monitoring would be allowed where estimated Pb concentrations were
predicted to be less than 50 percent of the NAAQS and where Pb in
ultra-coarse particulate was expected to be low. These commenters also
suggested that if at some point in the future the monitor were to show
that Pb-PM10 concentrations exceeded 50 percent of the
NAAQS, the monitoring agency would be required to replace the Pb-
PM10 monitor with a Pb-TSP monitor.
    We support this suggested approach, noting that it allows for the
use of Pb-PM10 in areas where we do not expect Pb
concentrations to exceed the Pb NAAQS without the burden and
uncertainty associated with the development and use of site-specific
scaling factors. As noted in section II.C.1, use of Pb-PM10
monitors in these locations offers the advantages of increased monitor
precision and decreased spatial variation of Pb-PM10
concentrations, without raising the same concerns over a lack of
protection against health risks from all particulate Pb emitted to the
ambient air that support retention of Pb-TSP as the indicator.
    However, we feel the combined requirements for allowing use of Pb-
PM10 monitors only in areas where the concentration is
expected to be less than 50% of the NAAQS and where Pb in ultra-coarse
particles is expected to be low may be too restrictive, especially in
light of the fact that a monitoring agency may request a waiver from
monitoring altogether if the expected concentration is less than 50% of
the NAAQS. We believe it is appropriate to allow Pb-PM10 in
lieu of Pb-TSP where the maximum 3-month arithmetic mean Pb
concentration is expected to be less than 0.10 [mu]g/m3
(i.e., two thirds of the NAAQS) and where sources are not expected to
emit ultra-coarse Pb. By limiting the use of Pb-PM10
monitoring to locations where the Pb concentrations are less than 0.10
[mu]g/m3 on a 3-month arithmetic mean and where ultra-coarse
Pb is expected to be low, we believe that the Pb-TSP concentrations
will also be less than 100% of the NAAQS. Examples of locations where
Pb-PM10 monitoring may be more representative of Pb-TSP
levels than others are urban areas away from Pb sources (i.e., non-
source-oriented monitoring locations), near airports, combustion
sources, and other Pb sources which are expected to only emit Pb in the
fine PM size fraction. Locations where it would not be appropriate to
monitor using Pb-PM10 samplers include near smelters,
roadways, and sources with significant fugitive dust emissions.
    We are revising the proposed allowance for the use of Pb-
PM10 monitors to allow Pb-PM10 monitors without
the use of scaling factors for non-source-oriented monitors (unless
existing data indicates maximum 3-month arithmetic mean Pb
concentration has exceeded 0.10 [mu]g/m3 in the last three
years) and for source-oriented monitors where maximum 3-month
arithmetic mean Pb concentration is expected to be less than 0.10
[mu]g/m3 (based on modeling or historic data) and where
ultra-coarse Pb is expected to be low. We are also requiring that a Pb-
TSP monitor be required at the site if at some point in the future the
Pb-PM10 monitor shows that the maximum 3-month arithmetic
mean Pb-PM10 concentration was equal to or greater than 0.10
[mu]g/m3. Section IV.E of this preamble discusses how data
from Pb-PM10 monitors will be used in comparison to the Pb
NAAQS.
e. Required Timeline for Monitor Installation and Operation
    We received several comments from monitoring agencies regarding the
proposed timeline for monitor installation. Commenters supported the
need for a staggered network deployment, especially if a large number
of new monitors would be required. Two commenters argued that even the
proposed two-year deployment would not provide enough time for
monitoring agencies to site and install the number of monitors needed.
    Based on the network design requirements being finalized with this
action, we estimate that approximately 135 facilities emit Pb at levels
over the ``emissions threshold'' of 1 ton per year and would result in
required monitoring. We are also requiring urban areas with populations
over 500,000 to site non-source-oriented monitors, thus another 101
monitors are required. Together the required source-oriented and non-
source-oriented monitors are expected to total 236 monitors. Some of
the existing 133 lead monitoring stations will be useful to support the
required network, but other stations may need to move. We are
estimating that approximately 90 of the existing stations are in
locations that are of benefit to other monitoring objectives, even when
well below the NAAQS (e.g., long-term trends or for use in a health
study) and are not part of the minimum network requirements being
finalized in today's action. Once the network is fully operational the
236 required stations plus an additional 90 stations in existing
locations that are not required results in an expected network of 326
lead monitoring stations to adequately support characterization of lead
across the country.
    We believe it would be unrealistic to require monitoring agencies
to site and install the required 240 new monitoring stations within one
year, even if some of these are already in the right locations.
However, we do believe it is reasonable to require monitoring

agencies to site and install half of these stations in one year with
the remaining stations deployed in the following year. Accordingly, and
as discussed further below, we are finalizing a two-year monitor
deployment schedule for required monitoring.
3. Decisions on Network Design Requirements
    We are finalizing new network design requirements for the Pb NAAQS
monitoring network that differ from those proposed in the following
aspects. The differences from the proposal reflect our consideration of
the comments on the proposed network design requirements and
consideration of the level, form, and averaging time for the final
NAAQS being promulgated today.
    We are adding a requirement that monitoring agencies conduct
ambient air Pb monitoring taking into account Pb sources which are
expected to or have been shown to contribute to a maximum Pb
concentration in ambient air in excess of the NAAQS, the potential for
population exposure, and logistics. At a minimum, there must be one
source-oriented SLAMS site located to measure the maximum Pb
concentration in ambient air resulting from each Pb source which emits
1.0 or more tons per year based on either the most recent NEI or other
scientifically justifiable methods and data (such as improved emissions
factors or site-specific data). We are maintaining the existing
authority for the EPA Regional Administrator to require additional
monitoring where the likelihood of Pb air quality violations is
significant or where the emissions density, topography, or population
locations are complex and varied. In addition, we are adding a clause
to the source-oriented monitoring requirement to clarify that a single
monitor may be used to monitor multiple Pb sources when the sources
contribute to a single maximum Pb concentration.
    In addition, monitoring agencies may consider the potential for
population exposure when siting source-oriented monitors. While this
change does not restrict monitoring agencies from monitoring at any
location meeting the definition of ambient air, this provision allows
monitoring agencies to consider the potential for population exposure
when siting the required source-oriented monitors at the maximum Pb
concentration.
    We are removing the proposed restriction that waivers may only be
granted for sites near sources emitting less than 1000 kg/yr. The EPA
Regional Administrator may approve waivers for the source-oriented
monitoring requirement for any site where the monitoring agency
demonstrates that the emissions from the source will not contribute to
a Pb-TSP concentration greater than 50 percent of the final NAAQS
(based on historic data, monitoring data, or other means).
    We are requiring one non-source-oriented monitor in every CBSA with
a population of 500,000 people or more. In addition, we are requiring
these monitors be placed in neighborhoods within urban areas impacted
by re-entrained dust from roadways, closed industrial sources which
previously were significant sources of Pb, hazardous waste sites,
construction and demolition projects, or other fugitive dust sources of
Pb.
    Monitoring agencies may use Pb-PM10 monitors to meet the
non-source-oriented monitoring requirements tied to CBSA population
provided that historical monitoring does not indicate Pb-TSP or Pb-
PM10 concentrations greater than an arithmetic 3-month mean
of 0.10 [mu]g/m3, and to meet the source-oriented monitoring
requirements where Pb concentrations are expected (based on historic
data, monitoring data, or other means) to be less than 0.10 [mu]g/
m3 on an arithmetic 3-month mean, and ultra-coarse Pb is
expected to be low. However, monitoring agencies are required to begin
monitoring for Pb-TSP within six months of a measured Pb-
PM10 arithmetic 3-month mean concentration of 0.10 [mu]g/
m3 or more. For example, if a Pb-PM10 monitoring
site measures an arithmetic 3-month mean concentration of 0.10 [mu]g/
m3 or more for the period March-May 2011, the responsible
monitoring agency would be required to install and begin operation of a
Pb-TSP monitor at the site no later than December 1, 2011.
    We are allowing monitoring agencies to stagger installation of any
newly required monitors over a two-year period. Each monitoring agency
is required to install and operate the required source-oriented
monitors by January 1, 2010. The non-source-oriented monitors are
required to be installed and operated by January 1, 2011. The annual
monitoring plan due July 1, 2009 must describe the planned monitoring
that will begin by January 1, 2010, and the plan due July 1, 2010 must
describe the planned monitoring that will begin by January 1, 2011.

C. Sampling Frequency

    We proposed to maintain the 1-in-6 day sampling frequency if the
final averaging time for the NAAQS standard was based on a quarterly
average. We did not receive any comments on our proposed sampling
frequency for a NAAQS based on a quarterly average. While the final
NAAQS is based on a moving 3-month average rather than a quarterly
average, the statistical and practical monitoring considerations are
the same. As such, we are maintaining the current 1-in-6 day minimum
sampling frequency as proposed (i.e., monitoring agencies will be
required to collect at least one 24-hour Pb sample every six days).

D. Monitoring for the Secondary Standard

    We did not propose any specific additional monitoring requirements
for the secondary standard because based on the available data, we do
not expect exceedances of either the primary or the secondary NAAQS
away from the point sources that will be addressed by the monitoring
requirements already described. We also noted that the Pb-
PM2.5 data collected as part of the Interagency Monitoring
of Protected Visual Environments (IMPROVE) program provide useful
information on Pb concentrations in rural areas that can be used to
track trends in ambient air Pb concentrations in rural areas including
important ecosystems. We received one comment supporting our proposed
reliance on the IMPROVE network Pb-PM2.5 data. We did not
receive any other comments on additional monitoring needs to support
the secondary Pb NAAQS. Thus, we are not finalizing any additional
requirements for Pb monitoring specifically for the secondary Pb NAAQS.

E. Other Monitoring Regulation Changes

    We are finalizing two other proposed changes to the monitoring
requirements for Pb, and making one editorial revision for ease of
reference. We are changing the reporting requirements to require the
reporting of average pressure and temperature for each Pb sample
collected. We are also removing Pb from the list of criteria pollutants
where data from special purpose monitors can be excluded from
consideration for designations. The proposed changes, comments
received, and final amendments are described in the following
paragraphs.
1. Reporting of Average Pressure and Temperature
    We proposed revisions to 40 CFR 58.16(a) to add a requirement that
the monitoring agency report the average pressure and temperature
during the time of sampling for both Pb-TSP monitoring and Pb-
PM10 monitoring. We did not receive any comments on this

proposed requirement. As such, we are finalizing this requirement as
proposed. Monitoring agencies may use site specific meteorological
measurements generated by on-site equipment (meteorological
instruments, or sampler generated), a representative nearby monitoring
station, or measurements from the nearest airport reporting ambient
pressure and temperature.
2. Special Purpose Monitoring
    We proposed to revise 40 CFR 58.20(e) by removing the specific
reference to Pb in the rule language. We proposed to make this change
because the form of the proposed Pb NAAQS would allow a non-attainment
finding to be based on as little as 3-months of data which would have
to be considered during mandatory designations. We did not receive any
comments on this proposed revision to the special purpose monitoring
requirements. As such, we are finalizing the revision to 40 CFR Section
58.20(e) as proposed.

VI. Implementation Considerations

    This section of the final rule discusses the specific CAA
requirements related to implementation of the revised Pb NAAQS based on
the structure outlined in the CAA, existing rules, existing guidance,
and in some cases revised guidance.
    The CAA assigns important roles to EPA, states, and tribal
governments in implementing NAAQS. States have the primary
responsibility for developing and implementing State Implementation
Plans (SIPs) that contain state measures necessary to achieve the air
quality standards in each area. EPA provides assistance to states and
tribes by providing technical tools, assistance, and guidance,
including information on the potential control measures.
    A SIP is the compilation of regulations and control programs that a
state uses to carry out its responsibilities under the CAA, including
the attainment, maintenance, and enforcement of the NAAQS. States use
the SIP development process to identify the emissions sources that
contribute to the nonattainment problem in a particular area, and to
select the emissions reduction measures most appropriate for the
particular area in question. Under the CAA, SIPs must ensure that areas
reach attainment as expeditiously as practicable, but by no later than
the statutory attainment date that is set for the area.
    The EPA's analysis of the available Pb monitoring data suggests
that a large percentage of recent Pb ambient air concentrations in
excess of 0.15 [mu]g/m\3\ have occurred in locations with active
industrial sources of lead emissions. Accordingly, we anticipate that
many areas may be able to attain the revised NAAQS by implementing air
pollution control measures on lead emitting industrial sources only.
These controls could include measures such as particulate matter fabric
filter control devices and industrial fugitive dust control measures
applied in plant buildings and on plant grounds. However, it may become
necessary in some areas to also implement controls on non-industrial,
or former industrial, type sources. Based on these considerations, EPA
believes that the regulations and guidance currently being used to
implement the pre-existing Pb NAAQS are still appropriate to implement
the revised Pb NAAQS with modifications in some cases.
    The regulations and guidance which address the implementation of
the pre-existing NAAQS for Pb are mainly provided in the following
documents: (1) ``State Implementation Plans; General Preamble for the
Implementation of Title I of the Clean Air Act Amendments of 1990'', 57
FR 13549, April 16, 1992, (2) ``State Implementation Plans for Lead
Nonattainment Areas; Addendum to the General Preamble for the
Implementation of Title I of the Clean Air Act Amendments of 1990'', 58
FR 67748, December 22, 1993, and (3) regulations listed at 40 CFR
51.117. These documents address requirements such as designating areas,
setting nonattainment area boundaries, promulgating area
classifications, nonattainment area SIP requirements such as Reasonably
Available Control Measures (RACM), Reasonably Available Control
Technology (RACT), New Source Review (NSR), Prevention of Significant
Deterioration (PSD), and emissions inventory requirements. The EPA
believes that the existing guidance and regulations are sufficient to
implement the revised Pb NAAQS at this time. As discussed below, EPA is
finalizing some changes to the existing guidance and regulations, and
EPA will, as appropriate, review, and revise or update these policies,
guidance, and regulations to ensure effective implementation of the Pb
NAAQS.
    Several commenters submitted comments stating that the usual agency
practice for revising the NAAQS has been to first promulgate a rule
setting the health and welfare based standards, and then to promulgate
a rule that addresses the numerous implementation issues relating to
the NAAQS. These commenters stated that the lead NAAQS proposal,
however, combines these two rulemakings into one compressed rule.
Commenters stated that they theoretically believe that this two-in-one
rule approach could benefit states and localities by preventing the
types of delays that have been encountered with the implementation of
other pollutants. The commenters, however, stated that they believe
that the lead NAAQS implementation provisions in the proposed rule are
insufficient to give state and local agencies adequate guidance to
implement the revised standard. Commenters further stated that they
believe that EPA should particularly update lead control strategy and
emissions inventory guidance documents to account for the change to the
level of the standard.
    As stated in the proposed rule, EPA believes that the regulations
and guidance currently being used to implement the pre-existing Pb
NAAQS are generally still appropriate to address the issues required to
begin implementing the revised Pb NAAQS. As discussed in the proposal,
EPA is revising the emission inventory requirements of 40 CFR
51.117(e)(1). In some areas, as discussed below, EPA is providing
additional guidance in response to comments. The EPA believes that
these policies, guidance and regulations should be used by states,
local, and Tribal governments as a basis for implementing the revised
Pb NAAQS. Also, as stated in the proposed rule, EPA will as
appropriate, further review and revise or update these policies,
guidance, and regulations in the future to ensure that states, local,
and Tribal governments have the appropriate information necessary to
fully implement the revised Pb NAAQS in a timely manner.
    As discussed below, the EPA is generally finalizing the guidance
concerning the implementation of the revised Pb NAAQS consistent with
the proposed rule.

A. Designations for the Lead NAAQS

1. Proposal
    As discussed in the proposed rule, after EPA establishes or revises
a primary and/or secondary NAAQS, the CAA requires EPA and the states
to begin taking steps to ensure that the new or revised NAAQS are met.
The first step is to identify areas of the country that do not meet the
new or revised NAAQS. The CAA defines EPA's authority to designate
areas that do not meet a new or revised NAAQS. Section 107(d)(1)
provides that ``By such date as the Administrator may reasonably
require, but not later than 1 year after promulgation of a new or
revised NAAQS for any pollutant under

section 109, the Governor of each state shall * * * submit to the
Administrator a list of all areas (or portions thereof) in the state''
that designates those areas as nonattainment, attainment, or
unclassifiable. Section 107(d)(1)(B)(i) further provides, ``Upon
promulgation or revision of a NAAQS, the Administrator shall promulgate
the designations of all areas (or portions thereof) * * * as
expeditiously as practicable, but in no case later than 2 years from
the date of promulgation. Such period may be extended by up to one year
in the event the Administrator has insufficient information to
promulgate the designations.'' The term ``promulgation'' has been
interpreted by the courts to mean the signature and dissemination of a
rule.\111\ By no later than 120 days prior to promulgating final
designations, EPA is required to notify states or Tribes of any
intended modifications to their boundaries as EPA may deem necessary.
States and Tribes then have an opportunity to comment on EPA's
tentative decision. It should be noted that, whether or not a state or
a Tribe provides a recommendation, EPA must promulgate the designation
that it deems appropriate.
---------------------------------------------------------------------------

    \111\ American Petroleum Institute v. Costle, 609 F.2d 20 (D.C.
Cir. 1979).
---------------------------------------------------------------------------

    In the proposal, EPA indicated that Governors and tribal leaders
would be required to submit their initial designation recommendations
to EPA no later than September 2009, and the initial designation of
areas for the new Pb NAAQS would occur no later than September 2010,
although that date may be extended by up to one year under the CAA (or
no later than September 2011) if EPA has insufficient information to
promulgate the designations. These dates were based on the court-
ordered schedule in effect at the time of proposal, which required a
final rule to be signed no later than September 15, 2008. The court-
ordered schedule was subsequently amended to require a notice of final
rulemaking to be signed no later than October 15, 2008.
    In the proposed rule, EPA also discussed issues related to possible
schedules for designations, and EPA took comment on issues related to
the anticipated designation schedule. The proposal identified two ``key
considerations'' in establishing a schedule for designations: ``(1) The
advantages of promulgating all designations at the same time; and (2)
the availability of a monitoring network and sufficient monitoring data
to identify areas that may be violating the NAAQS'' (73 FR 29267). The
EPA then stated its view that ``there are important advantages to
promulgating designations for all areas at the same time'' and
expressed its intention to do so.
    The proposal also discussed EPA's belief that the existing Pb
monitoring network is not adequate to evaluate attainment of the
revised Pb NAAQS at locations consistent with EPA's proposed new
monitoring network siting criteria and data collection requirements.
These new requirements would result in a more strategically targeted
network that would begin operation by January 1, 2010. The proposal
pointed out that taking the additional year provided under section
107(d)(1)(B)(i) of the CAA (which would allow up to 3 years to
promulgate initial designations following the promulgation of a new or
revised NAAQS) would allow the first year of data from the new
monitoring network to be available. The proposal also stated that, due
to the updated monitoring network design requirements, this additional
data would be of significant benefit for designating areas for the new
NAAQS.
    Accordingly, the proposal identified an initial designation
schedule under which states (and Tribes) would be required to submit
designation recommendations to EPA no later than one year following
promulgation of the new NAAQS. States would be able to consider ambient
data collected with the existing network FRM and FEM samplers through
the end of calendar year 2008 when formulating their recommendations.
The proposal further indicated that if, as EPA anticipated, EPA needed
an additional year to make designations due to insufficient
information, EPA would have access to Pb air quality monitoring data
from calendar year 2010, which state monitoring officials have
certified as being complete and accurate, since the deadline for such
certification is May 1, 2011. Under this schedule, EPA would be able to
consider data from calendar years 2008-2010 in formulating its proposed
revisions, if any, to the designations recommended by states and
Tribes. States and Tribes would then have an opportunity to comment on
EPA's proposed modifications, if any, prior to the promulgation of
designations by Fall 2011. The EPA solicited comment on whether EPA has
the authority to determine in this final rule that three years would be
necessary to make designations. The EPA also solicited comment on
making designations within two years from promulgation of a revised
NAAQS.
2. Comments and Responses
    Several commenters suggested that EPA should require that states
with current nonattainment or maintenance areas submit designation
recommendations for those counties or Metropolitan Statistical Areas
(MSAs) with nonattainment or maintenance areas within 120 days of
promulgation of the rule.
    Section 107(d)(1)(A) provides that States shall submit
recommendations for areas to be designated attainment, nonattainment,
and unclassifiable ``[b]y such date as the Administrator may reasonably
require, but not later than 1 year after promulgation of a new or
revised national ambient air quality standard for any pollutant under
section 109.'' EPA's consistent practice in revising NAAQS has been to
allow states a year to prepare their lists of designations, and the
proposal likewise indicated EPA's intent to allow a year for states to
prepare their recommendations. It is often true that when a standard is
made more stringent there will be existing nonattainment and
maintenance areas that may be expected to be nonattainment for the new
standard as well. Furthermore, EPA notes that the most recent three
years of available monitoring data for East Helena, MT, one of the two
current nonattainment areas, showed no violations of the current
standard, although the monitors were shut down in December 2001
following the shutdown of the large stationary source of lead emissions
there. The EPA also notes that preparing designation recommendations is
a complex task, and the magnitude of the reduction in the Pb NAAQS, and
the long interval since the last revision to the standard is likely to
add to the difficulty for states.
    Thus, while EPA considers the increased stringency of the standard
to be relevant to the question of when states should submit designation
recommendations, EPA does not believe that under the current
circumstances it would be reasonable to require states to submit a list
of areas to be designated attainment, nonattainment, or unclassifiable
sooner than one year following promulgation year.
    Therefore, pursuant to section 107(d)(1)(A), states shall, and
Tribes may, provide area designation recommendations to EPA no later
than October 15, 2009.\112\ In some areas, EPA

anticipates that state and Tribal officials will be able to base their
recommendations on existing monitoring data, and can therefore identify
an area as ``attainment'' or ``nonattainment.'' EPA also anticipates
that there will be other areas where state and Tribal officials will
not have sufficient information to make such a determination. State and
Tribal officials are advised to identify such areas as
``unclassifiable.'' For these areas EPA may wait until sufficient
ambient air quality data from the newly deployed Pb monitoring network
are available to take final action on the state and Tribal
recommendations.
---------------------------------------------------------------------------

    \112\ Under the CAA and the Tribal Authority Rule (TAR),
eligible Indian Tribes may develop and submit Tribal Implementation
Plans (TIPs) for EPA approval, to administer requirements under the
CAA on their reservations and in nonreservation areas under their
jurisdiction. However, Tribes are not required to develop TIPs or
otherwise implement relevant programs under the CAA. In cases where
a Tribal air quality agency has implemented an air quality
monitoring network which is affected by Pb emissions, the criteria
and procedures identified in this rule may be applied for regulatory
purposes. Certain Tribes may implement all relevant components of an
air quality program for purposes of meeting the various requirements
of this rule.
---------------------------------------------------------------------------

    Several commenters stated that EPA should promulgate designations
for the revised Pb NAAQS within the 2 year period provided in the CAA.
Commenters further stated that they do not understand why EPA needs to
take an additional year beyond the two years provided under the CAA to
do the designations. In addition, the commenters stated that they
believe EPA does not have the authority to take the additional year
(i.e., the 3rd year provided under section 107(d)(1)(B)(i) of the CAA)
to do designations for the Pb NAAQS because sufficient monitoring data
is available to do the designations within 2 years of promulgation of
the NAAQS.
    Other commenters stated that they agree with EPA that, given that
the current monitoring network for the Pb NAAQS is insufficient to base
designations on for the new NAAQS, EPA should not promulgate
designations until there is sufficient data from the new monitoring
network.
    Section 107(d)(1)(B)(i) provides that the Administrator shall
promulgate the designations of all areas as expeditiously as
practicable, but in no case later than 2 years from the date of
promulgation of the new or revised national ambient air quality
standard. Such period may be extended by up to one year in the event
the Administrator has insufficient information to promulgate the
designations.
    After considering the comments, and recognizing that in some
locations there may be monitoring data sufficient to determine whether
or not the area is attaining the standard, EPA now believes that the
benefits of identifying nonattainment areas as soon as possible, in
some areas as discussed shortly below, outweigh the potential
administrative benefits of designating all areas at the same time.
    At the same time, EPA continues to believe that the current
monitoring network is inadequate for making designations in many, if
not most, areas of the country, and agrees with those commenters who
stated that it would be preferable to wait until additional monitoring
data was available for those areas than to proceed to designate areas
based only on data from the current insufficient monitoring network.
The EPA notes that any delay in designations beyond two years would be
based on the lack of monitoring data (and the expectation that
additional monitoring data would be available if designations were
delayed) and would not be based on staffing and other non-data resource
issues.
    Accordingly, EPA believes that the most appropriate approach to
designations for the Pb NAAQS is for EPA to complete final designations
as expeditiously as possible, and to recognize that ``as expeditiously
as possible'' may result in making nonattainment designations at
different times for different areas. In some areas, EPA expects that it
will be possible to do designations within two years based on currently
available monitoring data. In other areas, EPA expects that taking the
additional year will prove necessary in order to collect the necessary
monitoring data before making designations.
3. Final
    After considering the comments and for the reasons discussed above,
EPA no longer plans to make all designations, and particularly all
nonattainment designations, at the same time. The EPA intends to make
designations as expeditiously as possible in areas where monitoring
data is currently sufficient, or will be sufficient in the immediate
future, to accurately characterize the areas as either not attaining or
attaining the new Pb NAAQS. In some cases this will be possible as
expeditiously as practicable, but no later than two years following
promulgation of the final rule. In other cases this will not be
possible until additional data are collected from the newly deployed
monitoring network, and may take up to three years.

B. Lead Nonattainment Area Boundaries

1. Proposal
    The process for initially designating areas following the
promulgation of a new or revised NAAQS is prescribed in section
107(d)(1) of the CAA. This section of the CAA provides each state
Governor an opportunity to recommend initial designations of
attainment, nonattainment, or unclassifiable for each area in the
state. Section 107(d)(1) of the CAA also directs the state to provide
the appropriate boundaries to EPA for each area of the state, and
provides that EPA may make modifications to the boundaries submitted by
the state as it deems necessary. A lead nonattainment area must consist
of that area that does not meet (or contributes to ambient air quality
in a nearby area that does not meet) the Pb NAAQS. Thus, a key factor
in setting boundaries for nonattainment areas is determining the
geographic extent of nearby source areas contributing to the
nonattainment problem. For each monitor or group of monitors that
exceed a standard, nonattainment boundaries must be set that include a
sufficiently large enough area to include both the area judged to be
violating the standard as well as the source areas that are determined
to be contributing to these violations.
    Historically, Pb NAAQS violations have been the result of lead
emissions from large stationary sources and mobile sources that burn
lead-based fuels. In some locations, a limited number of area sources
have also been determined to have contributed to violations. Since lead
has been successfully phased out of motor vehicle gasoline, these
sources are no longer a significant source of ambient lead
concentrations. At the revised standard level, EPA expects stationary
sources to be the primary contributor to violations of the NAAQS.
However, it is possible that fugitive dust emissions from area sources
containing deposited lead will also contribute to violations of the
revised Pb NAAQS. The location and dispersion characteristics of these
sources of ambient lead concentrations are important factors in
determining nonattainment area boundaries.
    In the proposed rule, EPA proposed to presumptively define the
boundary for designating a nonattainment area as the perimeter of the
county associated with the air quality monitor(s) which records a
violation of the standard. This presumption was also EPA's
recommendation for defining the nonattainment boundaries for the 1978
Pb NAAQS, and is described in the 1992 General Preamble (57 FR 13549).
In the proposed rule, EPA also requested comment on an option to
presumptively define the nonattainment boundary using the OMB-defined
Metropolitan Statistical Area (MSA) associated with

the violating monitor(s). This presumption was used historically, by
the CAA requirement, for the 1-hr ozone and CO NAAQS nonattainment
boundaries, and was also recommended by EPA as the appropriate
presumption for the 1997 8-hour ozone and PM2.5 NAAQS
nonattainment boundaries. In the proposed rule we stated that under
either option, the state and EPA may conduct additional area-specific
analyses that could lead EPA to depart from the presumptive boundary.
The factors relevant to such an analysis are described below.
    For the proposed Pb NAAQS, EPA recommended that nonattainment area
boundaries that deviate from presumptive county boundaries should be
supported by an assessment of several factors, which are discussed
below. The factors for determining nonattainment area boundaries for
the Pb NAAQS under this recommendation closely resemble the factors
identified in recent EPA guidance for the 1997 8-hour ozone NAAQS, the
1997 PM2.5 NAAQS, and the 2006 PM2.5 NAAQS
nonattainment area boundaries. For this particular option of the
proposal, EPA would consider the following factors in assessing whether
to exclude portions of a county and whether to include additional
nearby areas outside the county as part of the designated nonattainment
area:
     Emissions in areas potentially included versus excluded
from the nonattainment area.
     Air quality in potentially included versus excluded areas.
     Population density and degree of urbanization including
commercial development in included versus excluded areas.
     Expected growth (including extent, pattern and rate of
growth).
     Meteorology (weather/transport patterns).
     Geography/topography (mountain ranges or other air basin
boundaries).
     Jurisdictional boundaries (e.g., counties, air districts,
reservations, etc.).
     Level of control of emission sources.
    The proposal indicated that analyses of these factors may suggest
nonattainment area boundaries that are either larger or smaller than
the county boundary. A demonstration supporting the designation of
boundaries that are less than the full county would be required to show
both that violation(s) are not occurring in the excluded portions of
the county and that the excluded portions are not source areas that
contribute to the observed violations. Recommendations to designate a
nonattainment area larger than the county should also be based on an
analysis of these factors. The proposal stated that EPA would consider
these factors as well in evaluating state and Tribal recommendations
and assessing whether any modifications are appropriate.
    Under previous Pb implementation guidance, EPA advised that
Governors could choose to recommend lead nonattainment boundaries by
using any one, or a combination of the following techniques, the
results of which EPA would consider when making a decision as to
whether and how to modify the Governors' recommendations: (1)
Qualitative analysis, (2) spatial interpolation of air quality
monitoring data, or (3) air quality simulation by dispersion modeling.
These techniques are more fully described in ``Procedures for
Estimating Probability of Nonattainment of a PM10 NAAQS
Using Total Suspended Particulate or PM10 Data,'' December
1986 (see 57 FR 13549). In the proposed rule, EPA solicited comments on
the use of these factors and modeling techniques, and other approaches,
for adjusting county boundaries in designating nonattainment areas.
2. Comments and Responses
    Several commenters submitted comments stating that the
nonattainment boundaries should be limited to the smallest political
boundary that possesses an ambient monitor-based design value above the
standard, unless subsequent analyses demonstrate that the boundaries
should be larger or smaller. Commenters also stated that because lead
does not transport over long distances, monitoring data from upwind and
downwind sites illustrate that violations of the lead NAAQS are most
commonly isolated within a specific geographic area in close proximity
to a major source.
    The EPA agrees with the commenter that lead emissions do not
generally transport over long distances (as compared, e.g., to fine
particulate matter). In the proposed rule, EPA proposed to
presumptively define the boundary for designating a nonattainment area
as the perimeter of the county associated with the air quality
monitor(s) which records a violation of the standard. In the proposed
rule, EPA also stated that, at the revised level of the standard, EPA
expects stationary sources to be the primary contributor to violations
of the NAAQS, although we also believe that nearby area sources may
also contribute to concentrations of lead emissions that may affect a
violating monitor. In light of the possibility that a number of smaller
sources may collectively contribute to concentrations in excess of the
NAAQS, EPA believes that adopting the county boundary as the
presumptive boundaries for lead nonattainment areas is appropriate.
However, as stated in the proposed rule, a state, Tribe, or EPA may
conduct additional area-specific analyses that could lead to the
boundary for an area either being increased or decreased from the
presumptive county boundary. In situations where a single source,
rather than multiple sources, is causing a NAAQS violation, the EPA
believes that a state may well be able to use area-specific analyses to
identify whether a nonattainment area that is smaller than the county
boundary is appropriate.
    Several commenters stated that EPA should use the MSA as the
presumptive boundary for designating areas for the Pb NAAQS in order
for a broader range of source emissions to be taken into consideration
when the state develops its SIP for the nonattainment area.
    As stated previously, at the revised level of the standard, EPA
expects stationary sources to be the primary contributor to violations
of the Pb NAAQS, although we also expect that in some areas a number of
smaller sources may collectively contribute to concentrations in excess
of the NAAQS. MSAs are frequently composed of several counties.
Recognizing that lead emissions, particularly ultracoarse particles,
deposit relatively short distances from the proximity of their initial
source, EPA believes that adopting the county boundary surrounding a
violating monitor as the presumptive boundary for any given lead
nonattainment area is more appropriate than presuming the larger MSA
boundary. Furthermore, as stated in the proposed rule (and the previous
response), a state, Tribe, or EPA may conduct additional area-specific
analyses that could lead to the boundary for an area either being
increased or decreased from the presumptive boundary. Thus, where it
appears that emissions from one or more sources are contributing to
nonattainment throughout an MSA, the site-specific analysis may result
in the boundaries of the nonattainment area overlapping with those of
the MSA.
3. Final
    The EPA is finalizing the option to presumptively define the
boundary for designating a nonattainment area as the perimeter of the
county associated with the air quality monitor(s) which records a
violation of the standard as proposed.

This presumption was also EPA's recommendation for defining the
nonattainment boundaries for the pre-existing Pb NAAQS, and is
described in the 1992 General Preamble (57 FR 13549). As a part of the
county boundary presumption for nonattainment areas, the state and/or
EPA may conduct additional area-specific analyses that could lead EPA
to depart from the presumptive county boundary. The EPA is also
finalizing the factors relevant to such an analysis as described in the
proposed rule because we believe that they will allow for both the
State as well as EPA in some cases to define better the appropriate
boundaries for an area. The state may, in addition to submitting
recommendations for boundaries based on the factor analysis, also
choose to recommend lead nonattainment boundaries using any one, or a
combination of the following techniques, the results of which EPA would
consider when making a decision as to whether and how to modify the
Governors' recommendations: (1) Qualitative analysis, (2) spatial
interpolation of air quality monitoring data, or (3) air quality
simulation by dispersion modeling, as described more fully in
``Procedures for Estimating Probability of Nonattainment of a
PM10 NAAQS Using Total Suspended Particulate or
PM10 Data,'' December 1986 (see 57 FR 13549).

C. Classifications

1. Proposal
    Section 172(a)(1)(A) of the CAA authorizes EPA to classify areas
designated as nonattainment for the purpose of applying an attainment
date pursuant to section 172(a)(2), or for other reasons. In
determining the appropriate classification, EPA may consider such
factors as the severity of the nonattainment problem and the
availability and feasibility of pollution control measures (see section
172(a)(1)(A) of the CAA). The EPA may classify lead nonattainment
areas, but is not required to do so.
    While section 172(a)(1)(A) provides a mechanism to classify
nonattainment areas, section 172(a)(2)(D) provides that the attainment
date extensions described in section 172(a)(2)(A) do not apply to
nonattainment areas having specific attainment dates that are addressed
under other provisions of the part D of the CAA. Section 192(a), of
part D, specifically provides an attainment date for areas designated
as nonattainment for the Pb NAAQS. Therefore, EPA has legal authority
to classify lead nonattainment areas, but the 5 year attainment date
under section 192(a) cannot be extended pursuant to section
172(a)(2)(D). Based on this limitation, EPA proposed not to establish
classifications within the 5 year interval for attaining any new or
revised NAAQS. This approach is consistent with EPA's previous
classification decision for Pb in the 1992 General Preamble (See 57 FR
13549, April 16, 1992).
2. Comments and Responses
    Several commenters stated that they disagreed with EPA's proposal
not to classify lead nonattainment areas under CAA section
172(a)(1)(A). The commenters stated that existing nonattainment areas,
meaning areas that have not yet achieved the pre-existing Pb NAAQS,
would benefit from more rigorous SIP requirements associated with
classifications. The commenters stated that such classifications are
appropriate not only for deadline extensions (not applicable in this
case, as EPA notes), but ``for other purposes''. The commenters state
that such purposes should include lower emissions thresholds for
defining major stationary sources, higher offset ratios, and a more
ambitious definition of reasonable further progress.
    EPA stated in the proposed rule, that while section 172(a)(1)(A)
provides a mechanism to classify nonattainment areas, section
172(a)(2)(D) provides that the attainment date extensions described in
section 172(a)(2)(A) do not apply to nonattainment areas having
specific attainment dates that are addressed under other provisions of
part D of the CAA. Based on this limitation, EPA proposed not to
establish classifications within the 5 year interval for attaining any
new or revised NAAQS. This approach is consistent with EPA's previous
classification decision for Pb in the 1992 General Preamble (See 57 FR
13549, April 16, 1992) notes that subpart 2 of part D of the CAA
specifies mandatory control measures required for areas with different
classifications for the ozone standard, including such items as higher
offset ratios and specific percentage requirements for reasonable
further progress. Areas with higher classifications are subject to more
stringent controls, but also receive additional time to attain the
standard. Subpart 5 of part D contains no such provisions, but instead
requires submittal of a SIP within 18 months of designation of an area
as nonattainment, and requires attainment for all areas as
expeditiously as practicable, but no later than 5 years following
designation. Although EPA does have authority to establish
classifications for Pb, EPA continues to believe, taking into
consideration these differing statutory schemes (and particularly the
requirement to attain as expeditiously as practicable, but no later
than 5 years from designation) that it is not appropriate or necessary
to establish classifications for the revised Pb NAAQS.
3. Final
    The EPA is finalizing the guidance for classifications as provided
in the proposed rule. Therefore, there will be no classifications under
the revised Pb NAAQS.

D. Section 110(a)(2) Lead NAAQS Infrastructure Requirements

1. Proposal
    Under section 110(a)(1) and (2) of the CAA, all states are required
to submit plans to provide for the implementation, maintenance, and
enforcement of any new or revised NAAQS. Section 110(a)(1) and (2)
require states to address basic program elements, including
requirements for emissions inventories, monitoring, and modeling, among
other things. States are required to submit SIPs to EPA which
demonstrate that these basic program elements have been addressed
within 3 years of the promulgation of any new or revised NAAQS.
Subsections (A) through (M) of section 110(a)(2) listed below, set
forth the elements that a state's program must contain in the SIP.\113\
The list of section 110(a)(2) NAAQS implementation requirements are the
following:
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    \113\ Two elements identified in section 110(a)(2) are not
listed below because, as EPA interprets the CAA, SIPs incorporating
any necessary local nonattainment area controls would not be due
within 3 years, but rather are due at the time the nonattainment
area planning requirements are due. These elements are: (1) Emission
limits and other control measures, section 110(a)(2)(A), and (2)
Provisions for meeting part D, section 110(a)(2)(I), which requires
areas designated as nonattainment to meet the applicable
nonattainment planning requirements of part D, title I of the CAA.
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     Ambient air quality monitoring/data system: Section
110(a)(2)(B) requires SIPs to provide for setting up and operating
ambient air quality monitors, collecting and analyzing data and making
these data available to EPA upon request.
     Program for enforcement of control measures: Section
110(a)(2)(C) requires SIPs to include a program providing for
enforcement of measures and regulation and permitting of new/modified
sources.
     Interstate transport: Section 110(a)(2)(D) requires SIPs
to include provisions prohibiting any source or

other type of emissions activity in the state from contributing
significantly to nonattainment in another state or from interfering
with measures required to prevent significant deterioration of air
quality or to protect visibility.
     Adequate resources: Section 110(a)(2)(E) requires states
to provide assurances of adequate funding, personnel and legal
authority for implementation of their SIPs.
     Stationary source monitoring system: Section 110(a)(2)(F)
requires states to establish a system to monitor emissions from
stationary sources and to submit periodic emissions reports to EPA.
     Emergency power: Section 110(a)(2)(G) requires states to
include contingency plans, and adequate authority to implement them,
for emergency episodes in their SIPs.
     Provisions for SIP revision due to NAAQS changes or
findings of inadequacies: Section 110(a)(2)(H) requires states to
provide for revisions of their SIPs in response to changes in the
NAAQS, availability of improved methods for attaining the NAAQS, or in
response to an EPA finding that the SIP is inadequate.
     Section 121 consultation with local and Federal government
officials: Section 110(a)(2)(J) requires states to meet applicable
local and Federal government consultation requirements of section 121.
     Section 127 public notification of NAAQS exceedances:
Section 110(a)(2)(J) requires states to meet applicable requirements of
section 127 relating to public notification of violating NAAQS.
     PSD and visibility protection: Section 110(a)(2)(J) also
requires states to meet applicable requirements of title I part C
related to prevention of significant deterioration and visibility
protection.
     Air quality modeling/data: Section 110(a)(2)(K) requires
that SIPs provide for performing air quality modeling for predicting
effects on air quality of emissions of any NAAQS pollutant and
submission of data to EPA upon request.
     Permitting fees: Section 110(a)(2)(L) requires the SIP to
include requirements for each major stationary source to pay permitting
fees to cover the cost of reviewing, approving, implementing and
enforcing a permit.
    Consultation/participation by affected local government: Section
110(a)(2)(M) requires states to provide for consultation and
participation by local political subdivisions affected by the SIP.
2. Final
    The EPA is finalizing the guidance related to the submittal of SIPs
to address the infrastructure requirements of section 110(a)(1) and (2)
as stated in the proposed rule.

E. Attainment Dates

1. Proposal
    As discussed in the proposal, the maximum deadline date by which an
area is required to attain the Pb NAAQS is determined by the effective
date of the nonattainment designation for the area. For areas
designated nonattainment for the revised Pb NAAQS, SIPs must provide
for attainment of the NAAQS as expeditiously as practicable, but no
later than 5 years from the date of the nonattainment designation for
the area (see section 192(a) of the CAA). In the proposed rule, EPA
stated it would determine whether an area had demonstrated attainment
of the Pb NAAQS by evaluating air quality monitoring data from the one,
two, or three previous years as available.
2. Comments and Responses
    A commenter stated that the attainment deadline for the current
nonattainment and maintenance areas should be three years.
    Under the CAA, states are required to attain as expeditiously as
practicable (but in no case later than five years). If it is
practicable for a nonattainment area to attain the standard within
three years, then the SIP must provide for attainment within three
years. If, however, attainment within three years is not practicable,
then EPA has no authority to require attainment by that deadline.
2. Final
    The EPA is generally finalizing the guidance related to attainment
dates as provided in the proposed rule. States with nonattainment areas
will be required to attain the standard as expeditiously as
practicable, but in no event later than five years from the effective
date of the nonattainment designation. EPA wishes to clarify that it
will be considering air quality monitoring data from the three previous
years, as available, in determining whether areas have demonstrated
attainment (i.e., EPA would only consider data for less than the three
previous years in situations where the data for all three years was
unavailable).

F. Attainment Planning Requirements

    Any state containing an area designated as nonattainment with
respect to the Pb NAAQS must develop for submission, a SIP meeting the
requirements of part D, Title I, of the CAA, providing for attainment
by the applicable deadline (see sections 191(a) and 192(a) of the CAA).
As indicated in section 191(a) all components of the lead part D SIP
must be submitted within 18 months of the effective date of an area's
designation as nonattainment. Additional specific plan requirements for
lead nonattainment areas are outlined in 40 CFR 51.117.
    The general part D nonattainment plan requirements are set forth in
section 172 of the CAA. Section 172(c) specifies that SIPs submitted to
meet the part D requirements must, among other things, include
Reasonably Available Control Measures (RACM) (which includes Reasonably
Available Control Technology (RACT)), provide for Reasonable Further
Progress (RFP), include an emissions inventory, require permits for the
construction and operation of major new or modified stationary sources
(see also CAA section 173), contain contingency measures, and meet the
applicable provisions of section 110(a)(2) of the CAA related to the
general implementation of a new or revised NAAQS. It is important to
note that lead nonattainment SIPs must meet all of the requirements
related to part D of the CAA, including those specified in section
172(c), even if EPA does not provide separate specific guidance for
each provision.
1. RACM/RACT for Lead Nonattainment Areas
a. Proposal
    Lead nonattainment area SIPs must contain RACM (including RACT)
that address sources of ambient lead concentrations. In general, EPA
believes that lead NAAQS violation issues will usually be attributed to
emissions from stationary sources. In EPA's 2002 National Emissions
Inventory (NEI), there were 12 stationary sources in the country with
lead emissions over 5 tons per year, and 124 sources over 1 ton of lead
emissions per year.
    Some emissions that contribute to violations of the Pb NAAQS may
also be attributed to smaller area sources. At primary lead smelters,
the process of reducing concentrated ore to lead involves a series of
steps, some of which are completed outside of buildings, or inside of
buildings that are not totally enclosed. Over a period of time,
emissions from these sources have been deposited in neighboring
communities (e.g., on roadways, parking lots, yards, and off-plant
property). This historically deposited lead, when disturbed, may be

re-entrained into the ambient air and may contribute to violations of
the Pb NAAQS in affected areas.
    The first step in addressing RACM for lead is identifying potential
control measures for sources of lead in the nonattainment area. A
suggested starting point for specifying RACM in lead nonattainment area
SIPs is outlined in appendix 1 of the guidance entitled ``State
Implementation Plans for Lead Nonattainment Areas; Addendum to the
General Preamble for the Implementation of Title I of the Clean Air Act
Amendments of 1990'', 58 FR 67752, December 22, 1993. If a state is
aware of facts, or receives substantive public comments, that
demonstrate through appropriate documentation, that additional control
measures may be reasonably available in a specific area, the measures
should be added to the list of available measures for consideration in
that particular area.
    While EPA does not presume that these control measures are
reasonably available in all areas, a reasoned justification for
rejection of any available control measure should be prepared. If it
can be shown that measures, considered both individually as well as in
a group, are unreasonable because emissions from the affected sources
are insignificant, then the measures may be excluded from further
consideration as they would not be representative of RACM for the
affected area. The resulting control measures should then be evaluated
for reasonableness, considering their technological feasibility and the
cost of control in the area for which the SIP applies. In the case of
public sector sources and control measures, this evaluation should
consider the impact and reasonableness of the measures on the
municipal, or other governmental entity that must assume the
responsibility for their implementation. It is important to note that a
state should consider the feasibility of implementing measures in part
when full implementation would be infeasible. A reasoned justification
for partial or full rejection of any available control measure,
including those considered or presented during the state's public
hearing process, should be prepared. The justification should contain a
detailed explanation, with appropriate documentation, as to why each
rejected control measure is deemed infeasible or otherwise unreasonable
for implementation.
    Economic feasibility considers the cost of reducing emissions and
the difference between the cost of the emissions reduction approach at
the particular source in question and the costs of emissions reduction
approaches that have been implemented at other similar sources. Absent
other indications, EPA as a general matter expects 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 particular source category have in
fact applied the control technology or process change in question. The
EPA also encourages the development of innovative measures not
previously employed which may also be technically and economically
feasible.
    The capital costs, annualized costs, and cost effectiveness of an
emissions reduction technology should be considered 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,\114\ 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. 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. With respect to
a given pollutant, a measure is likely to be reasonable if it has a
cost per ton similar to other measures previously employed for 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 CAA's timeframes.
---------------------------------------------------------------------------

    \114\ 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.
---------------------------------------------------------------------------

    The fact that a measure has been adopted or is in the process of
being adopted by other states is also 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 difficulty of attaining
expeditiously. Nevertheless, states should consider and address RACT
and RACM measures developed for other areas, as part of a well reasoned
RACT and RACM analysis. The EPA's own evaluation of SIPs for compliance
with the RACT and RACM requirements will include comparison of measures
considered or adopted by other states.
    In considering what level of control is reasonable, EPA is not
adopting a specific dollar per ton cost threshold for RACT. 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 public health benefits from attaining the standard as
expeditiously as practicable. 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 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.
    The EPA believes that in determining appropriate emission control
levels, the state should consider the collective public health benefits
that can be realized in the area due to projected improvements in air
quality. Because EPA believes that RACT requirements 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 problems.
    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. It should be noted that such benefits estimates
are subject to significant uncertainty and that benefits per ton vary
in different areas. Nonetheless this information could be used in a way
that recognizes these uncertainties. If a per ton cost of implementing
a measure is significantly less than the anticipated benefits per ton,
this would be an indicator that the cost per ton is reasonable. 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, then the source should
support its claim by providing detailed and verified information
regarding the impact of imposing RACT on:
     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, and
     Employment costs.
    The technical guidance entitled ``Fugitive Dust Background Document
and Technical Information Document for Best Available Control
Measures'' (EPA-450/2-92-004, September 1992) provides an example for
states on how to analyze control costs for a given area.
    Once the process of determining RACM for an area is completed, the
individual measures should then be converted into a legally enforceable
vehicle (e.g., a regulation or permit program) (see section 172(c)(6)
and section 110(a)(2)(A) of the CAA). The regulations or other measures
submitted should meet EPA's criteria regarding the enforceability of
SIPs and SIP revisions. These criteria were stated in a September 23,
1987 memorandum (with attachments) from J. Craig Potter, Assistant
Administrator for Air and Radiation; Thomas L. Adams, Jr., Assistant
Administrator for Enforcement and Compliance Monitoring; and S. Blake,
General Counsel, Office of the General Counsel; entitled ``Review of
State Implementation Plans and Revisions of Enforceability and Legal
Sufficiency.'' As stated in this memorandum, SIPs and SIP revisions
that fail to satisfy the enforceability criteria should not be
forwarded for approval. If they are submitted, they will be disapproved
if, in EPA's judgment, they fail to satisfy applicable statutory and
regulatory requirements.
    The EPA's historic definition of RACT is 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.\115\ RACT applies
to the ``existing sources'' of lead in an area including stack
emissions, industrial process fugitive emissions, and industrial
fugitive dust emissions (e.g., on-site haul roads, unpaved staging
areas at the facility, etc.) (see section 172(c)(1)). The EPA's
previous guidance for implementing the pre-existing Pb NAAQS recommends
that stationary sources which emit a total of 5 tpy of lead or lead
compounds, measured as elemental lead, be the minimum starting point
for RACT analysis (see 58 FR 67750, December 22, 1993). Further, EPA's
existing guidance recommends that available control technology be
applied to those existing sources in the nonattainment area that are
reasonable to control in light of the attainment needs of the area and
the feasibility of such controls. Thus, under existing guidance, a
state's control technology analysis may need to include sources which
actually emit less than 5 tpy of lead or lead compounds in the area, or
other sources in the area that are reasonable to control, in light of
the attainment needs and feasibility of control for the area.
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    \115\ See for example, 44 FR 53762 (September 17, 1979) and
footnote 3 of that notice. Note that EPA's emissions trading policy
statement has clarified that the RACT requirement may be satisfied
by achieving ``RACT equivalent'' emission reductions in the
aggregate from the full set of existing stationary sources in the
area. See also EPA's economic incentive proposal which reflects the
Agency's policy guidance with respect to emissions trading, 58 FR
11110, February 23, 1993.
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    Given the proposal to promulgate a revised Pb NAAQS that is
significantly lower than the current level of 1.5 [mu]g/m\3\, EPA
requested comment on the appropriate threshold for the minimum starting
point for future Pb RACT analyses for stationary lead sources in
nonattainment areas. In the proposed rule, EPA requested comment on the
emissions level associated with the minimum network source monitoring
requirements. These source levels range from 200 kg/yr to 600 kg/yr.
The EPA also stated that one possible approach for RACT is to recommend
that RACT analyses for Pb sources be consistent with sources that are
required to monitor such that all stationary sources above 200 kg/yr to
600 kg/yr should undergo a RACT review. EPA also requested comment on
source monitoring for stationary sources that emit lead emissions in
amounts that have potential to cause ambient levels at least one-half
the selected NAAQS level. This suggests another potential
recommendation for the starting point for the RACT analysis. The EPA
sought comment on these ideas as well as any information which
commenters could provide that would help inform EPA's recommendation on
an appropriate emissions threshold for initiating RACT analyses.
b. Comments and Responses
    Several commenters stated that given the proposed level of the lead
NAAQS that EPA should set the threshold for RACT analysis for
stationary sources at a threshold level similar to the level being
considered for the source monitoring requirements, which is between 200
kg/yr-600 kg/yr. Several commenters suggested a lower threshold (such
as 45 kg/year) or stated that depending on the attainment needs for the
affected area, it may be necessary to evaluate control technology that
is reasonably available for sources with actual emissions that are
lower than the recommended RACM/RACT threshold to take into
consideration the actual attainment needs for the affected area. One
commenter suggested the threshold should be set only at a level at
which an exceedance of the NAAQS is expected, while another suggested
it should be set no higher than that level.
    The EPA believes that it is appropriate to set the recommended
threshold for the RACT analysis for the new standard at 0.5 tpy. The
existing Pb NAAQS is set at 1.5 [mu]g/m\3\ and the existing threshold
for RACT analysis is 5 tpy. Since the standard is being reduced by a
factor of ten, from 1.5 [mu]g/m\3\ to 0.15 [mu]g/m\3\, it is
appropriate to also reduce the threshold for RACT analysis by a factor
of 10, from 5 tpy to 0.5 tpy. Furthermore, the monitor siting criteria
include a requirement for monitoring agencies to conduct monitoring
taking into account sources that are expected to exceed the NAAQS, and
require monitoring for sources which emit Pb at a rate of one ton per
year. Although EPA expects that sources emitting less than one tpy may
also contribute to violations of the revised Pb NAAQS, EPA believes
that the one tpy requirement in the monitor siting criteria provides a
benchmark that is more likely to clearly identify sources that would
contribute to exceedances of the NAAQS. Accordingly, using 50% of that
figure (0.5 tpy) as the threshold for RACT analysis is generally
consistent with EPA's consideration in the proposal of setting the RACT
threshold to include those stationary sources that emit lead emissions
in amounts that have the potential to cause ambient levels at least
one-half the selected NAAQS.
    EPA believes that setting the RACT threshold higher (e.g., at 1
tpy) would not be appropriate because it is likely that in a
nonattainment area sources emitting less than one tpy are contributing
to the nonattainment of the NAAQS. EPA also does not believe a lower
threshold is warranted as a general matter, but EPA agrees with
commenters that the state's control technology analysis should also
include, as appropriate, sources which actually emit less than the
threshold level of 0.5 tpy of lead or lead compounds in the

area, or other sources in the area that are reasonable to control, in
light of the attainment needs and feasibility of controls for the
affected area.
    Several commenters stated that in the proposed rule EPA suggests
that the 1993 guidance document, which lists control measures as a
starting point for states' consideration, puts the burden on the public
to demonstrate through appropriate documentation that additional
control measures may be reasonably available in a particular
circumstance for an area. The commenters further stated that in light
of an anticipated substantial reduction in the Pb NAAQS, as well as the
failure of the remaining two existing nonattainment areas to achieve
attainment of the pre-existing (1978) NAAQS under the 1993 guidance,
that both EPA and the states should bear the principal responsibility
for developing an updated roster of successful control measures.
    As stated in the proposed rule, EPA believes that the regulations,
policies, and guidance currently in place for the implementation of the
pre-existing Pb NAAQS are still appropriate to address the issues
required to implement the revised Pb NAAQS. The EPA believes that these
guidance, policies, and regulations should be used by states, local,
and Tribal governments as a starting point to begin implementation of
the revised Pb NAAQS. The EPA expects that as states gain additional
experience with implementing the revised NAAQS, additional information
on successful control measures will become available to states, EPA,
and the public. The EPA will, as appropriate, review, and revise or
update policies, guidance, and regulations to provide for effective
implementation of the Pb NAAQS.
c. Final
    The EPA is finalizing the guidance related to RACM (including RACT)
for lead nonattainment areas consistent with the proposed rule. Based
upon the above considerations regarding the scale of the reduction in
the standard, the final monitor siting criteria, and the public
comments received related to the starting point for a RACT analysis,
EPA is recommending a threshold for RACT analysis such that at least
all stationary sources emitting 0.5 tpy or more should undergo a RACT
review.
2. Demonstration of Attainment for Lead Nonattainment Areas
a. Proposal
    The SIPs for lead nonattainment areas should provide for the
implementation of control measures for point and area sources of lead
emissions which demonstrate attainment of the Pb NAAQS as expeditiously
as practicable, but no later than the applicable statutory attainment
date for the area (see also 40 CFR 51.117(a) for additional control
strategy requirements). Therefore, if a state adopts less than all
available measures in an area but demonstrates, adequately, that
reasonable further progress (RFP), and attainment of the Pb NAAQS are
assured, and the application of all such available measures would not
result in attainment any faster, then a plan which requires
implementation of less than all technologically and economically
available measures may be approved (see 44 FR 20375 (April 4, 1979) and
56 FR 5460 (February 11, 1991)). The EPA believes that it would be
unreasonable to require that a plan which demonstrates attainment
include all technologically and economically available control measures
even though such measures would not expedite attainment. Thus, for some
sources in areas which demonstrate attainment, it is possible that some
available control measures may not be ``reasonably'' available because
their implementation would not expedite attainment for the affected
area.
b. Final
    The EPA is finalizing the guidance related to demonstration of
attainment for lead nonattainment areas as stated in the proposed rule.
Further discussion of modeling for attainment and other topics is
presented below.
3. Reasonable Further Progress (RFP)
a. Proposal
    Part D SIPs must provide for RFP (see section 172(c)(2) of the
CAA). Section 171 of the CAA defines RFP as ``such annual incremental
reductions in emissions of the relevant air pollution as are required
by part D, or may reasonably be required by the Administrator for the
purpose of ensuring attainment of the applicable NAAQS by the
applicable attainment date.'' Historically, for some pollutants, RFP
has been met by showing annual incremental emission reductions
generally sufficient to maintain linear progress toward attainment by
the applicable attainment date. The EPA believes that RFP for lead
nonattainment areas should be met by ``adherence to an ambitious
compliance schedule'' which is expected to periodically yield
significant emission reductions, and as appropriate, linear
progress.\116\ The EPA recommends that SIPs for lead nonattainment
areas provide a detailed schedule for compliance of RACM (including
RACT) in the affected areas and accurately indicate the corresponding
annual emission reductions to be achieved. In reviewing the SIP, EPA
believes that it is appropriate to expect early implementation of less
technology-intensive control measures (e.g., controlling fugitive dust
emissions at the stationary source, as well as required controls on
area sources) while phasing in the more technology-intensive control
measures, such as those involving the installation of new hardware.
Finally, failure to implement the SIP provisions required to meet
annual incremental reductions in emissions (i.e., RFP) in a particular
area could result in the application of sanctions as described in
section 179(b) of the CAA (pursuant to a finding under section
179(a)(4)), and the implementation of contingency measures required by
section 172(c)(9) of the CAA.
---------------------------------------------------------------------------

    \116\ As previously stated in the proposed rule, EPA believes
that most lead nonattainment problems will most likely be due to
emissions from stationary sources of lead. For this reason EPA
believes that the RFP for Pb should parallel the RFP policy for SO2
(see General Preamble, 57 FR 13545, April 16, 1992).
---------------------------------------------------------------------------

b. Comments and Responses
    Several commenters stated that EPA's proposal related to RFP would
allow states to avoid the need to demonstrate linear progress towards
attainment, departing from the typical method used, and statutorily
required in some cases, for other criteria pollutants. These commenters
further state that the recognition that some nonattainment urban areas
have numerous sources contributing to excessive ambient levels of lead
which undermines the reasoning employed to justify a non-linear
approach in the context of single source nonattainment areas. If areas
with large sources install key controls early on in the attainment
process, and thus achieve attainment ahead of schedule, that would
advance the goals and requirements of the CAA.
    Historically, for some pollutants, RFP has been met by showing
annual incremental emission reductions generally sufficient to maintain
linear progress toward attainment by the applicable attainment date. As
EPA has previously noted, we expect that some nonattainment
designations will be attributable to a single stationary source, and
others may be attributable to a number of smaller sources. Where a
single source is the cause of

nonattainment, EPA would not expect linear progress towards attainment.
Rather, there may be relatively less progress while the source adopts
non-technological control measures and begins to install necessary
technological controls, and then significant progress towards
attainment in a short period of time once all the controls are
operational. EPA expects that, since states are required to attain the
standard as expeditiously as practicable, the SIP will require large
sources to install ``key controls'' as expeditiously as practicable. At
the same time, where a number of sources are contributing to
nonattainment, it is more reasonable to expect that controls (both
technological and non-technological) may be adopted at different times,
making linear progress a more reasonable expectation. To accommodate
both of these possible situations, EPA concludes it is appropriate that
RFP for lead nonattainment areas should be met by the strict adherence
to an ambitious compliance schedule which is expected to periodically
yield significant emission reductions, and, to the extent appropriate,
linear progress.
c. Final
    The EPA is finalizing the guidance related to reasonable further
progress (RFP) consistent with the proposed rule. The EPA believes that
RFP for lead nonattainment areas should be met by the strict adherence
to an ambitious compliance schedule which is expected to periodically
yield significant emission reductions, and to the extent appropriate,
linear progress. The EPA recommends that SIPs for lead nonattainment
areas provide a detailed schedule for compliance of RACM (including
RACT) and accurately indicate the corresponding annual emission
reductions to be achieved. In reviewing the SIP, EPA believes that it
is appropriate to expect early implementation of less technology-
intensive control measures (e.g., work practices to control fugitive
dust emissions at the stationary sources) while phasing in the more
technology-intensive control measures, such as those involving the
installation of new hardware. The EPA believes that the expeditious
implementation of RACM/RACT at affected sources within the
nonattainment area is an appropriate approach to assure attainment of
the Pb NAAQS in an expeditious manner.
4. Contingency Measures
a. Proposal
    Section 172(c)(9) of the CAA defines contingency measures as
measures in a SIP that are to be implemented if an area fails to
achieve and maintain RFP, or fails to attain the NAAQS by the
applicable attainment date. Contingency measures must be designed to
become effective without further action by the state or the
Administrator, upon determination by EPA that the area has failed to
achieve, or maintain reasonable further progress (RFP), or attain the
Pb NAAQS by the applicable statutory attainment date. Contingency
measures should consist of available control measures that are not
already included in the primary control strategy for the affected area.
    Contingency measures are important for lead nonattainment areas,
which may violate the NAAQS generally due to emissions from stationary
sources, for several reasons. First, process and fugitive emissions
from these stationary sources, and the possible re-entrainment of
historically deposited emissions, have historically been difficult to
quantify. Therefore, the analytical tools for determining the
relationship between reductions in emissions, and resulting air quality
improvements, can be subject to some uncertainties. Second, emission
estimates and attainment analysis can be influenced by overly
optimistic assumptions about fugitive emission control efficiency.
    Examples of contingency measures for controlling area source
fugitive emissions may include measures such as stabilizing additional
storage piles. Examples of contingency measures for process-related
fugitive emissions include increasing the enclosure of buildings,
increasing air flow in hoods, modifying operation and maintenance
procedures, etc. Examples of contingency measures for stack sources
include reducing hours of operation, changing the feed material to
lower lead content, and reducing the occurrence of malfunctions by
modifying operation and maintenance procedures, etc.
    Section 172(c)(9) provides that contingency measures should be
included in the state SIP for a lead nonattainment area and shall
``take effect without further action by the state or the
Administrator.'' The EPA interprets this requirement to mean that no
further rulemaking actions by the state, or EPA, would be needed to
implement the contingency measures (see generally 57 FR 12512 and
13543-13544). The EPA recognizes that certain actions, such as the
notification of sources, modification of permits, etc., may be needed
before a measure could be implemented. However, states must show that
their contingency measures can be implemented with only minimal further
action on their part and with no additional rulemaking actions such as
public hearings or legislative review. After EPA determines that a lead
nonattainment area has failed to maintain RFP or timely attain the Pb
NAAQS, EPA generally expects all actions needed to affect full
implementation of the measures to occur within 60 days after EPA
notifies the state of such failure. The state should ensure that the
measures are fully implemented as expeditiously as practicable after
the requirement takes effect.
b. Comments and Responses
    Several commenters stated that EPA noted in the proposed rulemaking
that ``contingency measures are important for lead nonattainment
areas'' and that the CAA requires that contingency measures must ``take
effect without further action'' by the state or the Administrator.''
However, the commenters stated that EPA then interprets the ``take
effect without further action'' requirement too broadly, indicating
that it is satisfied if the contingency measure can take effect without
further rulemaking. The EPA would allow contingency measures that
require a state to undertake a permit modification before the
contingency measures would go into effect.
    As stated in the proposed rule, section 172(c)(9) of the CAA
defines contingency measures as measures in a SIP that are to be
implemented if an area fails to achieve and maintain RFP, or fails to
attain the NAAQS by the applicable attainment date. Contingency
measures must be designed to become effective without further action by
the state or the Administrator, upon determination by EPA that the area
has failed to achieve, or maintain reasonable further progress, or
attain the Pb NAAQS by the applicable statutory attainment date. As
stated in the proposed rule, the EPA believes that this requirement
means that no further rulemaking actions by the state, or EPA, would be
needed to implement the contingency measures (see generally 57 FR 12512
and 13543-13544). The EPA recognizes that in some circumstances minimal
actions, such as the notification of sources, modification of permits,
etc., may be needed before a measure could be implemented. However, as
also stated in the proposed rule, states must show that their
contingency measures can be implemented with only minimal further
action on their part and that no additional rulemaking actions will be
required, such as public hearings or legislative review, which will
delay the expeditious implementation of the

contingency measures in the affected area. To the extent that
modifications in title V operating permits would be required to
implement contingency measures, the SIP should provide that those
permits will be issued or modified prior to the time such contingency
measures may be needed to include alternative operating scenarios
providing for implementation of the contingency measures if necessary.
See 40 CFR 70.6(a)(9). The EPA generally expects that all actions,
including those actions related to modification of permits, that are
needed to affect full implementation of the contingency measures, must
occur within 60 days following EPA's notification to the state of such
failure.
c. Final
    The EPA is finalizing the guidance related to contingency measures
for lead nonattainment areas as stated in the proposed rule. The key
requirements associated with contingency measures are: (1) Contingency
measures must be fully adopted rules or control measures that are ready
to be implemented as expeditiously as practicable upon a determination
by EPA that the area has failed to achieve, or maintain reasonable
further progress, or attain the Pb NAAQS by the applicable statutory
attainment date; (2) The SIP should contain trigger mechanisms for the
contingency measures and specify a schedule for implementation; and (3)
The SIP must indicate that the measures will be implemented without
further action (or only minimal action) by the state or by the
Administrator. The contingency measures should also consist of control
measures for the area that are not already included in the control
strategy for the attainment demonstration of the SIP. The EPA believes
that the measures should provide for emission reductions that are at
least equivalent to one year's worth of reductions needed for the area
to meet the requirements of RFP, based on linear progress towards
achieving the overall level of reductions needed to demonstrate
attainment.
5. Nonattainment New Source Review (NSR) and Prevention of Significant
Deterioration (PSD) Requirements
a. Proposal
    The PSD and nonattainment NSR programs contained in parts C and D
of Title I of the CAA govern preconstruction review and permitting
programs for any new or modified major stationary sources of air
pollutants regulated under the CAA as well as any precursors to the
formation of that pollutant when identified for regulation by the
Administrator. The EPA rules addressing these regulations can be found
at 40 CFR 51.165, 51.166, 52.21, 52.24, and part 51, appendix S.
    States containing areas designated as nonattainment for the Pb
NAAQS must submit SIPs that address the requirements of nonattainment
NSR. Specifically, section 172(c)(5) of the CAA requires that states
which have areas designated as nonattainment for the Pb NAAQS must
submit, as a part of the nonattainment area SIP, provisions requiring
permits for the construction and operation of new or modified
stationary sources anywhere in the nonattainment area, in accordance
with the permit requirements pursuant to section 173 of the CAA.
Likewise, areas designated attainment must submit infrastructure SIPs
that address the requirements of PSD pursuant to section 110(a)(2)(C).
    Stationary sources that emit lead are currently subject to
regulation under existing requirements for the preconstruction review
and approval of new and modified stationary sources. The existing
requirements, referred to collectively as the New Source Review (NSR)
program, require all major and certain minor stationary sources of any
air pollutant for which there is a NAAQS to undergo review and approval
prior to the commencement of construction.\117\ The NSR program is
composed of three different permit programs:
---------------------------------------------------------------------------

    \117\ The terms ``major'' and ``minor'' define the size of a
stationary source, for applicability purposes, in terms of an annual
emissions rate (tons per year, tpy) for a pollutant. Generally, a
minor source is any source that is not ``major.'' ``Major'' is
defined by the applicable regulations--PSD or nonattainment NSR.
---------------------------------------------------------------------------

     Prevention of Significant Deterioration (PSD).
     Nonattainment NSR (NA NSR).
     Minor NSR.
    The PSD program and nonattainment NSR programs, contained in parts
C and D, respectively, of Title I of the CAA, are often referred to as
the major NSR program because these programs regulate only major
sources.
    The PSD program applies when a major source, that is located in an
area that is designated as attainment or unclassifiable for any
criteria pollutant, is constructed, or undergoes a major
modification.\118\ The nonattainment NSR program applies when a major
source of a criteria pollutant that is located in an area that is
designated as nonattainment for that pollutant is constructed or
undergoes a major modification. The minor NSR program addresses both
major and minor sources that undergoes construction or modification
activities that do not qualify as major, and it applies regardless of
the designation of the area in which a source is located.
---------------------------------------------------------------------------

    \118\ In addition, the PSD program applies to non-criteria
pollutants subject to regulation under the Act, except those
pollutants regulated under section 112 and pollutants subject to
regulation only under section 211(o).
---------------------------------------------------------------------------

    The national regulations that apply to each of these programs are
located in the CFR as shown below:

------------------------------------------------------------------------
                                                    Applications
------------------------------------------------------------------------
PSD.......................................  40 CFR 52.21, 40 CFR 51.166,
                                             40 CFR 51.165(b).
NA NSR....................................  40 CFR 52.24, 40 CFR 51.165,
                                             40 CFR part 51, Appendix S.
Minor NSR.................................  40 CFR 51.160-164.
------------------------------------------------------------------------

    The PSD requirements include but are not limited to the following:
     Installation of Best Available Control Technology (BACT);
     Air quality monitoring and modeling analyses to ensure
that a project's emissions will not cause or contribute to a violation
of any NAAQS or maximum allowable pollutant increase (PSD increment);
     Notification of Federal Land Manager of nearby Class I
areas; and
     Public comment on permit.
    Nonattainment NSR requirements include but are not limited to:
     Installation of Lowest Achievable Emissions Rate (LAER)
control technology;
     Offsetting new emissions with creditable emissions
reductions;
     A certification that all major sources owned and operated
in the state by the same owner are in compliance with all applicable
requirements under the CAA;
     An alternative siting analysis demonstrating that the
benefits of the proposed source significantly outweigh the
environmental and social costs imposed as a result of its location,
construction, or modification; and
     Public comment on the permit.
    Minor NSR programs must meet the statutory requirements in section
110(a)(2)(C) of the CAA which requires ``* * * regulation of the
modification and construction of any stationary source * * * as
necessary to assure that the [NAAQS] are achieved.''
    Areas which are newly designated as nonattainment for the Pb NAAQS
as a result of any changes made to the NAAQS will be required to adopt
a nonattainment NSR program to address major sources of lead where the
program does not currently exist for the Pb NAAQS. Prior to adoption of
the SIP

revision addressing NSR for lead nonattainment areas, the requirements
of 40 CFR part 51, appendix S will apply.
b. Comments and Responses
    Several commenters stated that given the significant changes being
proposed for the revised Pb NAAQS, EPA must promptly undertake
rulemaking action in order to satisfy the PSD requirements related to
the revised Pb NAAQS. The commenters further stated that EPA should
revise the current regulations related to the establishment of maximum
allowable increases or increments for lead under 40 CFR 51.166(a), and
a substantial reduction in the significant/de minimis emissions levels
for lead set forth in 40 CFR 51.166(b)(23)(i) and 40 CFR
52.21(b)(23)(i).
    As stated previously, the EPA believes that generally, there is
sufficient guidance and regulations already in place to fully implement
the revised Pb NAAQS. The EPA notes that, under section 110(a)(2)(D),
every minor source NSR program must be sufficiently complete and
stringent ``to assure that the [NAAQS] are achieved.'' The EPA will as
appropriate review and revise and update policies, guidance, and
regulations for implementing the revised Pb NAAQS following the
promulgation of the NAAQS.
c. Final
    The EPA is finalizing the guidance related to nonattainment NSR and
PSD requirements for lead nonattainment areas as provided in the
proposed rule.
6. Emissions Inventories
a. Proposal
    States must develop and periodically update a comprehensive,
accurate, current inventory of actual emissions affecting ambient lead
concentrations. The emissions inventory is used by states and EPA to
determine the nature and extent of the specific control strategy
necessary to help bring an area into attainment of the NAAQS. Emissions
inventories should be based on measured emissions or documented
emissions factors. Generally, the more comprehensive and accurate the
inventory, the more effective the evaluation of possible control
measures can be for the affected area (see section 172(c)(3) of the
CAA).
    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 as well as
their precursors. The EPA codified these requirements in 40 CFR part
51, subpart Q in 1979 and amended them in 1987. The 1990 Clean Air Act
Amendments (CAAA) revised many of the provisions of the CAA related to
attainment of the NAAQS. These revisions established new emission
inventory requirements applicable to certain areas that were designated
as nonattainment for certain pollutants.
    In June 2002, EPA promulgated the Consolidated Emissions Reporting
Rule (CERR) (67 FR 39602, June 10, 2002). The CERR consolidates the
various emissions reporting requirements that already exist into one
place in the Code of Federal Regulations (CFR), and establishes new
requirements for the statewide reporting of area (non-point) source and
mobile source emissions. The CERR establishes two types of required
emissions inventories: (1) Annual inventories, and (2) 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 will need to report data from all of their
point sources plus all of the area (non-point) and mobile sources on a
statewide basis.
    By merging emissions information from relevant point sources, area
sources, and mobile sources into a comprehensive emission inventory,
the CERR allows State, local and tribal agencies to do the following:
     Set a baseline for SIP development.
     Measure their progress in reducing emissions.
     Answer the public's request for information.
    The 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 Pb
NAAQS. 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. Our current regulations at 40
CFR 51.117(e) require states to include in the SIP inventory all point
sources that emit 5 or more tons of lead emissions per year. As stated
previously, in the proposed rulemaking EPA took comment on whether the
recommended threshold for RACT analysis should be less than the current
5 tons/yr (see section VI.F.1), and proposed that if EPA lowered the
recommended threshold for RACT in the final rulemaking, we would also
revise, to be consistent, the emissions threshold for including sources
in the inventory pursuant to 40 CFR 51.117(e). In the proposed rule, we
solicited comment on the appropriate threshold for Pb point source
inventory reporting requirements.
    The SIP inventory must be approved by EPA as a SIP element and is
subject to public hearing requirements, whereas the CERR inventory 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.
    The EPA has proposed the Air Emissions Reporting Rule (AERR) at 71
FR 69 (Jan. 3, 2006). When finalized, the AERR will update,
consolidate, and harmonize new emissions reporting requirements with
preexisting sets of reporting requirements under the CERR and the
NOX SIP Call. The AERR is expected to be a means by which
the Agency will implement additional data reporting requirements for
the Pb NAAQS SIP emission inventories.
b. Comments and Responses
    One commenter stated that states currently work with regional
offices in developing nonattainment area inventories and that this
approach should be encouraged. The commenter further indicated that
states should be allowed to start with the National Emissions Inventory
(NEI) and customize their nonattainment area inventories to analyze
nonattainment problems.
    The EPA encourages the states to continue to work closely with the
EPA Regional Offices in developing their nonattainment area emissions
inventories as well as any enhancements that need to be made to the
NEI. The EPA encourages the use of the NEI as a tool to assist states
in developing their nonattainment area SIP emissions inventory. States,
however, are reminded that the nonattainment area SIP emissions
inventory is required pursuant to 40 CFR 51.117(e) and must be approved
by EPA pursuant to the CAA, and is subject to the public hearing
requirements pursuant to section 110(a)(2).
    One commenter stated that EPA should develop additional guidance on
emission inventories related to the nonattainment area SIP submittal

because the requirements under the CERR and the AERR may not be enough
to adequately address the emissions inventory requirements related to
the attainment demonstration for the SIP.
    The EPA will review the need for additional guidance concerning the
emissions inventories related to the nonattainment area SIP submittal
on an ongoing basis. As stated previously, EPA believes that the
current guidance, policies, and regulations provide a sufficient basis
for states to implement the revised Pb NAAQS at this time. The EPA, as
appropriate, will review and revise or update these policies, guidance,
and regulations to provide for effective implementation of the Pb
NAAQS.
    Several commenters stated that EPA should revise 40 CFR
51.117(e)(1), relating to the emissions reporting threshold level for
lead nonattainment area SIPs. The current threshold level as stated in
51.117(e)(1), requires that the point source inventory on which the
summary of the baseline lead emissions inventory is based must contain
all sources that emit 5 or more tpy of lead.
    The EPA agrees with the commenters that the requirement for the
emissions inventory reporting threshold for lead nonattainment SIPs, as
stated in 40 CFR 51.117(e)(1), should be revised to reflect the
stringency of the revised Pb NAAQS. In the proposed rule, EPA proposed
to revise the current threshold level for emissions inventory reporting
from 5 tpy to be consistent with the threshold for the analysis of
RACM/RACT control measures. As discussed above, EPA is setting the
threshold for RACT analysis at 0.5 tpy. EPA concludes it is also
appropriate to set the threshold level of the emissions inventory
reporting requirement at 0.5 tpy.
c. Final
    The EPA is finalizing the guidance contained related to the
emissions inventories requirements for the Pb NAAQS as provided in the
proposed rule. The EPA is updating the emissions reporting requirements
for lead nonattainment area SIPs stated in 40 CFR 51.117(e)(1) by
revising the source emission inventory reporting threshold from 5 tpy
to 0.5 tpy.
7. Modeling
a. Proposal
    The lead SIP regulations found at 40 CFR 51.117 require states to
employ atmospheric dispersion modeling for the demonstration of
attainment for areas in the vicinity of point sources listed in 40 CFR
51.117(a)(1). To complete the necessary dispersion modeling,
meteorological, and other data are necessary. Dispersion modeling
should follow the procedures outlined in EPA's latest guidance document
entitled ``Guideline on Air Quality Models''. This guideline indicates
the types and historical records for data necessary for modeling
demonstrations (e.g., on-site meteorological stations, 12 months of
meteorological data are required in order to demonstrate attainment for
the affected area).
b. Comments and Responses
    One commenter stated that the SIPs for lead nonattainment areas
should provide for the implementation of control measures for point and
area sources of lead emissions which demonstrate attainment of the lead
NAAQS as expeditiously as practicable, but no later than the applicable
statutory attainment date for the area. The commenter further stated
that they believe that the requirements currently stated under 40 CFR
51.117(a)(1), related to additional control strategy requirements,
should be revised to reflect the stringency of the revised lead NAAQS.
The commenter stated that specifically, the threshold level of 25 tpy
as stated in 40 CFR 51.117(a)(1), related to modeling for point source
emissions, should be revised to reflect the stringency of the revised
NAAQS.
    The EPA agrees with the commenter that lead nonattainment area SIPs
must provide for the implementation of control measures for point and
area source emissions of lead in order to demonstrate attainment of the
Pb NAAQS as expeditiously as practicable, but no later than the
attainment date for the affected area. EPA notes that 40 CFR 51.117(a)
provides that states must include, as a part of their attainment
modeling demonstration, an analysis showing that the SIP will attain
and maintain the standard in areas in the vicinity of certain point
sources that are emitting at the level of 25 tpy, and also in ``any
other area that has lead air concentrations in excess of the national
ambient air quality standard concentration.'' EPA does not believe it
is necessary to amend the 25 tpy threshold in 40 CFR 51.117(a)(1)
because the provisions of 40 CFR 51.117(a)(2) are sufficient to ensure
an adequate attainment demonstration. Accordingly, EPA believes that
the current requirements concerning control strategy demonstration as
stated in 40 CFR 51.117(a) are adequate for states to develop SIPs
which address attainment of the revised Pb NAAQS. In doing the
analysis, required under 40 CFR 51.117(a)(2), EPA expects the state
will take into consideration all sources of lead emissions within the
nonattainment area that may be required to be controlled, taking into
consideration the attainment needs of the area.
c. Final
    The EPA is finalizing the guidance related to modeling attainment
demonstrations for lead nonattainment area SIPs as proposed. The EPA
will continue to review whether any additional changes related to
modeling demonstrations or applicable modeling guidance are
appropriate.

G. General Conformity

1. Proposal
    Section 176(c) of the CAA, as amended (42 U.S.C. 7401 et seq.),
requires that all Federal actions conform to an applicable
implementation plan developed pursuant to section 110 and part D of the
CAA. Section 176(c) of the CAA requires EPA to promulgate criteria and
procedures for demonstrating and assuring conformity of Federal actions
to a SIP. For the purpose of summarizing the general conformity rule,
it can be viewed as containing three major parts: Applicability,
procedure, and analysis. These are briefly described below.
    The general conformity rule covers direct and indirect emissions of
criteria pollutants, or their precursors, that are caused by a Federal
action, are reasonably foreseeable, and can practicably be controlled
by the Federal agency through its continuing program responsibility.
The general conformity rule generally applies to Federal actions
except: (1) Actions covered by the transportation conformity rule; (2)
Actions with respect to associated emissions below specified de minimis
levels; and (3) Certain other actions that are exempt or presumed to
conform.
    The general conformity rule also establishes procedural
requirements. Federal agencies must make their conformity
determinations available for public review. Notice of draft and final
general conformity determinations must be provided directly to air
quality regulatory agencies and to the public by publication in a local
newspaper.
    The general conformity determination examines the impacts of direct
and indirect emissions related to Federal actions. The general
conformity rule provides several options to satisfy air quality
criteria, such as modeling or offsets, and requires the Federal action
to also meet any applicable SIP requirements and emissions milestones.
Each Federal agency must determine

that any actions covered by the general conformity rule conform to the
applicable SIP before the action is taken. The criteria and procedures
for conformity apply only in nonattainment and maintenance areas with
respect to the criteria pollutants under the CAA: \119\ Carbon monoxide
(CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), particulate matter
(PM2.5 and PM10), and sulfur dioxide (SO2). The general conformity rule
establishes procedural requirements for Federal agencies for actions
related to all NAAQS pollutants, both nonattainment and maintenance
areas and will apply one year following the promulgation of
designations for any new or revised Pb NAAQS.\120\
---------------------------------------------------------------------------

    \119\ Criteria pollutants are those pollutants for which EPA has
established a NAAQS under section 109 of the CAA.
    \120\ 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. Transportation conformity applies to areas
that are designated nonattainment, and those areas redesignated to
attainment after 1990 (``maintenance areas'' with plans developed
under CAA section 175A) for transportation-related criteria
pollutants. In light of the elimination of Pb additives from
gasoline, transportation conformity does not apply to the Pb NAAQS.
---------------------------------------------------------------------------

2. Final
    The EPA is finalizing the guidance related to general conformity as
provided in the proposed rule.

H. Transition From the Current NAAQS to a Revised NAAQS for Lead

1. Proposal
    As discussed in the proposal, EPA believes that Congress's intent,
as evidenced by section 110(l), 193, and section 172(e) of the CAA, was
to ensure that continuous progress, in terms of public health
protection, takes place in transitioning from a current NAAQS for a
pollutant to a new or revised NAAQS. Therefore, EPA proposed that the
existing NAAQS be revoked one year following the promulgation of
designations for any new NAAQS, except that the existing NAAQS will not
be revoked for any current nonattainment area until the affected area
submits, and EPA approves, an attainment demonstration which addresses
the attainment of the new Pb NAAQS.
    The CAA contains a number of provisions that indicate Congress's
intent to not allow states to alter or remove provisions from
implementation plans if the plan revision would jeopardize the air
quality protection being provided by the plan. For example, section
110(l) provides that EPA may not approve a SIP revision if it
interferes with any applicable requirement concerning attainment and
RFP, or any other applicable requirement under the CAA. In addition
section 193 of the CAA prohibits the modification of a control, or a
control requirement, in effect or required to be adopted as of November
15, 1990 (i.e., prior to the promulgation of the Clean Air Act
Amendments (CAAA) of 1990), unless such a modification would ensure
equivalent or greater emissions reductions. One other provision of the
CAA provides additional insight into Congress's intent related to the
need to continue progress towards meeting air quality standards during
periods of transition from one standard to another. Section 172(e) of
the CAA, related to future modifications of a standard, applies when
EPA promulgates a new or revised NAAQS and makes it less stringent than
the previous NAAQS. This provision of the CAA specifies that in such
circumstances, states may not relax control obligations that apply in
nonattainment area SIPs, or avoid adopting those controls that have not
yet been adopted as required.
    The EPA believes that Congress generally did not intend to permit
states to relax levels of pollution control when EPA revises a standard
until the new or revised standard is implemented. Therefore, we believe
that controls that are required under the current Pb NAAQS, or that are
currently in place under the current Pb NAAQS, should generally remain
in place until new designations are established and, for current
nonattainment areas, new attainment SIPs are approved for any new or
revised standard. As a result, EPA proposed that the current Pb NAAQS
should stay in place for one year following the effective date of
designations for any new or revised NAAQS before being revoked, except
in current nonattainment areas, where the existing NAAQS will not be
revoked until the affected area submits, and EPA approves, an
attainment demonstration for the revised Pb NAAQS. Accordingly, the CAA
mechanisms, including sanctions, that help ensure continued progress
toward timely attainment would remain in effect for the existing Pb
NAAQS, and would apply to existing Pb nonattainment areas.
    Pursuant to CAA section 110(l), any proposed SIP revision being
considered by EPA after the effective date of the revised Pb NAAQS
would be evaluated for its potential to interfere with attainment or
maintenance of the new standard. The EPA believes that any area
attaining the revised Pb NAAQS would also attain the existing Pb NAAQS,
and thus reviewing proposed SIP revisions for interference with the new
standard will be sufficient to prevent backsliding. Consequently, in
light of the nature of the proposed revision of the Pb NAAQS, the lack
of classifications (and mandatory controls associated with such
classifications pursuant to the CAA), and the small number of
nonattainment areas, EPA believes that retaining the current standard
for a limited period of time until SIPs are approved for the new
standard in current nonattainment areas, or one year after designations
in other areas, will adequately serve the anti-backsliding goals of the
CAA.\121\
---------------------------------------------------------------------------

    \121\ The areas that are currently nonattainment for the pre-
existing Pb NAAQS are East Helena, Montana and Jefferson County
(part)/Herculaneum, Missouri. (See http://www.epa.gov/oar/oaqps/
greenbk/lnc.html)
---------------------------------------------------------------------------

2. Final
    The EPA is finalizing the guidance related to transition from the
current NAAQS to the new Pb NAAQS generally consistent with the
proposal that the existing standard be retained until one year
following the effective date of designations, except that for current
nonattainment areas the standard would remain in effect until approval
of a SIP for the new standard. EPA notes that the most recent three
years of available monitoring data from the East Helena nonattainment
area showed no violations of the current standard, although the
monitors were shut down in December, 2001 following the shutdown of the
large stationary source of lead emissions there. Accordingly, it is
unclear whether East Helena will be designated nonattainment for the
new standard, or whether it could possibly receive another designation.
In the event East Helena is designated unclassifiable or attainment for
the new standard, EPA believes it is still appropriate to retain the
existing standard until the state submits, and EPA approves, a
maintenance SIP for the new standard. Accordingly EPA has amended the
proposed text of 40 CFR 50.12 to reflect the possibility that in this
specific set of circumstances, the old standard could be revoked upon
EPA's approval of a maintenance SIP for the new standard.

VII. Exceptional Events Information Submission Schedule for Lead NAAQS

    EPA proposed changes to the original dates for submitting and
documenting exceptional event data claims and the Agency is adopting
the proposed changes with some minor revisions and they are described
below.
    Section A presents the information stated in the proposal. Section
B

summarizes and responds to all comments received regarding exceptional
events data submission. Section C provides the final preamble text
considering comments received and incorporating final revisions to the
proposal.

A. Proposal

    The EPA proposed Pb-specific changes to the deadlines, in 40 CFR
50.14, by which States must flag ambient air data that they believe has
been affected by exceptional events and submit initial descriptions of
those events, and the deadlines by which States must submit detailed
justifications to support the exclusion of that data from EPA
determinations of attainment or nonattainment with the NAAQS. The
deadlines in 40 CFR 50.14 are generic, and are not always appropriate
for Pb given the anticipated schedule for the designations of areas
under the proposed Pb NAAQS.
    For the specific case of Pb, EPA anticipates that designations
under the revised NAAQS may be made in September 2011 based on 2008-
2010 data, (or possibly in September 2010 based on 2007-2009 data if
sufficient data are available), and thus will depend in part on air
quality data collected as late as December 2010 (or December 2009).
(Section IV.C of the proposed preamble had a more detailed discussion
of the designation schedule and what data EPA intends to use.) There is
no way for a State to flag and submit documentation regarding events
that happen in October, November, and December 2010 (or 2009) by one
year before designation decisions that are made in September 2011 (or
2010).
    The proposed revisions to 40 CFR 50.14 involved only changes in
submission dates for information regarding claimed exceptional events
affecting Pb data. The proposed rule text showed only the changes that
would apply if designations are made three years after promulgation;
where a deadline would be different if designations were made at the
two-year point, the difference in deadline was noted in the proposed
preamble. We proposed to extend the generic deadline for flagging data
(and providing a brief initial description of the event) of July 1 of
the year following the data collection, to July 1, 2009 for data
collected in 2006-2007. The proposed extension included 2006 and 2007
data because Governors' designation recommendations will consider 2006-
2008 data, and possibly EPA will consider 2006-2008 or 2007-2009 data
if complete data for 2008-2010 are not available at the time of final
designations. EPA noted that it does not intend to use data prior to
2006 in making Pb designation decisions. The generic event flagging
deadline in the Exceptional Events Rule would continue to apply to 2008
and later years following the promulgation of the revised Pb NAAQS. The
Governor of a State would be required to submit designation
recommendations to EPA a year after promulgation of the revised NAAQS
(i.e., in Fall 2009). States would therefore have enough time to flag
data and submit their demonstrations and know what 2008 data need to be
excluded due to exceptional events when formulating their
recommendations to EPA.
    For data collected in 2010 (or 2009), we proposed to move up the
generic deadline of July 1 for data flagging to May 1, 2011 (or May 1,
2010) (which is also the applicable deadline for certifying data in AQS
as being complete and accurate to the best knowledge of the responsible
monitoring agency head). This would give a State less time, but EPA
believes still sufficient time, to decide what 2010 (or 2009) data to
flag, and would allow EPA to have access to the flags in time for EPA
to develop its own proposed and final plans for designations.
    Finally, EPA proposed to make the deadline for submission of
detailed justifications for exclusion of data collected in 2006 through
2008 be September 15, 2010 for the three year designation schedule, or
September 15, 2009 under the two year designation schedule. EPA
generally does not anticipate data from 2006 and 2007 being used in
final Pb designations. Under the three year designation schedule, for
data collected in 2010, EPA proposed to make the deadline for
submission of justifications be May 1, 2011. This is less than a year
before the designation decisions would be made, but we believe it is a
good compromise between giving a State a reasonable period to prepare
the justifications and EPA a reasonable period to consider the
information submitted by the State. Similarly, under the two year
designation schedule, for data collected in 2009, EPA proposed to make
the deadline for submission of justifications be May 1, 2010. Table 5
summarizes the three year designation deadlines in the proposal and
discussed in this section, and Table 6 summarizes the two year
designation deadlines.

     Table 5--Proposed Schedule for Exceptional Event Flagging and Documentation Submission if Designations
                                           Promulgated in Three Years
----------------------------------------------------------------------------------------------------------------
     Air quality data collected for                                         Detailed  documentation  submission
             calendar year                   Event flagging deadline                     deadline
----------------------------------------------------------------------------------------------------------------
2006...................................  July 1, 2009 *.................  September 15, 2010. *
2007...................................  July 1, 2009 *.................  September 15, 2010.
2008...................................  July 1, 2009...................  September 15, 2010. *
2009...................................  July 1, 2010...................  September 15, 2010. *
2010...................................  May 1, 2011 *..................  May 1, 2011. *
----------------------------------------------------------------------------------------------------------------
* Indicates proposed change from generic schedule in 40 CFR 50.14.

     Table 6--Proposed Schedule for Exceptional Event Flagging and Documentation Submission if Designations
                                            Promulgated in Two Years
----------------------------------------------------------------------------------------------------------------
     Air quality data collected for                                         Detailed  documentation  submission
             calendar year                   Event flagging deadline                     deadline
----------------------------------------------------------------------------------------------------------------
2006...................................  July 1, 2009 *.................  September 15, 2009.
2007...................................  July 1, 2009 *.................  September 15, 2009. *
2008...................................  July 1, 2009...................  September 15, 2009. *

2009...................................  May 1, 2010 *..................  May 1, 2010. *
----------------------------------------------------------------------------------------------------------------
* Indicates proposed change from generic schedule in 40 CFR 50.14.

    EPA invited comment on these proposed changes in the exceptional
event flagging and documentation submission deadlines.

B. Comments and Responses

    EPA received only one comment on the proposed revision to the
schedule for flagging and documenting exceptional event data which
could affect Pb designation decisions. The comment from the North
Carolina Department of Environment and Natural Resources' (NCDENR)
Division of Air Quality (DAQ) stated that: ``NCDAQ believes states need
proper time to provide exceptional events documentation before
designations are made.''
    EPA believes that the final schedule provides states with adequate
time for flagging exceptional values and providing documentation to
support exceptional event claims. Also, NCDAQ did not specifically
state either that the proposed deadlines were inadequate or ask for
more time; nor did it provide any alternative schedules for the
Agency's consideration.

C. Final

    EPA's final schedule for flagging and documenting exceptional event
data claims is shown in the tables that follow. Table 7 summarizes the
final deadlines for areas where final designations occur no later than
October 15, 2011 (i.e., no later than three years after promulgation of
a new NAAQS). Table 8 summarizes the final dealines for areas where
final desiginations occur no later than October 15, 2010 (i.e., no
later than two years after promulgation of a new NAAQS).

 Table 7--Final Schedule for Exceptional Event Flagging and Documentation Submission if Designations Promulgated
                                               within Three Years
----------------------------------------------------------------------------------------------------------------
     Air quality data collected for                                          Detailed documentation submission
             calendar year                   Event flagging deadline                     deadline
----------------------------------------------------------------------------------------------------------------
2006...................................  July 1, 2009 *.................  October 15 2010. *
2007...................................  July 1, 2009 *.................  October 15, 2010.