.  They
claim that EPA has no authority to displace the Congressionally-mandated
RACT requirement, that CAIR was designed to address regional pollution
transport (not to be an attainment strategy), and that EPA should remove
these proposed provisions in the final rule.  Commenters claim that the
EPA(s proposed approach to allow EGU emissions to be addressed solely
through CAIR would undermine states( efforts to meet the Federal PM2.5
health standard, particularly when EGU sources are among the most
cost-effective to control.  Another commenter claimed that EPA’s
proposal allowing states who that choose to fulfill their CAIR
requirements entirely through emission reductions from EGUs to also use
CAIR to satisfy their SO2 and NOx PM2.5 RACT requirements, thereby
equating these two requirements for the EGU sector, is flawed. This
commenter argued that allowing a cap-and-trade program, such as the
CAIR, to substitute for the RACT requirement undermines the
effectiveness of the controls by allowing facilities to use allowances
to offset emissions, rather than control them at the source.  The
Purchasepurchase of an allowanceallowances, they assert, does not
satisifysatisfy RACT requirements.  

	Response:  The EPA disagrees with these comments.  The Today’s final
rule does not displace the RACT requirement for any sources.  Instead,
EPA is exercising its authority to interpret the section 172 RACT and
RACM requirements for the purposes of implementing the 1997 PM2.5
standards.  For the reasons described in section (b) above, we believe
that states can rely on EPA’s determination presumption that
compliance with a CAIR SIP or FIP, meeting certain requirements,
satisfieswill satisfy the RACT/RACM requirement for certain EGU sources.
EPA historically issued control technology guidelines setting forth
presumptive levels of emissions control that satisfy the RACT
requirement for a given industry.  Today’s final rule is similar to
this practice in establishing a presumption that SO2 and NOx reductions
under the CAIR program satisfy the RACT/RACM requirement for EGUs in
CAIR states.  In identifying reasonably available control measures to
ensure attainment as expeditiously as practicable, States will need to
take CAIR reductions into account as well as any additional
cost-effective reductions that are technologically and reasonably
available.  

We further find that the attempt by many commenters to characterize CAIR
as a strategy to address only regional pollution transport and not an
attainment strategy as overly simplistic.  EPA analyses for CAIR show
that there are significant air quality benefits projected for individual
nonattainment areas as a result of SO2 and NOx reductions across the
multistate CAIR region.  The Act does not prevent States from properly
crediting measures that achieve multiple objectives (e.g. regional
transport or local nonattainment).  Moreover, Section 110(a)(2)(D)
requires SIPs to contain adequate provisions to assure that sources in
the State do not contribute significantly to nonattainment in any other
State.  The CAIR rule is an integral element in meeting the States’
Section 110 attainment obligations.  Accordingly, it is reasonable to
incorporate this consideration in determining what measures qualify as
RACT/RACM.

Finally, EPA does not interpret the provisions of Section 172(c)(1)
related to the RACT requirement as precluding States’ use of a cap and
trade approach as a means of regulating existing sources and achieving
RACT/RACM reductions, especially in light of Congresses’ expressed
authorization to auction emission rights in Section 172(c)(6). 

EPA has long recognized that RACT need not apply to individual sources. 
As stated earlier, our early guidance on RACT requirements stated that
States could establish RACT for an “individual sources or a group of
sources.” (emphasis added)  See Memo. Strelow (Dec. 1976) and 44 FR
71779.  Importantly, Congress ratified the early interpretations of RACT
and RACM when it enacted the 1990 Amendments. See 42 U.S.C. Section 7515
(Clean Air Act section 193).  Our 1986 emissions trading policy also
recognized a number of advantages offered through application of a
“bubble” approach including faster compliance with RACT limits and
earlier reductions. Moreover, Courts have upheld EPA’s approval of
States’ use of “bubbling” multiple units to meet RACT
requirements.  See e.g. Natural Resources Defense Council v. EPA, 941
F.2d 1207 (finding that EPA need not adhere to a source specific RACT
determination to satisfy RACT requirements and acknowledging EPA’s
special knowledge and expertise in the area.) 

	Comment:  The EPA(’s proposal to allow EGU emissions to be addressed
solely through CAIR undermines statesprospectively States( efforts to
meet the Federal PM2.5 health standard.  EGU sources are among the most
cost-effective to control.

	Response:  For the reasons described in section (b) above, EPA believes
that states can rely on EPA’s determination presumption that
compliance with a CAIR SIP or FIP, meeting certain requirements,
satisifies the SO2 and NOx RACT/RACM requirement for certain EGU
sources.  Areas can require “beyond RACTCAIR” EGU controls if
necessarya State determines that it is a necessary and reasonable means
to attain as expeditiously as practicable.  

	Comment:  CAIR fails to address the need for short-term reductions in
PM2.5 and precursor emissions on high pollution days.  While RACT
restricts emissions over a 1-hour to 24-hour period, CAIR only provides
for an annual or seasonal cap. Reliance on CAIR therefore fails to
recognize the importance of reducing short-term emissions, which was
recently highlighted by the EPA(s own proposal to tighten the 24-hour
PM2.5 health standard.  Local and short-term adverse air quality effects
of PM2.5, must he addressed in the final rule by requiring RACT for all
major facilities in addition to CAIR.  

	Response:  The EPA agrees that the CAIR program is oriented toward
reducing SO2 and NOx emissions in order to reduce air quality
valuesconcentrations on an annual or and seasonal basis.  AllBecause all
PM2.5 nonattainment areas were designated due to violations of the
annual standard.  However, (and the two designated areas in California
also violated the 24-hour standard), the focus of this implementation
rule is attainment of the annual standard.  CAIR approach is projected
to provide significant air quality benefits in 2010 and 2015 for eastern
PM2.5 nonattainment areas on both an annual basis and on a 98th
percentile 24-hour basis..  Since the PM2.5 24-hour standard was revised
in September 2006 from 65 micrograms per cubic meter to 35 micrograms
per cubic meter, EPA recommends that as States develop implementation
plans to address the annual standard, they consider adopting strategies
that also will provide benefits toward attaining the revised 24-hour
standard.  

	Comment:  The proposal is silent on the issue of whether EGUs are
subject to direct PM2.5 emissions RACT requirements.  It is critical
that RACT be required for all facilities with respect direct PM2.5
emissions, regardless of a facility(s participation in CAIR. 

	Response:  In the final rule and preamble, EPA has clarified that all
EGUs in nonattainment areas are subject to RACT/RACM for direct PM2.5
emissions.  The determination described above applies only to SO2 and
NOx RACT/RACM, not RACT/RACM for direct PM2.5 emissions from EGUs.  

	Comment:  The EPA fails to consider the geographical distributional
impacts of the emission reductions.  Equating CAIR with RACT fails to
take into account the substantial contribution that emissions from EGUs
within a nonattainment area may make toward that area(s PM2.5
nonattainment problem.  The EPA does not attempt to explain how such a
generalized determination satisfies RACT for PM2.5.

	Response:  The EPA acknowledges that some EGUs subject to the CAIR
cap-and-trade programs and located in a nonattainment area will not
install emission controls.  However, the determination in the final rule
that CAIR satisfies SO2 and NOx RACT for certain EGUs does not constrain
a State from requiring specific EGU sources to install emission controls
in order for an area to attain an air quality standard as expeditiously
as practicable.  For the reasons described in section (b) above, EPA
believes that states can rely on EPA’s determination that compliance
with a CAIR SIP or FIP, meeting certain requirements, satisifies the
RACT requirement for certain EGU sources.  We believe that these
collective regionwide reductions satisfy the SO2 and NOx RACT
requirements for certain EGUs, but we reiterate that States are not
constrained from seeking further reductions from EGUs in order to meet
the CAA requirement of attainment as expeditiously as practicable.  

	Response:  The establishment of recommended levels for RACT/RACM is an
area Congress delegated to the specific expertise of the Agency.  Based
on our analysis, we conclude that the CAIR emissions caps presumptively
represent the level of emissions control achievable through application
of “reasonably available” control technologies.  Nonetheless, in
developing attainment plans, each State will evaluate the impact of
stationary sources located within the nonattainment area in developing
its attainment strategies for the local area.

	Comment:  A few commenters stated that EPA should explain how this
proposal would be implemented for states that request an extension of an
attainment date because attaining in 5 years or less is impracticable;
i.e., whether EPA would still hold to its interpretation that CAIR
equals RACT for EGUs and not require additional reductions from EGUs
even if an area can(not attain in 5 years and controls on EGUs could
lead it to attain more expeditiously.  These commenters argue that, in
considering if additional RACT is needed in states that obtain
extensions of the attainment deadline after 2010, EPA cannot ignore
potential RACT for electric generating units any more than they would be
allowed legally to avoid consideration of any other RACT candidates. 
One commenter is particularly concerned that States would not include
EGUs in their RACT determinations and instead require smaller industrial
boilers or process heaters to control emissions.

	Response:  As stated above, the determination in the final rule does
not constrain a State from requiring specific EGU sources to install
emission controls in order for an area to attain the air quality
standard as expeditiously as practicable.  There may be some situations
in which States may need to require controls on specific power plants in
nonattainment areas to meet RACM requirements.	Response:  EPA’s
determination regarding CAIR and RACT is not limited to areas attaining
within five years.  The Agency’s rationale is presented in the
“final rule” section above.  We disagree that the CAIR-RACT
presumptions necessarily shift emission control burdens from EGUs to
smaller industry boilers and process heaters because, in implementing
the RACM requirement, the State may include an evaluation of control
options on those sources as part of their RACT/RACM analyses.  As stated
above, EPA concluded that the CAIR compliance dates represent an
aggressive schedule that reflects the limitations of the labor pool, and
equipment/vendor availability, and need for electrical generation
reliability for installation of emission controls.  Accordingly,
additional controls on EGUs may not be a reasonably available control
measure that can be effectively implemented in a manner that advances an
area’s attainment date.  Nonetheless, States should consider the
economic and technologic feasibility of implementing controls on all
types of sources (stationary, mobile, area)located in the nonattainment
area, given local conditions, in developing attainment plans.  

	Comment:  The EPA designated many partial counties nonattainment for
PM2.5 solely because the areas contained EGU emission sources thought to
cause or contribute to violations of the NAAQS.  In implementing
nonattainment plans, it makes sense to consider further control of these
sources, and because they are located in nonattainment areas, the
ability to do so is provided for and legal under the CAA.

	Response:  The EPA designated PM2.5 nonattainment counties because they
either had a violating monitor or they contributed to a nearby air
quality problem.  TheImportantly, EPA designated these areas without
considering the air quality benefits expected in the future from CAIR. 
Accordingly, the fact that an EGU is located in a partial county and we
included the partial county in the nonattainment area because we believe
that the EGU was causing or contributing to the nonattainment
violations, does not equate with a finding that more than CAIR is
required to remedy the nonattainment problem.  Nonetheless,   EPA
believes that States should evaluate the impact of stationary sources in
all designated counties, including those partial counties noted by the
commenter, in its assessment of reasonably available control strategies
to ensure attainment as expeditiouslykly as practicable.  

	Comment:  The EPA should adopt the Ozone Transport Commission(s (OTC(s)
approach to cap-and-trade programs. When the OTC developed its NOx
Budget Program (which was the basis for EPA(s NOx SIP call and
subsequently CAIR), it assumed that RACT was applied first. Thus the
cap-and-trade program operated in an environment that assumed RACT was
in force, not in lieu of RACT.

	Response:  Under the ozone national ambient air quality standards, NOx
and VOC RACT have been implemented progressively for the past 30 years
or more, prior to development of the NOx SIP call regional control
program.  In contrast, the PM2.5 implementation program is the first
instance in which we have required RACT has been required /RACM
specifically for fine particle pollution.  For this reason, the CAIR
program is not operating with SO2 and NOx RACT limits already in place
for attainment of the PM2.5 standards.  As Nonetheless, as discussed
above, EPA believes that implementation of the CAIR requirements will
provide for substantial progress in attaining the PM2.5 standards, and
that States may in a few areas require additional EGU controlspresume
that RACT/RACM requirements are equal to provide for expeditious
attainmment of the standards.  CAIR level of control.

	Comment: A few commenters stated that EPA should clarify and modify the
part of its proposal that explains why a State cannot rely on EPA’s
determination that CAIR can satisify the NOx RACT requirement for PM2.5
if the State (elect[s] to allow non-EGU sources to voluntarily enter the
EPA-administered CAIR trading program through an opt-in provision in the
CAIR model rule.( (70 FR 66025 col. 3). These commenters believe that
this part of the proposal might be construed to preclude states subject
to both the NOx SIP Call and included in the CAIR region for ozone from
relying on the NOx RACT determination for PM2.5 if the states choose (to
bring their non-CAIR [including non-EGU] NOx SIP Call trading sources
into the CAIR ozone season NOx cap and trade program.  (70 FR 49708,
49728 col. 3)  (August 24, 2005). The commenters assert that EPA gave
states the option of bringing non-EGU NOx SIP Call sources into the CAIR
seasonal NOx trading program  to ensure that non-CAIR sources, including
non- EGUs, that are subject to the NOx SIP Call rule would not be
(stranded,( starting in 2009, by being left in an ozone season NOx
control program with no EGU trading partners.  The commenters argued
that “EGUs should not be penalized, in the form of denial of CAIR =
RACT treatment, as a result of states exercising their option to avoid
financial and compliance difficulties for non-EGUs that otherwise would
be left without allowance trading partners in the EGU sector after the
NOx SIP Call trading program ends in 2008.”  These commenters point to
EPA’s determination in the final Phase 2 ozone implementation rule,
that participation in the CAIR trading programs can satisify NOx RACT
for ozone even if  a State brings non-EGUs in the NOx SIP Call trading
program into the trading program after 2008, see 70 FR 71657 col. 2,
provided the State retains an (EGU [emission] budget under CAIR that is
at least as restrictive as the EGU budget that was set in the State(s
NOx SIP call SIP,( id. At 71658 col. 1. These commenters argue that EPA
should make a similar determination here regarding NOx RACT for purposes
of PM2.5 NAAQS implementation.

Response:  All states with EPA approved CAIR SIPs or subject to a CAIR
FIP implementing the annual NOx emission reduction requirements, and
obtaining those reductions solely from EGUs may rely on EPA’s
determination that CAIR presumptively satisifies NOx RACT/RACM for PM2.5
for these sources.  This determination is unaffected by whether or not a
State permits NOx SIP Call non-EGUs to participate in the CAIR ozone
season trading program.  In the final rule, EPA clarifies thatwe have
included the determinationpresumption that NOx RACT/RACM for PM2.5 is
satisifiedsatisfied for EGUs complying with a CAIR SIP or CAIR FIP
implementing the annual CAIR NOx emission reduction requirements,
remains valid unless (provided the State elects to allow non-EGUs to
opt-in toimplementation of the CAIR NOx annual trading program. 
includes EGUs only). 

	In the final ozone implementation rule, EPA addressed numerous issues
relating to the transition from the NOx SIP Call to the CAIR ozone
season trading program, including the impact of bringing NOx SIP Call
non-EGUs into the CAIR ozone season trading program.  Commenters
suggestion that these determinations are relevant to this PM2.5
implementation rule ignores the fact that both the NOx SIP Call and the
CAIR ozone season trading program are seasonal, not annual, trading
programs.  The NOx SIP Call EGU and non-EGU budgets are seasonal NOx
budgets and do not address annual NOx emissions.  As discussed above,
PM2.5 levels year-round contribute to an area’s annual average
concentration, and NOx emissions during non-summer months contribute to
nitrate concentrations, which are typically highest in cooler
temperatures.  For these reasons, EPA believes it would be inappropriate
to accept commenters’ suggestion.  

8.  What are the required dates for submission and implementation of
RACT?

a. Background.  

	The EPA requested comment on a general approach for the dates for
submission and implementation of RACT rules.  The final rule retains the
proposed approach, as described in the following section.

b. Final Rule.  

The final rule requires the following:

(1) Date of submission.  States must submit adopted RACT rules to EPA
within 3 years of designation, at the same time as the attainment
demonstration due in April 2008. 

(2) Dates for implementation of control measures.  States should also
implement any measures determined to be RACT expeditiously, as required
by section 172.  Implementation of RACT measures should in no case start
later than the beginning of the year before the nominal attainment date.
  For example, if an area has an attainment date of April 2010, then any
required RACT measures should be in place and operating no later than
the beginning of 2009.  This is intended to help provide for clean air
in calendar year 2009.   As discussed in section II.D, if other criteria
are also met, EPA could then grant the area a 1-year attainment date
extension if the air quality level in the 3rd of the 3 years was below
the level of the standard. If the area observes a second year of clean
air, EPA could grant a second 1-year attainment date extension.  In this
case, the 2009 to 2011 period would then be reviewed to assess whether
the area attains the standards.)

(3) Provisions for a demonstration that additional time is needed. 
While EPA expects that States will implement required RACT controls by
January 2009 in most situations, there may be cases where additional
time is needed to implement an innovative control measure or to achieve
a greater level of reduction through a phased approach.  If a State has
provided an adequate demonstration showing that an attainment date
extension would be appropriate for an area, then the State may consider
phasing-in certain RACT controls after      January 2009.  The EPA would
allow the implementation of selected RACT controls after January 2009 if
the State can show why additional time is needed for implementation, and
such delayed implementation still would need to be on a schedule that
provides for expeditious attainment.  In no event could the State wait
to implement RACT controls until the last few years prior to the
attainment date without an adequate rationale for why earlier
implementation was not feasible.

c. Comments and Responsesresponses. 

Comment: One commenter supported EPA’s position that implementation of
RACT and RACM by January 1, 2009 is necessary to achieve the effect on
air quality for calendar year 2009.   

Response:  The EPA agrees with this comment.

Comment:  Some commenters supported allowing for an implementation
schedule that allowed for implementation of RACT and RACM for a time
frame extending beyond 2009.    These commenters favored such an
approach if States provided  an adequate demonstration of why the
measures cannot be implemented earlier.   Commenters noted that a phased
approach to emissions reductions in some cases could lead to additional
reductions that could not occur by 2009.  

	Response:  The EPA agrees with these comments.

	Comment:  One commenter believed that so long as a State
demonstatesdemonstrates attainment by 2015, EPA should not require
implementation of any RACT measures.  The commenter further  asserted
that it would be bad policy to require costly emissions reductions
through imposition of RACT on areas expected to attain the standards
through other means by 2015.

	Response:  The EPA disagrees with this comment.  The CAA requires
States to demonstrate that the nonattainment plan will attain the
standards as expeditiously as practicable and must include RACT and
RACM.   The requirement for “reasonable” measures does not require
that any theoretical measure be implemented, but does require
implementation of those reasonable measures which could advance the
attainment date by at least 1 year.  Given the health effects associated
with PM2.5, EPA believes this approach is sound public policy.     

9. Which pollutants must be addressed by States in establishing RACT and
RACM limits in their PM2.5 nonattainment plans?

a.   Background.

	 In the proposed rule, and in the final rule as discussed in detail in
section II.A above, EPA discusses the pollutants which States must
address in the nonattainment plans, in particular with respect to RACT,
RACM and NSR.   These pollutants include not only direct PM2.5, but also
gaseous precursors to the formation of PM2.5.  In general, the decisions
that States and EPA make with respect to which precursors are
significant contributors to an area’s PM2.5 nonattainment problem
define the pollutants and sources to be addressed by States in
developing RACT and RACM.  

b.   Final rule.

	In the final rule, in establishing RACT and RACM limits, those RACT and
RACM limits must address:

-- direct emissions of PM2.5

-- SO2, a precursor to PM2.5 formation, and

-- NOx, unless a State makes a finding that NOx emissions from sources
in the State do not significantly contribute to the PM2.5 problem in a
given nonattainment area or to other downwind area concerns.

	The EPA generally presumes that RACT and RACM limits are not needed for
ammonia or VOC unless that State or EPA determines otherwise for a given
nonattainment area.  RACT and RACM limits are needed for ammonia if a
State or EPA makes a finding that ammonia emissions significantly
contribute to the PM2.5 problem in a given nonattainment area or to
other downwind area concerns, and thus finds that control of ammonia
would help address the PM2.5 problem.  RACT and RACM limits are needed
for VOC only if a State or EPA makes a finding that VOC emissions
significantly contribute to the PM2.5 problem in a given nonattainment
area or to other downwind area concerns.  (As a point of clarification,
“VOCs,” which are gaseous organic precursors to the chemical
formation of secondary organic aerosol, are treated differently from
semivolatile or nonvolatile organic compounds which are addressed as
directly emitted PM2.5).  Issues related to the finding of
“significant contribution” for these pollutants are discussed in
Section II.A above.

10.  Under the PM2.5 implementation program, when does a State need to
conduct a RACT determination for an applicable source that already has a
RACT, BACT, LAER, or MACT determination in effect? tc "10.Under the
PM2.5 implementation program, does a State need to conduct a RACT
determination for an applicable source that already has a RACT
determination in effect? " \l 3  

a.  Background.

	For PM2.5 nonattainment areas, States are required to implement the
RACT requirement to reduce emissions of direct PM2.5 and PM2.5
precursors from applicable sources.  The EPA anticipates that for some
sources located in PM2.5 nonattainment areas, the State would have
previously conducted RACT determinations for VOC or NOx under the 1-hour
ozone standard, or for direct PM10 emissions under the PM10 standards. 
Some of the RACT determinations established under these other programs
would be relatively recent while other determinations may be more than
10 years old.  In some cases, a new RACT determination might reach the
conclusion that the preexisting determination is still valid and would
require the installation of similar control technology because the
relevant pollutant was addressed, the same emission points were
reviewed, and the same fundamental control techniques would still have
similar costs.  In other cases, however, a new RACT analysis could
determine, for example, that better technology has become available, and
that cost-effective emission reductions are achievable.  

	In the proposed rule, the EPA requested comments on a general approach
to taking prior RACT determinations into account, and within the general
approach, invited comments on two specific questions:  1) should new
RACT determinations be required for all existing determinations that are
older than a specified amount of time (such as 10 years old)?; and 2)
what supporting information should a State be required to submit as part
of its certification to demonstrate that a previous RACT analysis meets
the RACT requirement currently for purposes of the PM2.5 program?

	In the proposed rule, EPA also noted that sources subject to RACT may
also have been subject to other prior technology determinations such as
BACT, LAER or MACT determinations.  The proposed rule requested comment
on approaches to taking these prior technology determinations into
account. 

b.  Final rule.

	The EPA has determined that it is appropriate to follow the approach in
the proposed rule, which is described below.  State RACT SIPs for PM2.5
must assure that RACT is met, either through a new RACT determination or
a certification that previously required RACT controls represent RACT
for PM2.5.    

Where a State adopted and EPA approved a control measure as RACT for a
pollutant emitted from a specific stationary source or source category
under another NAAQS program, the State may submit as part of its SIP
revision a certification, with appropriate supporting information, that
the previous determination represents a current RACT level of control
for those emissions for purposes of the PM2.5 program.  Otherwise, the
State should revise the SIP to reflect a modified RACT requirement for
specific sources or source categories.

	In cases where the State’s prior RACT analysis under another NAAQS
program concluded that no additional controls were necessary, a new RACT
determination is required for that source.  In cases where the previous
RACT determination did not require any controls on the source, it is
more likely that a new review might find that emission controls are now
economically and technically feasible.  This is because emissions
reductions from a potential control measure are likely to be greater,
and the cost per ton of emission reduction is likely to be lower, than
in the case of a source that previously installed controls to meet RACT
under another program.

	A RACT determination for a source or source category subject to a prior
RACT determination is also required for any pollutants that were not the
subject of the prior RACT determination, but which the State has
determined should be regulated for purposes of PM2.5.   T   EPA advises
that the State should closely review any existing RACT determinations
established under another NAAQS program.  For RACT certifications and
determinations, States are to consider new information that has become
available since the earlier RACT determination.  For example, where
updated information on control technologies is presented as part of
notice-and-comment rulemaking, including a RACT SIP submittal for
sources previously controlled, States (and EPA) must consider the
additional information as part of that rulemaking.   Existing EPA
guidance on control technologies can be used to help inform RACT
decisions.  However, EPA believes it may not be sufficient for a State
to rely on technology guidance that is several years old and issued to
provide recommendations on control measures and levels for a different
NAAQS in evaluating RACT for PM2.5 

	With respect to prior technology determinations other than RACT, the
final rule provides that:

	(1) Prior BACT and LAER determinations.  In many cases, but not all,
best available retrofit technology (BACT) or lowest achievable emission
rate (LAER) provisions for new sources would assure at least RACT level
controls on such sources.  The BACT/LAER analyses do not automatically
ensure compliance with RACT since the regulated pollutant or source
applicability may differ and the analyses may be conducted many years
apart.  States may, however, rely on information gathered from prior
BACT or LAER analyses for the purposes of showing that a source has met
RACT to the extent the information remains valid.  We believe that the
same logic holds true for emissions standards for municipal waste
incinerators under CAA section 111(d) and NSR/PSD settlement agreements.
 Where the State is relying on these standards to represent a RACT level
of control, the State should present its analysis with its determination
during the SIP adoption process.

	(2) Compliance with MACT standards affecting VOC.  In situations where
the State has determined VOC to be a significant contributor to PM2.5
formation in an area, compliance with MACT standards may be considered
in VOC RACT determinations.  For VOC sources subject to MACT standards,
States may streamline their RACT analysis by including a discussion of
the MACT controls and relevant factors such as whether VOCs are well
controlled under the relevant MACT air toxics standard, which units at
the facility have MACT controls, and whether any major new developments
in technologies or costs have occurred subsequent to establishment of
the MACT standards.  We believe that there are many VOC sources that are
well controlled (e.g., through add-on controls or through substitution
of non-VOC non-HAP materials for VOC HAP materials) because they are
regulated by the MACT standards, which EPA developed under CAA section
112.  Any source subject to MACT standards must meet a level that is as
stringent as the best-controlled 12 percent of sources in the industry. 
Examples of these HAP sources that may effectively control VOC emissions
include organic chemical plants subject to the hazardous organic NESHAP
(HON), pharmaceutical production facilities, and petroleum refineries.16
 We believe that, in many cases, it will be unlikely that States will
identify VOC emission controls more stringent than the MACT standards
that are not prohibitively expensive and are thus unreasonable.  We
noted our view that this will allow States, in many cases, to conclude
that the control measures implemented to meet MACT standards satisfy any
requirement for VOC RACT.

	(3) Compliance with MACT standards affecting PM2.5 emissions.
Compliance with MACT standards may be considered in direct PM2.5 RACT
determinations.  For direct PM2.5 sources subject to MACT standards,
States may streamline their RACT analysis by including a discussion of
the MACT controls and relevant factors such as whether PM2.5 emissions
are well controlled under the relevant MACT air toxics standard, which
units at the facility have MACT controls, and whether any major new
developments in technologies or costs have occurred subsequent to the
MACT standards.  We believe that there are many direct PM2.5 sources
that are well controlled (e.g., through add-on controls that represent
State-of the art measures for PM2.5 reduction) because they are
regulated by the MACT standards which EPA developed under CAA section
112.  For some MACT standards, PM2.5 is used as a surrogate for
achieving MACT for HAPs such as heavy metals.  Any source subject to
MACT standards must meet a level that is as stringent as the
best-controlled 12 percent of sources in the industry.   We believe that
there will be sources for which it will be unlikely that States will
identify emission controls more stringent than the MACT standards that
are not prohibitively expensive and are thus unreasonable.   In
addressing whether a MACT standard represents best controls for PM2.5,
it is important that the State consider all PM2.5 sources at a given
facility and the nature of the PM limit (i.e., whether the limit ensures
control of the fine fraction of particulate matter).   Also, the State
should evaluate the degree of capture of PM2.5-- that is, the amount of
PM2.5 that is collected and sent to a pollution control device in
addition to the efficiency of the device itself.   This evaluation
should consider the PM2.5 emissions reductions that could by achieved by
improving the degree of capture.  

	(4) Year-round controls for NOx.  In some cases, sources subject to NOx
RACT for PM will also be subject to controls under the NOx SIP Call.  In
the 8-hour ozone implementation rule, EPA concluded that certain sources
which have installed emission controls to comply with the NOx SIP call
would be deemed to meet NOx RACT for the purposes of the 8-hour ozone
implementation program.  Some of these sources subject to the NOx SIP
call may choose to control NOx emissions only or primarily during the
ozone season.  For purposes of PM2.5, however, EPA concludes that the
operation of emission controls only or primarily during the ozone season
would not constitute RACT for PM2.5 purposes.   Indeed PM2.5 control
programs must address annual average concentrations, and in many areas
nitrate concentrations are generally highest in the winter.  Therefore,
RACT for PM2.5 is year-round operation of controls.  For sources subject
to both the NOx SIP call and NOx RACT for PM, we believe that, in most
cases, the additional costs of running the NOx SIP call controls
year-round would impose only modest, reasonable additional costs and the
cost  effectiveness would be better than the average cost effectiveness
for many other sources subject to PM RACT.   (See further discussion  in
section F.7 above related to EGU sources subject to CAIR requirements
for NOx).   

c. Comments and responses.

	Comments:   A number of commenters agreed with the requirement for the
State to conduct a new RACT determination for any source for which the
State’s prior RACT analysis under another NAAQS program concluded that
RACT was defined as no additional controls.  One commenter noted that
for a source having a previous RACT determination for ozone or PM10 to
show that its level of control currently meets RACT for PM2.5 purposes,
the source must provide supporting documentation showing that the
previous RACT determination was based on the same universe of controls
that are “reasonably available” for the source in the present day.  

	Response:  The EPA agrees with these comments.

	Comments:  A few commenters recommended that EPA clarify that RACT
determinations resulting only in “operational changes” should be
treated in an equivalent manner as those resulting in no controls.   The
commenters suggested that, unlike “physical modification,” such
operational changes should always be revisited with a new RACT
determination.  

	Response:   The EPA does not agree with the implicit recommendation to
impose different RACT review requirements based on the types of control
previously implemented.  Th The EPA believes that a reassessment of RACT
is warranted, irrespective of the type of control previously implemented
that would consider the reasonableness of modifying or adding controls
in the particular circumstances.   Furthermore, we are concerned that
making such a distinction based upon the fairly broad term
“operational change” would be difficult to interpret and implement,
and would invite unnecessary disputes concerning the application of the
term.  

	Comment:  Commenters differed on whether new RACT determinations should
be required for all existing determinations made before a specific date,
and on what that date should be.  Some commenters recommended that EPA
allow States to rely on any previous RACT determinations made after
1990, and one commenter recommended that EPA require states to review
only those older than 10-15 years, another recommended 10 years.    One
commenter believed that a 15-year period would be reasonable where
previous controls were installed, to allow for a 15-year amortization of
the cost of those controls.  Other commenters recommended that new RACT
determinations be made for any RACT determinations older than 5 years. 
Another commenter recommended that all RACT determinations should be
reviewed.

	Response:  The EPA has not included any specific time frame in the
final rule.  Th  EPA agrees that the more recent the RACT determination,
the greater the probability that technology advances or decreases in
control cost will not have occurred.  At the same time, technology
advances and decreases in control cost can and have occurred frequently.
 Accordingly, we believe it is necessary for States to review whether
such technology advances or decreases in control cost have occurred
before relying on previous RACT determinations.  We do not believe there
is any specific date or age that could be identified after which States
could ensure that no technology advances or decreases in control cost
will have occurred.

	Comment:  A number of commenters expressed concerns with the resources
required to conduct the certifications required by the proposed
approach, and argued that expending the resources required to review and
to certify previous RACT determinations would not be productive.  One
commenter recommended that EPA provide guidance on the previous RACT
categories for which old RACT determinations are believed to be out of
date.  Another commenter asserted that the only possible exception to
the acceptability of previous RACT measures for purposes of the ozone
standards would be when the new RACT is year-round for an existing
ozone-season RACT measure.

	Response:  The EPA believes that the proposed certification approach
strikes an appropriate balance in requiring States to verify whether
previous RACT determinations currently represent an appropriate RACT
level of control for PM2.5 purposes, while stopping short of requiring
an exhaustive re-analysis for all RACT sources.  The EPA believes that
much of the resource concerns expressed in comments were based upon
concerns that VOC sources are very numerous, and that this approach
would require detailed review for these sources.  As noted previously, a
RACT analysis for VOC sources is required only if a State makes a
finding that VOC sources significantly contribute to nonattainment in
the State or to other downwind air quality concerns.  We believe the
commenters likely overestimate the resource implications of the
certification process for prior RACT determinations.  Another mitigating
factor is that many of these same sources would be reviewed for purposes
of implementing the eight-hour ozone standard.  On the other hand, where
a State or EPA determines that it is appropriate to regulate VOC sources
for PM2.5, EPA believes that it likely would be productive to review the
previous determination for such sources, some of which have not been
reviewed for many years.

	Comment:  One commenter believed that EPA should acknowledge detailed
RACT and RACM analyses for the South Coast and San Joaquin Valley in
California prepared during the 1990s for purposes of implementing the
ozone and PM10 standards.   The commenter believes that EPA acceptance
of these determinations as RACT for PM2.5 would enable States to focus
resources on developing new measures needed for attainment.

	Response:  The EPA agrees that States should focus resources on new
technologies and new developments.  At the same time, EPA recognizes
that for most source categories, new technology continues to be
developed, and new information continues to be generated.  Thus, even
recent RACT determinations for a given source category may be outdated. 
Hence, the certification approach in the rule for the relevant sources
or source categories is a reasonable approach which is designed to
provide for the type of focused efforts suggested by the commenter.   

	Comment:   One commenter believed that a State certification should
only have to identify the existing RACT levels in a SIP and pollutants
affected, but the State should not be required to provide any additional
information.  

	Response:   The EPA disagrees with this comment.  EPA believes that
prior technology determinations should be taken into account in the RACT
determination process.  In reviewing existing RACT determinations, the
State should provide supporting information to show that the existing
technology in use should still be considered RACT, or it should show
that there have been technology advances that have occurred since the
previous RACT limits were developed that are technically and
economically feasible and would contribute to timely attainment.

	Comment:  Some commenters supported EPA’s requirement for year-round
operation of NOx pollution control devices as RACT, given that PM2.5 is
an annual standard, while ozone is a summertime problem.

	Response:  The EPA agrees with these comments.

	Comment:   One commenter concluded that BACT and LAER determinations
should be considered to satisfy RACT, regardless of the date they were
made, because BACT and LAER by definition are more stringent than RACT. 
 

	Response:  The EPA disagrees with this comment.  Th  EPA believes that
in many cases, but not all, BACT and LAER would assure RACT level of
controls.  Reasons that BACT and LAER might not satisfy RACT include:  
the pollutant of concern could have been different, the applicability
threshold for BACT and LAER may have excluded smaller sources
potentially subject to RACT controls, and technology advances or
reductions in control costs may have occurred since the old
determination was conducted.    

	Comment:   One commenter recommended that EPA allow States to use
information gathered from prior BACT or LAER analyses to complete the
RACT determination, as was allowed in the 8-hour ozone NAAQS
implementation rule. 

	Response:  The final rule allows for use of such information, to the
extent it remains valid, to inform a certification by the State that
BACT or LAER technology continues to exceed what would currently be
considered RACT.

	Comment:   Some commenters argued that any MACT determination that
controls the pollutants of concern should be more than sufficient to
satisfy RACT.  Some commenters made similar recommendations regarding
specific standards where PM limits were developed as a surrogate for
HAPs, such as the MACT standard for integrated iron and steel mills, the
MACT standard for iron and steel foundries, and the section 129
standards for waste to energy facilities.

	Response:  While agreeing that MACT controls are relevant, the EPA
disagrees that all MACT determinations should be automatically
considered to satisfy RACT.   Reasons include:  a MACT standard aimed at
toxics might not ensure that the relevant PM2.5 pollutant(s) are well
controlled, MACT applicability provisions might have excluded units
potentially subject to RACT, and technology advances or reductions in
control costs might have occurred since EPA conducted the MACT analysis.
 The EPA believes that the State should review whether technology
advances have occurred including available “beyond the MACT floor”
technologies that may be reasonable in the context of RACT for PM2.5
nonattainment, but which were not selected as MACT for purposes of
implementing section 112.  The EPA believes that RACT analyses should
evaluate whether increased capture of PM2.5 could be achieved, and
whether an increased efficiency in controlling the fine fraction of
particulate matter is reasonably available.   The EPA has, however,
added a specific recognition that MACT standards can reduce PM2.5 as
well as VOC, and that PM2.5 information gathered for MACT standards
development may inform a State’s conclusions on available technologies
for direct PM2.5 emissions.

	Comment:  One commenter expressed a concern that EPA should not presume
that MACT represents RACT where the MACT rule allows for a risk-based
exemption from the control technology requirement.

	Response:  The EPA agrees with this comment.

11.	How should condensable emissions be treated in RACT determinations?
tc "8.How should condensable emissions be treated in RACT
determinations? " \l 3  

a.  Background.

	Certain commercial or industrial activities involving high temperature
processes (fuel combustion, metal processing, cooking operations, etc.)
emit gaseous pollutants into the ambient air which rapidly condense into
particle form.  The constituents of these condensed particles include,
but are not limited to, organic material, sulfuric acid, and metals.  In
general, condensable emissions are taken into account wherever possible
in emission factors used to develop national emission inventories, and
States are required under the consolidated emissions reporting rule
(CERR)17 to report condensable emissions in each inventory revision. 
Currently, some States have regulations requiring sources to quantify
condensable emissions and to implement control measures for them, and
others do not.  In 1990, EPA promulgated Method 202 in Appendix M of 40
CFR Part 51 to quantify condensable particulate matter emissions.  In
the proposed rule, EPA discussed and requested comment on issues related
to condensable emissions in RACT determinations.

	In the proposed rule, we noted that EPA is in the process of developing
detailed guidance on a new test method which quantifies and can be used
to characterize the constituents of the PM2.5 emissions including both
the filterable and condensable portion of the emissions stream.   We
also noted that when a source implements either of these test methods
addressing condensable emissions, the State will likely need to revise
the source’s emissions limit to account for those emissions that were
previously unregulated.  For the purposes of determining RACT
applicability and establishing RACT emission limits, EPA indicated in
the proposal that it intends to require the State to adopt the new test
method once EPA issues its detailed guidance.   This guidance would be
for use by all sources within a PM2.5 nonattainment area that are
required to reduce emissions as part of the area’s attainment
strategy.  

b.  Final rule. 

	Issues and comments related to test method and emissions limit issues
for direct PM2.5 for RACT, including discussion of test methods for
condensables PM2.5, are discussed in section II.L.3 of this preamble. 
Th  EPA recognizes that in some cases condensable emissions are more
difficult to control than filterable emissions.  However, condensable
emissions may be assumed to be almost entirely in the 2.5 micrometer
range and smaller, so these emissions are inherently more significant
for PM2.5 than for prior particulate matter standards addressing larger
particles.  Therefore, EPA encourages States to conduct a thorough
evaluation of the potential for reducing condensable emissions when
evaluating potential measures for RACT.

12.  What criteria should be met to ensure effective regulations or
permits to implement RACT and RACM?

a. Final rule.

	After the State has identified a RACT or RACM measure for a particular
nonattainment area, it must then implement that measure through a
legally enforceable mechanism (e.g., such as a regulation or a permit
provision). a State rule approved into the SIP).  The regulation or
permit provision shouldlegally enforceable mechanism must meet four
important criteria.  

	First, the baseline emissions from the source or group of sources and
the future year projected emissions shouldmust be quantifiable so that
the projected emissions reductions from the sources can be attributed to
the specific measures being implemented.  It is important that the
emissions from the source category in question are accurately
represented in the baseline inventory so that emissions reductions are
properly calculated.  In particular, it is especially important to
ensure that both the filterable and condensable components of PM2.5 are
accurately represented in the baseline since traditional Federal and
State test methods have not included the condensable component of
particulate matter emissions and have not required particle sizing of
the filterable component.

	Second, the control measures must be enforceable.  This means that they
must specify clear, unambiguous, and measurable requirements.  When
feasible, the measurable requirements for larger emitting facilities
should include periodic source testing to establish the capability of
such facilities to achieve the required emission level.  Additionally,
to verify the continued performance of the control measure, specific
monitoring programs appropriate for the type of control measure employed
and the level of emissions must be included to verify the continued
performance of the control measure.  The control measures and monitoring
program must also have been adopted according to proper legal
procedures.

	Third, the measures should must be replicable.  This means that where a
rule contains procedures for interpreting, changing, or determining
compliance with the rule, the procedures are sufficiently specific and
nonsubjective so that two independent entities applying the procedures
would obtain the same result.

	Fourth, the control measures should must be accountable.  This means,
for example, that source-specific emission limits shouldmust be
permanent and must reflect the assumptions used in the SIP
demonstration.  It also means that the SIP must contain a mechanism
(such as a title V operating permit)establish requirements to track
emission changes at sources and provide for corrective action if
emissions reductions are not achieved according to the plan.

b. Comments and Responses

	Comment:  This	There were no comments on this section.  The language
above is identicalvery similar to thatthe language in the proposal, and
there were no comments.

G.  Reasonable Further Progress (RFP)

1.  Background

	Clean Air Act Section 172(c)(2) requires that nonattainment area plans
“shall require reasonable further progress,” which as defined in
Section 171(1) “means such annual incremental reductions in emissions
of the relevant air pollutant as are required by this part or may
reasonably be required by the Administrator for the purpose of ensuring
attainment of the applicable national ambient air quality standard by
the applicable date.”  This section describes the requirements the
Administrator is establishing for states to achieve reasonable further
progress.

	In general terms, the goal of these RFP requirements is for areas to
achieve generally linear progress toward attainment.  The RFP
requirements were included in the Clean Air Act to assure steady
progress toward attaining air quality standards, as opposed to deferring
implementation of all measures until the end date by which the standard
is to be attained.

2. Requirements for Areas with Attainment Dates of 2010 or Earlier

a.  Background

	EPA proposed in sectionIn 40 CFR 51.1009(b)(1) of the proposed rule,
EPA proposed that a State which submits an implementation plan in April
2008 and that demonstrates that a nonattainmentan area will achieve
attainment- by 2010 (i.e., achieves attainment level emissions during
2009 (and thereby attain the standards in 2010) would not be required to
submit a separate reasonable further progress plan for that area.  The
rationale for this approach is that the period between submittal of the
attainment demonstration and the date for attainment is very limited
(i.e. less than two years), and it would not be practical for the state
to be required to meet any set of interim emission reduction targets
prior to the end of 2009In such cases, EPA proposed that the attainment
demonstration would also be considered to demonstrate that the area is
achieving RFP.

b.  Summary of Final Rule

	In the final rule

	, EPA maintainsis maintaining the approach includeddescribed in the
proposed rule.  An area that demonstrates attainment by 2010 shall will
be considered to have satisfied the RFP requirement and need not submit
any additional material to satisfy the RFP requirement.  EPA shall will
view the attainment demonstration as also demonstrating that the area is
making reasonable further progress toward attainment.  

c. Comments and responses

	Comment:  A number of commenters supported EPA’s view that a
demonstration of attainment by 2010 would also demonstrate that the area
is making reasonable further progress toward attainment.  These
commenters asserted that the timetable for adoption of control measures
would not allow for adoption of additional measures any sooner that
would yield more rapid progress toward attainment.  

	Response:  EPA agrees with these comments.  appreciates the support and
is adopting the supported approach.

	Comment:  A set of commenters characterize EPA’s approach as assuming
that adequate interim progress is already being made in areas that
purport to demonstrate attainment, and they assert that this policy
unlawfully waives the RFP requirement for an area demonstrating
attainment by 2010.  The commenters object to a “blanket finding of
compliance with RFP requirements for any area submitting a SIP that
purports to demonstrate attainment by 2010,” noting that a SIP that
provides no annual reductions or even allows interim increases should
not be considered to meet RFP simply by virtue of a purported attainment
demonstration.  The commenters object to EPA allowing areas to avoid any
interim progress, let alone the linear progress that EPA has
historically required.  These commenters state that a variety of
uncertainties in the attainment process enhances the importance of the
RFP requirement and the accountability that RFP is intended to provide. 

	These commenters also claim that PM2.5 nonattainment areas must meet
the requirements of Subpart 4 of Part D of Title I of the Clean Air Act,
including a requirement in Section 189(c) for quantitative progress
milestones to be achieved every 	Comment:  A set of commenters objects
to EPA’s proposal, arguing that EPA cannot waive RFP requirements for
areas where the state purports to demonstrate attainment.  These
commenters believe that Subpart 4 of Part D requires milestones prior to
2009, and these commenters believe that even Subpart 1 requires a
demonstration of interim progress that EPA cannot waive.

	Response:  In brief, EPA is not waiving the RFP requirements for any
area.  Instead, EPA is concluding that a demonstration of attainment by
2010 also serves to demonstrate achievement of RFP.  If the state
submittal purports to demonstrate attainment but does not adequately
make this demonstration, then the submittal also would not demonstrate
achievement of RFP.  The nature of the RFP requirement would then depend
on whether the remedied attainment demonstration provides for attainment
by 2010.  Finally, as discussed above, EPA believes that Subpart 4
requirements do not apply to PM-2.5 plans.  More detailed discussion of
this comment and EPA’s response are provided in the response to
comments document.

3 years from the date of designation.  Thus, in the case of an area
submitting .  Requirements for Areas With Attainment Dates Beyond 2010 

a SIP in 2008 which demonstrates attainment by 2010, the commenters
believe that progress milestones for 2008 should be submitted as part of
the implementation plan.  (For areas that expect to attain in 2015,
these commenters assert that milestones achieving RFP must be submitted
for 2008, 2011, and 2014.)  They believe that EPA’s proposal to
“waive RFP requirements” for areas expected to attain the standard
within 5 years would be . Background  

	The proposed rule required a State to submit an RFP plan along with its
attainment demonstration and SIP due in April 2008 for any area for
which the State demonstrates that 2011 or later is the most expeditious
attainment date.    SEQ CHAPTER \h \r 1 EPA proposed that the 2008 RFP
plan must provide adequate emission reductions by 2009 and, in some
cases, by 2012.  The plan must demonstrate that emissions will decline
in a manner that represents generally linear progress from the 2002
baseline year to the attainment year.  

b. Final Rule

	The final rule requires a State to submit an RFP plan along with its
attainment demonstration and SIP due in April 2008 for any area for
which the State justifies an extension of the attainment date beyond
2010.  The RFP plan must provide emission reductions such that emissions
in 2009 represent generally linear progress from the 2002 baseline year
to the attainment year.  Where the state justifies an extension of the
attainment deadline to 2014 or 2015, the state must additionally provide
emission reductions such that emissions in 2012 represent generally
linear progress from the 2002 baseline year to the attainment year. 

	If the state demonstrates that attainment will occur by 2010 or
earlier, EPA will consider the attainment demonstration to “pick and
choose among the dictates of the Clean Air Act.”  The commenters also
observe that Section 189(f) provides a limited set of potential
exemptions from Subpart 4 requirements under a limited set of
circumstances, and they conclude that the absence of additional
exemptions clearly illustrates the intent of Congress that EPA not
provide other exemptions from Subpart 4 requirements.

	The commenters also claim that waiving the RFP requirements would be
unlawful even if EPA could implement the PM2.5 standards under Subpart 1
of Part D.  The commenters observe that subpart 1 [section 172(c) of the
Act] requires all nonattainment areas to achieve RFP, and that EPA
cannot undo that requirement by administrative rule.  

	Response:   As discussed elsewhere in today’s action, EPA believes
that implementation of the PM2.5 standards is governed by subpart 1 of
the Act rather than subpart 4.  Subpart 4 explicitly addresses PM10 and
was included in the 1990 Clean Air Act amendments to address the PM10
standards established in 1987.  At the time subpart 4 was adopted, the
PM2.5 standards were not in existence.  Subpart 1 was included in the
Act to address any new standards adopted after 1990.  Although elements
of subpart 4 may provide useful guidance in terms of implementing other
standards addressing particulate matter, it was not developed
specifically to address the fine particle standards.  

	The Act provides substantial flexibility for defining how the RFP
requirement is to be met.  EPA believes that areas that submit plans in
April 2008 demonstrating they will achieve attainment-level emissions
during the 2009 emissions year should not be required to establish and
meet any interim emission reduction targets.  Any policy that would
require interim targets, given the short time between the SIP submittal
date and the attainment date, could not be practicably implemented. 
More time would be needed to adopt and implement control measures and to
verify that interim reduction levels had been achieved.  For this
reason, EPA believes that demonstrating attainment by 2010 should be
considered to satisfy the requirement for demonstrate achievement of
reasonable further progress.

	The commenters misinterpret some aspects of EPA’s proposal.  They
imply that a SIP submittal that claims to demonstrate attainment but
later is determined by EPA as not approvable would nevertheless be found
to satisfy the RFP requirement.  This is not the case.  Under the final
rule, if EPA concludes that a state submittal does not satisfactorily
demonstrate attainment by 2010, then the state would be required to
revise its submittal to ensure that it adequately demonstrates
attainment by 2010, or it must submit a revised attainment demonstration
with an attainment date of 2011 or later.  In any demonstration for an
attainment date of 2011 or beyond, the state would be required to
include an RFP plan with milestones for 2010 and possibly 2013 as
required in section 51.1009 of the final rule.  

	The commenters also claim that EPA is waiving the RFP requirement.  EPA
does not believe it would be reasonable to require interim emissions
milestones between the date that SIPs are due in 2008 and the end of
2009.  EPA asserts that in fact the RFP requirement is being retained,
and EPA is addressing how this requirement should be met.  EPA believes
that a state that submits a plan in 2008 successfully demonstrating
attainment by 2010 will need to include as part of its plan an
assessment and accounting of the measures that will achieve progress in
emissions reductions and air quality improvement between 2008 and the
end of 2009.  Submitting an approvable attainment demonstration combined
with actually attaining the standard in 2010 (based on 2007-9 data)
would meet the reasonable further progress requirement for areas with
2010 attainment dates, and would not constitute an exemption from the
requirement.  

3.  Requirements for Areas With Attainment Dates Beyond 2010

a. Background

	The proposed rule required a State to submit an RFP plan along with its
attainment demonstration and SIP due in April 2008 for any area for
which the State determines that 2011 or later is the most expeditious
attainment date.    SEQ CHAPTER \h \r 1 EPA proposed that the 2008 RFP
plan must provide emission reduction and program implementation
milestones to be achieved by January 1, 2010 (based on the 2009
emissions year), and, if necessary, milestones to be achieved by January
1, 2013 (based on the 2012 emissions year).  The emissions milestones
must represent generally linear progress from the 2002 baseline year to
the attainment year.  

b. Final Rule

	The final rule requires a State to submit an RFP plan along with its
attainment demonstration and SIP due in April 2008 for any area for
which the State determines that 2012 or later is the most expeditious
attainment date.  The RFP plan must provide emission reduction and
program implementation milestones to be achieved by January 1, 2011
(based on the 2010 emissions year), and, if necessary, milestones to be
achieved by January 1, 2013 (based on the 2012 emissions year).  The
emissions milestones must represent generally linear progress from the
2002 baseline year to the attainment year.

If the state demonstrates that attainment will occur by 2011 or earlier,
EPA will consider the attainment demonstration as meeting the reasonable
further progress requirement, and the State will not be required to
submit an additional RFP plan for the area.  

	This policy changes the initial milestone year from the 2009 emissions
year (as proposed) to the 2010 emissions year primarily because of the
limited amount of time States would have to implement control measures
between submittal of the SIP in April 2008 and the beginning of the 2009
emissions year.  Therefore, EPA’s final rule requires RFP plans only
for areas that justify an extension of the attainment date to 2012 or
later.  

c. Comments and Responsesresponses

	Comment:  For areas that demonstrate attainment by 2015 without
adopting additional measures, a commenter recommended that the
attainment demonstration be viewed as also demonstrating that the area
is achieving RFP.  The commenter therefore recommended that the state
not be required to submit an RFP plan for such an area.

	Response:  A submittal that demonstrates attainment at the latest
allowable date and does not address interim air quality fails to show
that the path to attainment will yield interim incremental air quality
improvements.  States have ample opportunity to adopt measures that
would provide interim air quality improvement long before 2015.  Indeed,
as discussed elsewhere as part of the discussion of attainment dates, a
submittal that only addresses 2015 would also fail the attainment
demonstration requirement, insofar as it would not be addressing the
requirement for attainmentwhether attainment is as expeditiously as
practicable, because the submittal would fail to assess whether
attainment could be achieved earlier.  Therefore, irrespective of
whether additional measures are needed to attain by 2015, the Clean Air
Act mandates assessing progress at reasonable interim dates as well as
mandating attainment.

4. Generally linear progress and associated timeline

a. Background

	EPA proposed that states with areas needing an extension of the
attainment deadline beyond 2010 would be required to submit a plan
demonstrating that emissions would be sufficiently reduced by 2009 to
achieve a generally linear incremental improvement in air quality.  The
notice of proposed rulemaking provided an example calculation for an
area with a 2013 attainment date, i.e. an area that achieves attainment
level emissions in 2012.  (See section III.G.4.b.iv of the proposal, 70
FR 66013.)  In this example, the 2009 emissions year represents 7/10 of
the period extending from the baseline year of 2002 to the 2012 year of
attainment year.level emissions.  Therefore, for this example, EPA’s
proposed requirement would be for this area to achieve emission
reductions by 2009 representing approximately 7/10 of the emission
reductions needed to attain the standards.  For states with areas
needing the attainment deadline extended to 2014 or 2015, EPA proposed
that they would be required to address require achievement of generally
linear emission reductions at two RFP milestone dates—years—the 2009
and 2012 emission years—demonstrating that the area would achieve
generally linear emission reductions by January 1 of 2010 and 2013,
respectively.  .

	The paragraph above identifies several RFP policy elements that EPA
preferred over other alternatives.  The most prominent alternative would
have required a fixed percentage emission reduction, patterned after the
requirement in Subpart 2 of Part D/Title I of the Clean Air Act
(applicable to ozone plans) for RFP defined as a three percent per year
emission reduction.  Also, implicit in an option that focuses on
expected air quality improvements is that the assessment reflects
consideration of all relevant control measures.	EPA received several
comments on various elements of its proposed approach.  Several
commenters objected to EPA’s proposed requirement to achieve linear
progress toward attainment, asserting that EPA cannot reasonably expect
states to achieve a significant amount of progress within a short time
after plan submittals are due.  Some commenters recommended requiring a
specific emission reduction percentage, similar to the rate of progress
requirement for ozone.  These comments are addressed below. 

b. Final Rule

	EPA is requiring states with areas needing an extension of the
attainment deadline to submit RFP plans.  These plans must demonstrate
that generally linear reductions in emissions will occur by 2009, i.e.
that emissions in 2009 will be reduced at least to the extent
represented by a generally linear progression from 2002 base year
emissions to attainment-level emissions.  For any area that needs an
extension of the attainment deadline to 2014 or 2015, the state’s RFP
plan would also need to demonstrate that generally linear reductions
will be achieved in the 2012 emissions year as well.  

c.  Comments and Responses

	Comment:  Several commenters objected to EPA’s proposed requirement
that states demonstrate linear progress toward attainment.  For example,
a commenter stated that a “generally linear reduction process may not
be practicable.”  A contrasting alternative would exclude
consideration of federally adopted measures such as the Federal Motor
Vehicle Control Program and focus solely on measures adopted by the
state.  Another contrasting alternative would be patterned after Section
182(b)(1) (specifying ozone RFP requirements), in which several specific
types of emission reductions are not creditable for RFP purposes.  The
preceding paragraph also highlights the timeline EPA proposed to follow,
including the base year of the assessment, the end year of the
assessment, and the progress target date for which interim emission
reductions are evaluated.  

	EPA received several comments on various elements of its proposed
approach.  Several commenters objected to EPA’s proposed requirement
to achieve linear progress toward attainment, typically commenting that
EPA cannot reasonably expect states to achieve a significant amount of
progress within a short time after plan submittals are due.  Some
commenters recommended requiring a specific emission reduction
percentage, similar to the rate of progress requirement for ozone. 
These comments are addressed below.

	b. Final Rule

	EPA is requiring states with areas needing an extension of the
attainment deadline to at least 2012 to submit RFP plans.  These plans
must demonstrate that generally linear reductions in emissions will
occur by 2010, i.e. that emissions in 2010 will be no higher than the
level represented by a generally linear progression from 2002 base year
emissions to attainment-level emissions.  For any area that needs an
extension of the attainment deadline to 2014 or 2015, the state’s RFP
plan would also need to demonstrate that further generally linear
reductions will be achieved in the 2012 emissions year as well.  For any
area that can demonstrate attainment by 2011 (i.e., that achieves
attainment level emissions by 2010), the attainment plan shall be
considered to demonstrate that the area is achieving RFP, and no
additional RFP submittal shall be necessary.

	One significant difference between EPA’s proposed RFP requirement and
the final RFP requirement is the first RFP progress target date.  In
response to comments regarding achievement of linear reductions, EPA
reevaluated the date by which states could reasonably be required to
implement accelerated measures as necessary to provide for interim
progress.  Since EPA is requiring RFP plans in conjunction with
attainment plans, due in April 2008, EPA concluded that a progress
target date of 2009 would not provide adequate opportunity to implement
additional measures sufficiently for a 2009 progress target date to be
an appropriate requirement.  Therefore, EPA is revising the first
progress target date to 2010.  EPA is setting the second progress target
date as 2012 (where applicable) as proposed.

c.  Comments and Responses

	Comment:  Several commenters objected to EPA’s proposed requirement
that states demonstrate linear progress toward attainment.  For example,
a commenter stated that a “generally linear reduction process may not
be practicable.”  One commenter stated that it “agrees that areas
should be able to take credit for reductions from 2002 forward, [but]
EPA should allow for fewer reductions (as opposed to linear reductions)
prior to 2008.”

	A commenter noted that EPA’s “proposed approach ignores several
important realities about PM NAAQS implementation.  First, . . . [n]ot
until SIP submittal in April 2008, some 6 years after the RFP baseline
date, will any local measures be finally adopted and approved.  Under
[the example EPA provided in its proposed rulemaking], states will be
required to play ‘catch-up’ by achieving 70 percent of the required
reductions in 2009. . . . Second, the ‘generally linear’ approach
ignores that EPA intends for states to rely in large part on mobile
source reductions and reductions in NOx and SOx from CAIR implementation
to achieve attainment in many areas.  These measures fail a ‘generally
linear’ test since most of the reductions they provide will not be
realized until after 2009.”  This commenter continues that the
incremental reductions in emissions required in the Clean Air Act need
not be equal increments, that the absence of a specific statutorily
mandated increment (such as the 3 percent per year requirement for
ozone) allows EPA to be more flexible and to rely more heavily on later
reductions.  The commenter also argues that EPA’s proposal is more
stringent than the ozone RFP requirement, insofar as the ozone RFP
requirement provides for averaging over 3 years.  Similar comments were
submitted by other associated industry commenters.  

	Another commenter supported EPA’s proposal.  This commenter supported
requiring demonstrations that areas achieve emission reductions that
will yield incremental improvement in air quality on a path toward
expeditious attainment.  

	Response:  The commenters objecting to the requirement for generally
linear progress appear to be assuming that only minimal emission
reductions can be expected before 2008, so that a requirement for
generally linear progress would require plans submitted in 2008 to
compensate by achieving unrealistically high levels of emission
reductions.  EPA disagrees with this assumption.  In fact, substantial
emission reductions are occurring and can be expected to occur in the
next few years.  While	Response:  EPA believes that the requirement for
generally linear reductions is reasonable because it allows States to
take credit for early reductions achieved due to federal, State, and
local programs.  We find that it appropriately implements the RFP
requirement in the Clean Air Act.  For these reasons, EPA is finalizing
the requirement that RFP plans for areas needing an attainment deadline
extension must show that generally linear progress in reducing emissions
will occur by 2009, and areas needing an attainment deadline extension
to 2014 or 2015 (i.e. attainment level emissions projected to start in
2013 or 2014) must additionally show that generally linear progress in
reducing emissions will occur by 2012.

	The commenters objecting to the requirement for generally linear
progress appear to be assuming that only minimal emission reductions can
be expected before 2008, so that a requirement for generally linear
progress would require plans submitted in 2008 to compensate by
achieving unrealistically high levels of emission reductions.  EPA
disagrees with this assumption.  

	In fact, substantial emission reductions have occurred in the past few
years and can be expected to occur through the 2009 emissions year.  EPA
has promulgated significant mobile source rules recently that will yield
substantial benefits in the coming years, and these benefits follow a
series of prior rules that provide a steady progression of emission
reductions as newer, cleaner vehicles replace older, dirtier vehicles. 
For utilities, a major portion of the emission reductions expected after
2002 are from significant NOx reductions occurred in 2004 under the NOx
SIP Call occurred around 2004.  Also, with EPA revising the first
progress target date (i.e. the first date by which RFP must be achieved)
to 2010, a call, and substantial fraction of the SO2 emission reductions
are expected from to occur under the CAIR will be achieved by the
progress target date.trading program prior to 2010 due to incentives for
early reductions and the banking of allowances.  

	EPA is allowing credit for these existing measures in assessing whether
RFP is being met.  While different control measures require various
timelines for implementation, EPA believes that many of the additional
measures that states might adopt for attainment planning purposes can be
implemented in timely fashion for addressing RFP requirements,
particularly with a revised first progress target date of 2010. 
Consequently, EPA believes that its requirement for the combination of
existing and additional measures to provide generally linear progress in
reducing emissions is a very reasonable requirement.  For this reason,
and because this approach appropriately reflects the applicable RFP
requirement in the Clean Air Act, EPA is finalizing the requirement that
RFP plans for areas needing the attainment deadline extended to at least
2012 (i.e. attainment level emissions projected to start no sooner than
2011) must show that generally linear progress in reducing emissions
will occur by 2010, and areas needing an attainment deadline extension
to 2014 or 2015 (i.e. attainment level emissions projected to start in
2013 or 2014) must additionally show that generally linear progress in
reducing emissions will occur by 2012.

	EPA has also promulgated many other regulations that will reduce
particulate matter and particulate matter precursor emissions before as
well as after 2009.  States have also been implementing a variety of
measures.  With use of a 2002 baseline, the assessment of RFP allows
credit for these measures.  The following is a partial list of the
measures that have been adopted and will contribute to achieving
generally linear reductions:

NOx SIP Call

Tightened emission limits for new gasoline and diesel vehicles

Numerous regulations requiring Maximum Achievable Control Technology,
including regulations for

		- Iron and steel plants, including coke plants

		- Industrial boilers

		- Cement plants

		- Lime plants

		- Primary aluminum plants	

Numerous consent decrees for refineries

Numerous consent decrees for power plants

The Clean Air Interstate Rule for utilities

Retrofitted controls on diesel vehicles, and related programs for
reducing diesel vehicle emissions

Closures of coke plants and other facilities (and, from a national
perspective, replacement with cleaner new facilities)

	While different control measures require various timelines for
implementation, EPA believes that many of the additional measures that
states might adopt for attainment planning purposes can be implemented
in a timely fashion for addressing RFP requirements.  Thus, EPA believes
that states can reasonably be expected to assure that the combination of
existing measures and additional measures as necessary will provide for
generally linear progress in reducing emissions.  Furthermore,
particularly with respect to the 2009 RFP milestone year, when EPA
evaluates whether the emission levels in a state plan represent
generally linear progress, EPA will consider the availability of
measures that can be implemented by 2009.  

   	It is difficult to compare the stringency of this RFP requirement to
the RFP requirement for ozone.  The RFP requirement for ozone measures
one form of progress that occurs after 3 years, and the requirement for
PM-2.5 measures a different form of progress that occurs after 87 years
(and for some areas also after 10 years).  That is, the ozone RFP
requirement applies a fixed, universally applicable emission reduction
percentage for one pollutant (VOC), whereas EPA is defining the PM-2.5
RFP requirement as an area-specific combination of emission reductions
for multiple pollutants, defined on the basis of each area’s
attainment demonstration.

	EPA believes that the Clean Air Act mandates not merely eventual
attainment by 2015 but also that states demonstrate that emissions are
being incrementally reduced in earlier years.  (As discussed elsewhere,
states must also demonstrate attainment by earlier than 2015 if
feasible.)  The requirement for RFP reflects Congressional intent that
areas make steady progress toward attainment in the years before
attainment occurs, and states have ample opportunity to assure that
reductions occur well before 2015.  

	Comment:  A commenter observes that the PM-2.5 nonattainment areas in
its state also violate the ozone standard.  The commenter observes,
“I[i]n setting plan requirements, U.S. EPA should choose options that
best facilitate harmonization of fine particulate and ozone control
programs. This includes using a fixed percentage of emission reductions
per year for reasonable further progress (RFP). We recommend the ozone
RFP metric of three percent annual emission reductions averaged over
three years.”  Another commenter also supports a more prescriptive RFP
requirement, and comments that “As suggested by EPA, nonattainment
areas must be required to achieve ‘a fixed percentage reduction of the
emissions of direct PM2.5 and regulated PM2.5 precursors & in specific
milestone years’ between the base year and the attainment year
proposed in the attainment demonstration.”  A third commenter
supported establishing a requirement for a fixed emission reduction
percentage, set at “no less than the 3 percent rate” in Section 182,
with the possibility of higher rates in areas with more severe air
quality problems.

	Other commenters prefer the approach that EPA proposed.  For example
one commenter states that it agrees with EPA’s approach of using the
attainment demonstration to define the parameters for determining what
constitutes RFP, and the commenter supports the flexibility of EPA’s
proposed approach “rather than requiring fixed linear percentage
reductions.”  Regarding the proposed option to require 3 percent per
year emission reductions for areas classified as serious, some
commenters recommended against establishing classifications and a fixed
emission reduction percentage for any area. 

	Response:  Requiring a fixed annual emission reduction percentage would
impose a “one-size-fits-all” approach to address a range of
circumstances.  Requiring a fixed annual emission reduction percentage
would overstate the reductions needed to achieve timely attainment in
some areas and would understate the reductions needed to achieve timely
attainment in other areas.  EPA believes that defining the RFP
requirement in terms of achieving generally linear progress toward the
emission reductions needed for timely attainment assures that each area
will achieve a steady rate of progress most appropriate for the area to
achieve timely attainment.

	EPA recognizes that many areas are nonattainment for both PM-2.5 and
ozone and that the control programs for the two pollutants are
sufficiently intertwined that harmonization of planning for meeting
requirements applicable to the two pollutants is important.  However,
because the statutory requirements set forth in section 182 do not apply
to PM2.5 RFP plans, EPA believes it is neither necessary nor appropriate
to impose these requirements for PM 2.5.  Indeed, given the multiple
pollutants that contribute to PM-2.5 and the variations that exist in
the nature and composition of PM-2.5 across the country, EPA believes
that the PM-2.5 RFP requirements for generally linear reductions are
better defined to reflect these variations and thus be better targeted
toward the emission reductions that in each area can be expected to lead
toward timely attainment.  Further, EPA believes that application of a
different form of the RFP requirement does not cause conflicts in
implementation planning for the two standards.  For example, reductions
of NOx emissions will generally reduce concentrations of both ozone and
PM-2.5, and NOx emission reductions are creditable for meeting both the
ozone and the PM-2.5 RFP requirements.  

	An important distinction between PM-2.5 and ozone is the multiple
components ofthat fine particle formation is in general a more complex
process, affected by both direct emissions and multiplicity of
precursors to PM-2.5.numerous precursor pollutants.  EPA does not
believe that RFP targets for PM2.5 should requirebe the same as those
used for the ozone implementation program, nor should the same
percentage reduction be used for all PM2.5 related pollutants.  Instead,
EPA believes that RFP plans should reflect an appropriate combination of
pollutant reductions that most effectively provides for attainment. 
Therefore, EPA has defined an RFP requirement in which target emission
reductions are established in conjunction with the area’s attainment
plan.

5.  Geographic Coverage of Emissions Sources

a. Background

	PM-2.5 concentrations reflect a combination of impacts over a wide
range of geographic scales.  For some components of PM-2.5, observed
concentrations typically arise predominantly from sources with within
the nonattainment area.  For other components, PM2.5 concentrations may
be impactedinfluenced by sources across a broad area extending outside
the nonattainment area.  EPA’s intent is to define the RFP requirement
in terms of emissions reductions that can be expected to provide
generally linear improvements in air quality in the nonattainment area. 
For this purpose, EPA continues to believe that RFP requirements for
PM2.5 are best defined such that states evaluate emissions of each
pollutant throughout the area that contributes to in which the emissions
substantially influence PM2.5 concentrations in the nonattainment area. 

	As described in the proposed rulemaking, EPA expects each area’s
attainment demonstration to identify many of the parameters for
determining whether the area is achievingused to define the emission
reductions that would represent RFP.  First, the attainment plan will
identify the pollutants that are being reduced to achieve attainment. 
Second, the attainment plan will identify the amount of reduction of
each pollutant and the date by which attainment can be achieved.  This
information suffices to calculate a baseline set of reductions to be
achieved by 20102009 to provide for RFP.  Third, where a state chooses
to achieve RFP by reducing some pollutants earlier than others, the
attainment plan will provide the information needed to assess whether
the intended set of reductions can be expected to provide equivalent a
comparable level of air quality improvement.  Fourth, if the State
intends to include emissions sources located outside the nonattainment
area in its RFP plan, the attainment plan must provide information
justifying thenecessary to justify inclusion of such sources will likely
be found in the attainment plan.

 	EPA’s proposed rulemaking identified several expectations regarding
regional versus local impacts.  For directly emitted fine particulate
matter PM-2.5 (including organic and other carbonaceous particles as
well as miscellaneous inorganic particles and including condensable
particulate matter), EPA recognized that impacts are commonly localized,
and that direct PM2.5 emissionsemissions of PM-2.5 outside the
nonattainment area should not be included in the RFP plan.  Conversely,
EPA recognized the regional nature of secondarily-formed sulfate and
nitrate, and proposed that states could justify inclusion in the RFP
plan of SO2 and NOx emissions sources located within 200 kilometers of
the nonattainment area.

	EPA recognizes that fine particles travel over long distances, and that
distant emissions of SO2 and NOx emissions can influence a nonattainment
area’s air quality.  At the same time, distant sources can be expected
to have less impact than sources closer to the nonattainment area. 
EPA’s procedures for assessing RFP rely on a general assumption that
all the sources included in the assessment have a comparable impact per
ton of emissions.  For this reason, it would be inappropriate to include
distant emission sources in the assessment.  Indeed, the limiting of the
consideration of SO2 and NOx emissions to a 200 kilometer range is
intended to assure that only sources with comparable impacts are
included in the assessment.

b. Final Policy

	The policy for addressing direct PM-2.5 emissions in RFP plans remains
unchanged from the proposal:  only emissions from within the
nonattainment area may be included.  Conversely, for SO2 and NOx, EPA
believes that states could be able to justify considering not only all
emissions in the nonattainment area but also emissions within a distance
that may be up to 200 kilometers from the nonattainment area.  States
may also be able to justify consideration of VOC and ammonia emissions
outside the nonattainment area on a case-by-case basis.  As we explain
more fully below in responding to comments, in situations where the
state demonstrates that VOCs are a significant contributor to PM2.5
concentrations in the area, it may be appropriate to include VOC
emission sources within a distance of up to 100 kilometers of the
nonattainment area.  Given the uncertainties regarding ammonia emission
inventories and the effects of reducing ammonia, EPA is not establishing
a policy on this issue with respect to ammonia.  States that expect to
regulate ammonia should consult with their regional offices to determine
appropriate approaches for those areas.  The justification for
considering emissions outside the nonattainment area shall include
justification of the state’s recommended definition of the area used
in the RFP plan for each pollutant.

	EPA received comments objecting to the possibility that RFP inventories
for areas outside the nonattainment area could include selected sources
expecting substantial emission reductions while excluding other nearby
sources expecting emission increases.  Based on its review of these
comments, EPA is revising its approach for considering regional
emissions.  If the state justifies consideration of precursor emissions
for an area outside the nonattainment area, EPA will expect state RFP
assessments to reflect emissions changes from all sources in this area. 
The State cannot include only selected sources providing emission
reductions in the analysis.  The inventories for 2002, 2009, 2012 (where
applicable) and the attainment year would all reflect the same source
domain (i.e. the same set of sources except for the addition of any
known new sources or removal of known, creditably and permanently
shutdown sources).

	In cases where the state justifies consideration of emissions of
specified precursors from outside the nonattainment area, the state must
provide separate information regarding on-road mobile source emissions
within the nonattainment area for transportation conformity budget
purposes.  As discussed in the July 1, 2004 preamble for regulations for
transportation conformity (cf. 69 FR 40004), these regulations provide
for emission budgets that address the designated nonattainment area. 
For this reason, if the state addresses emissions outside the
nonattainment area for a pertinent precursor (i.e. a precursor for which
mobile sources are significant, as discussed in the May 6, 2005
transportation conformity rule on PM2.5 precursors at 72 FR 24280), the
on-road mobile source component of the RFP inventory will not satisfy
the requirements for establishing a transportation conformity budget.  

	In such a case, the state must supplement the RFP inventory with an
inventory of on-road mobile source emissions to be used to establish a
transportation conformity budget.  This inventory must address on-road
motor vehicle emissions that occur within the designated nonattainment
area, must be provided for the same milestone year or years (i.e. 2009
and 2012 as applicable), and must satisfy other applicable requirements
of the transportation conformity regulations.  So long as the state
provides this separate emissions budget EPA believes that this approach
will optimally address both the RFP and the transportation conformity
provisions of the Act.

	EPA is restricting the geographic area for RFP assessments to include
only areas within the state or states represented in the nonattainment
area.  For a single state nonattainment area, only emissions within that
state would be considered, even if other states may be within 200
kilometers of the nonattainment area.  For multi-state nonattainment
areas, only regions within states represented in the nonattainment area
shall be included in the RFP assessment.  This restriction is intended
to address commenters’ concerns about the enforceability of emission
reductions included in the RFP assessment and helps assure
accountability for these reductions.  This topic is discussed further in
the discussion below about multi-state nonattainment areas.

	Based on its review of the comments, EPA is revising its approach for
considering regional emissions.  EPA will continue to support
consideration of SO2 and NOx emissions out to as much as 200 kilometers
from the nonattainment area (provided the state justifies these
emissions as having substantial impact within the nonattainment area). 
However, for the area outside the nonattainment area, EPA will expect
state RFP assessments to reflect emissions changes from all sources in
this area other than onroad mobile sources.  The State cannot include
only selected sources providing emission reductions in the analysis.   
EPA is retaining the approach that RFP assessments may not include
direct PM-2.5 emissions from sources outside the nonattainment area.  If
a State regulates VOC or ammonia emissions as part of its attainment
strategy, the RFP plan must include emissions of these pollutants.  In
the event that a State technical demonstration indicates that emissions
of VOC or ammonia from sources outside the nonattainment area contribute
significantly to PM2.5 concentrations in the nonattainment area, EPA
will consider on a case-by-case basis whether it would be appropriate to
include emissions from such sources in the RFP plan.  

c. Comments and Responsesresponses

	EPA received numerous comments on its proposal regarding how regional
versus local impacts would be addressed.  Multiple commenters objected
to EPA’s proposal that states could consider sources reducing
emissions but ignore neighboring sources increasing emissions. Other
commenters recommended that EPA support granting credit for primary
emission reductions of direct PM-2.5 emissions that occur outside
nonattainment areas.  A few commenters also recommended different
treatment of selected pollutants, in particular recommending the EPA
provide for consideration of VOC and ammonia emission reductions outside
the nonattainment area. 

	Comment:  Several commenters objected to the methods by which EPA
proposed to account for reductions outside the nonattainment area.  A
According to a set of commenters stated that, if indeed sources outside
the nonattainment area contribute to nonattainment , “then EPA cannot
lawfully or rationally allow the state to claim RFP credit from a single
source’s reductions without including in the baseline emissions from
all sources (mobile, area and stationary) within the same distance from
the nonattainment area, and without calculating the impacts of increases
and decreases in such emissions on RFP. Viewing reductions from a single
‘outside the area’ source in isolation will invariably provide an
incomplete and inaccurate picture of the actual increase or decrease in
emissions contribution to the nonattainment area from all ‘outside the
area’ sources.  Moreover, EPA’s proposal creates numerous
opportunities to game and undermine the system.  By allowing
nonattainment areas to rely on RFP reductions made outside the
nonattainment area, the proposed rule strays from the Act’s focus on
achieving emissions reductions from sources within the nonattainment
area.”  Another commenter insisted that states should not be allowed
to consider emissions from sources outside the area unless they can
demonstrate the impacts of these sources on nonattainment area
concentrations. 

	In addition, a commenter objectedobjects to consideration only of
sources that are reducing emissions and recommendrecommends that EPA
allow credit for upwind source reductions only “on the condition that
all other major sources in the 200 kilometer boundary are also not
allowed to increase emissions.” Another commenter supportedsupports an
option which states would only consider emissions within the
nonattainment area, observing that to consider emissions outside the
nonattainment area would be difficult to administer and might
inappropriately “dilute the reductions needed in the nonattainment
area.”  This commenter also observedobserves that a 200 kilometer
limit does not include much of the emissions that yield long range
transport.  Another commenter supportedsupports crediting reductions
outside the nonattainment area but requestedrequests that EPA define the
area to be considered.

	Response:  EPA agrees that examining emissions reductions of only
selected sources outside the nonattainment area gives an inaccurate
assessment of the progress that an area is making.  For example, if a
state took credit for emission reductions at Source A but ignored equal
emission increases at neighboring Source B, the state would claim
emission reductions in its RFP plan when in fact no net emission
reductions had occurred.  

	The commenters suggest various remedies for this problem.  One
suggestion is to include all sources within the area that is used. 
Another suggestion is to allow no consideration of emissions outside the
nonattainment area.  Yet another suggestion is to allow consideration of
selected sources so long as other sources do not increase emissions.  

	EPA is adopting the first of these suggestions:  for the pertinent area
outside the nonattainment area, the RFP assessment must include
emissions (for all years evaluated) for all sources.  EPA believes that
inclusion of all sources is needed to ensure that the RFP plan reflects
the actual net emissions changes that are occurring in the relevant
area.

	In cases where the state justifies consideration of emissions of
specified precursors from outside the nonattainment area, EPA is
accepting the recommendation of various commenters that the inventories
of these precursors used for RFP purposes shall include mobile source
emissions as well as stationary and area source emissions.  However, in
these cases, for pollutants for which mobile sources are significant,
the state would need to submit additional information for transportation
conformity purposes.  As discussed above, in accordance with regulations
described in the July 1, 2004 final transportation conformity rule that
addressed requirements for 8-hour ozone and PM2.5 areas at 69 FR 40004,
the transportation conformity budget must reflect an inventory of
on-road mobile source emissions for the nonattainment area. 
Consequently, in these cases, the state would need to supplement its RFP
inventory with information identifying the inventory of on-road mobile
source emissions within the nonattainment area for the pertinent
precursor(s) for the applicable year or years (i.e. 2009 and potentially
2012) to be used to establish a transportation conformity budget. 

	The relevant comments in general did not address the dimensions of
spatial domain of the sources outside the nonattainment area that would
be used in assessing RFP.  EPA agrees with a commenter urging, as a
prerequisite to including sources of the pertinent pollutants outside
the nonattainment area in the assessment, that states must justify the
inclusion of sources outside the nonattainment area.  This justification
would need to demonstrate that these emissions have a substantial impact
on nonattainment concentrations that warrants including these emissions
along with nonattainment area emissions in assessing RFP.  Another
commenter recommends that EPA define the area to be included.  Since the
demonstrations of impact are best done by states, in conjunction with
their attainment planning, EPA intends to allow States to justify the
area to be included, within distance limits discussed above.  

	Comment:  Numerous commenters recommended recommend that EPA allow
credit for primary emission reductions of direct PM-2.5 emissions
outside the nonattainment area.  Some of these commenters also
recommended that EPA allow credit for mobile source emission reductions
outside the nonattainment area.  Other commenters supported EPA’s
proposed approach, in which states may justify considering precursor
emissions outside the nonattainment area but must evaluate primarydirect
PM-2.5 emissions based solely on emissions within the nonattainment
area.

	Response:  Under Section 107 of the Clean Air Act, EPA is to
promulgatedesignate nonattainment areas that include areas nearby to the
violations that contribute to the violations.  Given the spatial scale
of the impacts of primarydirect PM-2.5 emissions, EPA believes that any
primarydirect PM-2.5 emission source that demonstrably influences
nonattainment area violations (i.e., contributesand thus would
contribute to these violations) would also be considered to be nearby to
the violations for designation purposes.  EPA believes that it has
properly defined the nonattainment areas to include all nearby
contributing sources.  Nevertheless, EPA asks anyone with evidence that
an additional source or source area contributes to violations in a
nonattainment area to submit that information to EPA and to recommend
incorporation of that source or source area into the nonattainment area.

	EPA has commented on consideration of mobile source emissions above. 
For direct PM-2.5 emissions, EPA believes that the nonattainment area
properly defines the area of consideration, and emissions from mobile
sources outside the nonattainment area, like emissions from stationary
sources outside the nonattainment area, should not be considered.  For
precursors for which consideration of emissions outside the
nonattainment area is justified, the applicable inventories would
include emissions from all sources including mobile sources as well as
stationary sources.

	Comment:   A commenter states that “RFP credits for VOC should be
granted for reductions achieved within the nonattainment area as well as
[within] geographical limits outside of the nonattainment area.”  This
commenter supports consistency with the ozone policy, which allows
credit for NOx reductions within 200 kilometers and VOC reductions
within 100 kilometers of the nonattainment area.  Another commenter
makes similar comments regarding VOC and comments that “[a]s the
science and understanding of PM-2.5 formation increases, EPA must
revisit the 200 kilometer parameter and develop a possible proposal for
ammonia.”

	Response:   Conceptually, EPA agrees that in areas where anthropogenic
VOC emissions outside the nonattainment area are shown to be a
significant contributor to nonattainment area PM-2.5 concentrations,
presumably by reducing the formation of organic particles that influence
nonattainment area concentrations, reduction of these VOC emissions
could help improve air quality in the nonattainment area air quality. 
Therefore, EPA is revising its policy to accommodate consideration of
these potential impacts.  EPA’s presumptions for RACM (including RACT)
purposes reflect its judgment that these impacts will generally be
small, but the impacts are appropriate to consider when theyEPA believes
that as the impacts of anthropogenic VOC on PM2.5 concentrations are
better understood, it may in some cases be appropriate to consider
sources outside the nonattainment area in RFP plans if the impacts from
such sources can be properly quantified and justified.

	Nevertheless, EPA must highlight the technical challenges involved in
assessing the impacts of VOC emission reductions.  First, it is
essential that the impacts of secondary organic particle formation from
anthropogenic VOC emissions be differentiated from the impacts caused by
biogenic VOC emissions and from the impacts of primarydirect organic
particle emissions.  Second, the process of organic particle formation
is highly complex, and currently available atmospheric models typically
perform poorly in assessing the mass of particles thus formed.  Third,
the distance range of impacts, and to be more precise the distance range
over which source impacts are comparable, is especially uncertain. 
While the distance range for organic particle formation is not
necessarily the same as for the influence of VOC on ozone formation, it
may be appropriate to focus oninclude sources within 100 kilometers of
the nonattainment area for both purposes, as the commenter recommended. 
However, any state wishing to include such sources outside the
nonattainment area must justify the distance range that is appropriate
for the area.

	EPA is not prepared at this time to establish generally applicable
guidance with respect to how RFP plans should address ammonia in cases
where that precursor is found to be significant.  EPA expects most state
plans not to regulate ammonia emissions, so for most states this will be
a moot issue.  States that do expect to regulate ammonia emissions
should consult their regional office regarding appropriate approaches
for their particular areas. 

	Finally, EPA agrees with the commenter that EPA should revisit the
range of issues regarding geographic distances of impacts as more
information and understanding become available.

6.  Pollutants to be addressed in the RFP plan

a. Background

	A number of commenters appeared to be confused by the discussion in the
notice of proposed rulemaking regarding the pollutants to be included in
the RFP assessment.  EPA proposed that the attainment demonstration
would provide the key parameters of the RFP demonstration, and that the
list of pollutants to be addressed in the RFP demonstration would match
the list of pollutants regulated as part of the attainment
demonstration.  However, the notice of proposed rulemaking also
suggested that the presumptions regarding whether different pollutants
are to be regulated under NSR and RACM (including RACT) would also apply
to RFP.  This led some commenters to recommend different treatment of
specific pollutants.  

	In fact, the presumptions of applicability that EPA is promulgating for
RACM are not germane to RFP.  The pollutant coverage of RFP assessments
is determined on an area-specific basis according to each area’s
attainment demonstration, and EPA need not establish presumptions as to
what pollutants are included in the RFP assessment.  For example, if a
state includes no NOx emission reductions in its attainment plan, then
the RFP plan would not include NOx, irrespective of whether the
(uncontrolled) NOx emissions contribute significantly to the areas
PM-2.5 concentrations.    

	The contrast between establishment of presumptions for RACM and having
no such presumptions for RFP (or for attainment demonstrations) reflects
differences in regulatory context.  For RACM, at issue is whether the
impact of the pollutant is sufficient to warrant full implementation of
the RACM requirements.  For RFP (as for attainment plans), in contrast,
EPA is allowing states to implement no incremental reductions for any
particular pollutant or pollutants, so long as compensating extra
incremental reductions are made for other pollutant(s), and there is no
need to make a judgment as to whether the reductions for a particular
pollutant are significant.  For this reasonIn contrast, for RFP (as for
attainment plans), EPA is establishing an overall progress requirement
that may be met by applying various control levels to various
pollutants, so long as overall emission reductions are adequate. 
Indeed, if the state chooses not to control a particular pollutant in
its attainment plan, then the presumption is that that pollutant would
not be reduced in the RFP plan either.  Furthermore, states have the
flexibility to meet the overall progress with any adequate combination
of control of relevant pollutants, regardless of the significance or
insignificance of these pollutants’ impacts.  For these reasons, EPA
is making no presumptions as to what pollutants will be included in RFP
plans.

b. Final Policy

	As proposed, the pollutants to be addressed in the RFP plan are those
pollutants that are subject to control measures in the attainment plan.

c. Comments and Responsesresponses

	Comment:  A commenter states that “VOC should be considered a
presumptive PM-2.5 precursor.”  Another commenter recommends presuming
that VOC and ammonia are included in the RFP plan.  

	A third commenter recommends against including condensables in RFP
plans.  This commenter is concerned that states would set milestones
based on current understanding of condensable emission rates and then
changes in the understanding of condensable emission rates would yield
violations of those milestone levels through no fault of the sources
with condensable emissions.

	Response:   EPA’s approach to RFP does not rely on presumptions as to
whether a pollutant does or does not warrant regulation as a precursor. 
Instead, pollutants are to be included or excluded according to whether
the attainment demonstration includes emission controls for the
pollutant that yield quantitative air quality benefits.  Thus,
irrespective of the presumptions applicable to RACM, the RFP plan would
not include VOC unless the attainment plan reflects air quality
improvements from VOC emission controls.  The challenges of addressing
VOC as part of an RFP plan were discussed earlier in this section. 
Similarly, ammonia would not be included in the RFP plan if and only if
the attainment plan regulatesdoes not regulate ammonia emissions.

	The comment on condensables appears to reflect a misunderstanding of
the nature of RFP milestones.  EPA views the RFP as a planning
requirement, wherein states apply current understanding of emissions to
judge whether areas can be expected to achieve suitable reductions in
emissions at specified interim dates.  Today’s rule does not establish
specific requirements for states to conduct a review for example in 2011
to assess whether the milestones projected in the April 2008 RFP plan
were met.  As explained in section 9 below, EPA is instead relying more
heavily on midcourse reviews.  For areas with attainment deadlines
extended at least to 2014, EPA believes that a complete reassessment of
the attainment plan would provide a more timely and productive
evaluation of whether the areas are on track toward timely attainment. 
In this reassessment, changes in our estimations of condensable
emissions would be used along with improvements in our understanding of
atmospheric chemistry and other attainment plan elements.  

	The treatment of condensable emissions in RFP plans differs slightly
from the treatment of other pollutants, insofar as condensable emissions
are often only a subset of a broader category of emissions.  In
particular, condensable organic particle emissions would commonly be
treated as a subset of total organic particle emissions.  The RFP plan
must address organic particle emissions if the attainment plan involves
control of organic particle emissions, in which case the condensable
fraction of organic particle emissions would be included in the
assessment, irrespective of whether control of the condensable fraction
is planned.  Nevertheless, the concern about inclusion of condensable
emissions in the RFP plan is misplaced, insofar as EPA does not
contemplate an RFP milestone review process, and areas would not fail an
RFP milestone review simply because our knowledge of condensable
emissions improved.

7. Equivalent air quality improvement

a. Background

	EPA proposed that states could use alternative combinations of various
types of emission control programs to meet RFP requirements if the
alternative would be expected provide air quality improvements that are
approximately equivalent to those of the benchmark emission reductions. 
Some control programs for some pollutants can be implemented more
quickly than other control programs.  EPA believes that it is
unnecessary to require that all pollutants be reduced at the same rate
or by the same fraction of the ultimate attainment plan reductions.  EPA
believes instead that the states should have flexibility to “mix and
match” control strategies, so long as they provide a demonstration
that the adopted approach can be expected to yield approximately the
same air quality progress as an approach in which the state achieves an
identical fraction of the attainment strategy for all pollutants by the
progress targetRFP milestone date. 

	The notice of proposed rulemaking presents illustrativepresented
examples of the assessment of RFP, illustrating EPA’s recommended
approach for establishing a benchmark set of emission reductions and
illustrating EPA’s recommended procedures for whether modified
approaches that control some pollutants earlier than other pollutants
may be considered equivalent.  Those examples willWhile not be repeated
here. , the examples remain appropriate for describing the approach
included in the final rule.  (See 70 FR 66012-66013). 

	Most commenters supported EPA’s proposal to allow alternative
combinations of control that can be shown by simple means to be
equivalent.  A set of environmental commenters objected to this
approach, given the uncertainties involved in the equivalency
assessment.  Nevertheless, for this aspect of RFP policy, EPA’s final
policy reflects the policy that it proposed.

b. Final Policy

	EPA is adopting an approach that establishes a benchmark level of
controls but allows states the flexibility to adopt any combination of
controls of the various pollutants that can be shown to provide
equivalent benefits using procedures that EPA is recommending.  The
first step is to determine the ratio of the number of years from the
baseline year to the progress target RFP review year (e.g., the 87 years
from 2002 to 20102009) divided by the number of years from the baseline
year to the year in which attainment level emissions are achieved (e.g.
the 10 years from 2002 to 2012, for an area with a 2013 attainment
deadline).  The benchmark level of controls is then determined by
multiplying this ratio times the level of control being achieved for
each pollutant.  For example, for an area with an attainment deadline
extended to 2013, the benchmark level of controls would reflect 87/10 of
the emission reductions of each pollutant that is controlled in the
attainment plan.

	The equivalency process involves consideration of the air quality
benefits for the emission reductions in the alternative plan for each
regulated pollutant.  In effect, the air quality benefits for each
pollutant are used as weighting factors, such that pollutants for which
controls yield larger benefits are weighted more heavily in determining
the adequacy of the resulting plan.  For each pollutant, the first step
is to find the ratio of the emission reductions achieved by the RFP
reviewmilestone date (e.g. the emission reductions achieved between 2002
and 20102009) divided by the emission reductions achieved by the
attainment date.  The second step is to multiply this ratio times the
air quality improvement attributable to full implementation in the
attainment year of the attainment strategy relevant to that pollutant. 
The third step is to add these pollutant-specific results to obtain a
total estimated air quality benefit of the alternative plan.  

	The air quality benefits of the benchmark reductions are easier to
determine.  The first step, inherent to defining the benchmark
reductions, is to determine the ratio of the number of years to the RFP
review divided by the number of years to attainment level emissions (in
the example above, 87/10).  The second step is simply to multiply this
ratio times the quantity of air quality improvement achieved by the
attainment plan.  (Conceptually, the calculations are the same as are
done for the alternative plan, but the mathematics are simpler because
one is applying the same assumed fraction of the attainment plan
emission reductions (e.g. 7/10) for all pollutants, so that there is no
need to subdivide by pollutant.)  For each milestone date, any
alternative that provides estimated air quality benefits by the RFP
milestone date that at a minimum are generally equivalent to the
estimated benefits of the benchmark level of emission reductions will be
considered to satisfy RFP requirements.

c. Comments and Responsesresponses

	Comment:  A set of commenters argues that the equivalency process is
too uncertain, and recommends instead that states be required to achieve
at least a fixed percentage reduction for all pollutants.  The
commenters cite the uncertainties acknowledged by EPA, including
potential nonlinearity (i.e. that a given percentage of an emission
reduction may yield a different percentage of the related air quality
benefit).  The commenters contrast EPA’s willingness to accommodate
these uncertainties, for purposes of giving states flexibility for
alternate RFP plan designs, with EPA’s unwillingness to accommodate
the uncertainties inherent in regulating ammonia emissions.  The
commenters state that “Rather than propose a standardized process for
coherently determining ‘equivalency,’ EPA embraces the possibility
that States will invent multiple and disparate methodologies.”  The
commenters argue that the need for certainty in achieving emission
reductions trumps the benefits of state flexibility, not the other way
around.  The commenters state that if “EPA decides nonetheless to
accept equivalency demonstrations, it should at least . . . require
States to conduct dispersion modeling” to confirm equivalency.  The
commenters further find unlawful the fact that EPA would allow “rough
equivalency” rather than full equivalency to the benchmark approach. 
The commenters would prefer that EPA required a fixed percentage
reduction of the emissions of direct PM-2.5 emissions and of each
precursor.  

	Response:   EPA believes that its proposed approach satisfies the
intent of the RFP requirement, which is to make ongoing, steady progress
toward attainment rather than backloading control strategies.  A
requirement to obtain at least a given percentage of each of the
pollutants that contribute to PM-2.5 concentrations would impose an
inflexibility that EPA concludes is unnecessary where not required by
the statute.  EPA proposed to require that areas achieve emission
reductions that are generally linear, and a plan that provides for rough
equivalency to the benchmark approach would indeed provide generally
linear reductions.  The commenters’ request asking EPA to establish a
standardized process for assessing equivalency is superfluous, because
EPA in fact proposed and is finalizing a standardized process for
assessing equivalency.In response to commenters’ requests for a
standardized process for assessing equivalency, EPA believes the process
outlined in the final rule is responsive to this request.  It is not
clear whether the fixed reduction percentage that the certain commenters
are recommendingrecommended would be an area-specific percentage (such
as EPA uses to define the benchmark approach) or a universally
applicable percentage (such as 3 percent per year).  If the former, then
EPA would repeat the response above regarding flexibility being
consistent with the Act’s requirements;  if the latter, then responses
in III.H.4 regarding a fixed reduction percentage apply.  EPA believes
that the procedures it is establishing to assess equivalency are
adequate for assessing RFP and that dispersion modeling need not be
required for this purpose.

8. Other RFP Issues

a. Multi-state nonattainment areas

	As stated in the proposed rulemaking, EPA seeks to ensure that
nonattainment areas that include more than one State meet RFP
requirements as a whole.  Some commenters expressed concern about how
one state’s submittal should address emissions in other states,
including how the state might address questions about the enforceability
of another state’s requirements.

	The issues here resemble the issues for attainment demonstrations.  In
that context as well, EPA seeks plans that reflect active consultation
by the affected states and provide a combination of reductions that are
enforceable by the respective states that collectively provide for
attainment.  The active involvement of regional planning organizations
helps assure a collective design of a plan with specific requirements to
be adopted by specific states.  Likewise for RFP, EPA would expect
states with multi-state nonattainment areas to consult with other
involved states, to formulate a list of the measures that they will
adopt and the measures that the other state(s) will adopt, and then to
adopt their list of measures under the assumption that the other
state(s) will adopt their listed measures.  That is, each state would be
responsible for adopting and thereby providing for enforcement of its
list of measures, and then that state and ultimately EPA (at such time
as the plan is approved) would be responsible for assuring compliance
with the SIP requirements.

	In accordance with this view of RFP, as is the case for attainment
plans, EPA expects states sharing a multi-state nonattainment to submit
a common assessment of whether RFP will occur.  As a default, if the
assessment only includes emissions within the nonattainment area, then
each state would submit an assessment based on emissions from the full
nonattainment area including portions of the area in other states.  If
the assessment includes precursor emissions from additional area outside
the nonattainment area, then the states should have a common rationale
for the area included, and all affected states would use the same
inventory of the same multi-state area thus defined in assessing whether
RFP will occur.  EPA would judge such submittals based on 1) whether the
overall projected emission reductions will achieve RFP and 2) whether
the submitting state has adopted the necessary enforceable measures to
assure that the reductions projected within its boundaries will in fact
occur.

	As a point of clarification, even if a state justifies consideration of
emissions outside the nonattainment area in its RFP assessment, EPA
intends that these assessments not use emissions from outside the state
or states represented in the nonattainment area.  For single state
nonattainment areas, only emissions within that state would be
considered.  This will help assure accountability for the emission
reductions included in the plan.

b. Tribal areas

	EPA received no comments on its proposed policy regarding RFP for
tribal areas, and EPA is finalizing the proposed policy.  Under its
Tribal Authority Rule (40 CFR 49.4), EPA found that it was not
appropriate to apply SIP schedule requirements to tribes.  For similar
reasons, EPA is not requiring tribes to submit RFP plans.  Generally
this exemption will have limited if any impact on the achievement of RFP
by an area.  Nevertheless, consistent with its general role in
implementing programs for tribes where “necessary and appropriate,”
EPA will work with the affected tribes and states to ensure that
emissions on tribal lands are appropriate addressed appropriately.  EPA
intends to ensure that areas that include both state and tribal lands
will satisfy RFP on a collective basis, similar to the policy applicable
to multi-state nonattainment areas.

9. Mid-Course Review 

a. Background

	EPA proposed requiring mid-course reviews on a case-by-case basis.  The
proposal described a mid-course review as a combination of reviews aimed
at assessing whether a nonattainment area is or is not making sufficient
progress toward attainment of the PM2.5 standards.  The proposal
describesdescribed the mid-course review as involving “three basic
steps:  (1) Demonstrate whether the appropriate emission limits and
emission reduction programs that were approved as part of the original
attainment demonstration and SIP submittal were adopted and implemented;
(2) analyze available air quality, meteorology, emissions and modeling
data and document relevant findings; and (3) document conclusions
regarding whether progress toward attainment is being made using a
weight of evidence determination.”  (Cf. 70 FR 66010) 

	EPA is promulgatingviews mid-course review requirements as part of a
set of requirements for implementing the Clean Air Act requirements for
reasonable further progress.  For areas that demonstrate attainment by
20112010, EPA believes that this attainment demonstration also
demonstrates that reasonable further progress is being achieved.  For
areas that demonstrate attainment after 20112010, EPA is requiring
states to submit aan RFP plan, due in April 2008, showing that emissions
in 20102009 and, in some cases, in 2012, will be sufficiently reduced to
provide generally linear progress toward levels that are expected to
yield attainment.  At issue here is how then to conduct ongoing tracking
of whether the planned progress toward attainment is in fact occurring. 
Subparts 2 (for ozone) and 4 (for PM-10) include explicit requirements
for ongoing milestone tracking.  Since Subpart 1 (applicable for PM-2.5)
allows EPA flexibility in determining how ongoing progress is to be
tracked, EPA has the flexibility to may adopt other approaches for
achieving the necessary assurances that ongoing progress toward
attainment is occurring.  

	Milestone reviews can be confounded by changes in inventory methods (a
concern expressed by a commenter particularly with respect to
condensable emissions) and involve lengthy delays while inventories are
compiled before planning can begin.  Other approaches involving only air
quality data reviews also do not provide for timely planning, insofar as
such approaches involve waiting for three years of air quality data
after implementation of controls before planning can begin.  EPA
believes that a mid-course review provides the most productive approach,
in lieu of establishing milestone tracking or other requirements, to
assure that ongoing reasonable further progress in reducing emissions is
being achieved.  For this reason EPA proposed a requirement for
mid-course reviews in its proposed rulemaking. .

	EPA proposed a process for establishing and implementing mid-course
review.  After the state submits an attainment plan (due in April 2008),
EPA would evaluate whether a mid-course review is warranted after
considering various factors including factors identified in the
proposal.  EPA did not propose to conduct further rulemaking on
establishing this requirement, but EPA proposed that “[w]here EPA
finds that a MCR would be required, the approval of the [attainment]
demonstration would be contingent on a commitment from the State to
conduct the MCR.”   The mid-course review would then be due April
2010.  EPA’s proposal also stated that “EPA would determine [based
on review of the mid-course review] whether additional emissions
reductions are necessary,” so that states would need to complete the
mid-course review “three or more years before the applicable
attainment date to ensure that any additional controls that may be
needed can be adopted [in timely fashion]”  Finally, EPA stated
“[i]f a mid-course review will be required for certain PM2.5
nonattainment areas, separate PM2.5 mid-course review guidance will be
written to address the specific requirements of PM2.5 nonattainment
areas.”

	EPA received numerous comments objecting to EPA’s proposed approach. 
Several commenters noted the inconsistency between requiring a
mid-course review in April 2010 versus requiring a mid-course review due
3 or more years before an attainment date of 2012 or earlier.  Multiple
commenters objected to EPA requiring a mid-course review only 2 years
after the initial attainment plan is due.  A commenter requested
“nationally applicable guidance on when an MCR would be required and
what it would need to include.”  No commenters supported EPA’s
timeline for mid-course reviews.

	Based on the comments that EPA received, EPA has reevaluated the
process for mid-course reviews.  Upon reevaluation, EPA shares many of
the concerns expressed by commenters about the proposal.  The proposal
indeed presents conflicting dates for submittal.  EPA agrees that a
deadline just two years after the initial SIP submittal is too soon for
states to conduct meaningful analyses of whether areas are progressing
towardmaking progress towards attainment.  This problem would be
exacerbated by the proposed process, in particular the fact that states
would not know to begin work on a mid-course review until after they had
submitted their initial SIP and after EPA had sufficiently reviewed the
submittal to determine the need for a mid-course review.  An early
mid-course review also would defeat someone of the purposepurposes of
the mid-course review, which is to take advantage of advances in the
science and understanding of the nature of condensables and other
components of PM-2.5, to adjust plans to be better targeted at solving
problems. 

	For these reasons, EPA is significantly revising its approach to
mid-course reviews as recommended by the commenters.  EPA is
establishing a rule which provides more certainty to the states as to
applicability and content of mid-course review requirements, thereby
avoiding the need for future EPA rulemakings on the subject.  EPA’s
rule clearly does not require states with early attainment dates to
conduct a mid-course review and would clearly mandate a mid-course
review only for areas with later attainment dates.  EPA’s final rule
clarifies the content of mid-course reviews and provides for states to
make decisions on whether further controls are needed rather than having
EPA make this determination.  The mid-course review shall include an
updated modeled attainment demonstration as well as a review of the
implementation of measures in the April 2008 SIP and a review of recent
air quality data.  EPA believes that all of these elements are necessary
and should be sufficient for the state to identify whether additional
measures are needed to achieve attainment by the attainment date in the
approved plan.  EPA believes that states, not EPA, should make the
initial determination as to whether additional measures are needed, and
EPA has designed its mid-course review requirements to provide for the
states to make this determination.

	EPA is promulgating a fixed date of April 2011 as a date for submittal
of mid-course reviews for areas with attainment dates of 2014 or 2015. 
This fixed date will facilitate joint planning for multiple areas to
apply common assumptions regarding regional transport.  This date also
gives states adequate notice for preparing these reviews and adequate
time after the April 2008 submittal to incorporate new information and
understanding of PM-2.5 nonattainment problems to adjust attainment
strategies as appropriate.

	EPA is exempting not requiring areas demonstrating attainment by 2013
or before from the requirement forto conduct a mid-course review.  Such
areas will plan to have attainment level emissions by 2012, and EPA
believes that an April 2011 mid-course review would not provide a timely
reassessment of such areas’ attainment plans.  Instead, EPA is
clarifying that mid-course reviews are only required for areas that
cannot demonstrate that attainment will be achieved before a need for an
attainment date extension at least to 2014.  

b. Summary of Final Rule

	EPA is requiring mid-course reviews for areas with attainment date
extensions to 2014 or 2015.	For each area with an approved attainment
date of 2014 or 2015, EPA is requiring the State to submit a mid-course
review by April 2011.  The EPA would require submittal of the mid-course
review by April 2011.  The mid-course reviews shall include an updated
attainment demonstration as well as a review of the implementation
status of measures included in the April 2008 submittal and a review of
recent air quality data.  The state shall determine whether additional
measures are needed for timely attainment, just as the state is
responsible for determining whether additional measures are needed in
the April 2008 attainment demonstration, subject to formal EPA SIP
review.  EPA is not requiring RFP milestone reviews, and EPA is
requiring mid-course reviews for areas with sufficiently extended
attainment dates in lieu of any other form of tracking reasonable
progress.

c. Comments and Responsesresponses

	Comment:  Multiple A number of commenters objected to EPA's proposed
timeframe that would have areas submit a mid-course review only two
years after the initial SIP is due.  They recommended, instead, that
areas with attainment dates two years or more beyond the first five-year
period submit mid-course reviews three years after the SIPs are due
(April 2011) and every three years thereafter, if necessary.  Their
reason for this suggestion is that the timing of mid-course review
requirements needs to be clearer and should allow adequate time between
plans and mid-course reviews if they are to serve as meaningful reviews.
 

	Multiple	Several commenters also noted an inconsistency in the timing
of mid-course review requirements under EPA’s proposal.  EPA proposed
that mid-course review submittals would be due 5 years after the initial
designation, which for all the original designations means 5 years after
April 2005, i.e. April 2010.  However, EPA also proposed that mid-course
reviews would be due 3 years before the attainment date, which for areas
with an April 2012 attainment date means April 2009.  The commenters
considered April 2009 for a mid-course review submittal to be too soon
after the initial SIP submittal in April 2008, arguing that EPA would
not have had time to review the 2008 SIP submittal, and the States would
not have time to prepare a mid-course review by 2009.  Some of these
commenters expressed a view that EPA should not require mid-course
reviews earlier than three years after the SIP submittal date.  

	Response:  EPA agrees with these comments.  EPA is remedying the
inconsistency in submittal dates by establishing the single submittal
due date of April 2011 that was recommended by the commenters.  As
requested by commenters, EPA is also clarifying the applicability of the
mid-course review requirement.  The requirement shall apply to areas
with attainment dates of 2014 or 2015; mid-course reviews shall not be
required for areas that are expected to attain the standards by 2013.  

	Comment:  A commenter supports mid-course reviews as a means of
assuring that areas with longer-term compliance dates are on track to
attain the NAAQS as expeditiously as practicable.

	Response:  The EPA agrees that mid-course reviews can be a critical
step in assuring expeditious attainment for areas with extended
attainment dates.  Indeed, EPA is relying on mid-course reviews rather
than milestone reviews or other forms of RFP tracking to serve this
purpose.

	Comment: A commenter recommended eliminating mid-course review
requirements for any area with less than seven years between SIP
submittal and attainment.  The commenter urged that EPA carefully
reconsider its overall time lines for PM2.5 while considering the
feasibility and practical usefulness of the steps required of States and
emission sources.

	Response:  EPA agrees with this comment.  In response, EPA is
eliminating that the proposed timeline potentially required mid-course
reviews in areas where such reviews would not be warranted, and the
timeline did not provide the clarity as to the applicability of the
requirement for that states need to fulfill their planning
responsibilities.  In response, EPA is not requiring mid-course reviews
for areas demonstrating attainment prior to 2014.  For those areas that
cannot demonstrate that attainment will occur prior to 2014, EPA has
streamlined the mid-course review process so that the state bears
responsibility for making the initial determination as to whether
additional measures are needed to achieve timely attainment, rather than
requiring additional steps of EPA rulemaking and initial findings by EPA
as to the level of controls needed in the state’s SIP.  With the
revised timetable, states can be assured of a meaningful mid-course
review effort that focuses on the areas that particularly warrant such a
review and for which time is available for a productive assessment of
the need for additional measures.  

	Comment: One commenter stated that the proposal that allows the Agency
to determine whether or not a State needs to submit a mid-course review
with their attainment demonstration on a case- by-case basis lacks
sufficient information.  Since these attainment demonstrations must meet
rigorous criteria, and require substantial work by the States, despite
the onerous burden facing the States, the commenter is concerned that
the proposal neglects to outline the criteria EPA will use to make the
case-by-case mid-course review determinations. The commenter asks that
EPA provide the States with nationally applicable guidance on when an
MCR would be required and what it would need to include. This guidance
should be timely, and must be consistent for all areas	

	Response:  EPA agrees with this comment.  In particular, EPA agrees
that establishing clear criteria for applicability and content of a
mid-course review requirement will provide states the opportunity to
plan for these reviews and conduct appropriate reviews in a timely
fashion.  Therefore, this final rule is establishing specific criteria
for the applicability of the mid-course review requirement, namely that
a mid-course review shall be conducted for any area that cannot
demonstrate attainment before 2014.  This final rule is also identifying
the necessary elements of this mid-course review, i.e. a review of the
implementation of measures in the 2008 SIP, and review of recent air
quality data, and an updated modeled attainment demonstration.  EPA
agrees that its guidance must be timely and consistent for all areas,
and EPA believes that its final rule achieves these imperatives.

H.  Contingency Measures

a.  Background.

	Under subpart 1 of the CAA, all PM2.5 nonattainment areas must include
in their SIPs contingency measures consistent with section 172(c)(9). 
Contingency measures are additional control measures to be implemented
in the event that an area fails to meet RFP or fails to attain the
standards by its attainment date.  These contingency measures must be
fully adopted rules or control measures that are ready to be implemented
quickly upon failure to meet RFP or failure of the area to meet the
standard by its attainment date.  The preamble to the proposal stated
that the SIP should contain trigger mechanisms for the contingency
measures, specify a schedule for implementation, and indicate that the
measures will be implemented without significant further action by the
State or by EPA. The contingency measures should consist of other
control measures for the area that are not included in the control
strategy for the SIP.

	The April 16, 1992 General Preamble provided the following guidance: 
(States must show that their contingency measures can be implemented
without further action on their part and with no additional rulemaking
actions such as public hearings or legislative review.  In general, EPA
will expect all actions needed to affect full implementation of the
measures to occur within 60 days after EPA notifies the State of its
failure.(  (57 FR at 13512.)  This could include Federal measures and
local measures already scheduled for implementation, as explained below.

	The EPA has approved numerous SIPs under this interpretation ( i.e.,
that use as contingency measures one or more Federal or local measures
that are in place and provide reductions that are in excess of the
reductions required by the attainment demonstration or RFP plan.  (62 FR
15844, April 3, 1997; 62 FR 66279, December 18, 1997; 66 FR 30811, June
8, 2001; 66 FR 586 and 66 FR 634, January 3, 2001.)  The key is that the
statute requires that contingency measures provide for additional
emission reductions that are not relied on for RFP or attainment and
that are not included in the demonstration  to provide a cushion while
the plan is being revised to meet the missed milestone.  In other words,
contingency measures are intended to achieve reductions over and beyond
those relied on in the attainment and RFP demonstrations.  Nothing in
the statute precludes a State from implementing such measures before
they are triggered.  In fact, a recent court ruling upheld contingency
measures that were previously required and implemented where they were
in excess of the attainment demonstration and RFP SIP.  See LEAN v. EPA,
382 F.3d 575, 5th Circuit., 2004.

	One basis EPA recommends for determining the level of reductions
associated with contingency measures is the amount of actual PM2.5
emissions reductions required by the control strategy for the SIP to
attain the standards. The contingency measures are to be implemented in
the event that the area does not meet RFP, or attain the standards by
the attainment date, and should represent a portion of the actual
emissions reductions necessary to bring about attainment in area. 
Therefore, the emissions reductions anticipated by the contingency
measures should be equal to approximately 1 year(s worth of emissions
reductions necessary to achieve RFP for the area. 

	As stated previously, EPA believes that contingency measures should
consist of other available control measures beyond those required to
attain the standards, and may go beyond those measures considered to be
RACM for the area.  It is important, however, that States make decisions
concerning contingency measures in conjunction with their determination
of RACM for the area, and that all available measures needed in order to
demonstrate attainment of the standards must be considered first; all
remaining measures should then be considered as candidates for
contingency measures.  It is important not to allow contingency measures
to counteract the development of an adequate control strategy
demonstration.

	The preamble to the proposal stated that contingency measures must be
implemented without “significant further action” after EPA
determines that the area has either failed to meet RFP, or has failed to
attain the standard by its attainment date.  The purpose of the
contingency measure provision is to ensure that corrective measures are
put in place automatically at the time that EPA makes its determination
that an area has either failed to meet RFP or failed to meet the
standard by its attainment date.  The EPA is required to determine
within 90 days after receiving a State(s RFP demonstration, and within 6
months after the attainment date for an area, whether these requirements
have been met.  The consequences for states which fail to attain or to
meet RFP are described in section 179 of the CAA. 

2.  Final Rule.

	Section 51.100x of the The final rule includes regulatory text for
contingency measures and maintains the overall policy approach as
described in the preamble to the proposal.  The key requirements
associated with contingency measures are:

- Contingency measures must be fully adopted rules or control measures
that are ready to be implemented quickly upon failure to meet RFP or
failure of the area to meet the standard by its attainment date.  

- The SIP should contain trigger mechanisms for the contingency
measures, specify a schedule for implementation, and indicate that the
measures will be implemented without further action by the State or by
EPA.

- The contingency measures should consist of other control measures for
the area that are not included in the control strategy for the SIP.

- The measures should provide for emission reductions equivalent to
about 1 year of reductions needed for RFP, based on the overall level of
reductions needed to demonstrate attainment divided by the number of
years from the 2002 base year to the attainment year.  Contingency
measures are those measures that would not be included in the attainment
strategy for various reasons; for example, they may not be as
economically feasible as other measures that are considered to be RACM,
or it may not be possible to implement the measures soon enough to
advance the attainment date (e.g. federal mobile source measures based
on the incremental turnover of the motor vehicle fleet each year).  

3.  Comments and Responses

	Comment:  Several comments were received concerning the requirement for
contingency measures under section 172(c)(9).  The proposal indicated
that contingency measures adopted as part of the State plan are to be
equal to approximately 1 year(s worth of emissions reductions necessary
to achieve RFP, as determined by the attainment demonstration for the
area.  One commenter indicates that this amount of reductions for
contingency measures may be excessive in some cases.  The commenter
stated that States should be allowed to demonstrate appropriate amount
of reductions for contingency measures in each area based on the degree
of the PM2.5 nonattainment area problem and the progression of emission
reductions planned for the area as a part of the SIP.

	Response:   The EPA agrees that the CAA does not include the specific
level of  emission reductions that must be adopted to meet the
contingency measures requirement under section 172(c)(9).  One possible
interpretation of the CAA would assume that contingency measures should
be in place in the event that all of the State(s measures fail to
produce their expected emission reductions.  Under this scenario, the
State theoretically would be required to adopt sufficient contingency
measures to make up for the entire short fall.  In other words, the
State would have to adopt (double( the measures required to statisfy the
applicable emissions reduction requirements.  

	The EPA believes that this scenario would be highly unlikely and that
this interpretation would be an unreasonable requirement.  The adoption
of double the measures needed for attainment would be difficult for
States.  Therefore, the EPA believes that it is reasonable that
contingency measures should, at a minimum, ensure that an appropriate
level of emissions reduction progress continues to be made if attainment
of r RFP is not achieved, or if an area fails to attain the standard by
its statutory attainment date and additional planning is needed by the
State.  The EPA believes that the contingency measures adopted by the
State for the affected area should  represent a portion of the actual
emissions reductions necessary to bring about attainment in the area. 
Therefore, EPA believes that it is reasonable to require states to adopt
contingency measures equal to approximately 1 year(s worth of emissions
reductions necessary to achieve RFP for the area.

	Comment:  One commenter claimed that EPA incorrectly quoted the CAA as
requiring SIPs to provide for implementation of contingency measures
upon an attainment or RFP failure, without (significant( further action
by the State or EPA.   The commenter stated that section 172(c)(9) does
not contain the word (significant.(  The CAA requires that contingency
measures take effect (without further action( by the State or EPA.  

	Response:  The EPA agrees with the commenter that the general
requirements for nonattainment area plans specified under section
172(c)(9) State that each plan must contain additional measures that
will take effect without (further action( by the State or EPA if an area
either fails to make RFP or fails to attain the standard by the
applicable attainment date.  Section 51.100x1012 of the final rule
describes the contingency measures requirement and does not include the
word “significant.” However, as a matter of practicality states need
to take minimal steps to make contingency measures effective and alert
the affected public that the measures are in force. Thus, EPA has
indicated based on conclusions first made in the 1992 General Preamble
that states should complete all of these administrative steps within 60
days and that all regulatory steps be completed before SIP submission. 

	Comment:  The commenter further states that EPA is wrong in asserting
that contingency measures can include Federal measures and local
measures already scheduled for implementation, or previously implemented
measures that provide (excess( reductions.  The CAA requires contingency
measures to consist of controls (to be undertaken if( the area fails to
meet attainment or RFP.  The commenter states that this language clearly
states that such measures are to be new measures that will be undertaken
upon the triggering event specifically to address RFP or failure to
attain, not measures already in place, or measures required for other
reasons.  

	Further, the commenter claims that EPA can not rationally refer to any
reductions prior to an attainment or RFP failure as (excess( when total
reductions in the area in fact prove insufficient to meet attainment
RFP.  The commenter states that EPA cites a 5th Circuit case as support,
but the commenter respectfully submits that the case was incorrectly
decided on this issue for the aforementioned reasons.

	Response:  In response to comments claiming that EPA is wrong in
asserting that contingency measures can include Federal measures and
local measures already scheduled for implementation, or previously
implemented measures that provide (excess( reductions, as stated
previously, the EPA has approved numerous SIPs under this
interpretation.  The statute requires that contingency measures provide
for additional emission reductions that are not relied on for RFP or
attainment and that are included in the attainment demonstration for the
area.  These measures are intended  to provide a “cushion” in terms
of emissions reductions for the area while the State is revising the SIP
for the area due to the failure to show RFP or attain.  In other words,
contingency measures are intended to achieve reductions over and beyond
those relied on in the attainment and RFP demonstrations.  Nothing in
the statute precludes a State from implementing such measures before
they are triggered. 

	As noted above, EPA’s General Preamble interpreted the control
measure requirements of sections 172(c)(9) and 182(c)(9) to allow
nonattainment areas to implement their contingency measures early.  57
FR 13498, 13511 (April 16, 1992).   The EPA has applied this
interpretation in rulemakings. See, for example, 67 FR 6,590, 6,591-92
(September 26, 2002).    See also rulemakings cited in the Background
section, above.  As set forth above, the Fifth Circuit has upheld
EPA’s interpretation.  Louisiana Environmental Action Network v. EPA,
382 F.3d 575 (Fifth Cir. 2004). (“LEAN”)   Commenters have not
provided a basis for concluding  that the Fifth Circuit in the LEAN case
wrongly interpreted the CAA.

	Commenters contend that the language in the CAA  regarding contingency
measure controls “to be undertaken” requires measures not already in
place or required for other reasons.  The Fifth Circuit disagreed,
finding that the terms in section 172(c)(9) — “to be undertaken”
and “to take effect” –  were ambiguous, and finding persuasive
EPA’s interpretation that this language allows measures already in
place or otherwise required.  The Court held:

“Here, the EPA’s allowance of early reductions to be used as
contingency measures comports with a primary purpose of the CAA  – the
aim of ensuring that nonattainment	areas reach NAAQS compliance in an
efficient manner – and necessary requirements of the CAA.”   382
F.3d at 583.

The Court further found that “By utilizing contingency measures early,
the contingency measures ensured that ‘an appropriate level of
emissions reduction progress’ would be implemented while the State
‘adopt[ed] newly required measures resulting from the bump-up to a
higher classification.” [citing the General Preamble].  Id.

	In addition, the Court agreed with EPA that “early reductions are
necessary in order to create an incentive for nonattainment areas to
implement ‘all reasonably available control measures as expeditiously
as practicable’” in accordance with section 172(c)(1) of the CAA. 
Thus the Court concluded  that it would be “illogical to penalize
nonattainment areas that are taking extra steps , such as implementing
contingency measures prior to a deadline, to comport with the CAA’s
mandate that such states achieve NAAQS compliance as ‘expeditiously as
practicable.’” Id. at 583-584.

       The Fifth Circuit also endorsed the concept of “excess”
reductions, noting that the reductions credits at issue in that case,
“although already implemented, are in effect set aside, ‘to be
applied in the event that attainment is [not] achieved’ and such
reduction credits ‘are not available for any other use.’ [citations
omitted].  The setting aside of a continuing, surplus emissions
reduction fits neatly within the CAA’s requirement that a necessary
element of a contingency measure is that it must ‘take effect without
further action by the State or [EPA]’.”   The Court concluded that
“the early activation of continuing contingency measures is consistent
with the purpose and requirements of the CAA statute.”  Id. at 584.

	Thus, EPA’s approval of early implemented contingency measures is
consistent with the CAA, as well as with EPA guidance.    For example,
EPA has consistently taken the position that ozone nonattainment areas
classified moderate and above must include sufficient contingency
measures so that “upon implementation of such measures, additional
emissions reductions of up to 3 percent of the emissions in the adjusted
base year inventory (or such lesser percentage that will cure the
identified failure) would be achieved in the year following the year in
which the failure has been identified.” 57 FR at 13,511 (EPA’s
General Preamble).  Thus the contingency measures are supposed to ensure
that progress towards attainment will occur while the relevant State
adopts whatever additional controls may be necessary to correct a
shortfall in emissions reductions. Id.  EPA has historically allowed
early reductions – that is, reductions achieved before the contingency
measure is “triggered” – to be used as contingency measures,
because if it did not do so it would discourage areas from implementing
“all reasonably available control measures as expeditiously as
practicable” as required by CAA section 172(c)(1). .  See also August
13, 1993 Memorandum from G.T. Helms: Early Implementation of Contingency
Measures for Ozone and Carbon Monoxide (CO) Nonattainment Areas).  

     The commenter’s argument that emission reductions cannot be valid
contingency measures if  they are otherwise required  is also misplaced.
   A State must have the legal authority to require whatever reductions
it may require as a contingency measure.  As EPA has previously stated,
“all contingency measures must be fully adopted rules or measures.” 
62 FR 15,844, 15,846 (April 3, 1997).  The fact that the State or
Federal government  has already exercised that authority is irrelevant
because, as noted above, contingency measures must “take effect
without further action by the State or [EPA].”  Section 172(c)(9). 
Thus, by definition, the State necessarily will have already exercised
its legal authority to require reductions as a contingency measure
before the measure is triggered.   It does not matter whether or not a
specific contingency measure is already required by law, as long as the
emissions reductions that will result from that contingency measure have
not been accounted for in the attainment and reasonable further progress
demonstrations.   If the reductions from the contingency measure are not
available for any other use, then they are surplus that is set aside in
the event reasonable further progress or attainment is not achieved.  

	A key element of a valid contingency measure reduction is that the
State may not use the reduction in its attainment or reasonable further
progress demonstrations if it is already using the reduction as a
contingency measure.  Those demonstrations must account for the actual
emissions reductions that will make reasonable further progress towards,
and achieve attainment of the NAAQS in the absence of contingency
measures.  

I.  Transportation Conformity

	Transportation conformity is required under CAA section 176(c) (42
U.S.C. 7506(c)) to ensure that Federally supported highway and transit
project activities are consistent with (“conform to”) the purpose of
the SIP.  Conformity currently applies to areas that are designated
nonattainment, and those redesignated to attainment after 1990
(“maintenance areas” with plans developed under CAA section 175A)
for the following transportation-related criteria pollutants:  ozone,
particulate matter (PM2.5 and PM10), carbon monoxide (CO), and nitrogen
dioxide (NO2).  Conformity to the purpose of the SIP means that
transportation activities will not cause new air quality violations,
worsen existing violations, or delay timely attainment of the relevant
NAAQS (or “standards”).

	Today’s final PM2.5 implementation rule does not contain any
revisions to the transportation conformity regulation.  The EPA
addressed the transportation conformity requirements that apply in PM2.5
nonattainment and maintenance areas in three separate rulemakings as
described below.

	First, on July 1, 2004, EPA published a final rule (69 FR 40004) that
addressed the majority of requirements that apply in PM2.5 areas
including: 

regional conformity tests to be used in conformity determinations both
before and after SIPs are submitted and motor vehicle emissions budgets
are found adequate or are approved;

consideration of direct PM2.5 emissions in regional emissions analyses;

consideration of re-entrained road dust in PM2.5 regional emissions
analyses;

consideration of transportation construction-related fugitive dust in
PM2.5 regional emissions analyses; and

compliance with PM2.5 SIP control measures.

	Then on May 6, 2005, EPA promulgated a final rule (70 FR 24280) that
specified the transportation-related PM2.5 precursors and when they
apply in transportation conformity determinations in PM2.5 nonattainment
and maintenance areas.

	Finally, on March 10, 2006, EPA promulgated a final rule entitled,
“PM2.5 and PM10 Hot-Spot Analyses in Project-Level Transportation
Conformity Determinations for the New PM2.5 and Existing PM10 National
Ambient Air Quality Standards“ (71 FR 12468).  This final rule
establishes the criteria for determining which transportation projects
must be analyzed for local particle emissions impacts in PM2.5 and PM10
nonattainment and maintenance areas.  This rule establishes new
requirements in PM2.5 areas and revises existing requirements in PM10
areas.  If required, an analysis of local particle emissions impacts is
done as part of a transportation project’s conformity determination.

	Transportation conformity for the PM2.5 standards started applying in
PM2.5 nonattainment areas on April 5, 2006, 1 year after the effective
date of EPA’s PM2.5 nonattainment designations (i.e., April 5, 2005). 
The CAA section 176(c)(6) and 40 CFR 93.102(d) provide a 1-year grace
period before conformity applies in areas newly designated nonattainment
for a new standard.  State attainment demonstrations and SIP submittals
would identify any on-road motor vehicle emissions budgets for direct
PM2.5 or PM2.5 precursors, as appropriate.  These budgets would be used
for satisfying transportation conformity requirements, when found
adequate or approved by EPA. 

	For example, PM2.5 SIPs must address SO2 emissions from applicable
sources, as described in today’s final rule.  State and local agencies
would consider during the development of the PM2.5 SIP whether on-road
mobile source SO2 emissions are a significant contributor to an area’s
PM2.5 air quality problem, and if so, establish a SO2 motor vehicle
emissions budget for transportation conformity purposes.  Any such
budgets would be used in future conformity determinations after they are
found adequate or are approved by EPA.  If the state and local agencies
conclude that on-road sources of SO2 are not a significant contributor
to an area’s PM2.5 air quality problem, motor vehicle emissions
budgets would not be established for SO2 even though emissions of SO2
would be addressed in the area’s attainment demonstration and/or RFP
plan.  

J.   General conformity

a. Background 

	The General Conformity regulations promulgated in 1993 establish an
implementation process where Federal agencies are responsible for making
their own determination of conformity with State implementation plans
(SIPs), and EPA plays an advisory role.  Recognizing that it was
impracticable to evaluate all Federal actions for conformity, EPA
created a number of exemptions in those regulations for actions with
insignificant or not reasonably foreseeable emission increases,
including exemptions for Federal actions with emissions below specified
de minimis levels.  When a Federal agency must demonstrate conformity
for an action, the regulations provide several methods for making that
demonstration.  With the designations of PM2.5 nonattainment areas on
April 5, 2005, requirements for demonstrating conformity become
effective in those areas on April 5, 2006.    

	On July 17, 2006 EPA issued a final rule (71 FR 40420) to amend the
General Conformity Regulations to establish de minimis levels for PM2.5
for the General Conformity program.  The final rule established 100
tons/year of direct PM2.5 emissions and its precursors as the de minimis
level where the General Conformity regulations would apply in PM2.5
nonattainment areas.  In the process of finalizing the de minimis level
for PM2.5 three comments were received.  One commenter was concerned
about emissions from burning by Federal agencies.  Another commenter
proposed that the de minimis level for emissions of direct PM2.5 should
be set significantly lower than 100 tons – in the range of 25-50 tons
per year (TPY) in areas that are likely to attain the PM2.5 national
ambient air quality standard within 5 years, and a level of 10-25 TPY in
areas that are likely to take more than 5 years to achieve the national
ambient air quality standard.  A third commenter supported the proposed
de minimis level.  

	The final rule revises the tables in sub-paragraphs (b)(1) and (b)(2)
of the General Conformity Regulations by adding a de minimis emission
level for PM2.5 and its precursors. This action maintained our past
policy of consistency between the conformity de minimis emission levels
and the size of a major stationary source under the New Source Review
program (70 FR 65984).  These levels are also consistent with the levels
promulgated for Reasonably Available Control Technology applicability
levels for volatile organic compound and nitrogen oxide emissions in
subpart 1 areas under the 8-hour ozone implementation strategy (68 FR
32843).  Since EPA is not finalizing any classifications for the PM2.5
nonattainment areas, we did not establish differing PM2.5 de minimis
emission levels for higher classified nonattainment areas.  

	 

c.b.  Comments and Responses

	Comment:   One commenter requests that EPA communicate to all Federal
agencies the value of the agencies advising the States as soon as
possible of any planned future projects in nonattainment areas that may
be above the General Conformity de minimis values or that will have to
be evaluated to show that they are below de minimis. This is for
projects that are very likely to proceed. The aim is to consider these
future emissions in any growth projections during SIP development since
such growth may not be anticipated well by the available growth model
(E-GAS). States can communicate with existing Federal facilities now
concerning this issue.

	Response:  The EPA sees the value in Federal agencies working with
States to anticipate growth in emissions and include those anticipated
emissions in the applicable SIP.  The EPA is in the process of proposing
regulatory amendments to the General Conformity regulations that provide
a framework for Federal facilities to work with States to account for
facility-wide emissions in SIPs and to include Federal facility
emissions in future SIPs.  The EPA anticipates that these rule
amendments should be proposed before the end of summer 2006.

	Comment:  Some commenters stated that the de minimis level for PM2.5
for conformity applicability should be less than 100 tons per year. A
level of 50 tons per year was suggested for direct PM2.5 emissions. 

	Response:  Similar comments were received when the PM2.5 de minimis
level was proposed on April 5, 2006.  The response to those comments can
be found in the preamble to the final rule setting the de minimis level
for PM2.5 at 71 FR 40420.

	Comment: Are the precursors for general conformity consistent with this
rulemaking or with the transportation conformity rulemaking?  

	Response:  The precursors for general conformity are generally
consistent both with this rule and the transportation conformity rule. 
The only difference between the transportation rule and this rule is
that SO2 is not considered a precursor for transportation conformity
determinations that occur prior to a PM2.5 SIP unless EPA or the State
air agency finds on-road mobile source emissions significant.  For more
information, see the May 6, 2005 transportation conformity rule on PM2.5
precursors at 70 FR 24283.  Since general conformity includes analysis
of stationary sources the general conformity rule requires SO2 as a
precursor both before and after a PM2.5 SIP is submitted.

	Comment:  When will rulemaking containing the de minimis levels for
PM2.5 and for the precursors be issued? There is some confusion, since
the proposed rule says that states should assume 100 tpy for all PM2.5
pollutants, as this would make it consistent with the levels for NOx and
VOC for the subpart 1 areas under 8-hour ozone. However, since New
Jerseys classification is moderate under the 8-hour ozone standard and
we are in an Ozone Transport Region, the de minimis level for VOC is 50
tons per year.

	Response:  On July 17, 2006 EPA issued a final rule (71 FR 40420) to
amend the General Conformity Regulations to establish de minimis levels
for PM2.5 for the General Conformity program.  The final rule
established 100 tons/year of direct PM2.5 emissions and its precursors
as the de minimis level where the General Conformity regulations would
apply in PM2.5 nonattainment areas.  Since EPA is not finalizing any
classifications for the PM2.5 nonattainment areas, we did not establish
differing PM2.5 de minimis emission levels for based on a classification
scheme.  

	Comment:  If a Statement of Conformity has been issued on a project and
if the project has not been completed to date, are they required to
address PM2.5 prior to completion of the project or will they be
grandfathered in?  

	Response:  If a Federal action has completed a conformity determination
and the action has started (regardless of whether the project is
complete or not) then no new determination is needed.  If the conformity
determination was completed, but the action did not start in 5 years a
new determination is needed under the general conformity rules.  

	Comment:  What guidance should states use to establish budgets for
large facilities or military bases?

	Response:  The EPA has not issued any guidance for States and Federal
facilities to establish facility-wide budgets in the applicable SIP. 
There is nothing in the General Conformity regulations preventing this
approach which would allow Federal actions that do not increase total
facility emissions over the budget in the SIP from determining the
action conforms on the basis of its compliance with the budget limit. 
The EPA sees this practice as a positive step to encourage States and
Federal agencies to work together to account for emissions in a SIP so
they conform with the purposes and goals of the SIP.  The EPA intends to
address the approach and provide guidance in planned revisions to the
General Conformity regulations which are expected to be proposed in
2006.

K.	What emission Emission inventory requirements should apply under the
PM2.5 NAAQS? tc \l2 "What emission inventory requirements should apply
under the PM2.5 NAAQS? 

a.  Background for Existing Emission Inventory Requirement.

Emission inventories are critical for the efforts of State, local,
tribal and federal agencies to attain and maintain the NAAQS that EPA
has established for criteria pollutants including PM2.5.  Pursuant to
its authority under section 110 of Title I of the CAA, EPA has long
required States to submit emission inventories containing information
regarding the emissions of criteria pollutants and their precursors. 
The EPA codified these requirements in 40 CFR part 51, subpart Q in 1979
and amended them in 1987.

The 1990 CAAA revised many of the provisions of the CAA related to
attainment of the NAAQS and the protection of visibility in mandatory
Class I Federal areas (certain national parks and wilderness areas). 
These revisions established new emission inventory requirements
applicable to certain areas that were designated nonattainment for
certain pollutants.  In the case of particulate matter, the emission
inventory provisions are in the general provisions under Section
172(c)(3).

In June 2002, EPA promulgated the Consolidated Emissions Reporting Rule
(CERR)(67 FR 39602; June 10, 2002).), 40 CFR part 51 subpart A.  The
CERR consolidated the various emissions reporting requirements that
already existed into one place in the CFR, established new reporting
requirements for PM2.5 and ammonia, and established new requirements for
the statewide reporting of area source and mobile source emissions.

The CERR established two types of required emission inventories:  annual
inventories, and 3-year cycle inventories.  The annual inventory
requirement is limited to reporting statewide emissions data from the
larger point sources.  For the 3-year cycle inventory, States need to
report data from all of their point sources plus all of the area and
mobile sources on a statewide basis.  A special case existed for the
first 3-year cycle inventory for the year 2002 which was due on June 1,
2004.  

The EPA designatedissued guidance suggesting that 2002 be used as the
new Base Year for 8-hour ozone, PM2.5 and regional haze planning efforts
(November 18, 2002 EPA memorandum (2002 Base Year Emission Inventory SIP
Planning:  8-hr Ozone, PM2.5 and Regional Haze Programs(   HYPERLINK
"http://www.epa.gov/ttn/chief/eidocs/2002baseinven_102502new.pdf" 
http://www.epa.gov/ttn/chief/eidocs/2002baseinven_102502new.pdf ).  

  SEQ CHAPTER \h \r 1 States should estimate mobile source emissions by
using the latest emissions models and planning assumptions available at
the time the SIP is developed.  Information and guidance on the latest
emissions models is available at
http://www.epa.gov/otaq/stateresources/transconf/policy.htm#models and
at http://  HYPERLINK "http://www.epa.gov/otaq/models" 
www.epa.gov/otaq/models .htm.

By merging the information on point sources, area sources and mobile
sources into a comprehensive emission inventory, State, local and
Tribaltribal agencies may do the following:

set a baseline for SIP development.  

measure their progress in reducing emissions.  

have a tool to support future trading programs.

answer the public(s request for information.

	EPA uses the data submitted by the States to develop the National
Emission Inventory (NEI).  The NEI is used by EPA to show national
emission trends, as modeling input for analysis of potential
regulations, and other purposes.

Most importantly, States need these inventories to help in the
development of control strategies and demonstrations to attain the
annual and 24-hour PM2.5 NAAQS.  In April 1999, EPA published the
(Emissions Inventory Guidance for Implementation of Ozone and
Particulate Matter National Ambient Air Quality Standards (NAAQS) and
Regional Haze Regulations,( EPA-454/R-99-006.  The EPA updated this
guidance in AugustNovember 2005.111  The current version of this
guidance is available at:
http://www.epa.gov/ttn/chief/eidocs/eiguid/index.html.  The  HYPERLINK
"http://www.epa.gov/ttn/chief/eidocs/eiguid/index.html" 
http://www.epa.gov/ttn/chief/eidocs/eiguid/index.html . EPA developed
this guidance document to complement the CERR and to provide specific
guidance to State and local agencies and Tribes on how to develop
emissions inventories for 8-hour ozone, PM2.5, and regional haze SIPs. 
While the CERR sets forth requirements for data elements, EPA guidance
complements these requirements and indicates how the data should be
prepared for SIP submissions.  

The SIP inventory must be approved by EPA as a SIP element and is
subject to public hearing requirements, whereas the CERR is not. 
Because of the regulatory significance of the SIP inventory, EPA will
need more documentation on how the SIP inventory was developed by the
State as opposed to the documentation required for the CERR inventory. 
In addition, the geographic area encompassed by some aspects of the SIP
submission inventory will be different from the statewide area covered
by the CERR emissions inventory.    SEQ CHAPTER \h \r 1  The CERR
inventory was due June 1, 2004, while the SIP inventory due date is
later.  Because of this time lapse, the State may choose to revise some
of the data from the CERR when it prepares its SIP inventory to account
for improvements in emissions estimates.  If a State's 2005 emission
inventory (or a later one) becomes available in time to use for an
timely development of a nonattainment area subsequently redesignated
nonattainmentplan, then that inventory shouldcan be used.  We also
encourage the cooperation of the Tribes and the State and local agencies
in preparing their emissions inventories.

2.  Summary of b.  Final Rule.  

	In the proposed rulemaking, EPA asked “What emission inventory
requirements should apply under the PM2.5 NAAQS.”  Several specific
questions followed this general question to assess whether or not
additional emission inventory requirements or guidance are needed to
implement the proposed standard.  It was noted in the proposal that the
basis for EPA’s emission inventory program is specified in the
Consolidated Emissions Reporting Rule (CERR) and the related guidance
document titled Emissions Inventory Guidance for Implementation of Ozone
and Particulate Matter National Ambient Air Quality Standards (NAAQS)
and Regional Haze Regulations,” September 2005.

	Subsequent to the proposed rulemaking, EPA proposed the Air Emissions
Reporting Rule (AERR) at 71 FR 69.  The AERR will update CERR reporting
requirements; ensure additional emissions reporting needed to verify
reductions required by the Clean Air Interstate Rule (CAIR); harmonize,
reduce, and simplify the emissions reporting requirements; and make
complying with emissions reporting requirements easier.  At this time,
EPA is reviewing comments submitted on the AERR proposal and expects to
finalize this rulemaking during early calendar year 2007.   The AERR is
expected to be the means by which the Agency will implement any
additional data reporting requirements for PM2.5 SIP emission
inventories.  Since the AERR rulemaking is in progress, EPA believes it
is appropriate to defer responding to comments on the proposed PM 2.5
Implementation Rule that relate to data reporting and emission inventory
requirements that were discussed in the AERR proposal.  Those comments
will be addressed in the final AERR rulemaking.

	Significant comments that are separable from the AERR rulemaking and
relate to data reporting and emission inventory requirements for the
PM2.5 NAAQS are addressed below.

3.  Comments and Responses

A.  Should EPA specify an inventory approval process?

	Comment:  EPA received many comments on whether or not the Agency
should specify an inventory approval process.  Several commenters
indicated that the current process of approving SIP inventories by EPA
regional offices is appropriate and did not believe that additional
approval requirements were necessary.  Some commenters noted that
flexibility is needed to address regional needs such as nonattainment
areas that are influenced by regional emissions may not require as
rigorous an approval process as those influenced by local sources. 
Several commenters noted that SIP emission inventories may include
requirements or information in addition to data required by the
Consolidated Emissions Reporting Rule (CERR).  A few commenters felt
that additional guidance was needed on the SIP emission inventory
approval process.

	One commenter noted that EPA regional offices already approve Quality
Assurance Project Plans (QAPPs) which outline the basic inventory
collection, estimation and review processes conducted by each state. 
The same commenter noted that the National Emissions Inventory (NEI) is
often used as a starting point for developing SIP and modeling
inventories and observed that States routinely develop information
outside the CERR for purposes of their SIP development.  This commenter
believed that additional requirements need not be defined by EPA but
should be left to states to fulfill their own business requirements.	 
SEQ CHAPTER \h \r 1 In the proposed rulemaking, in section 51.1008(a),
to meet the emission inventory requirements of section 172(c)(3),  EPA
proposed to require submission of the CERR inventories as well as “any
additional emission inventory information needed to support an
attainment demonstration and RFP plan ensuring expeditious attainment of
the annual and 24-hour PM2.5 standards.” Section 51.1008(b) set forth
specifications for baseline emissions inventories for attainment
demonstrations and RFP requirements.  Section 51.1008 of the final rule
reflects our proposed rule but is different from the draft regulatory
text.  The proposal did not specify a deadline for submission of the
emission inventory.  To ensure clarity, the final rule contains language
addressing the deadline for submission of emissions inventories for
nonattainment areas under section 172(c)(3) and section 172(b), and
reflects the statutory requirement of no later than 3 years after
designation of the area.  See section 51.1008(a).  In addition, section
51.1008(a)(1) of the proposed rule has been changed for purposes of
clarification.  The proposal referred to the requirement to submit
statewide emission inventories under the (CERR), contained in 40 CFR
part 51, subpart A.  The final regulatory text clarifies this to refer
to the requirements for data elements under 40 CFR part 51, subpart A. 
EPA did not intend that the emissions inventories developed under the
CERR, which are statewide, would be appropriate for and satisfy all
aspects of SIP inventories developed for SIP submissions. Section
51.1008(b) has a minor change to clarify that this subsection refers to
the inventories required for submission under paragraph (a) of section
51.1008, and also clarifies the reference to 40 CFR Part 51 subpart A,
which currently contains the CERR.  In addition, section 51.1008(b) as
finalized provides that “The baseline emission inventory for calendar
year 2002 or other suitable year shall be used for attainment planning
and RFP plans for areas initially designated nonattainment for the PM2.5
NAAQS in 2004.”  EPA added this flexibility to be consistent with
EPA’s ozone implementation rule, and to enable a State to use a more
recent and improved base year inventory if it is completed in time to
allow for timely development of the attainment plan.  As noted above, we
expect that States will consult the guidance document titled Emission
Inventory Guidance for Implementation of Ozone and Particulate Matter
National Ambient Air Quality Standards (“NAAQS”) and Regional Haze
Regulations, November 2005,and submit inventories that are appropriate
for the geographic area at issue and consistent with regulations and
this guidance.  We expect the States to include in their SIP submission
documentation explaining how the emissions data were calculated.

	In the proposed rulemaking, EPA asked “What emission inventory
requirements should apply under the PM2.5 NAAQS.”  Several specific
questions followed this general question to assess whether or not
additional emission inventory requirements or guidance are needed to
implement the proposed standard.  It was noted in the proposal that the
basis for EPA’s emission inventory program is specified in the
Consolidated Emissions Reporting Rule (CERR) and the related guidance
document titled Emissions Inventory Guidance for Implementation of Ozone
and Particulate Matter National Ambient Air Quality Standards (NAAQS)
and Regional Haze Regulations.”

	Subsequent to the proposed rulemaking, EPA proposed the Air Emissions
Reporting Rule (AERR) at 71 FR 69 (Jan. 3, 2006).  The AERR would update
CERR reporting requirements by consolidating and harmonizing new
emissions reporting requirements with pre-existing sets of reporting
requirements under the Clean Air Interstate Rule (CAIR) and the NOx SIP
Call.  At this time, EPA is reviewing comments submitted on the AERR
proposal and expects to finalize this rulemaking during calendar year
2007.   The AERR is expected to be a means by which the Agency will
implement additional data reporting requirements for PM2.5 SIP emission
inventories.  Since the AERR rulemaking is in progress, EPA believes it
is appropriate to defer responding to certain comments on the proposed
PM2.5 Implementation Rule related to data reporting and emission
inventory requirements that were discussed in the AERR proposal.  Those
comments will be addressed in the final AERR rulemaking.  Significant
comments that are separable from the AERR rulemaking and relate to data
reporting and emission inventory requirements for the PM2.5 NAAQS are
addressed below and in EPA’s Responses to Comments document.

	With respect to emission inventory requirements under today’s
rulemaking, EPA recognizes NOX, SO2, VOCs, and ammonia as potential
precursors of PM2.5 because these pollutants can contribute to the
formation of PM2.5 in the ambient air.  To provide a technical
foundation for understanding contributions to PM2.5 nonattainment
problems and for identifying potential future measures to reduce PM2.5
concentrations, EPA is requiring under 40 CFR part 51 subpart A and 40
CFR 51.1008 of this rule that States develop and submit inventories for
direct PM2.5 and all precursors of PM2.5.  This requirement stands apart
from the policies in this rule regarding the required treatment of
various precursor emissions in the development of control strategies for
attaining the PM2.5 standards.  With respect to the latter requirements,
EPA has not made a finding that all precursors should be evaluated for
potential control measures in each specific nonattainment area.  The
policy approach in the rule instead requires evaluation of control
measures for direct PM2.5 and sulfur dioxide in all areas, and describes
general presumptive policies that NOx sources need to be evaluated for
control measures in all areas unless findings of insignificance are
made, but that control measure evaluations are not required for sources
of ammonia and VOC unless findings of significance are made.  The rule
also provides a mechanism by which the State and/or EPA can make an
area-specific demonstration to reverse the general presumption for these
three precursors.  (See section II.A.8 for additional discussion on
these issues.)

c.  Comments and Responses

1.  Should EPA specify an inventory approval process?

	Comment:  Several commenters indicated that the current process of
approving SIP inventories by EPA regional offices is appropriate and did
not believe that additional approval requirements were necessary.  Some
commenters noted that flexibility is needed to address regional
concerns.  Several commenters noted that SIP emission inventories may
include requirements or information in addition to data required by the
Consolidated Emissions Reporting Rule (CERR).  One commenter observed
that States routinely develop information outside the CERR for purposes
of their SIP development and that additional requirements should not be
defined by EPA.  Another commenter indicated that States should be
allowed to customize a nonattainment area inventory from or in place of
national database inventory for use in the analysis of nonattainment. 
One commenter recommended that requirements for nonattainment area
emission inventories be incorporated in the CERR or AERR.  A few
commenters felt that additional guidance was needed on the SIP emission
inventory approval process.	    

	Response:  EPA notesThe SIP emissions inventory is a plan provision
thatthat must be approved by EPA under section 110(k) of the CAA and is
subject to public hearing requirements pursuant to section 110(a)(2). 
EPA believes that it need not further specify a SIP approval process for
emissions inventories beyond that set forth in the statute, regulation
51.1008, other related sections of this rulemaking and EPA’s current
guidance.  EPA agrees with many of the commenters that the approval
process for SIP emission inventories need not be further defined and
that approval should be conducted at the regional level to provide
flexibility to address regional concerns.  EPA also agrees that use of
Quality Assurance Project Plans developed for each state will be helpful
in establishing the proper approval process.  EPA addresses the issue of
what data elements are needed for SIP approval in the responses to
comments below, including the responses to comments under Issue 2,
below.

	As suggested by two commenters EPA describes procedures for approval of
SIP inventories are discussed in thea document titled Emissions
Inventory Guidance for Implementation of Ozone and Particulate Matter
National Ambient Air Quality Standards (NAAQS) and Regional Haze
Regulations,” September, November 2005.  Section 2.5, Inventory
Approval, references a memorandum titled Public Hearing Requirements for
1990 Base-Year Emissions Inventories for Ozone and CO Nonattainment
Areas, September 29, 1992.  EPA intends to use the procedures discussed
in the guidance and memorandum to the extent that they are applicable to
approval of PMPM2.5 emission inventories submitted as part of the SIP. 
40 CFR section 51.1008 sets forth the requirements for emissions
inventories under section 172(c)(3), which will be reviewed in the
context of the SIP approval process. See also sections 51.1007 and
51.1009 regarding attainment demonstrations and RFP plans.  Thus, EPA
believes that its existing SIP approval process is adequately described
in statute, regulation and guidance, and that it provides flexibility to
deal with issues that arise in individual nonattainment areas.  

	EPA agrees with comments suggesting that flexibility is needed to
address regional needs and will continue to work with States through its
regional offices on development and approval of emission inventories for
PM SIPs.  EPA recognizes that there may be emission inventory needs for
specific areas which extend beyond the minimum data reporting
requirements established in the CERR since applicability of the CERR is
to all geographic areas, regardless of attainment status.

B.2.  Are the data elements specified within the CERR sufficient to
develop adequate SIPs?  For example, in the determination of RACT,
should more information on existing control devices be required?

	Comments:  One commenter recommended no additional reporting
requirements because EPA had not presented compelling evidence (1) for
the need to collect additional information; (2) that the costs to state
and local agencies and the regulated community could be justified; or
(3) that the effectiveness of the additional information could be
demonstrated to improve the national emissions inventory.  The commenter
also suggested that any additional reporting requirements be addressed
through the CERR/AERR and associated guidance.

		Comment:  Several commenters recommended that any additional reporting
requirements should be addressed through the CERR/AERR and associated
guidance and that no additional reporting requirements should be
specified in the Rule.	 Another commenter stated that although they
believe that more detail concerning control equipment would be helpful
within all parts of emissions inventories, the commenter invited
discussion with EPA concerning whetherbut was concerned about the
additional burden on industry compared to the benefit to the state and
local agencies would warrant requiring this data.  The commenter , and
suggested further examination of the benefit to the inventory of having
more information on RACT-related and other control devices.

	 that this would be further addressed in the context of comments on the
AERR.  One commenter believed that the reporting requirements within the
CERR are sufficient to develop a PM2.5 SIP for most areas andbut noted
that nonattainment areas substantially influenced by local sources may
require additional inventory information, but this should be evaluated
which will need evaluation on a case-by-case basis.  AnyThe commenter
further stated that any additional inventory requirements should be
identified during the SIP development process, in cooperation with the
EPA regional office, and should not be part of this rule.

 

	Response:  EPA agrees with the comments that requirements for
additional data should be addressed under the AERR (	Response:  In
section 40 CFR 51.1008(a)(1) of the final rule, EPA incorporates the
requirements for data elements required under 40 CFR part 51 subpart A,
which contains the CERR, for inventories submitted under this section. 
EPA notes, however, that the issue of whether to require additional
reporting requirements beyond those required in the CERR is currently
being addressed in the Air Emissions Reporting Rule (AERR.) 71 FR 69, 
(January 3, 2006).  The AERR proposed the addition of several data
elements, including emission release point type, control status and
emission type.  Emission release point type is a code for the physical
configuration of the emission release point (e.g., vertical stack,
fugitive, etc.).  Control status is a code that represents whether
emissions reported are controlled or uncontrolled and is needed to
correctly project future emissions and properly evaluate the impact of
emission control programs.  Emission type is a code describing the
temporal period of emissions reported (e.g., annual, daily, etc.) and is
needed to ensure that emission estimates are used properly.  EPA is
reviewing comments submitted on the AERR and will address the issues
noted by the commenters in the final AERR rulemaking  At this time EPA
believes that the requirements for data elements under the CERR, in
conjunction with the other provisions of section 51.1008, as well as
sections 51.1007 and 51.1009, are generally adequate to meet the needs
for PM2.5 nonattainment emission inventory SIP development.  The AERR as
proposed includes additional provisions which may be helpful for PM2.5
SIP emission inventory development.  EPA will address this aspect of the
AERR, including comments received in this rulemaking on the issues
raised and the additional elements proposed in the AERR, in the final
AERR rulemaking. Today’s final rule indicates that States shall
include data elements for PM2.5 inventories as required under 40 CFR
part 51 subpart A.  In addition, 40 CFR 51.1008(a)(2) requires that
States submit “any additional emission inventory information needed to
support an attainment demonstration and RFP plan ensuring expeditious
attainment of the annual and 24-hour PM2.5 standards.” See also
sections 51.1007 and 51.1009.  Thus States should be aware that data
elements in addition to those required under the CERR may be needed to
support attainment demonstrations and RFP inventories.  Additional data
elements needed for other SIP emission inventory purposes should be
handled on a case-by-case basis.  Because of the nature of SIP
development, which varies depending on the nature and needs of
individual areas, it may not be possible to require a level of detail in
regulations that will enable a “one-stop-shop” information request
as suggested by one of the commenters.

C.     As recommended by one commenter, guidance on reporting
requirements is contained in Emissions Inventory Guidance for
Implementation of Ozone and Particulate Matter National Ambient Air
Quality Standards (NAAQS) and Regional Haze Regulations
(EPA-454/R-05-001, November 2005).  For example, Section 3.2.1 for
Pollutant and Pollutant Precursors to be Inventoried presents guidance
to states on PM2.5 pollutants and their components that should be
reported for PM2.5 SIP development.  See also section 5, Emission
Inventory Development, and other related sections of the guidance.  

     With respect to the comment on additional detail on control
requirements, see also EPA’s Response to Comment Document.

3.  Currently the CERR requires the reporting of SO2, VOC, NOx, CO, Pb,
PM10, PM2.5, and NH3.  VOC and PM are speciated by the emissions
processing models based on speciation profiles for specific source
categories.  Is this approach sufficient, or should EPA require more
specific emission component reporting such as groups of compounds or
reporting of elemental carbon and organic carbon? 

	Comment:  Most commenters supported retaining the existing reporting
requirements under the CERR.  Others encouraged expansion of the
requirements to include reporting of specific organic compounds and
organic fractions although some thought this should be a requirement
while others thought it should be optional.    AnotherOne commenter
thought that EPA should work with industry trade groups to develop and
improve the speciation profiles of the most important source categories
rather than asking the state and local agencies to characterize VOC and
PM species.  Several commenters thought that EPA should encourage the
reporting of PM components (filterable, condensable and total).) for
development of control strategies and attainment demonstrations. 
Another commenter noted that including condensable emissions raises
“uncertainty” issues and urged EPA to devote resources to developing
better test methods.  One commenter believed that in addition to
reporting PM2.5 and its components, states should report all precursors
to PM2.5 (SO2, NOx, ammonia and VOC).  

	Response:  The recently proposed AERR identifies data elements to be
reported by state and local agencies to EPA and would require reporting
of the total PM2.5 emissions and as well as the filterable and
condensable components.  It would also require reporting of precursors
to PM2.5, which include emissions of SO2, NOx, VOC and ammonia.  EPA is
not proposing to require reporting of speciated emissions or of carbon
fractions (organic and elemental).  Comments regarding the reporting of
PM filterable and condensable components, speciated compounds and carbon
fractions will be addressed in the final rulemaking on the AERR.  

	Comment:  One commenter thought that EPA should work with industry
trade groups to develop and improve the speciation profiles of the most
important source categories rather than asking the state and local
agencies to characterize VOC and PM species.

	Response:  EPA agrees with the comment that it should improve
speciation profiles for VOC and PM and is in the process of updating its
SPECIATE database.  SPECIATE is a central repository for data related to
VOC and PM species and can be used for developing species data needed
for air quality modeling analyses.

D.  The CERR allows states to adopt EPA developed emission estimates
from area and mobile sources in lieu of making these estimates
themselves if they accept these estimates for their emission inventory. 
Since 2002 has been designated as the new base year, should EPA require
that States develop their own estimates for area and mobile sources?

	Comment:  One commenter believed that EPA should require States to
develop their own estimates for area and mobile sources.  All other
commenters thought that the existing requirement under the CERR that
allows States to adopt EPA developed emission estimates for area and
mobile sources was adequate.  One commenter thought that adding new
reporting requirements would be a significant burden for State agencies
and would add uncertainty to the emission inventory estimates.

	Response:  The recently proposed AERR would continue to allow states to
stipulate that EPA estimates be used to satisfy CERR data submittal
requirements for mobile and nonpoint (area) source sectors, and would
also allow states the option of providing emission inventory estimation
model inputs in lieu of submitting actual emissions data which could
lead to an improved NEI.  As discussed earlier, EPA will respond to
comments on the emission reporting requirements for area and mobile
sources in the final AERR rulemaking.

9/12/06 version compared to 8/16/06 version

	Response:  EPA agrees with the commenters who argued that the need for
additional speciation should be determined based on specific SIP needs. 
40 CFR part 51, subpart A which contains the CERR, does not require
reporting of specific compounds or compound groups nor does it require
reporting of organic and elemental carbon fractions.  As discussed in
the response to comment above, EPA believes that the requirements for
data elements contained in 40 CFR part 51 subpart A, in conjunction with
the provisions of section 51.1008, are generally adequate to meet the
needs for PM2.5 nonattainment emissions inventory SIP development. 
Section 51.1008(a)(1) applies the data element requirements contained in
40 CFR part 51 subpart A.  Section 51.1008(a)(2) requires States to
submit “any additional emission inventory information needed to
support an attainment demonstration and RFP plan ensuring expeditious
attainment of the annual and 24-hour PM2.5 standards.”  Thus data
elements in addition to those required under the CERR may be needed to
support attainment demonstrations and RFP inventories under 40 CFR Part
51.1008(a)(2).  Additional data elements needed for other SIP emission
inventory purposes should be handled on a case-by-case basis.  Where
States need to develop speciated emissions for PM2.5 SIP emission
inventories, EPA provides guidance in the document titled Emissions
Inventory Guidance for Implementation of Ozone and Particulate Matter
National Ambient Air Quality Standards (NAAQS) and Regional Haze Ozone
Regulations, November 2005.  Section 3.2.1, Pollutants and Pollutant
Precursors to be Inventoried identifies pollutants and their components
to be reported for PM2.5 SIPs.  Section 3.3.5, Speciation Procedures,
discusses the preferred approach for speciating PM2.5 emission
inventories for use in ambient air quality simulations.  The approach
discussed in the guidance is application of emission models which use
speciation profiles to estimate the mass of specific compounds and
compound groups for VOC and elemental and organic carbon fractions for
PM. EPA encourages further research and development of technical tools
to better characterize emissions inventories for specific VOC compounds
and to determine the extent of specific VOC compounds and organic PM
mass.  EPA also encourages States to continue efforts to refine their
ammonia inventories.  See Sections II A. 3 and II A. 4 of the Preamble.

	As discussed in the guidance document, EPA encourages reporting of
organic and elemental fractions of PM2.5 by state agencies (see Section
3.2.1, Pollutants and Pollutant Precursors to be Inventoried).  While
elemental or black carbon (EC/BC) and organic carbon (OC) will be
identified in default speciation profiles, more locally-specific data
should be collected where available as an input to model preprocessing. 
Where such data are available, they should be provided to EPA to help in
improving EPA’s speciation profiles.  Certain organic gases have been
identified as precursors to secondary organic aerosols (SOA).  Toluene,
xylene and ethyl benzene are known to be important SOA precursors. 
Additional organic gases may be identified by ongoing research.  While
these gases will be identified in default speciation profiles, more
locally-specific data should be collected, where available, as an input
to model preprocessing.  State, local and Tribal agencies can contact
EPA’s EIAG for more information.

	EPA agrees with the comment that it should take the lead in updating
VOC and PM profiles for most important source categories.  The Agency is
close to completing a multi-year effort to update the SPECIATE database.
 SPECIATE is EPA's repository of Total Organic Compound (TOC) and
Particulate Matter (PM) speciated profiles for a wide variety of
sources.  The profiles in this system are provided for air quality
dispersion modeling and as a library for source-receptor and source
apportionment type models.  This recent initiative to update SPECIATE
was needed because speciated emissions profiles continue to be developed
and the data in the existing EPA database (SPECIATE 3.2) was becoming
outdated.

	This work was coordinated with interested parties including industry
through an Agency sponsored workgroup.  It has depended largely on the
collection and review of existing profile data to accomplish, as the
commenter suggests, delivering the best results for the least amount of
resources spent.  Previously, these data were not widely available to
emission inventory developers and lacked the quality assurance review
and evaluation needed to develop profiles used by emissions models to
generate speciated emissions.  As suggested by the commenter, the
workgroup was used to help prioritize source categories for
investigation to ensure that updates to existing profiles and
development of new profiles focused on areas of greatest need.

	SPECIATE v4.0 contains more than 2500 source profiles and is currently
undergoing peer review.  EPA expects the final work product to be
available for use by emission inventory preparers during early calendar
year 2007 and it will be distributed through EPA’s CHIEF Web site. 

	EPA agrees with a commenter who noted that in order to meet the
requirements under section 172(c) of the CAA for “a comprehensive,
accurate, current inventory...,” condensable  emissions of PM2.5 and
PM2.5 precursors are important to support development of local control
strategies and attainment demonstrations.  EPA believes that the final
rule provides for the submission of PM2.5 nonattainment area inventories
meeting the requirements of section 172(c)(3).

	Section 51.1008(a)(1) requires that States submit emission inventories
for PM2.5 that satisfy the data elements reporting requirements under 40
CFR part 51 subpart A, which contains the CERR.  The CERR requires
reporting of “Primary PM2.5” which is defined as the sum of the
filterable and condensable portions of PM2.5.  Therefore, SIP base year
inventories will include the condensable fraction of PM which was of
concern to several commenters.  The CERR also requires reporting of SOx,
NOx, ammonia and VOC which are potential precursors to PM2.5.  EPA notes
that the AERR as proposed would require reporting of the same precursors
and would also require reporting of Primary PM2.5.  However, the
proposed AERR requires the reporting of the filterable and condensable
fractions of PM2.5 (optional under the CERR) in addition to the primary
PM2.5 total mass.  EPA will address this requirement in its final
rulemaking on the AERR.

	As noted above, in addition to the data element requirements under
section 51.1008(a)(1), under section 51.1008(a)(2) States must submit
“any additional emission inventory information needed to support” an
attainment demonstration and RFP plan.  Thus States should be aware that
data elements in addition to those required under the CERR may be needed
to support attainment demonstrations and RFP inventories under 40 CFR
Part 51.1008(a)(2).  Additional data elements needed for other SIP
emission inventory purposes should be handled on a case-by-case basis.

	EPA is aware of the issues raised by one commenter regarding
measurement uncertainty for condensable PM.  This issue is addressed in
detail under Section II. L of the preamble (“Condensable particulate
matter test methods and related data issues,”).  We believe that for
purposes of emissions inventories and attainment demonstrations, States
should continue to describe the impacts of baseline emissions and
develop future air quality strategies using information available on
primary PM2.5 emissions, including condensable PM2.5.  However, with
respect to developing enforceable emissions limits for condensable PM2.5
emissions, the final rule reflects EPA’s adoption of a transition
period during which we will allow time for development of emissions
limits for condensable PM2.5.  See Section 51.1002(c).  

     For additional comments and responses related to speciation issues,
see the Response to Comments Document.

4.  The CERR allows states to adopt EPA developed emission estimates
from area and mobile sources in lieu of making those estimates
themselves if they accept these estimates for their emission inventory. 
Since 2002 has been designated as the new base year, should EPA require
that States develop their own estimates for area and mobile sources?

	Comment:  One commenter thought that EPA should require States to
develop their own estimates for area and mobile sources based on the
specified 2002 base year.  Three commenters thought that the existing
process (under the CERR) was adequate.  One of the commenters expressed
concerns about the reporting burden for States if they were required to
compile their own mobile and area source inventories.  Another commenter
did not believe that States should be required to submit data on area
and mobile sources but noted that many States would continue to run the
MOBILE model and calculate area source data for SIP emission
inventories.  Two of the commenters thought that the existing process
provided flexibility needed by States to focus on source categories of
most concern and address problematic areas with special inventory needs.
 One commenter recommended that EPA continue developing models for area
and mobile sources.

	Response:  EPA strongly encourages states to submit their own estimates
for area (nonpoint) and mobile sources unless they can establish that it
is impracticable to do so, given time and resources.  We will continue,
in appropriate circumstances, to allow a. State to use EPA-developed
emission estimates for mobile and nonpoint sources in lieu of making
those estimates itself if the State accepts the estimates for its
emission inventory.  While this has been the case with respect to
reporting under the CERR for the 3-year cycle inventories, for
development of emission inventories to support PM2.5 SIPs, the ability
to rely on EPA-developed emission estimates for development of emission
inventories to support PM2.5 SIPS is more complex and problematic.  For
mobile sources, the practical use of these EPA-developed mobile source
inventories in a SIP may be very limited.  While EPA has developed
inventories for 2002, states will still have to develop attainment year
inventories, including projections of future activity and the effects of
control measures.  For mobile sources, future year inventories are not
developed by simply growing a base year inventory, but instead are
developed by running an emissions model with appropriate inputs for the
future year.  In order to develop an attainment demonstration that
accurately accounts for the change in emissions from the base year to
the attainment year, inventories for both of those years will need to be
developed using consistent methods and modeling assumptions.  For mobile
sources especially, it may be very difficult for states to replicate the
methods used by EPA for the base year when creating the attainment year
inventory.  

	In addition, states cannot use the EPA developed inventories for the
base year if newer models or planning assumptions are available at the
time they begin working on the SIP.  For example, if new or better
information about the composition of the local fleet of highway vehicles
in the base year becomes available to the state after the EPA developed
inventories were created, that information should be used by the state
to create a new base year inventory.

	Given the need for emissions modeling for mobile sources in the
projection year, the need for consistency in tools and methods between
the base year and attainment year, and the need to use latest available
models and planning assumptions, EPA believes that most if not all
states will choose to develop their own base year inventories for mobile
sources. 

	With respect to nonpoint (area) source emissions, States must make
every effort, consistent with available timing and resources to ensure
that their area source emission inventories are as accurate as possible.
 While EPA prepares a national area source emission inventory that
covers all counties, it is designed for national analyses.  EPA does not
have access to the more detailed information available to States that is
used to develop an area source inventory.  Therefore, states should
develop as much of their area source inventory as possible using local
and State information, and in particular should develop the inventory
for the most significant area source categories which are critical to
ensuring overall accuracy.  Where time and resources preclude a State
from developing the estimates for less-critical area source categories,
the State may rely on EPA-developed area source emissions information
for those categories. 

     EPA points out that although guidance has recommended that 2002 be
used as the base year for emissions inventories for states initially
designated nonattainment in 2004-5, states remain free to use an
alternate base year, as appropriate.  Section 51.1008(b) provides in
relevant part that “The baseline emission inventory for calendar year
2002 or other suitable year shall be used for attainment planning and
RFP plans for areas initially designated nonattainment for the PM2.5
NAAQS in 2004.”

EPA agrees with the comment that it should continue to develop models
and other emission estimation tools.  As an example, EPA’s Office of
Transportation and Air Quality (OTAQ) is developing a modeling system
termed the MOtor Vehicle Emission Simulator (MOVES). This new system
will estimate emissions for on-road and nonroad sources, cover a broad
range of pollutants, and allow multiple scale analysis, from fine-scale
analysis to national inventory estimation. When fully implemented MOVES
will serve as the replacement for MOBILE6 and NONROAD.  In addition, as
the NEI is reengineered, OAQPS will examine the need for updating
emissions estimation guidance materials and developing tools which will
assist State agencies in estimating emissions from area source
categories.  See also EPA’s “Emissions Inventory Guidance for
Implementation of Ozone and Particulate Matter National Ambient Air
Quality Standards (NAAQS) and Regional Haze Regulations,(  November
2005.

5.	Other Inventory Issues

	EPA’s responses to additional comments concerning  emission inventory
issues can be found in EPA’s Response to Comments Document.

L.  Condensable particulate matter test methods and related data issues

a.  Background.  

	As noted in the preamble to the November 1, 2005 proposed rule, certain
commercial or industrial activities involving high temperature processes
(fuel combustion, metal processing, cooking operations, etc.) emit
gaseous pollutants into the ambient air which rapidly condense into
particle form.  The constituents of these condensed particles include,
but are not limited to, organic material, sulfuric acid, and metals. 
Because condensable emissions exist almost entirely in the 2.5
micrometer range and smaller, these emissions are inherently more
significant for PM2.5 than for prior particulate matter standards
addressing larger particles.  Therefore, we believe that it is important
that the air quality management of particulate matter promote a
comprehensive approach to condensable particulate matter.   

	We proposed to require a comprehensive inclusion of condensable PM for
all aspects of SIP development for PM2.5.   Under the proposal, EPA
would require condensable PM to be considered in the emissions
inventories and analyses used in attainment demonstrations.   Also under
the proposal, any stationary source emissions limits developed to
implement RACT or RACM would reflect control and measurement of
condensable PM.

	We received numerous comments on whether these requirements were
unreasonable in light of the current state of knowledge of and
uncertainties around the measurement of direct PM2.5.  Most commenters
supported the overall view that condensable PM should be addressed in
order to provide a complete air quality management program for PM2.5. 
On the other hand, many commenters raised concerns about the
availability and implementation of test methods and related issues about
the uncertainties in existing data for condensable PM2.5.  As a result
of the concerns, these commenters believed EPA would be premature in
requiring a comprehensive evaluation of condensable PM2.5, especially as
it related to developing any new emissions limits for stationary
sources.  In recognition of these concerns, the final rule reflects
EPA’s adoption of a transition period during which we will assess
possible revisions to available test methods and we will allow time for
States to update emissions inventories as needed to address direct PM2.5
emissions.  In this section of the preamble, we outline the elements of
the final rule addressing inventories reflecting control of direct
PM2.5.  We also discuss the specific comments raised regarding methods
for measuring direct PM2.5, both filterable and condensable PM, in
implementing the rule.  The particular comment areas include defining
test methods, quantifying direct PM2.5 for inventories, and a transition
period for developing effective regulations.  Below are also our
responses to those comments. 

b. Final rule

	For the final rule, EPA addresses two broad issues related to inclusion
of condensable PM.  The first issue is whether emissions inventories and
attainment demonstrations should include the condensable portion of
direct PM2.5 emissions.   The second issue is whether direct PM2.5
emissions limitations established by States for purposes of RACT and
RACM must include limits on condensable PM emissions or limits on total
direct PM2.5 that includes the condensable PM fraction.

For purposes of developing emissions inventories and attainment
demonstrations, the final rule reflects a requirement to account for
significant contributors of direct PM2.5 emissions, both filterable and
condensable PM2.5.  We recognize that some States have established
inventories consistent with requirements of the consolidated emissions
reporting rule (CERR) to report direct PM2.5 emissions, including
condensable PM, in each inventory revision.  While uncertainties remain
with significant issues to address related to our current knowledge base
on condensable PM emissions, we believe that for purposes of emissions
inventories and attainment demonstrations, States should continue to
describe the impacts of baseline emissions develop future air quality
strategies using information available on direct PM2.5 emissions
including condensable PM.

With respect to developing enforceable emissions limits for condensable
PM emissions, we note that some States have established emissions limits
or otherwise require PM emissions testing that includes measurement of
condensable PM.  We recognize that in some States there remain questions
about the viability of available test methods, the availability of
representative direct PM2.5 emissions data, the uncertainty of the
methods used to establish inventories, and the short time frame within
which States must develop SIPs.  In response we have decided to provide
a transition period for developing emissions limits and regulations for
condensable PM2.5.  During this transition period, we will provide
technical support to States as requested in establishing effective PM2.5
emissions limits and corresponding emissions testing requirements.

	As described further below, we will devote resources early during this
transition period to assessing and improving the available test methods
for condensable PM.  During this transition period, we will also solicit
the involvement of stakeholders with an interest in conducting emissions
testing to collect updated direct PM2.5 emissions data.  The purpose of
these stakeholder projects will be to collect new direct filterable and
condensable PM emissions data using methodologies that provide data more
representative of source direct PM2.5 emissions.  EPA, States, and
others will use these data to improve emissions factors and to help
define or revise source emissions limits in permits and State
implementation plans.  

	The time required for our stakeholders and EPA to complete the test
method assessment will limit the degree to which State and local
agencies can address effectively the necessary direct PM2.5 regulations
in inventories and in the 2008 SIP submittals.  In recognition of this,
we will not require that the emissions limits included in the 2008
submittals account for the condensable fraction of direct PM2.5 or to
establish limits for total direct PM2.5, including condensable PM.  

We will expect States to continue developing more complete inventories
with regard to direct PM2.5 emissions, particularly for condensable PM,
during this transition period.  We expect no such allowance period for
method assessment or data collection to be necessary for implementing
regulations addressing precursor PM2.5 emissions.  

The period of transition for establishing emissions limits for
condensable direct PM2.5 will end January 1, 2011.  We expect States to
address the control of direct PM2.5 emissions, including condensable PM,
with any new actions taken after January 1, 2011.  For example, States
must address condensable PM emissions in any direct PM2.5 emissions
limits resulting from midcourse reviews.  Additionally, EPA expects that
any direct PM2.5 regulations or limits developed under any new NAAQS for
particulate matter would also address condensable PM emissions.

Notwithstanding the issues and uncertainties related to condensable PM,
EPA encourages States to identify measures for reducing condensable PM
emissions, particularly where those emissions are deemed significant
contributors to the control strategy needed for expeditious attainment. 
We wish to clarify that in order to take credit in the SIP for reduction
of any such condensable PM emissions, there must be enforceable
limitations that ensure that reduction in condensable PM emissions.  
These enforceable limits could take the form of a limitation on the
condensable PM emissions or total direct PM2.5 emissions (or a
commitment to develop such limitations after the end of the transition
period described above).  Alternatively, these enforceable limitations
could provide for enforceable conditions that ensure that the effect on
condensable PM emissions is assured (for example, enforceable
limitations on operating temperature, or limits on FGD scrubber
operations which have the effect of reducing condensable PM emissions). 

c. Comments and responses.  

	We received many comments on quantification of direct PM2.5 emissions
particularly about the need to conduct further validations for the
available test methods, the availability of direct filterable or
condensable PM2.5 data or lack thereof for representative baselines, and
the procedures for applying baseline data for developing effective
regulations.

1. Method 202

	Comment:  A majority of commenters characterized the performance of
Method 202 as lacking in reliability.  Some commenters characterized the
formation of artifacts in Method 202 as significant and the primary
reason for their recommendation to defer the inclusion of condensable
particulate matter in the baseline assessments and regulatory
development for the initial SIPs.  The commenters Stated that the
principal artifact formed when using Method 202 was the result of SO2
dissolving in the impinger water and converting to sulfuric acid.

	Response:  We agree that SO2 in particular, and perhaps other gaseous
compounds, can react with the collecting liquids used in the method to
form materials (artifacts) that would not otherwise be solid or liquid
or would not condense upon exiting the stack.  We believe that when
Method 202 is applied appropriately (i.e., with the N2 purge as
prescribed), the SO2 artifact formation is reduced by as much as or more
than 90 percent; however, we agree that further verification and
refinement would be appropriate to verify the potential for artifact
formation.  

	In response, we are undertaking laboratory studies in collaboration
with several stakeholders to characterize the artifact formation and
other uncertainties associated with conducting Method 202, and to
identify procedures to be used in applying methods to minimize
uncertainties.  We are involving stakeholders representing industry and
State and local agencies in the project design and results review. 
Stakeholders who have expressed interest in participating in these
studies include the Electric Power Research Institute, companies
belonging to National Environmental Development Association’s Clean
Air Project (NEDA/CAP), the Portland Cement Association, the Lime
Manufacturing Association, the American Foundry Association, the
National Aluminum Association, and several governmental organizations
represented by State and Territorial Air Pollution Program
Administrators and the Association of Local Air Pollution Control
Officials (STAPPA/ALAPCO).  Other parties may participate in the study
as well.

	By the end of 2007, we intend to have conducted a comprehensive
laboratory study that examines the relationship between several critical
condensable PM sampling and analysis parameters (e.g., SO2
concentration, moisture concentration, sample duration, water acidity)
and the artifact formation associated with the measurements.  One
intended result of the project will be identifying possible
modifications to Method 202 to minimize and quantify the uncertainties. 
We will publish the results of the laboratory study along with an
assessment of other input and data from stakeholders on the EPA website
and, to the extent possible, in a widely circulated peer review journal.
 Also, to the extent necessary, we intend to propose revisions to the
method to incorporate improvements and to clarify application.

2. Conditional Test Methods 039 and 040

	Comment: Several commenters cited as a deficiency that neither
conditional test method 040 (CTM-040) for measuring filterable PM2.5 nor
the dilution sampling method (CTM-039) has been thoroughly validated
through EPA Method 301.  There were also comments that neither of the
CTMs was published in the Federal Register.

	Response:  We agree with the comments that neither method has been
subjected to public notice and comment rulemaking.  Taking that step
will facilitate application of the appropriate methods for implementing
the SIPs.  On the other hand, there are a number of levels of validation
already achieved for one or more of these methods that will determine
what, if any, additional validation work will be necessary.  For
example, while we could seek resources to evaluate dilution sampling
technology, including CTM-039, and to request public involvement in the
project planning, conduct, and review with the possibility of a Federal
Register proposal, our preference would be to incorporate by reference
an approved voluntary consensus test method (e.g., ASTM standard).

	We believe that a dilution sampling method for measuring direct PM2.5
eliminates essentially all artifact formation and provides the most
accurate emissions quantification.  To the extent that we need to and
can secure resources and stakeholder interest, we plan to perform
additional validation testing of CTM-039 or other dilution sampling
technologies to characterize the precision of this approach.  In
conjunction with our validation efforts, we intend to continue
participation in the ASTM D22 committee work on a dilution sampling
method and encourage other volunteers on that committee to approve the
consensus based dilution sampling method.  We believe that this work is
nearly complete.  As outlined above, we are already undertaking
laboratory studies to assess the method and to identify possible
modifications to reduce formation of these artifacts.  Preliminary
laboratory evaluations conducted by EPA and by Environment Canada
indicate that additional artifact reductions of 60 to 90 percent may be
achieved with other minor modifications to Method 202.  These
preliminary findings indicate that Method 202 is essentially a viable
method that these proposed laboratory studies will serve to enhance. 
Within 18 months we intend to propose, if necessary, modifications to
Method 202 or similar methodologies suitable for measuring condensable
PM2.5.

	As for CTM-040, we believe that that further validation of this method
is unwarranted since the technology and procedures are based upon the
same as evaluated for promulgated Method 201A.  Method 201A has
undergone public review and comment (55 FR 14246, April 17, 1990). 
Also, as noted earlier, we have already begun laboratory and data
evaluation work the possible result of which would be a revised Method
202 to be proposed in the Federal Register to include improvements
indicated by the evaluation.  At that same time, we could propose
CTM-040 to be used in combination with Method 202 for measuring direct
PM2.5 with additional guidance on appropriate approaches to testing for
direct PM2.5 emissions from various types of control measures (e.g.,
electrostatic precipitator and flue gas desulphurization combinations).

3. Role of condensable PM emissions in defining RACT

	Comment:  Commenters indicated that States must reassess and revise
emissions limits if the States adopt methods for measuring direct PM2.5
including condensable PM where not required previously.  Commenters
noted that most existing PM emissions limits are not reflective of data
collected with methods that measure condensable or filterable PM2.5 and,
therefore, not enforceable using a new or different test method.  

	Response:  We agree that coordinating the test method with the
pollutant defined by the emissions limit is critical to an effective
regulation.  In the case of direct PM2.5 regulations, the methods for
measuring filterable and condensable PM provide data significantly
different than do methods often used in implementing many current
regulations (i.e., filterable plus condensable PM2.5 versus filterable
PM only).  The existing PM emissions regulations implementing many
current SIPs have focused almost exclusively on filterable PM at stack
conditions or other elevated temperatures (e.g., 250°F) with little or
no measurement of condensable PM, let alone filterable PM2.5.  These
deficiencies exist in spite of the Agency’s policies and guidance
presented in documents such as the 1987 PM-10 SIP Development Guideline
and the General Preamble for the Implementation of Title 1 of the Clean
Air Act Amendments of 1990  issued in 1992.  These documents set forth
Agency policy stating that direct PM10 and direct PM2.5 emissions
include both filterable and condensable particulate matter.  The
policies are reinforced by a 2005 directive from the CAA Advisory
Committee.   

	More to the point, the use of test methods that quantify only
filterable PM would limit the capability of any assessment of control
measures available for developing cost effective strategies to achieve
attainment of the PM2.5 NAAQS.  Examples include an attainment
demonstration that includes control methodologies for PM precursors
which are likely to result in a significant decrease in the emissions of
direct PM2.5 (for example, alkaline scrubbers to reduce SO2 emissions)
and incorporate these direct PM2.5 emissions reductions in their
attainment demonstration or allow for the use of these reductions as
credits for other programs.

	Some States may decide to act to measure and control condensable PM
emissions prior to the end of the transition period.  To the extent that
a State has the supporting technical information and test methods, the
State may also assess the capabilities of current control technologies,
possible modifications to such technologies, or new technologies as
appropriate relative to control of condensable PM2.5 emissions in
developing effective control strategies and regulations.  As an example,
a specific approach for controlling condensable PM could be a change in
control device operating temperature to achieve necessary emissions
reductions.  We also note that it is important that implementation of
any new or revised rules and test methods should be prospective and
clearly differentiated from existing regulations to avoid confusion over
status of compliance relative to existing PM emissions limits.

4. Sufficiency of current baselines relative to direct PM2.5 for
regulatory development

	Comment:  Many commenters indicated that the currently available
baselines for direct PM2.5 emissions are not sufficient for States to
develop effective emissions control regulations.  One commenter claimed
that States will need additional information regarding how to arrive at
enforceable PM2.5 emissions limitations through application of
correlations to existing PM10 emissions limitations. 

	Response:  We agree that State inventories accounting for direct PM2.5
emissions are important to the NAAQS implementation decision-making
process.  For example, the current national emissions inventories have
characterized the contribution of the condensable PM emissions to range
from 40 to 80 percent of the direct PM2.5 emissions particularly from
combustion source categories.  We also agree in many cases, the
emissions baselines are not sufficiently representative of significant
direct PM2.5 contributors to allow States to develop effective and
enforceable emissions limitations for sources that may require control
of direct filterable or condensable PM2.5 emissions in order for States
to come into attainment with the PM2.5 NAAQS.

	We note that States are already required under the consolidated
emissions reporting rule (CERR) to report direct PM2.5 emissions,
including condensable PM, in each inventory revision.  That means that
inventories and associated baselines must address sources and
contributions of direct PM2.5 emissions, both filterable and condensable
PM, from individual sources and groups of sources as well as for future
year projected emissions.  These data are important for the purposes of
calculating emissions reductions and demonstrating that such reductions
are attributable to the control measures being implemented.  

	In taking the process to the next step, we contend that many current
baselines established using the available direct filterable and
condensable PM2.5 national industry average emissions factors (e.g.,
those found in AP-42 and WebFIRE,
http://www.epa.gov/ttn/chief/efpac/index.html) often are of quality
insufficient to establish effective source-specific emissions limits. 
First, national industry average emissions factors are subject to
significant uncertainties as they usually represent data from a very
limited number of example facilities in a category and for a very
limited number of operating conditions.  Second, the available emissions
factors databases may not include direct PM2.5 emissions data for
specific source types that appear in some State and local inventories.  

	In short, we believe that States should rely on directly measured
emissions data in developing source category or pollutant-specific
emissions limits for regulations.  This approach is preferable to the
use of these national industry average emissions factors such as those
found in AP-42.  If there are no directly measured emissions data
available from the subject sources, national average emissions factors
should be used only with appropriate and significant adjustments for
uncertainty.  Based on our initial study of the uncertainties associated
with national average emissions factors when applied to site-specific or
rule-development activities, we would expect multipliers of 0.1 to 3.3
for an A-rated national average filterable and condensable direct PM2.5
emissions factors.  The level of a particular multiplier would depend on
how representative of the source category the applicable emissions
factor is, the quantity of data supporting that emissions factor, and
the specific application.  Determining what adjustment may apply for a
particular application requires detailed knowledge of the emissions
control variability, the expected range of operational and process
variability, and the statistical uncertainty in the measured emissions
data.  While more general adjustment to emissions factors are possible
for these purposes, we believe that the better approach is to improve
and update the emissions factors used in the database for a particular
area with measured direct PM2.5 emissions data.  For these reasons and
to allow time for data collection and analysis, we have determined the
need for a period of transition for States in developing direct PM2.5
emissions reduction strategies.

5. Transition period

	Comment:  Some commenters suggested that EPA should allow States to
base their initial 2008 SIPs on NOx, SO2, and filterable PM or PM10 (as
a surrogate for filterable PM2.5) rather than require State and local
agencies to develop direct PM2.5 emissions regulations immediately. 
Commenters suggested that EPA provide a transition period for sources to
adopt SIPs that address direct PM2.5 and applying the appropriate test
methods.  The commenters proposed that during this transition period, a
source should be able to continue to use Method 5, Method 17, or
whatever method was used to set the underlying limit then contained in
the source’s title V operating permit.  Commenters believe that such a
transition plan must provide additional time to collect data related to
condensable PM emissions.  Commenters believe that this additional time
is necessary because it is unrealistic to develop SIP revisions
addressing condensable emissions by April 2008.  Other commenters
suggested that source emissions inventories used for regulatory
decision-making and identifying regulatory control measures must be
based on accurate measurements.

	Response:  As outlined above, we agree that a transition period will be
allowed to allow time to resolve and adopt appropriate testing
procedures for condensable PM emissions, to collect total (filterable
and condensable) PM2.5 emissions data that are more representative of
the sources in their areas, and develop effective regulations for
control of direct PM2.5, including condensable PM.

6.  Data collection for regulatory development  

	Comment:  Several commenters recommended that EPA should be responsible
for developing data of emissions from common sources of direct PM2.5.  

	Response:  We disagree with the commenters’ recommendation that EPA
should be primarily or solely responsible for developing baseline data
on common sources of direct PM2.5 emissions.  Commenters are suggesting
that we should collect data representative of direct PM2.5 emissions
from source categories potentially subject to regulation of direct PM2.5
emissions.  Furthermore, they suggest that we expand or improve the
current compilation of national industry average emissions factors such
as found in AP-42 and WebFIRE
(http://www.epa.gov/ttn/chief/efpac/index.html).  Given the limited
extent to which national industry average emissions factors are suitable
for developing State or local regulations that set limits on direct
PM2.5 emissions, we believe that it is inherent that States instead have
primary responsibility for reviewing and applying measured emissions
data collected from their sources in enhancing their current baselines. 
In some cases, this will mean that States and other stakeholders will
need to conduct more focused direct PM2.5 emissions data collection and
improve relevant emissions factors.

	This approach is appropriate for several reasons.   First, we believe
that stakeholders other than EPA are better equipped to identify
specific data needs and that they have the means to collect the data. 
Second, we believe we are better positioned to provide guidance on test
planning, data collection, and emissions factors calculations with a
less direct role in data collection and evaluation.  Third, we believe
that States in need of additional information can also benefit from
experience of other States with similar source types and who are
developing regulations to implement the NAAQS including the control of
condensable PM.   See also the discussion in section II.L.2.c.1 above on
the currently active collaborative study to assess direct PM2.5
emissions measurement technologies and to collect updated direct PM2.5
emissions data.

7.  Developing effective regulations for direct PM2.5, including
condensable PM, emissions.

	Most current PM regulations focus on the control and measurement of
filterable PM emissions and do not account for condensable PM emissions.
 At issue are assessing and accounting for the differences in
methodology and applicable limits when changing to a program designed to
achieve reductions in PM2.5 emissions, including condensable PM. 

	Comment:  A number of respondents commented that EPA needs to
promulgate a PM2.5 test method and adopt regulatory language that
determines the PM2.5 limits based on that promulgated PM2.5 test method
as soon as possible.  Other commenters suggested that EPA and States
have no choice but to revise the underlying standard by adopting new
monitoring requirements through a notice and comment rulemaking. 
Further, these commenters indicate that it is essential that EPA require
that no change in a test method or in methods of monitoring for
determining compliance until such time as EPA or the permitting agency
have undertaken a notice and comment process to determine how the
emissions limitations must be revised.  A number of commenters cited
specific components necessary for effective regulations.

	Response:  We agree that notice and comment rulemaking is appropriate
for establishing effective regulations.  As noted above, we are already
undertaking a study of the available test methods to determine the need
for regulatory revisions.  We also agree that new regulations limiting
direct PM2.5 emissions must include effective emissions limitations to
the extent that a State must reduce sources of direct PM2.5.  How a
State determines to take such regulatory action depends on the State’s
implementation plan.  Regarding the specific components necessary for
effective regulations, see section O below on enforcement and compliance
issues.  

M.	Improving source monitoring 

a. Background.  

	In the November 1, 2005 proposal, we discussed a number of actions the
EPA would undertake to improve the effectiveness of existing and new
regulations with improved source monitoring provisions.  Specifically,
we repeated a plan outlined on January 22, 2004 (69 FR 3202; a Federal
Register notice describing requirements for monitoring in operating
permits), that includes a four-part strategy for improving monitoring of
emissions at the source where necessary through rulemaking.  One element
of that plan is for EPA to develop guidance on how States can reduce
PM2.5 emissions by improving source monitoring related to PM2.5
emissions limits.  We noted that we expect to describe in such guidance
methods of improving monitoring frequency or adopting more appropriate
monitoring for States to consider in developing their PM2.5 SIPs and to
illustrate the amount of credit that States could receive in PM2.5 SIPs
for adopting such improved monitoring.  We suggested that States with
areas where additional reductions are needed to help the area achieve
compliance with the NAAQS could implement improved monitoring measures
to obtain additional emissions reductions.  We put forward that State
agencies could receive SIP credits as a result of enforceable improved
monitoring or voluntary programs meeting EPA voluntary program policies.

	Specific examples of improved monitoring we outlined included: 1)
conducting the currently required monitoring more frequently (i.e.,
increased monitoring frequency), 2) changing the monitoring technique to
a parameter more closely related to control of direct or precursor PM2.5
emissions (i.e., a correlated parametric monitoring technique), 3)
changing the technique to more measurement of direct PM2.5 emissions and
PM2.5 precursors, or 4) a combination of these improvements.  These
types of monitoring improvements could be conducted for both controlled
and uncontrolled emissions units. The improved monitoring control
measure would require facilities to pay more attention to the operation
of add-on air pollution control devices, work practices, and other
process activities.  The additional attention will reduce periods during
which control devices and other control measures do not operate as
intended or required.  The result would be increased emissions
reductions from implementing existing and new rules

	We discussed a range of currently applied and new monitoring
technologies.  We addressed concerns we have about the limitations of
the widespread use of visual emissions (VE) monitoring techniques, such
as visible emissions checks, to show compliance with PM emissions
limits.  We noted particular concerns about VE approaches, even with
frequent application, having the ability to verify compliance when the
margin of compliance is minimal or the ability to detect relatively
significant changes in emissions control performance.  The other concern
we noted about the use of VE tools is the limited frequency at which
they are conducted.  We cited studies on the availability of continuous
instrumental methods for monitoring opacity and operational parameters
closely related to PM control levels including the development of
repeatable correlations between parameter levels and PM emissions.  We
noted that PM continuous emissions monitoring systems (PM CEMS)
technology provides the opportunity to quantify PM emissions levels
(concentration or emissions rates).  These additional data provide the
source owner/operator with a level of information that can be useful for
understanding and operating the process and the control measures in ways
to minimize emissions, improve operating efficiencies, and reduce
enforcement liabilities.  Furthermore, we noted that this technology
will provide the State with quantitative information on PM emissions
which will help improve the inventories and to implement effective
control strategies to meet the NAAQS.

	We also discussed at some length what we believe constitutes improved
monitoring and the potential for monitoring-related emissions
reductions.  We discussed a study of how these emissions reductions
would be achieved by increasing the monitoring frequency or improving
the monitoring of an add-on air pollution control device or other
process activity above the level currently required in existing rules. 
The increased frequency or improved technique would allow owners or
operators to achieve greater emissions reductions by identifying and
responding more quickly to periods of ineffective control measure
operation.  States could use an improved monitoring control measure in
regulations or through other means to reduce emissions levels and
receive credits towards attainment.  Specifically, we cited materials
that indicate that source owners and operators who increase monitoring
frequency could achieve emissions reductions up to 13 percent and those
who improve the monitoring technique could achieve emissions reductions
up to 15 percent.  States with nonattainment areas in need of additional
reductions to achieve compliance with the NAAQS could implement an
improved monitoring measure and develop additional emissions reductions
credits.  We outlined several specific examples.

	In order to inform our improved monitoring guidance development
efforts, we used the 2005 proposal to solicit specific comments on 1)
how potentially inadequate source monitoring in certain SIPs could be
improved; 2) how improved PM2.5 monitoring relates to title V
monitoring; 3) whether instrumental techniques are more appropriate than
visual emissions (VE) techniques for monitoring compliance with PM
emissions limits; and 4) a basis for determining whether improved
monitoring would be effective and under what conditions should be
required.  We also requested comment on the feasibility of monitoring of
co-pollutant control measures and requested examples of improved
monitoring for any applications.

b. Final rule.  

	We maintain that improved monitoring is critical to implementing the
PM2.5 direct and precursor emissions reductions programs.  We also
believe that improving monitoring both in terms of increasing data
collection and analysis frequency and in measuring the pollutant of
interest more directly will accomplish several important and
advantageous outcomes.  First, improved monitoring will improve
verification of compliance and assurance of the intended emissions
reductions.  Second, improved monitoring can provide additional
emissions reductions through quicker detection and correction of control
measure problems.  Third, improved monitoring can improve operating
efficiencies that often result in cost savings to the facility exceeding
the cost of the monitoring.  We will continue to evaluate the effects of
improved monitoring on emissions reductions and ways to quantify the
benefits associated with improved monitoring.

	We intend to move forward with developing and providing additional
technical and informational materials regarding technologies
constituting improved monitoring and for developing regulations with
improved monitoring.  These materials may also include guidance and
tools for establishing emissions reductions credits and the economic
benefits associated with improved monitoring.  As noted in section L
above, we also reaffirm our policy that effective regulations must
include certain elements that define applicable emissions limitations,
the testing and monitoring requirements, and compliance, reporting, and
corrective action obligations.  

c. Comments and Responsesresponses.

	We expected to receive practical advice concerning improved PM2.5
source emissions monitoring methods and field-tested examples.  Instead,
commenters focused on 1) critiquing PM CEMS technology 2) insisting that
improving monitoring changes stringency of existing rules and requires
rulemaking, and 3) critiquing the theoretical study linking emissions
reductions with improved monitoring.  

1. Currently available PM CEMS for monitoring direct PM2.5 emissions

	Comment:  Commenters noted that because currently available PM CEMS
measure filterable PM at stack conditions or at other elevated
temperatures, the instruments do not measure the condensable portion of
PM2.5.  

	Response:  We agree with this comment relative to PM CEMS in use to
date and the ability to detect condensable PM.  PM CEMS as applied today
can be calibrated to measure filterable PM2.5 emissions with very good
sensitivity and repeatability.  Note that we are aware of a number of PM
CEMS vendors developing devices relying on much the same technology but
modified to measure condensable PM.  Further, we are aware of at least
one manufacturer offering a source PM CEMS that also complies with ASTM
requirements for mobile source emissions monitoring.  We also believe
that monitoring for filterable PM2.5 will be as important in some cases
as monitoring for condensable PM and that PM CEMS in use today are
markedly better at monitoring PM emissions than other frequently used
monitoring approaches.

	We realize that PM CEMS represent just one of a range of monitoring
options that constitute improvements over the current monitoring.  For
instance, we believe that improved monitoring would include replacing
current periodic VE measurements or daily recording of pressure drop of
fabric filters with continuous bag leak detectors.  We know of projects
(e.g., ASTM committee work) for continuing the development of optical,
as well as electromagnetic, monitoring tools to increase sensitivity and
cost-effectiveness.  Such monitoring would increase monitoring frequency
and would yield data much more closely related to and more sensitive to
control device operation than most currently applied monitoring.  To the
extent that condensable PM control is critical in implementing a
regulation, we believe that monitoring must address that need.  We will
continue to collect and also provide information on source monitoring
approaches that are improvements over current methods in both frequency
and representativeness relative to implementing PM2.5 emissions control
strategies.

2. Status of guidance relative to regulations

	Comment:  A significant majority of commenters suggested that improving
monitoring in an existing regulation increases its stringency and
requires notice and comment rulemaking, not guidance.  Just one
commenter suggested guidance could be developed and used.

	Response:  There are two aspects to the comments on this issue.  One is
whether improved monitoring would change source operations.  We agree
with the commenters that increasing the frequency of data collection or
providing data more directly related to the pollutant of concern with
improved monitoring could result in changes in how a facility is
operated relative to compliance.  We disagree with commenters that such
changes in process operation resulting from improved monitoring
constitute an increase in a regulation’s stringency with respect to
compliance.  First, as mentioned in the preamble to the Credible
Evidence rule (62 FR 8326, February 24, 1997), an emissions standard’s
required stringency is unaffected by the frequency of monitoring given
no decrease in averaging time or emissions limitation.  Secondly, data
from improved monitoring will provide a facility operator better
information on control measure performance more quickly and allow for
reducing the duration and the number of periods that may lead to
compliance problems.  Reducing the duration of excess emissions periods,
for example, with improved monitoring is not an increase in regulatory
stringency but a decrease in enforcement liability.  

	The second aspect to the comment is questioning whether we can issue
technical information about improved monitoring as guidance without
applying it to a Federal Register notice and comment process.  We
disagree with commenters who believe that our developing and
disseminating technical resource information is limited to notice and
comment rulemaking.  We note that making technical and other information
materials available to the public, states, and industry is an important
Agency function.  There are many examples of the Agency dispensing such
information including the Monitoring Knowledge Base (  HYPERLINK
"http://cfpub.epa.gov/mkb/"  http://cfpub.epa.gov/mkb/ ) that provides
just such information on improved monitoring.  On the other hand, we
agree with commenters that any significant change to an existing
regulation, including the addition of new monitoring requirements, would
be subject to notice and comment rulemaking.  To the extent that States
determine the need for changing existing or developing new regulations,
public notice and comment rulemaking is appropriate.   Our role in
developing technical resources and information informing the states in
developing those revised or new regulations does not require, nor should
be subject to the rulemaking process.  In that light, we recognize the
value in obtaining and responding to public comments and suggestions on
informative technical materials.  	Further, we believe rulemaking is not
necessarily required for source owners or operators who volunteer to
participate in an optional improved monitoring program, such as the one
mentioned in the proposal.  That program seeks to provide SIP credits to
source owners or operators who agree to improve their PM monitoring
approaches.  We plan on continuing to prepare and offer non-regulatory
incentives for source owners and operators who volunteer to improve
existing monitoring.  

3. Study of improved monitoring- induced emissions reductions

	Comment:  Commenters recommended that the proposal’s theoretical
study showing PM emissions reductions from the use of improved
monitoring needs to be validated with field data.  

	Response:  We agree with commenters that one should base any costs and
benefits findings as well as validating the approach on available data. 
To the extent that this applies to assessing the benefits of emissions
reductions achieved through improved monitoring, we requested that
commenters provide data or leads to other information or to other
alternatives that show how improved monitoring yields emissions
reductions and ways to quantify possible PM credits for SIPs.  In fact,
we are disappointed that commenters failed to provide these data or
examples of other approaches.  As resources allow, we will investigate
opportunities for field validation of the theoretical study, as well as
other means to offer incentives for use of improved monitoring.	

N.	Guidance Specific to Tribes

a. Background.  

	The proposal set forth guidance for Tribes regarding various aspects of
air quality management, and this uidance remains largely the same as
described in the section below. 

b. Final rule.  

	The 1998 Tribal Authority Rule (TAR) (40 CFR part 49), which implements
section 301(d) of the CAA, gives Tribes the option of developing tribal
implementation plans (TIPs).  Specifically, the TAR provides for the
Tribes to be treated in the same manner as a State in implementing
sections of the CAA.  However, Tribes are not required to develop
implementation plans.  The EPA determined in the TAR that it was
inappropriate to treat Tribes in a manner similar to a State with regard
to specific plan submittal and implementation deadlines for
NAAQS-related requirements, including, but not limited to, such
deadlines in CAA sections 110(a)(1), 172(a)(2), 182, 187, and 191. (Add
footnote)  See 40 CFR Part 49.4(a). In addition, EPA determined it was
not appropriate to treat tribes similarly to states with respect to
provisions of the CAA requiring as a condition of program approval the
demonstration of criminal enforcement authority or providing for the
delegation of such criminal enforcement authority.  See 40 CFR Part
49.4(g).  To the extent a tribe is precluded from asserting criminal
enforcement authority, the federal government will exercise primary
criminal enforcement responsibility.  See 40 CFR Part 49.8.  In such
circumstances, tribes seeking approval for CAA programs provide
potential investigative leads to an appropriate federal enforcement
agency. (end footnote)

If a Tribe elects to do a TIP, we will work with the Tribe to develop an
appropriate schedule which meets the needs of the Tribe, and which does
not interfere with the attainment of the NAAQS in other jurisdictions. 
The Tribe developing a TIP can work with the EPA Regional Office on the
appropriateness of addressing RFP and other substantive SIP requirements
that may or may not be appropriate for the Tribe’s situation.

The TAR indicates that EPA is ultimately responsible for implementing
CAA programs in Indian country, as necessary and appropriate, if Tribes
choose not to implement those provisions.  For example, an unhealthy air
quality situation in Indian country may require EPA to develop a FIP to
reduce emissions from sources on the reservation.  In such a situation,
EPA, in consultation with the Tribe and in consideration of their needs,
would work to ensure that the NAAQS are met as expeditiously as
practicable.  Likewise, if we determine that sources in Indian country
could interfere with a larger nonattainment area meeting the NAAQS by
its attainment date, we would develop a FIP for those sources in
consultation with the Tribe, as necessary or appropriate.

The TAR also provides flexibility for the Tribe in the preparation of a
TIP to address the NAAQS.  If a Tribe elects to develop a TIP, the TAR
offers flexibility to Tribes to identify and implement on a
Tribe-by-Tribe, case-by-case basis only those CAA programs or program
elements needed to address their specific air quality problems.  In the
proposed Tribal rule, we described this flexible implementation approach
as a modular approach.  Each Tribe may evaluate the particular
activities, including potential sources of air pollution within the
exterior boundaries of its reservation (or within non-reservation areas
for which it has demonstrated jurisdiction), which cause or contribute
to its air pollution problem.  A Tribe may adopt measures for
controlling those sources of PM2.5-related emissions, as long as the
elements of the TIP are reasonably severable from the package of
elements that can be included in a whole TIP.  A TIP must include
regulations designed to solve specific air quality problems for which
the Tribe is seeking EPA approval, as well as a demonstration that the
Tribal air agency has the authority from the Tribal government to
develop and run their program, the capability to enforce their rules,
and the resources to implement the program they adopt.  In addition, the
Tribe must receive an eligibility determination from EPA to be treated
in the same manner as a State and to receive authorization from EPA to
run a CAA program.

 EPA would review and approve, where appropriate, these partial TIPs as
one step of an overall air quality plan to attain the NAAQS.  A Tribe
may step in later to add other elements to the plan, or EPA may step in
to fill gaps in the air quality plan as necessary or appropriate.  In
approving a TIP, we would evaluate whether the plan interferes with the
overall air quality plan for an area when Tribal lands are part of a
multi-jurisdictional area.

Because many of the nonattainment areas will include multiple
jurisdictions, and in some cases both Tribal and

State jurisdictions, it is important for the Tribes and the States to
work together to coordinate their planning efforts.  States need to
incorporate Tribal emissions in their base emission inventories if
Indian country is part of an attainment or nonattainment area.  Tribes
and States need to coordinate their planning activities as appropriate
to ensure that neither is adversely affecting attainment of the NAAQS in
the area as a whole.

c.	Comments and Responses

	No public comments were received on this section.

O.	Requirements related to enforcementEnforcement and compliance

a.  Background.

	The proposed rule included a discussion of the specific requirements
that must be addressed in order for SIP regulations to be enforceable.  

b.  Final Rule.

	The final rule includes similar guidance on enforceable SIP
regulations, with some additional discussion about specific elements
that must be addressed regarding compliance testing and compliance
monitoring.  

	In general, for a SIP regulation to be enforceable, it must clearly
spell out which sources or source types are subject to its requirements
and what its requirements (e.g., emission limits, work practices, etc.)
are.  The regulation also needs to specify the time frames within which
these requirements must be met, and must definitively state
recordkeeping and monitoring requirements appropriate to the type of
sources being regulated.  The recordkeeping and monitoring requirements
must be sufficient to enable the State or EPA to determine whether the
source is complying with the emission limit on a continuous basis.  An
enforceable regulation must also contain test procedures in order to
determine whether sources are in compliance.

Under the Title V regulations, major sources have an obligation to
include in their Title V permit applications all emissions for which the
source is major and all emissions of regulated air pollutants.  The
definition of regulated air pollutant in 40 CFR ( 70.2 includes any
pollutant for which a NAAQS has been promulgated, which would include
both PM10 and PM2.5.  To date, some permitted entities have been using
PM10 emissions as a surrogate for PM2.5 emissions.  Upon promulgation of
this rule, EPA will no longer accept the use of PM10 as a surrogate for
PM2.5.  Thus, sources will be required to include their PM2.5 emissions
in their Title V permit applications, in any corrections or supplements
to these applications, and in applications submitted upon modification
and renewal.119  Sources must continue to identify their PM10 emissions
in their applications as described above because the original PM10 NAAQS
remains in effect.

	We reaffirm our policy as stated in White Paper Number 2 for Improved
Implementation of the Part 70 Operating Permits Program that effective
Complete and effective regulations that ensure compliance with an
applicable emissions limit must include requirements for both
performance testing of emissions and ongoing monitoring of the
compliance performance of control measures.  SIP regulations must
include certain elements that define applicable emissions limitations,
the testing and monitoring requirements, and compliance, reporting, and
corrective action obligations.  This policy applies particularly to
developing new regulations implementing limits on direct PM2.5 emissions
and the increased potential to reduce condensable PM emissions using
methods that heretofore may not have been applied.  The policy also
reflects the increased understanding of the need for clarity in defining
and demonstrating compliance with applicable requirements that has come
with the issuance of operating permits.

	Complete and effective regulations that ensure compliance with an
applicable emissions limit must include requirements for both
performance testing of emissions and ongoing monitoring of the
compliance performance of control measures.  We strongly suggest that
regulations include the following critical elements of regulatory
compliance testing provisions:

Indicator(s) of compliance - the pollutant or pollutants of interest
(e.g., filterable PM2.5 plus condensable PM2.5) and the applicable
measurable units for expressing compliance (e.g., ng/J of heat input,
lb/hr); 

Test method - reference to a specific EPA or other published set of
sample collection and analytical procedures, equipment design and
performance criteria, and the calculations providing data in units of
the indicator of compliance (see section II.P.4 below for descriptions
of available and potential improved test methods); 

Averaging time - the minimum length of each required test run and the
requirement to average the results of the test runs (e.g., three runs)
representing a specified period of time (e.g., 8 hours); and 

Frequency - the maximum time between conduct of emissions or performance
tests (e.g., within 30 days of facility start-up and once each
successive quarter, every 6-month period, year, permit termly).  

	In order to be complete with regard to compliance monitoring
provisions, we strongly suggest thatSIP regulations must include the
following critical elements:

  SEQ CHAPTER \h \r 1 Indicator(s) of performance - the parameter or
parameters measured or observed for demonstrating proper operation of
the pollution control measures or compliance with the applicable
emissions limitation or standard.  Indicators of performance may include
direct or predicted emissions measurements, process or control device
(and capture system) operational parametric values that correspond to
compliance with efficiency or emissions limits, and recorded findings of
verification of work practice activities, raw material or fuels
pollutant content, or design characteristics.  Indicators may be
expressed as a single maximum or minimum value, a function of process
variables (e.g., within a range of pressure drops), a particular
operational or work practice status (e.g., a damper position, completion
of a waste recovery task), raw material or fuel pollutant content, or an
interdependency between two or more variables;

Measurement technique - the means used to gather and record information
of or about the indicators of performance.  The components of the
measurement technique include the detector type or analytical method,
location and installation specifications, inspection procedures, and
quality assurance and quality control measures.  Examples of measurement
approaches include continuous emissions monitoring systems, continuous
opacity monitoring systems, continuous parametric monitoring systems,
performance testing, vendor or laboratory analytical data, and manual
inspections and data collection that include making records of process
conditions, raw materials or fuel specifications, or work practices;

Monitoring frequency - the number of times to obtain and record
monitoring data over a specified time interval.  Examples of monitoring
frequencies include at least one data value every 15 minutes for
continuous emissions or parametric monitoring systems, at least every 10
seconds for continuous opacity monitoring systems, upon receipt or
application of raw materials or fuel to the process, and at least once
per operating day (or week, month, etc.) for performance testing, work
practice verification, or equipment design inspections; and 

Averaging time - the period over which to average and use data to verify
compliance with the emissions limitation or standard or proper operation
of the pollution control measure.  Examples of averaging time include a
3-hour average in units of the emissions limitation, a 30-day rolling
average emissions value, a daily average of a control device operational
parametric range, periodic (e.g., monthly, annual) average of raw
materials or fuel pollutant content, and an instantaneous alarm.

These regulatory elements are essential for effective implementation of
the rules and clear and enforceable applicable requirements.  We believe
that approval of regulations implementing the SIPs must ensure that
these critical elements are present and clearly defined to be
approvable.  We reiterate that the compliance obligations, including
emissions limits and other applicable requirements, must be
representative of and accountable to the assumptions used in the SIP
demonstration.  This accountability includes the ability to transfer the
applicable regulatory requirements to an operating permit subject to EPA
and public review and interpretation.. 

Under the Title V regulations, sources have an obligation to include in
their Title V permit applications all emissions for which the source is
major and all emissions of regulated air pollutants.  The definition of
regulated air pollutant in 40 CFR 70.2 includes any pollutant for which
a NAAQS has been promulgated, which would include both PM10 and PM2.5. 
To date, some permitted entities have been using PM10 emissions as a
surrogate for PM2.5 emissions.  Upon promulgation of this rule, EPA will
no longer accept the use of PM10 as a surrogate for PM2.5.  Thus,
sources will be required to include their PM2.5 emissions in their Title
V permit applications, in any corrections or supplements to these
applications, and in applications submitted upon modification and
renewal.  The degree of quantification of PM2.5 emissions required will
depend on the types of determinations that a permitting authority needs
to address for a particular source, the requirements of title V, and the
informational needs and requirements of the particular State in
question.  Sources must continue to describe their PM10 emissions in
their applications as indicated above because the original PM10 NAAQS
remains in effect.

c.	Comments and Responses

	Comment:  One commenter disagreed with language in the preamble to the
proposal regarding Title V permitting requirements.  The proposal stated
that a Title V source needs to  and the requirement to include various
emissions information in its permit application emissions for PM2title V
permit applications.  As described in 40 CFR 70.5(c)(3)(i) and
71.5(c)(3)(i), sources are required to include in their permit
applications all otheremissions for which the source is major and all
emissions of regulated air pollutants.  To date,In the preamble to the
proposal, the EPA stated that in the past some permitted entities have
been using PM10 emissions as a surrogate for PM2.5 emissions (in permit
applications, corrections, modification applications, and permit renewal
applications).  , or in corrections or supplements to applications.  The
EPA stated that upon promulgation of today’s rule, the EPA will no
longer accept the use of PM10 as a surrogate for PM2.5.   

	The commenter disagreed with language in the proposal stating that
after this clean air fine particle implementation rule is finalized, EPA
would not accept use of PM10 as a surrogate for PM2.5, and sources would
be required to detail or quantify PM2.5 emissions in future permit
applications, or in corrections or supplements to these applications,
and applications submitted for modifications or renewal.  The commenter
asserts that the inclusion of PM2.5 emissions information is required in
a Title V permit application only if there is an applicable requirement
in existence for which the source’s applicability is in question.  The
commenter believes that the source would have no obligation to quantify
PM2.5 emissions for corrections or supplements as well. and cited to
various examples from the memorandum entitled “White Paper for
Streamlined Development of Part 70 Permit Applications,” from Lydia N.
Wegman, Deputy Director, Office of Air Quality Planning and Standards,
to Air Division Directors, Regions I-X, dated July 10, 1995.  

	Response:  As stated in the proposed preamble, under the Title V
permitting regulations in 40 CFR parts 70 and 71, major sources have an
obligation to include in their Title V permit applications all emissions
for which the source is major and all emissions of regulated air
pollutants.  See 40 CFR 70.5(c)(3)(i) and 71.5(c)(3)(i).  The definition
of regulated air pollutant in 40 CFR 70.2 and 71.2 includes any
pollutant for which a NAAQS has been promulgated, which would include
both PM10 and PM2.5.  

	EPA disagrees with the commenter that the inclusion of PM2.5 emissions
information is required in a Title V permit application only if there is
an applicable requirement in existence for which the source’s
applicability is in question.  Although an applicable requirement can
trigger the need for a source to apply for a Title V permit, it is one
of only a number of the applicability criteria discussed in 40 CFR 70.3
and 71.3.  Applicability of the Title V permitting program and
applicability of a standard are two different issues and it is the
former that is the subject of this response. 

	As a result, EPA reaffirms the statements made in the preamble to the
proposed rule regarding regulated air pollutants, title V permitting,
and the fact that EPA will no longer accept the use of PM10 as a
surrogate for PM2.5 in title V applications upon promulgation of this
rule.  Thus, upon promulgation of this rule, sources will be required to
include their PM2.5 emissions, in addition to their PM10 emissions, in
their Title V permit applications, in any corrections or supplements to
these applications, and in applications submitted upon modification or
renewal.	Response:  The commenter is concerned that as a result of this
rule all applications (including initial, modification, and renewal
applications) will need to include a quantification of PM2.5 emissions,
and that a State will request that every source supplement or correct
any existing title V application in order to provide an estimation of
PM2.5 emissions at the source.  

	The EPA is not implying that this is the case.  The degree of
quantification of PM2.5 emissions required in an application (including
an initial, modification, or renewal application), or in a correction or
supplement to an existing application, depends on the types of
determinations that a permitting authority needs to address for a
particular source, the requirements of title V, and the informational
needs and requirements of the particular State in question.  For
example, if a source which emits PM2.5 emissions has submitted a title V
application, but a draft permit has not yet been issued, then the source
is required to submit information relative to the quantification of its
PM2.5 emissions if such information is needed or requested and it has
not previously submitted such information.  See 40 CFR 70.5(b) and
70.7(a)(1)(i); 40 CFR 71.5(b)).  

	Circumstances necessitating the quantification of PM2.5 emissions and
71.7(a)the submittal of this information include: (1)(i).  For more
background information on regulated air ) determining all of the
pollutants, see for which a source is major; (2) determining whether an
EPA memo entitled “Definition of Regulated Air Pollutant for Purposes
of Title V,” from Lydia N. Wegman, Deputy Director, Office of Air
Quality Planning and Standards, to Air Division Directors, Regions I-X,
dated April 26, 1993).applicable requirement or program applies, e.g.,
determining the applicability of a SIP requirement or a PSD or
nonattainment NSR program, etc.; or (3) determining what fees a source
owes a permitting authority as a result of considering PM2.5 emissions. 

In all circumstances, however, a State may require that a source
quantify its PM2.5 emissions information in an application, supplement,
or correction, even if it not needed for the particular determination at
issue.  The State, for example, may choose to obtain this information
for air quality planning purposes, developing emission inventories, or
for other purposes related to its air quality management goals. 
Requesting such emissions information is an option for any title V
permitting authority.  

The “White Paper for Streamlined Development of Part 70 Permit
Applications,” referenced by the commenter, was a confirmation of EPA
policy with respect to the fact that the specificity of emissions
quantification can vary significantly, depending on the circumstances of
a particular source.  It is also important to note that this guidance
document is a statement regarding the range of discretion available to
permitting authorities in implementing the emissions quantification
requirement, not a restriction of that discretion to minimum practices. 
Thus, States can implement this guidance document at their option,
either in part or in its entirety.  

	In summary, the purpose of the statements made in the preamble to the
proposal was to notify sources that as of the promulgation of today’s
final rule, the EPA will no longer accept the use of PM10 emissions
information as a surrogate for PM2.5 emissions information given that
both pollutants are regulated by a National Ambient Air Quality Standard
and therefore are considered regulated air pollutants.  See the
definition of regulated air pollutant in 40 CFR 70.2 and 71.2.  The
degree of quantification of PM2.5 emissions now required in an
application (including an initial, modification, or renewal
application), or provided in a correction or supplement to an existing
application, will depend on the types of determinations that a
permitting authority needs to address for a particular source, the
requirements of title V, and the informational needs and requirements of
the particular State in question.  

P.	Emergency episode requirementsepisodes

a. 	Background.

In the proposal, we noted that subpart H of 40 CFR part 51 specifies
requirements for SIPs to address emergency air pollution episodes and
for preventing air pollutant levels from reaching levels determined to
cause significant harm to the health of persons.  We noted that we
anticipate proposing a separate rulemaking in the future to update
portions of that rule.

The preamble to the proposal 

b.  	Final Rule.

	We have not yet proposed any rule revision related to emergency
episodes.

c.	Comments and Responses.

	We received no comments on this aspectsection of the proposal.

Q.	Ambient monitoring requirements

a. 	Background.

	Ambient air quality monitoring for PM2.5 plays an important role in
identifying areas violating the NAAQS, control strategy development, and
tracking progress to attainment.  We indicated in the proposal that
States are required to monitor PM2.5 mass concentrations using Federal
Reference Method devices to determine compliance with the NAAQS.120  We
did not propose any revisions to current ambient monitoring requirements
listed in 40 CFR part 58.  

Currently, there are more than 1200 FRM monitors located across the
country.  States will need to maintain monitors in designated
nonattainment areas in order to track progress toward attainment and
ultimately determine whether the area has attained the PM2.5 standards.

In addition to the FRM network, EPA and the States have also deployed
more than 250 speciation monitoring sites around the country to sample
for chemical composition of PM2.5.  The data provided from these
speciation monitors are invaluable in identifying contributing source
categories and developing control strategies to reach attainment. 
Source apportionment and other receptor modeling techniques rely on the
detailed data on species, ions, and other compounds obtained from
chemical analysis.  Analyses of rural versus urban sites to identify
which PM2.5 components comprise the (urban excess( (urban minus rural
levels) portion of PM2.5 mass also rely on data from speciation
monitors.  The EPA encourages states to expand their data analysis
efforts using the wealth of information provided from the speciation
monitoring network.

b.  	Final Rule.

	There is no change from the proposal.  We are not promulgating any
additional monitoring requirements as part of this rulemaking.  A review
of the PM NAAQS will be issued in September 2006 and is expected to
include certain amendments to the PM monitoring requirements originally
established in 1997.  

c.	Comments and Responses.

	There were no comments on this section.  

III.  STATUTORY AND EXECUTIVE ORDER REVIEWS

A.	Executive Order 12866:  Regulatory Planning and Review tc \l2
"Executive Order 12866: Regulatory Planning and Review 

	  SEQ CHAPTER \h \r 1 Under Executive Order (EO) 12866 (58 FR 51735,
October 4, 1993), this action is a “significant regulatory
action.”” because it raises novel legal or policy issues arising out
of legal mandates, the President’s priorities, or the principles set
forth in the EO.  Accordingly, EPA submitted this action to the Office
of Management and Budget (OMB) for review under EO 12866 and any changes
made in response to OMB suggestions or recommendations had have been
documented in the docket for this action.

  SEQ CHAPTER \h \r 1 In addition, EPA is preparing an analysis of the
potential costs and benefits associated with this attaining the 1997
PM2.5 NAAQS.  A copy of the analysis is available in the docket for this
action and the analysis is briefly summarized here. [Add reference to PM
NAAQS Regulatory Impact Analysis; insert title of document and reference
number, if applicable]. 

B.	Paperwork Reduction Act tc \l2 "Paperwork Reduction Act 

	The information collection requirements in this rule will 

be submitted for approval to the Office of Management and

Budget (OMB) under the Paperwork Reduction Act, 44 U.S.C. 

3501 et seq.  The information collection requirements are 

not enforceable until OMB approves them other than to the extent
required by statute..  This action does

	not add any new requirements involving the collection of 

information as defined by the Paperwork Reduction Act, 44 

U.S.C. 3501 et seq. 

This rule provides the framework for the States to develop SIPs to
achieve a new or revised NAAQS.  This framework reflects the
requirements prescribed in CAA sections 110 and part D, subpart 1 of
title I.  In that sense, the present final rule does not establish any
new information collection burden on States.  Had this rule not been
developed, States would still have the legal obligation under law to
submit nonattainment area SIPs under part D of title I of the CAA within
specified periods after their nonattainment designation for the PM2.5
standards, and the SIPs would have to meet the requirements of part D.  

	A SIP contains rules and other requirements designed to achieve the
NAAQS by the deadlines established under the CAA, and it also contains a
demonstration that the State(s requirements will in fact result in
attainment.  The SIP must meet the CAA requirements in subpart 1 to
adopt RACM, RACT, and provide for RFP toward attainment for the period
prior to the area(s attainment date.  After a State submits a SIP, the
CAA requires EPA to approve or disapprove the SIP.  If EPA approves the
SIP, the rules in the SIP become Federally enforceable.  If EPA
disapproves the SIP (or if EPA finds that a State fails to submit a
SIP), the CAA requires EPA to impose sanctions (2:1 offsets for major
new or modified sources and restrictions on Federal highway funding)
within specified timeframes; additionally, EPA must prepare and publish
a FIP within 2 years after a disapproval or finding of failure to
submit.  The SIP must be publicly available.  States must maintain
confidentiality of confidential business information, however, if used
to support SIP analyses.  The SIP is a one-time submission, although the
CAA requires States to revise their SIPs if EPA requests a revision upon
a finding that the SIP is inadequate to attain or maintain the NAAQS. 
The State may revise its SIP voluntarily as needed, but in doing so must
demonstrate that any revision will not interfere with attainment or RFP
or any other applicable requirement under the CAA (see section 110(l)).

	This rule does not establish requirements that directly affect the
general public and the public and private sectors, but, rather,
interprets the statutory requirements that apply to States in preparing
their SIPs.  The SIPs themselves will likely establish requirements that
directly affect the general public, and the public and private sectors.

	The EPA has not yet projected cost and hour burden for the statutory
SIP development obligation but has started that effort and will shortly
prepare an Information Collection Request (ICR) request.  However, EPA
did estimate administrative costs atAt the time of promulgation of the
PM2.5 standards in 1997, EPA estimated administrative costs associated
with implementing the standards.  See Chapter 10 of U.S. EPA 1997,
Regulatory Impact Analyses for the Particulate Matter and Ozone National
Ambient Air Quality Standards, Innovative Strategies and Economics
Group, Office of Air Quality Planning and Standards, Research Triangle
Park, N.C., July 16, 1997.  The EPA has begun developing revised cost
and burden hour estimates for the statutory SIP development obligations
in this implementation rule and will include them in a revised
Information Collection Request (ICR) in the near future.  Assessments of
some of the administrative cost categories identified as a part of the
SIP for the PM2.5 standards have already been conducted as a result of
other provisions of the CAA and associated ICRs (e.g. emission inventory
preparation, air quality monitoring program, conformity assessments,
NSR, 8-hour ozone, I/M program).  The new ICR will take these revised
administrative cost assessments into account and will reflect updated
assumptions regarding milestones for the first 3 year period.  The PM2.5
NAAQS implementation rule ICR and supporting statement will follow a
similar approach to that used in the ICR for the 8-hour ozone NAAQS
implementation rule.  The approach also will reflect recent changes in
the procedures for the ICR preparation and approval process.  

	The burden estimates in the ICR for this rule are incremental to what
is required under other provisions of the CAA.  Burden means the total
time, effort, or financial resources expended by persons to generate,
maintain, retain, or disclose or provide information to or for a Federal
agency.  This includes the time needed to review instructions; develop,
acquire, install, and utilize technology and systems for the purposes of
collecting, validating, and verifying information, processing and
maintaining information, and disclosing and providing information;
adjust the existing ways to comply with any previously applicable
instructions and requirements; train personnel to be able to respond to
a collection of information; search data sources; complete and review
the collection of information; and transmit or otherwise disclose the
information.  

	An agency may not conduct or sponsor, and a person is not required to
respond to a collection of information unless it displays a currently
valid OMB control number.  The OMB control numbers for EPA's regulations
in 40 CFR are listed in 40 CFR part 9.  When this ICR is approved by
OMB, the Agency will publish a technical amendment to 40 CFR part 9 in
the Federal Register to display the OMB control number for the approved
information collection requirements contained in this final rule. 
However, the failure to have an approved ICR for this rule does not
affect the statutory obligation for the States to submit SIPs as
required under part D of the CAA.

C.	Regulatory Flexibility Act

	The information collection requirements associated with NSR permitting
for ozone are covered by EPA(s request to renew the approval of the ICR
for the NSR program, ICR 1230.17, which was approved by OMB on January
25, 2005.  The information collection requirements associated with NSR
permitting were previously covered by ICR 1230.10 and 1230.11.  The OMB
previously approved the information collection requirements contained in
the existing NSR regulations at 40 CFR parts 51 and 52 under the
provisions of the Paperwork Reduction Act, and assigned OMB control
number 2060-0003.  A copy of the approved ICR may be obtained from Susan
Auby, Collection Strategies Division; U.S. Environmental Protection
Agency (2822T); 1200 Pennsylvania Ave., NW, Washington, DC 20460 or by
calling (202) 566-1672. [See Lakeshia Walker’s e-mail of 7/27]

C.   Regulatory Flexibility Act tc \l2 "C.   Regulatory Flexibility Act 

	The Regulatory Flexibility Act (RFA) generally requires an
Agencyagency to prepare a regulatory flexibility analysis of any rule
subject to notice and comment rulemaking requirements under the
Administrative Procedures Act or any other statute unless the
Agencyagency certifies that the rule will not have a significant
economic impact on a substantial number of small entities.  Small
entities include small businesses, small organizations, and small
governmental jurisdictions.  

For purposes of assessing the impacts of today( this proposed ruleaction
on small entities, small entity is defined as: (1) a small business, as
definesdefined by the Small Business Administration’s (SBA)
regulations at 13 CFR 121.201; (2) a small governmental jurisdiction
that is a government of a city, county, town, school district, or
special district with a population of less than 50,000; and or (3) a
small organization that is any not-for-profit enterprise whichthat is
independently owned and operated and is not dominant in its field.

	After considering the economic impacts of today(s final rule on small
entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities.  The final
rule governing SIPs will not directly impose any requirements on small
entities.  Rather, this rule interprets the obligations established in
the CAA for States to submit implementation plans in order to attain the
PM2.5 NAAQS. 

	 Additionally, with respect to NSR, this proposed rule does not itself
create the obligation to obtain an NSR permit for new major stationary
sources and modifications resulting in emissions of PM2.5 and its
precursors.  Rather, the preexisting rules establish this obligation,
and this final rule clarifies how that obligation will be implemented. 

	We believe that the existing Regulatory Flexibility Screening Analysis
(RFASA) further supports the conclusion that the NSR proposal will not
have a significant economic impact on a substantial number of small
entities.  The RFASA, developed as part of a 1994 draft Regulatory
Impact Analysis (RIA) and incorporated into the September 1995 ICR
renewal analysis, showed that the changes to the NSR program due to the
1990 CAA Amendments would not have an adverse impact on small entities. 
This analysis encompassed the entire universe of applicable major
sources that were likely to also be small businesses (approximately 50
”small business” major sources).  Because the administrative burden
of the NSR program is the primary source of the NSR program(s regulatory
costs, the analysis estimated a negligible ”cost to sales”
(regulatory cost divided by the business category mean revenue) ratio
for this source group.  Currently, there is no economic basis for a
different conclusion.  We do not believe the number of ”small
business” major sources will increase appreciably because all sources
who are major for PM2.5 or one of its precursors (SO2, NOx. or VOC) will
already be major for PM10 or such precursor.  

D. 	Unfunded Mandates Reform Act tc \l2 "Unfunded Mandates Reform Act 

	Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and Tribal
governments and the private sector.  Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with (Federal mandates( that may
result in expenditures to State, local, and tribal governments, in the
aggregate, or to the private sector, of $100 million or more in any 1
year.  Before promulgating an EPA rule for which a written statement is
needed, EPA is required by section 205 of the UMRA generally requires
EPA to identify and consider a reasonable number of regulatory
alternatives, and adopt the least costly, most cost-effective or least
burdensome alternative that achieves the objectives of the rule.  The
provisions of section 205 do not apply when they are inconsistent with
applicable law.  Moreover, section 205 allows EPA to adopt an
alternative other than the least costly, most cost-effective or least
burdensome alternative if the Administrator publishes with the final
rule an explanation why that alternative was not adopted.  Before EPA
establishes any regulatory requirements that may significantly or
uniquely affect small governments, including Tribal governments, it must
have developed under section 203 of the UMRA a small government agency
plan.  The plan must provide for notifying potentially affected small
governments, enabling officials of affected small governments to have
meaningful and timely input in the development of EPA regulatory
proposals with significant Federal intergovernmental mandates, and
informing, educating, and advising small governments on compliance with
the regulatory requirements.

	The EPA has determined that this rule does not contain a 	This rule
contains no Federal mandate that may result in expenditures of $100
million or more for State, local, and Tribal governments, in the
aggregate, or the private sector in any 1 year.  The estimated
administrative burden hour and costs associated with implementing the
PM2.5 NAAQS were developed upon promulgation of the standard and
presented in Chapter 10 of U.S. EPA 1997, Regulatory Impact Analyses for
the Particulate Matter and Ozone National Ambient Air Quality Standards,
Innovative Strategies and Economics Group, Office of Air Quality
Planning and Standards, Research Triangle Park, N.C., July 16, 1997. 
The estimated costs presented there for States in 1990 dollars totaled
$0.9 million.  The corresponding estimate in 1997 dollars is $1.1
million.  Thus, today(s rule is not subject to the requirements of
section 202 and 205 of the UMRA.  In addition, EPA carried out
consultations with governmental entities affected by this rule.  EPA has
determined that this rule contains no regulatory requirements that may
significantly or uniquely affect small governments, including Tribal
governments.  

	The CAA imposes the obligation for States to submit SIPs to implement
the PM2.5 NAAQS.  In this rule, EPA is merely providing an
interpretation of those requirements.  However, even if this rule did
establish an independent requirement for States to submit SIPs, it is
questionable whether a requirement to submit a SIP revision would
constitute a Federal mandate in any case.  The obligation for a State to
submit a SIP that arises out of section 110 and section 172 (part D) of
the CAA is not legally enforceable by a court of law, and at most is a
condition for continued receipt of highway funds.  Therefore, it is
possible to view an action requiring such a submittal as not creating
any enforceable duty within the meaning of section 421(5)(9a)(I) of UMRA
(2 U.S.C. 658(a)(I)).  Even if it did, the duty could be viewed as
falling within the exception for a condition of Federal assistance under
section 421(5)(a)(i)(I) of UMRA (2 U.S.C. 658(5)(a)(i)(I)).

	In the proposal, EPA has determined that this proposed rule contains no
regulatory requirements that may significantly or uniquely affect small
governments, including Tribal governments.  Nonetheless, EPA carried out
consultations with governmental entities affected by this rule.

E.  Executive Order 13132: Federalism tc \l2 "Executive Order 13132:
Federalism 

	Executive Order 13132, entitled (Federalism( (64 FR 43255, August 10,
1999), requires EPA to develop an accountable process to ensure
(meaningful and timely input by State and local officials in the
development of regulatory policies that have Federalism implications.( 
(Policies that have Federalism implications( is defined in the Executive
Order to include regulations that have (substantial direct effects on
the States, on the relationship between the national government and the
States, or on the distribution of power and responsibilities among the
various levels of government.(

		 This proposedfinal rule does not have Federalism implications.  It
will not have substantial direct effects on the States, on the
relationship between the national government and the States, or on the
distribution of power and responsibilities among the various levels of
government, as specified in Executive Order 13132.  As described in
section D, above (on UMRA), EPA previously determined the costs to
States to implement the PM2.5 NAAQS to be approximately $0.9 million in
1990 dollars.  The corresponding estimate in 1997 dollars is $1.1
million.  While this proposed rule considers options not addressed at
the time the NAAQS were promulgated, the costs for implementation under
these options would rise only marginally   This rule clarifies the
statutory obligations of States in implementing the PM2.5 NAAQS. 
Finally, the CAA establishes the scheme whereby States take the lead in
developing plans to meet the NAAQS.  This proposedfinal rule would not
modify the relationship of the States and EPA for purposes of developing
programs to implement the NAAQS.  Thus, Executive Order 13132 does not
apply to this proposedfinal rule.

	Although section 6 of Executive Order 13132 does not apply to this
rule, EPA actively engaged the States in the development of this
proposed rule.  The EPA held a number of calls with representatives of
State and local air pollution control agencies. 

In the spirit of Executive Order 13132, and consistent with EPA policy
to promote communications between EPA and State and local governments,
EPA specifically solicits comment on this proposed rule from State and
local officials.hosted a public hearing in Washington, DC in November
2005.  

F.	Executive Order 13175: Consultation and Coordination with Indian
Tribal Governments tc \l2 "Executive Order 13175: Consultation and
Coordination with Indian Tribal Governments 

	Executive Order 13175, entitled "Consultation and Coordination with
Indian Tribal Governments" (65 FR 67249, November 9, 2000), requires EPA
to develop an accountable process to ensure "meaningful and timely input
by Tribal officials in the development of regulatory policies that have
Tribal implications."  This proposedfinal rule does not have "Tribal
implications" as defined in Executive Order 13175.  This rule concerns
the requirements for State and tribal implementation plans for attaining
the PM2.5 air quality standards.  The CAA provides for States to develop
plans to regulate emissions of air pollutants within their
jurisdictions.  The Tribal Air Rule (TAR) under the CAA gives Tribes the
opportunity to develop and implement CAA programs such as programs to
attain and maintain the PM2.5 NAAQS, but it leaves to the discretion of
the Tribe the decision of whether to develop these programs and which
programs, or appropriate elements of a program, they will adopt. 

Although Executive Order 13175 does not apply to this rule, EPA did
reach out to Tribal leaders and environmental staff in developing this
rule.  From 2001 – 2004, the EPA supported a National Designations
Workgroup to provide a forum for tribal professionals to give input to
the designations process. In 2006, EPA supports a national "Tribal Air
call" which provides an open forum for all Tribes to voice concerns to
EPA about the NAAQS implementation process, including the PM2.5 NAAQS. 
In these meetings, EPA briefed call participants and Tribal
environmental professionals gave input as the rule was under
development.   Furthermore, in December 2005, EPA sent individualized
letters to all federally recognized Tribes about the proposal to give
Tribal leaders the opportunity for consultation.   

	This proposedfinal rule does not have Tribal implications as defined by
Executive Order 13175.  It does not have a substantial direct effect on
one or more Indian Tribes, since no Tribe has implemented a CAA program
to attain the PM2.5 NAAQS at this time.  The EPA notes that even if a
Tribe were implementing such a plan at this time, while the rule might
have Tribal implications with respect to that Tribe, it would not impose
substantial direct costs upon it, nor would it preempt Tribal law.

	Furthermore, this rule does not affect the relationship or distribution
of power and responsibilities between the Federal government and Indian
Tribes.  The CAA and the TAR establish the relationship of the Federal
government and Tribes in developing plans to attain the NAAQS, and this
rule does nothing to modify that relationship.  As this rule does not
have Tribal implications, Executive Order 13175 does not apply.

	Although Executive Order 13175 does not apply to this rule, EPA did
reach out to Tribal leaders and environmental staff regarding this
proposal.  The EPA supports a national "Tribal Designations and
Implementation Work Group" which provides an open forum for all Tribes
to voice concerns to EPA about the designations and implementation
process for the NAAQS, including the PM2.5 NAAQS.  In conference calls
EPA briefed Work Group participants and Tribal environmental
professionals gave input as the rule was under development.  
Furthermore, EPA is sending individualized letters to all Federally
recognized Tribes about this proposal to give Tribal leaders the
opportunity for consultation.  EPA specifically solicits additional
comment on this proposed rule from tribal officials.

G.	Executive Order 13045: Protection of Children from Environmental
Health and Safety Risks tc \l2 "Executive Order 13045: Protection of
Children from Environmental Health and Safety Risks 

	Executive Order 13045: (Protection of Children Fromfrom Environmental
Health and Safety Risks( (62 FR 19885, April 23, 1997) applies to any
rule that (1) is determined to be (economically significant( as defined
under Executive Order 12866, and (2) concerns an environmental health or
safety risk that EPA has reason to believe may have disproportionate
effect on children.  If the regulatory action meets both criteria, the
Agency must evaluate the environmental health or safety effects of the
planned rule on children, and explain why the planned regulation is
preferable to other potentially effective and reasonably feasible
alternatives considered by the Agency.

	The proposed This rule is not subject to Executive Order 13045. 
Nonetheless, we because it is not economically significant as defined in
Executive Order 12866, and because the Agency does not have reason to
believe the environmental health or safety risks addressed by this
action present a disproportionate risk to children.  This rule
implements a previously promulgated health-based Federal standard –
the PM2.5 NAAQS.  We have evaluated the environmental health or safety
effects of the PM2.5 NAAQS on children.  The results of this evaluation
are contained in the 1997 Federal Register notice establishing the PM2.5
standards.  In a number of locations in that notice, children are
identified as one of the principle sub-populations that are particularly
sensitive to exposure to fine particle pollution.  Today(s proposedfinal
rule provides the framework by which States will require sources to
reduce pollutant emissions, thereby improving air quality and reducing
the exposure of children and others to unhealthy levels of fine particle
pollution.  

H.  	Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use tc \l2 "Executive Order 13211: Actions That
Significantly Affect Energy Supply, Distribution, or Use 

	This proposedfinal rule is not a (significant energy action( as defined
in Executive Order 13211, (Actions That Significantly Affect Energy
Supply, Distribution, or Use,( (66 FR 28355, May 22, 2001) because it is
not likely to have a significant adverse effect on the supply,
distribution, or use of energy.  This rule is not a “significant
energy action,” because it does not establish requirements that
directly affect the general public and the public and private sectors,
but, rather, interprets the statutory requirements that apply to States
in preparing their SIPs.  The SIPs themselves will likely establish
requirements that directly affect the general public, and the public and
private sectors.

I.  	National Technology Transfer Advancement Act tc \l2 "National
Technology Transfer Advancement Act 

		As noted in the proposed rule, Section 12(d) of the National
Technology Transfer Advancement Act of 1995 (“NTTAA”), Public Law
No. 104-113, section 12(d) (15 U.S.C. 272 note) directs EPA to use
voluntary consensus standards (VCS) in its regulatory activities unless
to do so would be inconsistent with applicable law or otherwise
impractical.  Voluntary consensus standards are technical standards
(e.g., materials specifications, test methods, sampling procedures, and
business practices) that are developed or adopted by VCS bodies.  The
NTTAA directs EPA to provide Congress, through OMB, explanations when
the Agency decides not to use available and applicable VCS.

This proposedfinal rulemaking does not involve technical standards. 
Therefore, EPA is not considering the use of any VCS.

	 The EPA will encourage the States and Tribes to consider the use of
such standards, where appropriate, in the development of the their
implementation plans.

Executive Order 12898: Federal Actions to Address Environmental Justice
in Minority Populations and Low-Income Populations tc \l2 "Executive
Order 12898: Federal Actions to Address Environmental Justice in
Minority Populations and Low-Income Populations 

	J. Executive Order 12898: Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations	

Executive Order 12898 requires that each Federal agency make achieving
environmental justice part of its mission by identifying and addressing,
as appropriate, disproportionate high and adverse human health or
environmental effects of its programs, policies, and activities on
minorities and low-income populations.

	The EPA believes that this proposedfinal rule should not raise any
environmental justice issues.  The health and environmental risks
associated with ozonefine particles were considered in the establishment
of the PM2.5 NAAQS.  The level is designed to be protective with an
adequate margin of safety.  The proposedThis final rule provides a
framework for improving environmental quality and reducing health risks
for areas that may be designated nonattainment.

K.  Petitions for Judicial Review tc \l2 "L.  Petitions for Judicial
Review 

Under section 307(b)(1) of the CAA, petitions for judicial review of
this action must be filed in the United States Court of Appeals for the
District of Columbia Circuit by [insert date 60 days after publication].
 Filing a petition for reconsideration by the Administrator of this
final rule does not affect the finality of this rule for the purposes of
judicial review nor does it extend the time within which a petition for
judicial review may be filed, and shall not postpone the effectiveness
of such rule or action.  This action may not be challenged later in
proceedings to enforce its requirements.  See CAA section 307(b)(2).

L.  Determination Under Section 307(d) tc \l2 "M.  Determination Under
Section 307(d) 

Pursuant to sections 307(d)(1)(E) and 307(d)(1)(V) of the CAA, the
Administrator determines that this action is subject to the provisions
of section 307(d).  Section 307(d)(1)(V) provides that the provisions of
section 307(d) apply to "such other actions as the Administrator may
determine."  While the Administrator did not make this determination
earlier, the Administrator believes that all of the procedural
requirements, e.g., docketing, hearing and comment periods, of section
307(d) have been complied with during the course of this rulemaking.

 Congressional Review Act

The Congressional Review Act, 5 U.S.C. section 801 et seq., as added by
the Small Business Regulatory Enforcement Fairness Act of 1996,
generally provides that before a rule may take effect, the agency
promulgating the rule must submit a rule report, which includes a copy
of the rule, to each HourseHouse of the Congress and to the Comptroller
General to the United State.  The EPA will submit a report
contactingcontaining the rule and other required information to the U.S.
Senate, the U.S. House of Representatives, and the Comptroller General
of the United States prior to publication of the rule in the Federal
Register.  A Major rule cannot take effect until 60 days after it is
published in the Federal Register.  This action is/is not a “major
rule” as defined by 5 U.S.C. section 804(2).  This rule will be
effective [INSERT DATE 60 DAYS FROM PUBLICATION].	

LIST OF SUBJECTS 

[add]

Administrative practice and procedure 

Air pollution control 

Intergovernmental relations 

Nitrogen dioxide 

Ozone

Particulate matter 

Sulfur oxides 

Transportation 

Volatile organic compound

_________________________________________________

Date

_______________________________________________________

Stephen L. Johnson,

Administrator.

The authority citation for part 51 continues to read as follows: 
Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.

5.  A new Subpart Y is added to read as follows:

Subpart Y ( Provisions for Implementation of PM2.5 National Ambient Air
Quality Standards.

(51.1000	Definitions.

The following definitions apply for purposes of this subpart.  Any term
not defined herein shall have the meaning as defined in 40 CFR 51.100.

(a) Act means the Clean Air Act as codified at 42 U.S.C. 7401 - -7671q.
(2003).

(b) Attainment date means the date by which an area, under an approved
State implementation plan, is required to attain the PM2.5 NAAQS (based
on the average of three consecutive years of ambient air quality data).

(c) Baseline year inventory for the RFP plan is the emissions inventory
for the year also used as the base year for the attainment
demonstration.  

(d) Benchmark RFP plan means the reasonable further progress plan that
requires generally linear emission reductions in pollutants from the
baseline emissions year through the milestone inventory year.

(e) Date of designation means the effective date of the PM2.5 area
designation as promulgated by the Administrator. 

(f) Direct PM2.5 emissions means solid particles emitted directly from
an air emissions source or activity, or gaseous emissions or liquid
droplets from an air emissions source or activity which condense to form
particulate matter at ambient temperatures.  Direct PM2.5 emissions
include elemental carbon, directly emitted organic carbon, directly
emitted sulfate, directly emitted nitrate, and other inorganic particles
(including but not limited to crustal material, metals, and sea salt).

(g) Existing control measure means any Federally enforceable national,
State, or local control measure that has been approved in the SIP and
that results in reductions in emissions of PM2.5 or PM2.5 precursors in
a nonattainment area. 

(h) Full implementation inventory is the projected RFP emission
inventory for the year preceding the attainment date, representing a
level of emissions that demonstrates attainment.

(i) Milestone year inventory is the projected RFP emission inventory for
the applicable RFP milestone year (i.e. 2009 and, where applicable,
2012).

(j) PM2.5 NAAQS means the particulate matter national ambient air
quality standards (annual and 24-hour) codified at 40 CFR Part 50.7.

(k) PM2.5 design value for a nonattainment area is the highest of the
three-year average concentrations calculated for the monitors in the
area, in accordance with 40 CFR part 50, appendix N.

(l) PM2.5 nonattainment plan precursor means SO2 and those other PM2.5
precursors emitted by sources in the State which the State must evaluate
for emission reduction measures to be included in its PM2.5
nonattainment area or maintenance area plan. 

(m) PM2.5 precursor means those air pollutants other than PM2.5 direct
emissions that contribute to the formation of PM2.5.  PM2.5 precursors
include SO2, NOx, volatile organic compounds, and ammonia. 

(n) Reasonable further progress (RFP) means the incremental emissions
reductions toward attainment required under section 172(c)(2) and
section 171(1). 

(o) Subpart 1 means the general nonattainment plan requirements found in
subpart 1 of part D of title I of the Act.

(51.1001	Applicability of Part 51.  

The provisions in subparts A- through X of this part 51 apply to areas
for purposes of the PM2.5 NAAQS to the extent they are not inconsistent
with the provisions of this subpart.

(51.1002	Submittal of State Implementation Plan.

(a) For any area designated by EPA as nonattainment for the PM2.5
NAAQS, the State must submit a State implementation plan satisfying the
requirements of section 172 of the Act and this subpart Y of 40 CFR part
51 to EPA by the date prescribed by EPA which will be no later than 3
years from the effective date of designation.  

(b) The State must submit a plan consistent with the requirements of
section 110(a)(2) of the Act unless the State already has fulfilled this
obligation for the purposes of implementing the PM2.5 NAAQS. 

(c) Pollutants contributing to fine particle concentrations.  The State
implementation plan must identify and evaluate sources of PM2.5 direct
emissions and PM2.5 nonattainment plan precursors in accordance with
((51.1009 and 51.1010 of this subpart.  After January 1, 2011, for
purposes of establishing emissions limits under 51.1009 and 51.1010,
States must establish such limits taking into consideration the
condensable fraction of direct PM2.5 emissions.  Prior to this date,
States are not prohibited from establishing source emission limits that
include the condensable fraction of direct PM2.5. 

(1) The State must address sulfur dioxide as a PM2.5 nonattainment plan
precursor and evaluate sources of SO2 emissions in the State for control
measures.

(2) The State must address NOx as a PM2.5 nonattainment plan precursor
and evaluate sources of NOx emissions from sources in the State for
control measures, unless the State and EPA provide an appropriate
technical demonstration for a specific area showing that NOx emissions
from sources in the State do not significantly contribute to the PM2.5
nonattainment problem in the nonattainment area.

(3)  The State is not required to address VOC as a PM2.5 nonattainment
plan precursor and evaluate sources of VOC emissions from sources in the
State for control measures, unless:

(i) the State provides an appropriate technical demonstration for a
specific area showing that VOC emissions from sources in the State
significantly contribute to the PM2.5 nonattainment problem in the
nonattainment area and such demonstration is approved by EPA,; or

(ii) EPA provides such a technical demonstration.

(4)  The State is not required to address ammonia as a PM2.5
nonattainment plan precursor and evaluate sources of ammonia emissions
from sources in the State for control measures, unless:

(i) the State provides an appropriate technical demonstration for a
specific area showing that ammonia emissions in the State significantly
contribute to the PM2.5 nonattainment problem in the nonattainment area
and such demonstration is approved by EPA,; or

(ii) EPA provides such a technical demonstration. 

(5) The State must submit a demonstration to reverse any presumption in
this rule for a PM2.5 precursor with respect to a particular
nonattainment area, if the administrative record related to development
of its SIP shows that the presumption is not technically justified for
that area.

(51.1003. [Reserved] 

(51.1004	Attainment dates.  

(a) Consistent with section 172(a)(2)(A) of the Act, the attainment date
for an area designated nonattainment for the PM2.5 NAAQS will be the
date by which attainment can be achieved as expeditiously as
practicable, but no more than five years from the date of designation. 
The Administrator may extend the attainment date to the extent the
Administrator determines appropriate, for a period no greater than 10
years from the date of designation, considering the severity of
nonattainment and the availability and feasibility of pollution control
measures.

(b) In the SIP submittal for each of its nonattainment areas, the State
must submit an attainment demonstration justifying its proposed
attainment date.  For each nonattainment area, the Administrator will
approve an attainment date at the same time the Administrator approves
the attainment demonstration for the area, consistent with the
attainment date timing provision of section 172(a)(2)(A) and paragraph
(a) of this section.

(c) Upon a determination by EPA that an area designated nonattainment
for the PM2.5 NAAQS has attained the standard, the requirements for such
area to submit attainment demonstrations and associated reasonably
available control measures, reasonable further progress plans,
contingency measures, and other planning SIPs related to attainment of
the PM2.5 NAAQS shall be suspended until such time as:  the area is
redesignated to attainment, at which time the requirements no longer
apply; or EPA determines that the area has violated the PM2.5 NAAQS, at
which time the area is again required to submit such plans.  

(51.1005	One-year extensions of the attainment date.

(a) Pursuant to section 172(a)(2)(C)(ii) of the Act, a State with an
area that fails to attain the PM2.5 NAAQS by its attainment date may
apply for an initial 1-year attainment date extension if the State has
complied with all requirements and commitments pertaining to the area in
the applicable implementation plan, and:

(1) For an area that violates the annual PM2.5 NAAQS as of its
attainment date, the annual average concentration for the most recent
year at each monitor is 15.0 μg/m3 or less (calculated according to the
data analysis requirements in 40 CFR part 50, appendix N).

(2) For an area that violates the 24-hour PM2.5 NAAQS as of its
attainment date, the 98th percentile concentration for the most recent
year at each monitor is 65 μg/m3 or less (calculated according to the
data analysis requirements in 40 CFR part 50, appendix N).

(b) An area that fails to attain the PM2.5 NAAQS after receiving a
1-year attainment date extension may apply for a second 1-year
attainment date extension pursuant to section 172(a)(2)(C)(ii) if the
State has complied with all requirements and commitments pertaining to
the area in the applicable implementation plan, and:

(1) For an area that violates the annual PM2.5 NAAQS as of its
attainment date, the two-year average of annual average concentrations
at each monitor, based on the first extension year and the previous
year, is 15.0 μg/m3 or less (calculated according to the data analysis
requirements in 40 CFR part 50, appendix N).

(2) For an area that violates the 24-hour PM2.5 NAAQS as of its
attainment date, the two-year average of annual 98th percentile
concentrations at each monitor, based on the first extension year and
the previous year, is 65 μg/m3 or less (calculated according to the
data analysis requirements in 40 CFR part 50, appendix N).

(51.1006	Redesignation to nonattainment following initial designations
for the PM2.5 NAAQS.

Any area that is initially designated (attainment/unclassifiable( for
the PM2.5 NAAQS may be subsequently redesignated to nonattainment if
ambient air quality data in future years indicate that such a
redesignation is appropriate.  For any such area that is redesignated to
nonattainment for the PM2.5 NAAQS, any absolute, fixed date that is
applicable in connection with the requirements of this part is extended
by a period of time equal to the length of time between the effective
date of the initial designation for the PM2.5 NAAQS and the effective
date of redesignation, except as otherwise provided in this subpart.

(51.1007	Attainment demonstration and modeling requirements.

(a) For any area designated as nonattainment for the PM2.5 NAAQS, the
State must submit an attainment demonstration showing that the area will
attain the annual and 24-hour standards as expeditiously as practicable.
 The demonstration must meet the requirements of (51.112 and Part 51,
Appendix W and must include inventory data, modeling results, and
emission reduction analyses on which the State has based its projected
attainment date.  The attainment date justified by the demonstration
must be consistent with the requirements of 40 CFR 51.1004(a).  The
modeled strategies must be consistent with requirements in (51.1009 for
RFP and in (51.1010 for RACT and RACM.  The attainment demonstration and
supporting air quality modeling should be consistent with EPA’s PM2.5
modeling guidance.

(b) Required time frame for obtaining emissions reductions.  For each
nonattainment area, the State implementation plan must provide for
implementation of all control measures needed for attainment as
expeditiously as practicable, but no later than the beginning of the
year prior to the attainment date.  Consistent with section 172(c)(1) of
the Act, the plan must provide for implementation of all RACM and RACT
as expeditiously as practicable.  The plan also must include RFP
milestones in accordance with (51.1009, and control measures needed to
meet these milestones, as necessary.



(51.1008	Emission inventory requirements for the PM2.5 NAAQS. 

(a) For purposes of meeting the emission inventory requirements of
section 172(c)(3) of the Act for nonattainment areas, the State shall,
no later than three years after designation:

(1) Submit to EPA Statewide emission inventories for PM2.5 and PM2.5
precursors as required under the Consolidated Emissions Reporting Rule
(CERR) (40 CFR part 51, subpart A), or as required under any subsequent
national emission inventory reporting regulation that supersedes the
CERR.  For purposes of defining the data elements for these inventories,
the PM2.5 and PM2.5 precursor-relevant data element requirements under
40 CFR part 51 subpart A shall apply.

(2) Submit any additional emission inventory information needed to
support an attainment demonstration and RFP plan ensuring expeditious
attainment of the annual and 24-hour PM2.5 standards.  

(b) AFor inventories required for submission under paragraph (a) of this
section, a baseline emission inventory is required for the attainment
demonstration required under (51.1007 and for meeting RFP requirements
under (51.1009.  As determined on the effective date of an area(s
nonattainment designation, the base year for this inventory shall be the
most recent calendar year for which a complete inventory was required to
be submitted to EPA pursuant to the Consolidated Emissions Reporting
Rule in40 CFR part 51 subpart A of this part.  The baseline emission
inventory for calendar year 2002 or other suitable year shall be used
for attainment planning and RFP plans for areas initially designated
nonattainment for the PM2.5 NAAQS in 2004-2005.

(51.1009	Reasonable further progress (RFP) requirements. 

(a) Consistent with section 172(c)(2) of the Act, State implementation
plans for areas designated nonattainment for the PM2.5 NAAQS must
demonstrate reasonable further progress as provided in sections
51.1009(b) through (h).  

(b) If the State submits to EPA an attainment demonstration and State
implementation plan for an area which demonstrates that it will attain
the PM NAAQS within five years of the date of designation, the State is
not required to submit a separate RFP plan.  Compliance with the
emission reduction measures in the attainment demonstration and State
implementation plan will meet the requirements for achieving reasonable
further progress for the area. 

(c) For any area for which the State submits to EPA an approvable
attainment demonstration and State implementation plan that demonstrates
the area needs an attainment date of more than five years from the date
of designation, the State also must submit an RFP plan.  The RFP plan
must describe the control measures that provide for meeting the
reasonable further progress milestones for the area, the timing of
implementation of those measures, and the expected reductions in
emissions of direct PM2.5 and PM2.5 nonattainment plan precursors.  The
RFP plan is due to EPA within three years of the date of designation. 

(1) For any State that submits to EPA an approvable attainment
demonstration and State implementation plan justifying an attainment
date of more than five and less than nine years from the date of
designation, the RFP plan must include 2009 emissions milestones for
direct PM2.5 and PM2.5 nonattainment plan precursors demonstrating that
reasonable further progress will be achieved for the 2009 emissions
year.  

(2) For any area that submits to EPA an approvable attainment
demonstration and State implementation plan justifying an attainment
date of nine or ten years from the date of designation, the RFP plan
must include 2009 and 2012 emissions milestones for direct PM2.5 and
PM2.5 nonattainment plan precursors demonstrating that reasonable
further progress will be achieved for the 2009 and 2012 emissions years.
 

(d) The RFP plan must demonstrate that in each applicable milestone
year, emissions will be at a level consistent with generally linear
progress in reducing emissions between the base year and the attainment
year.  

(e) For a multi-State nonattainment area, the RFP plans for each State
represented in the nonattainment area must demonstrate RFP on the basis
of common multi-State inventories. The States within which the area is
located must provide a coordinated RFP plan.  Each State in a
multi-State nonattainment area must ensure that the sources within its
boundaries comply with enforceable emission levels and other
requirements that in combination with the reductions planned in other
state(s) will provide for attainment as expeditiously as practicable and
demonstrate reasonable further progress 

(f) In the benchmark RFP plan, the State must identify the pollutants
regulated under the PM2.5 nonattainment plan and specify target emission
reduction levels to be achieved during the milestone years.  In
developing the benchmark RFP plan, the State must develop emission
inventory information for the geographic area included in the plan and
conduct the following calculations:  

(1) For each pollutant addressed in the attainment strategy, the full
implementation reduction is calculated by subtracting the full
implementation inventory from the baseline year inventory.

(2) The "milestone date fraction" is the ratio of the number of years
from the baseline year to the milestone inventory year divided by the
number of years from the baseline year to the full implementation year.

(3) For each pollutant addressed in the attainment strategy, a benchmark
emission reduction is calculated by multiplying the full implementation
reduction by the milestone date fraction

(4) The benchmark emission level in the milestone year is calculated for
each pollutant by subtracting the benchmark emission reduction from the
baseline year emission level.  The benchmark RFP plan is defined as a
plan that achieves benchmark emission levels for each pollutant
addressed in the attainment strategy for the area.

(5) In comparing inventories between baseline and future years for a
pollutant, the inventories must be derived from the same geographic
area. The plan must include emissions estimates for all types of
emitting sources and activities in the geographic area from which the
emission inventories for each pollutant addressed in the plan are
derived.

(6) For purposes of establishing the transportation conformity budgets
for a PM2.5 nonattainment area, the State shall include in its RFP
submittal an inventory of on-road mobile source emissions in the
nonattainment area.

(g) The RFP plan due three years after designation must demonstrate that
emissions for the milestone year are either:

(1) At levels that are roughly equivalent to the benchmark emission
levels for all applicable pollutants to be addressed in the plan; or 

(2) At levels included in an alternative scenario that is projected to
result in a generally equivalent improvement in air quality by the
milestone year as would be achieved under the benchmark RFP plan.

(h) The equivalence of an alternative scenario to the corresponding
benchmark plan must be determined by comparing the expected air quality
changes of the two scenarios at the design value monitor location.  This
comparison must use the information developed for the attainment plan to
assess the relationship between emissions reductions of the pollutants
addressed in the attainment strategy and the ambient air quality
improvement for the associated ambient species.  

(51.1010	Requirements for reasonably available control technology (RACT)
and reasonably available control measures (RACM).

(a) For each PM2.5 nonattainment area, the State shall submit with the
attainment demonstration a SIP revision demonstrating that it has
adopted all reasonably available control measures (including RACT for
stationary sources) necessary to demonstrate attainment as expeditiously
as practicable and to meet any RFP requirements.  The SIP revision shall
contain the list of the potential measures considered by the State, and
information and analysis sufficient to support the State’s judgment
that it has adopted all RACM, including RACT. 

(b) In determining whether a particular emission reduction measure or
set of measures must be adopted as RACM under section 172(c)(1) of the
Act, the State must consider the cumulative impact of implementing the
available measures.  Potential measures that are reasonably available
considering technical and economic feasibility must be adopted as RACM
if, considered collectively, they would advance the attainment date by
one year or more. 

(51.1011	Requirements for mid-course review. 

(a) Any State that submits to EPA an approvable attainment plan for a
PM2.5 nonattainment area justifying an attainment date of nine or ten
years from the date of designation also must submit to EPA a mid-course
review six years from the date of designation.  

(b) The mid-course review for an area must include:

(1) a review of emissions reductions and progress made in implementing
control measures addressing pollutants contributing to PM2.5
concentrations in the area

(2) an analysis of changes in ambient air quality data for the area

(3) revised air quality modeling analysis to demonstrate attainment

(4) any new or revised control measures adopted by the State, as
necessary to ensure attainment by the attainment date in the approved
SIP of the nonattainment area.  

(51.1012	Requirement for contingency measures

(a) Consistent with section 172(c)(9) of the Act, the State must submit
in each nonattainment area plan specific contingency measures to be
undertaken if the area fails to make reasonable further progress, or
fails to attain the PM2.5 NAAQS by its attainment date.  The contingency
measures must take effect without significant further action by the
State or EPA.  

 

 In the 1997 PM NAAQS revision, EPA also revised the standard for
particles with a nominal aerodynamic diameter of 10 micrometers or less
(also known as PM10).  The original PM10 standard was established in
1987.  The revised PM10 standard was later vacated by the court, and
thus the 1987 PM10 standard remains in effect.  Today(s proposed
implementation rule and guidance does not address PM10.

 Environmental Protection Agency. (1996)  Air Quality Criteria for
Particulate Matter.  Research Triangle Park, NC: National Center for
Environmental Assessment-RTP Office; report no. EPA/600/P-95/001aF-cF.
3v.

 See www.epa.gov/cair.

 See 64 FR 35714, July 1, 1999.  

 See Tier II emission standards at 65 FR 6698, February 10, 2000.

 See heavy-duty diesel engine regulations at 66 FR 5002, January 18,
2001.

 For more information on the proposed nonroad diesel engine standards,
see EPA(s website:  http://www.epa.gov/nonroad/.

 NARSTO (2004) Particulate Matter Assessment for Policy Makers: A NARSTO
Assessment. P. McMurry, M. Shepherd, and J. Vickery, eds. Cambridge
University Press, Cambridge, England. ISBN 0 52 184287 5.

 The policy is the same as proposed, with the clarification regarding
downwind areas discussed above (Section A.2.b).

 The policy is the same as proposed, with the clarification regarding
downwind areas discussed above (Section A.2.b).

 The policy is the same as proposed, with the clarification regarding
downwind areas discussed above (Section A.2.b).

 The policy is the same as proposed, with the clarification regarding
downwind areas discussed above (Section A.2.b).

 More information on the Clean Air Interstate Rule is available at:
www.epa.gov/cair. 

 See section 51.1005 of the proposed regulation. 

 Memorandum of December 14, 2004, from Steve Page, Director, EPA Office
of Air Quality Planning and Standards to EPA Air Division Directors,
(Clean Data Policy for the Fine Particle National Ambient Air Quality
Standards.(  This document is available at: 
http://www.epa.gov/pmdesignations/guidance.htm

 The recommendations contained in the modeled attainment demonstration
guidance are separate from the Agency’s future hot-spot modeling
guidance for transportation conformity purposes.

 In the March 10, 2006, final transportation conformity rule (71 FR
12468), EPA committed to develop PM2.5 and PM10 quantitative hot-spot
modeling guidance for transportation conformity determinations for
highway and transit projects of local air quality concern.

 Application of the unmonitored area analysis is limited to locations
which are appropriate to allow the comparison of predicted PM2.5
concentrations to the NAAQS, based on PM2.5 monitor siting requirements
and recommendations. 

 Under the Tribal Air Rule (TAR), requirements for RACT and RACM may be
considered to be severable elements of implementation plan requirements
for Tribes. ADVANCE \d 12 

 See, 44 FR 53782, September 17, 1979, and 1976 memorandum from Roger
Strelow, Assistant Administrator for Air and Waste Management to
Regional Administrators, “Guidance for Determining Acceptability of
SIP Regulations in Non-attainment Areas” (Dec. 9, 1976)

 See e.g. Workshop on Requirements for Non-atttainment Area
Plans-Compilation of Presentations (OAQPS No. 1.2-103, revised edition
April 1978)

 Under the Tribal Air Rule (TAR), requirements for RACT and RACM may be
considered to be severable elements of implementation plan requirements
for Tribes. ADVANCE \d 12 

 In Sierra Club v. EPA, 294 F.3d 155 (D.C. Cir. 2002), the court stated
in upholding EPA’s statutory interpretation of RACM that the Act does
not compel a state to consider a measure without regard to whether it
would expedite attainment.  

 In this notice, where we use the shorthand phrase “advance the
attainment date,” it means “advance the attainment date by one year
or more.”

 In the context of the PM10 NAAQS, EPA has concluded that “advancement
of the attainment date” should mean an advancement of at least 1
calendar year.  See State Implementation Plans; General Preamble for the
Implementation of Title I of the CAA Amendments of 1990, 57 FR 12498
(April 16, 1992).  See also Sierra Club v. EPA, 294 F.3d 155 (D.C. Cir.
2002).

 In the context of the PM10 NAAQS, EPA has concluded that “advancement
of the attainment date” should mean an advancement of at least 1one
calendar year.  See State Implementation Plans; General Preamble for the
Implementation of Title I of the CAA Amendments of 1990, 57 FR 12498
(April 16, 1992).  See also Sierra Club v. EPA, 294 F.3d 155 (D.C. Cir.
2002). ADVANCE \d 12 

 The EPA believes that it is not necessary to identify every possible
variation of every type of control measure, or all possible combinations
of technologies and measures that would apply to a given source or
activity if the State has properly characterized the potentially
available emissions reductions and their costs.   For example, EPA
believes that the State can conduct a thorough analysis of VMT reduction
measures without including every possible level or stringency of
implementation of certain possible measures or combinations of measures
for reducing VMT, so long as those measures would not affect the overall
assessment of VMT reduction capabilities and the associated costs.  

 For example, see past EPA guidance on PM2.5 control technologies:
Stationary Source Control Techniques Document for Fine Particulate
Matter (EPA-452/R-97-001), EPA Office of Air Quality Planning and
Standards, October 1998.

 Stationary Source Control Techniques Document for Fine Particulate
Matter (EPA-452/R-97-001), EPA Office of Air Quality Planning and
Standards, October 1998. See also:  Controlling SO2 Emissions: A Review
of Technologies (EPA/600/R-00/093), EPA Office of Research and
Development, November 2000.

 See EPA’s website for more information: 
http://www.epa.gov/ttn/emc/monitor.html.

 EPA Air Pollution Control Cost Manual - Sixth Edition (EPA
452/B-02-001), EPA Office of Air Quality Planning and Standards,
Research Triangle Park, NC, Jan 2002. ADVANCE \d 12 

10 U.S. EPA, 2003 Technical Support Package for Clear Skies; U.S. EPA,
2003. See also:  Draft Regulatory Impact Analysis: Control of Emissions
from Nonroad Diesel Engines. United States Environmental Protection
Agency Office of Air and Radiation EPA420-R-03-008, April 2003. ADVANCE
\d 12 

  There are a number of sources of information on technologies for
reducing emissions of PMPM2.5 and its precursors, including:  Stationary
Source Control Techniques Document for Fine Particulate Matter
(EPA-452/R-97-001), EPA Office of Air Quality Planning and Standards;
STAPPA and ALAPCO Controlling Fine Particulate Matter Under the Clean
Air Act:  A Menu of Options; Control Measures “White Papers” from
the Lake Michigan Air Directors Consortium (  HYPERLINK
"http://www.ladco.org"  www.ladco.org );  New Jersey “Reducing Air
Pollution Together” workgroups (  HYPERLINK
"http://www.nj.gov/dep/airworkgroups/" 
http://www.nj.gov/dep/airworkgroups/ ); California SB 656 Program to
identify available PM measures (  HYPERLINK
"http://www.arb.ca.gov/pm/pmmeasures/pmmeasures.htm" 
http://www.arb.ca.gov/pm/pmmeasures/pmmeasures.htm ).  .  Links are
provided to a number of national, state and local air quality agency
sites from EPA’s PM2.5 website: http://www.epa.gov/pm/measures.html 

11 12See Clean School Bus USA program at
http://www.epa.gov/cleanschoolbus/.  See also:  AWhat You Should Know
About Diesel Exhaust and School Bus Idling", (June 2003,
EPA420-F-03-021) at
http://www.epa.gov/otaq/retrofit/documents/f03021.pdf. ADVANCE \d 12 

12 See EPA’s voluntary diesel retrofit program web site at
http://www.epa.gov/otaq/retrofit/overfleetowner.htm. ADVANCE \d 12 

13 See EPA’s voluntary diesel retrofit program web site at
http://www.epa.gov/otaq/retrofit/idling.htm. ADVANCE \d 12 

14 See EPA’s website on transportation control measures at
http://www.epa.gov/otaq/transp/traqtcms.htm. ADVANCE \d 12 

15 See EPA’s web site on nonroad engines, equipment, and vehicles at
http://www.epa.gov/otaq/nonroad.htm. ADVANCE \d 12 

 Under the ozone program, EPA has identified presumptive levels of
control for RACT for various source categories through control
techniques guidelines.   When RACT is a specified level of control, RACT
(unlike RACM) is unrelated to pollution levels and attainment needs of
individual areas.

 Because CAIR is designed to achieve highly cost effective emission
reductions to abate interstate pollution transport and to provide
flexibility on the location of reductions, the projected impact of CAIR
in reducing nonattainment area EGU emissions varies significantly by
area. 

 See the regulatory impact analysis chapter on air quality for the 2006
PM NAAQS review at
http://www.epa.gov/ttn/ecas/regdata/RIAs/Chapter%204--Air%20Quality.pdf.

 EPA’s CAIR-RACT presumption also would not apply if a State required
sources other than EGUs to achieve a portion of the reductions required
by CAIR (e.g., the State’s CAIR SIP achieved some reductions from EGUs
but took credit for non-EGU reductions achieved under new, more
stringent requirements implemented to meet NOx SIP call caps).  Under
the CAIR rule such a State would not be eligible to participate in the
EPA-administered CAIR trading system.

16 There are some MACT categories for which it may not be possible to
determine the degree of VOC reductions from the MACT standard without
additional analysis; for example, the miscellaneous metal parts and
products (40 CFR part 60, subpart MMMM) due to the uncertainty of the
compliance method that will be selected. ADVANCE \d 12 

 There are some MACT categories for which it may not be possible to
determine the degree of VOC reductions from the MACT standard without
additional analysis; for example, the miscellaneous metal parts and
products (40 CFR part 60, subpart MMMM) due to the uncertainty of the
compliance method that will be selected.

17 The consolidated emissions reporting rule was published in the
Federal Register on June 10, 2002, pages 39602-39616. ADVANCE \d 12 

 The consolidated emissions reporting rule was published in the Federal
Register on June 10, 2002, pages 39602-39616. ADVANCE \d 12 

 The RFP test uses inventories for the full year, e.g. the year of 2009
or the year of 2012.  EPA does not specifically require that the
relevant measures be implemented by the beginning of the year, but RFP
inventories must reflect the fact that measures that are implemented
later in the year have correspondingly less impact on the year’s
annual total emissions.

111 Emissions Inventory Guidance for Implementation of Ozone and
Particulate Matter National Ambient Air Quality Standards (NAAQS) and
Regional Haze Regulations,(  EPA-454/R-05-001, August 2005.

 Emissions Inventory Guidance for Implementation of Ozone and
Particulate Matter National Ambient Air Quality Standards (NAAQS) and
Regional Haze Regulations,(  EPA-454/R-05-001, November 2005.

  “Optimized Method 202 Sampling Train to Minimize the Biases
Associated with Method 202 Measurement of Condensable Particulate Matter
Emissions,” John Richards, Tom Holder, and David Goshaw, Air Control
Techniques, P.C.; Air & Waste Management Association, Hazardous Waste
Combustion Specialty Conference AWM, November 2-3, 2005, St. Louis, MO.

 U.S. Environmental Protection Agency. PM-10 SIP Development Guideline.
Office of Air Quality Planning and Standards, Research Triangle Park,
NC. EPA Publication No. EPA-450/2-86-001. June 1987.

  The General Preamble is available online at   HYPERLINK
"http://www.epa.gov/ttn/oarpg/t1pfpr.html" 
http://www.epa.gov/ttn/oarpg/t1pfpr.html .

 Clean Air Act Advisory Committee, Recommendations to the Clean Air Act
Advisory Committee - Phase I and Next Steps, Air Quality Management Work
Group, Environmental Protection Agency,   HYPERLINK
"http://www.epa.gov/air/caaac/pdfs/report1-17-05.pdf" 
http://www.epa.gov/air/caaac/pdfs/report1-17-05.pdf , January 2005.

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 Option Paper 4 - Providing Guidance Regarding The Use Of Emissions
Factors For Purposes Other Than Emissions Inventories, September 2005,
http://www.epa.gov/ttn/chief/efpac/projects.html

119 See 40 CFR (( 70.5(c)(3)(i), 70.5(b), and 70.7(a)(1)(i); 40 CFR ((
71.5(c)(3)(i), 71.5(b), and 71.7(a)(1)(i).

 White Paper Number 2 for Improved Implementation of The Part 70
Operating Permits Program, Lydia N. Wegman, Deputy Director, Office of
Air Quality Planning and Standards, March 5, 1996 (  HYPERLINK
"http://www.epa.gov/ttn/oarpg/t5wp.html" 
http://www.epa.gov/ttn/oarpg/t5wp.html 

 See 40 CFR 70.5(c)(3)(i), 70.5(b), and 70.7(a)(1)(i); 40 CFR
71.5(c)(3)(i), 71.5(b), and 71.7(a)(1)(i).

 For background information on issues surrounding implementation of the
PM2.5 NAAQS, see the EPA memo entitled “Implementation of New Source
Review Requirements in PM-2.5 Nonattainment Areas,” from Stephen D.
Page, Director, Office of Air Quality Planning and Standards, to
Regional Air Directors, Regions I-X, dated April 5, 2005.

 For background information on regulated air pollutants, see the EPA
memo entitled “Definition of Regulated Air Pollutant for Purposes of
Title V,” from Lydia N. Wegman, Deputy Director, Office of Air Quality
Planning and Standards, to Air Division Directors, Regions I-X, dated
April 26, 1993.

120 The PM2.5 monitoring regulations are located at 40 CFR Part 58.

 The PM2.5 monitoring regulations are located at 40 CFR Part 58.

 See 62 FR 38652-38760, National Ambient Air Quality Standards for
Particulate Matter, Final Rule; also 40 CFR Part 50.

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