would likely be limited to those living in Metropolitan Statistical
Areas (MSAs) having populations of more than 350,000. Other commenters
noted the difficulty in defining the boundaries of new attainment/non-
attainment areas without additional monitoring in the MSAs below
350,000.
    EPA recognizes that the issues raised by the commenters are
important. EPA intends to address these issues as part of its proposed
monitoring rule.
    In relation to the proposed secondary standard options, EPA invited
comment on whether, where, and how monitoring in rural areas
specifically focused on the secondary NAAQS should be required. As
noted in the O3 NAAQS proposal and described earlier in this
section, existing O3 monitoring requirements and current
State monitoring practices are primarily oriented towards protecting
against health effects in people and therefore the primary NAAQS. This
accounts for the current focus of the monitoring requirements on urban
areas, where large populations reside, in which significant emissions
of O3 -forming precursors are found, and where O3
concentrations of concern are likely to occur.
    There are no EPA requirements for O3 monitoring in less
populated areas outside of MSA boundaries or in rural areas. However,
at present there are about 250 O3 monitors in counties that
are not part of MSAs. These monitors are operated by State, local, and
tribal monitoring agencies for a variety of objectives including the
assessment of O3 transport and the support of research
programs including studies of atmospheric chemistry and ecosystem
impacts. Additionally, EPA operates a network of about 56 O3
monitors as part of its Clean Air Status and Trends Network (CASTNET).
The National Park Service (NPS) operates about 27 monitors at other
CASTNET sites. On an overall basis, the spatial density of non-urban
O3 monitors is relatively high in the eastern one-third of
the U.S. and in California, with significant gaps in coverage elsewhere
across the country.
    Some commenters expressed concern about the quality assurance
practices at CASTNET sites with regard to certain aspects of
O3 monitoring. They recommended that EPA upgrade such
practices to meet the 40 CFR part 58 Appendix A quality assurance
requirements already followed by the States so that the resulting data
could be used in assessing compliance with the revised secondary
standard. EPA notes that such upgrades have been completed at some of
the CASTNET sites, and that such upgrades will be completed at all
CASTNET sites by 2009. EPA notes that the resulting O3
ambient data from the upgraded sites will meet Appendix A requirements
as is presently the case for O3 data from State operated
monitors and NPS monitors. These data will be deemed acceptable for
NAAQS-comparison objectives and available in the AQS database beginning
in 2008.
    Most commenters noted the relative lack of rural O3
monitors, stating that EPA should consider adding monitoring
requirements that support a revised secondary O3 standard by
requiring O3 monitors in locations that contain
O3-sensitive plants or ecosystems. These commenters also
noted that the placement of current O3 monitors may not be
appropriate for evaluating vegetation exposure since many of these
monitors were likely located to meet other objectives.
    In light of the Administrator's decision to revise the 8-hour
secondary standard, EPA believes that it is appropriate to consider
whether the existing urban-based monitoring requirements described
elsewhere in this section are adequate and appropriate to characterize
the exposure in more rural areas where O3-sensitive plant
species and more sensitive ecosystems exist and where resulting
vegetation damage would adversely affect land usage. Such areas would
likely include public lands that are protected areas of national
interest (e.g., national parks, wilderness areas).
    In consideration of the spatial gaps that currently exist in the
rural ozone monitoring network, and to the extent that the existence of
such gaps has contributed to the overall uncertainty that exists in the
level of protection that would be provided by the revised secondary
standard, EPA believes that there is merit in considering whether
additional monitoring requirements in certain rural areas would help
support ongoing ecosystem research studies as well as future reviews of
the O3 NAAQS by providing a more robust data set with which
to assess the relationship of vegetation damage to O3
concentrations.
    Accordingly, as part of its separate monitoring rulemaking, EPA
intends to consider specific requirements for a minimum number of rural
monitors per State, with detailed rule language to ensure that States
locate such monitors in appropriate areas. For example, these areas
could include Federal, State, or Tribal lands characterized by areas of
sensitive vegetation species subject to visible foliar injury, seedling
and mature tree biomass loss, and other adverse impacts to a degree
that could be considered adverse depending on the intended use of the
plant and its significance to the public welfare. EPA is also
considering recommending that States and Tribes employ other
quantitative tools, such as photochemical modeling and/or the spatial
interpolation of ambient data from existing O3 monitors, to
determine the adequacy of existing locations of rural monitors and to
inform the locations of new or relocated monitors that might be
required to meet revised rural minimum monitoring requirements.
    Finally, EPA solicited comment on the issue of O3
monitoring seasons. Unlike the year-round monitoring required for other
criteria pollutants, the

required O3 monitoring seasons \31\ vary in length due to
the inter-relationship of O3-forming photochemical activity
with ambient temperature, strength of solar insolation, and length of
day. For example, in States with colder climates such as Montana and
South Dakota, the O3 season has a length of 4 months. In
States with warmer climates such as California, Nevada, and Arizona,
the O3 season has a length of 12 months.
    With the decision to revise the 8-hour primary standard to a level
of 0.075 ppm, and to set the secondary standard identical in all
respects to the primary standard, the issue arises of whether in some
areas the required O3 monitoring season should be made
longer. EPA notes that under the existing regulations, the Regional
Administrator may approve State-requested deviations from the
established O3 monitoring season, but EPA may not increase
the length of the season for an area at EPA's own initiative other than
by notice and comment rulemaking.
    EPA has done a preliminary analysis of 2004-2006 ambient data to
address the issue of whether extensions of currently required
O3 monitoring seasons are appropriate in light of the
revised level for the primary and secondary O3 standards and
the revised breakpoints for the AQI. The results of the analysis
demonstrated that out-of-season exceedances of the revised level
occurred in eight States during the study period. Additionally, the
frequency of days with O3 concentrations that reached the
revised Moderate AQI category (based on a breakpoint of 0.060 ppm) was
much greater compared with the frequency of days with concentrations
that reached the pre-existing Moderate AQI category (based on a
breakpoint of 0.065 ppm). This increased frequency of days with
Moderate AQI levels was noted to occur during periods before and after
the currently required O3 seasons.
    Based on these preliminary analyses, EPA intends to consider
changes to the length of the required O3 season for the
coming monitoring rulemaking. Such changes could be based solely on the
frequency of exceedances of the revised primary and secondary
standards, or could also consider the frequency of concentrations in
the Moderate category of the AQI.

VII. Implementation and Related Control Requirements

A. Future Implementation Steps

    In today's rule, EPA is replacing the existing (1997) standards
with revised primary and secondary O3 standards. However,
the 1997 standards--and the implementation rules for those standards--
will remain in place for implementation purposes as EPA undertakes
rulemaking to address the transition from the 1997 O3
standards to the 2008 O3 standards. States are required to
continue to develop and implement their State Implementation Plans
(SIPs) for the 1997 standards as they begin the process of recommending
designations for the 2008 standards.
1. Designations
    After EPA establishes or revises a NAAQS, the CAA requires EPA and
States to begin taking steps to ensure that the new or revised
standards are met. The first step is to identify areas of the country
that do not attain the new or revised standards, or that contribute to
violations of the new or revised standards. Section 107(d)(1) provides
``By 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, 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 non-attainment, attainment, or unclassifiable. Section
107(d)(1)(B)(i) further provides, ``Upon promulgation or revision of a
national ambient air quality standard, 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 for 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 be
signature and dissemination of a rule.\32\ As noted above, the CAA
requires EPA to establish a deadline for the States' submission of the
designation recommendations, but under the CAA, it can be no later than
March 12, 2009, one year after the promulgation of this rule.
Therefore, Governors of States should submit their designation
recommendations to EPA no later than March 12, 2009. EPA's promulgation
of designations must occur no later than March 12, 2010, although that
date may be extended by up to one year under the CAA (no later than
March 12, 2011) if EPA has insufficient information to promulgate the
designations.
    EPA intends to provide additional guidance to the States concerning
the technical considerations for establishing boundaries for designated
areas. For the revised primary and secondary standards, we anticipate
relying on past O3 designation guidance issued by EPA prior
to the designations for the 1997 O3 standards.\33\ We
anticipate working closely with State air agencies and Tribes on
establishing new guidance on designations, if needed.
2. State Implementation Plans
    CAA section 110 provides the general requirements for SIPs. Within
3 years after the promulgation of new or revised NAAQS (or such shorter
period as the Administrator may prescribe) each State must adopt and
submit ``infrastructure'' SIPs to EPA to address the requirements of
section 110(a)(1). Thus, States should submit these SIPs no later than
March 12, 2011. These ``infrastructure SIPs'' provide assurances of
State resources and authorities, and establish the basic State
programs, to implement, maintain, and enforce new or revised standards.
    In addition to the infrastructure SIPs, which apply to all States,
CAA title I, part D outlines the State requirements for achieving clean
air in designated nonattainment areas. These requirements include
timelines for when designated nonattainment areas must attain the
standards, deadlines for developing SIPs that demonstrate how the State
will ensure attainment of the standards, and specific emissions control
requirements. EPA plans to address how these requirements, such as
attainment demonstrations and attainment dates, reasonable further
progress, new source review, conformity, and other implementation
requirements, apply to the revised O3 NAAQS in a proposed
rulemaking in Fall 2008. Also in that rulemaking EPA will establish
deadlines for submission of nonattainment area SIPs but anticipates
that the deadlines will be no later than 3 years after final
designation. Depending on the classification of an area, the SIP must
provide for attainment within 3 years (for areas classified marginal)
to 20 years (for areas classified extreme) after final designations.
3. Trans-boundary Emissions
    Cross border O3 contributions from within North America
(Canada and Mexico) entering the U.S. are generally thought to be
small. Section 179B of the

Clean Air Act allows designated nonattainment areas to petition EPA to
consider whether such a locality might have met a clean air standard
``but for'' cross border contributions. To date, few areas have
petitioned EPA under this authority. The impact of foreign emissions on
domestic air quality in the United States is a challenging and complex
problem to assess. EPA is engaged in a number of activities to improve
our understanding of international transport. As work progresses on
these activities, EPA will be able to better address the uncertainties
associated with trans-boundary flows of air pollution and their
impacts.
4. Monitoring Requirements
    As discussed more fully in section VI, EPA intends, in light of the
revisions of the O3 standards, to issue a monitoring rule to
address a variety of monitoring-related issues identified in the
preamble to the proposed rule or in comments received by the Agency on
the proposal. EPA intends to issue a proposed monitoring rule in June
2008 and a final rule by March 2009.
---------------------------------------------------------------------------

    \31\ See 40 CFR Part 58 Appendix D, section 2.5 for a table of
required O3 seasons.
    \32\ American Petroleum Institute v. Costle, 609 F.2d 20 (D.C.
Cir. 1979).
    \33\ Memorandum of March 28, 2000 from John Seitz, ``Boundary
Guidance on Air Quality Designations for the 8-Hour Ozone National
Ambient Air Quality Standards (NAAQS or Standard).''
---------------------------------------------------------------------------

B. Related Control Requirements

    The man-made oxides of nitrogen (NOX) and volatile
organic carbon (VOC) emissions that contribute to O3
formation in the United States come from a variety of source
categories, including mobile sources, industrial processes, area-wide
sources (which include consumer and commercial products), and the
electric power industry.\34\ Emissions from natural sources, such as
trees and wildfires can also constitute a significant portion of total
VOC emissions in certain regions of the country, especially during the
O3 season. Natural sources such as wildfires, lightning, and
soils also emit NOX. Emissions of VOCs and NOX
from these sources are considered natural background emissions.\35\
---------------------------------------------------------------------------

    \34\ National Emission Inventory posted at the following Web
site: http://www.epa.gov/ttn/chief/trends/index.html.
    \35\ In some cases natural emissions may cause or significantly
contribute to violations of the ozone standard. EPA has issued rules
that address how these ``exceptional events'' can be discounted in
regulatory determinations. The Exceptional Events Rule (72 FR 13560
(March 22, 2007) implements CAA section 319(b)(3)(B) and section
107(d)(3) authority to exclude air quality monitoring data from
regulatory determinations related to exceedances or violations of
the National Ambient Air Quality Standards (NAAQS). If an event is
determined by EPA to be a qualifying exceptional event, the affected
area may avoid being designated as nonattainment, being redesignated
as nonattainment, or being reclassifed to a higher classification.
The requirements for demonstrating that elevated ozone levels are
the result of a qualifying exceptional event are provided in the
Exceptional Events Rule.
---------------------------------------------------------------------------

    EPA has developed new emissions standards for many types of
stationary sources and for nearly every class of mobile sources in the
last decade to reduce O3 by decreasing emissions of
NOX and VOC. These programs complement State and local
efforts to improve air quality and to meet the national O3
standards. Under the Federal Motor Vehicle Control Program (FMVCP, see
title II of the CAA, 42 U.S.C. 7521-7574), EPA has established new
emissions standards for nearly every type of automobile, truck, bus,
motorcycle, earth mover, and aircraft engine, and for the fuels used to
power these engines. Also, EPA established new standards for the
smaller engines used in small watercraft, lawn and garden equipment.
Recently, EPA proposed new standards for locomotive and marine diesel
engines. Vehicles and engines are replaced over time with newer,
cleaner models. In time, these programs will yield substantial
emissions reductions. Emissions reductions associated with fuel
programs generally begin as soon as a new fuel is available.
    The reduction of VOC emissions from industrial processes and
consumer and commercial product categories has been achieved either
directly or indirectly through implementation of control technology
standards, including reasonably available control technology, best
available control technology, and maximum achievable control technology
standards; or is anticipated due to proposed or upcoming proposals
based on generally available control technology or best available
controls under provisions related to consumer and commercial products.
These standards have resulted in VOC emissions reductions of almost a
million tons per year accumulated starting in 1997 from a variety of
sources including combustion sources, coating categories, and chemical
manufacturing. In 2006 and 2007, EPA issued national rules and control
techniques guidelines for control of VOC emissions from 10 categories
of consumer and commercial products. EPA is currently working to
finalize new Federal rules, or amendments to existing rules, intended
to establish new nationwide VOC content limits for several categories
of consumer and commercial products, including aerosol coatings,
architectural and industrial maintenance coatings, and household and
institutional commercial products. EPA anticipates that final rules
addressing emissions from these sources will take effect in 2009.
    Fuel combustion is one of the largest anthropogenic sources of
emissions of NOX in the United States. Power industry
emission sources include large electric generating units and some large
industrial boilers and turbines. The EPA's landmark Clean Air
Interstate Rule (CAIR), issued on March 10, 2005, permanently caps
power industry emissions of NOX in the eastern United
States. The first phase of the cap begins in 2009, and a lower second
phase cap begins in 2015. By 2015, EPA projects that the CAIR and other
programs in the Eastern U.S. will reduce power industry annual
NOX emissions in that region by about 60 percent from 2003
levels.
    With respect to agricultural sources, the U.S. Department of
Agriculture (USDA) has recommended conservation systems and activities
that can reduce agricultural emissions of NOX and VOC.
Current practices that may reduce emissions of NOX and VOC
include engine replacement programs, management of pesticide
applications, and manure management techniques. The EPA recognizes that
USDA has been working with the agricultural community to plan
conservation systems and activities to manage emissions of
O3 precursors.
    These conservation systems and activities can be voluntarily
adopted in areas where mitigation of O3 precursors have been
identified as an air quality concern through the use of incentives
provided to the agricultural producer. In cases where the States need
these measures to attain the O3 standards, agricultural
producers could choose to adopt these measures. The EPA will continue
to work with USDA on planning the implementation of these conservation
systems and activities in order to identify and/or improve mitigation
efficiencies, prioritize their adoption, and ensure that appropriate
criteria are used for identifying the most effective application of
conservation systems and activities.
    The EPA will work together with USDA and with States to identify
appropriate measures to meet the primary and secondary standards,
including site-specific conservation systems and activities. Based on
prior experience identifying conservation measures and practices to
meet the PM NAAQS requirements, the EPA will use a similar process to
identify measures that could meet the O3 requirements. The
EPA anticipates that certain USDA-approved conservation systems and
activities that reduce agricultural emissions of NOX and VOC
may be able to satisfy the requirements for

applicable sources to implement reasonably available control measures
for purposes of attaining the primary and secondary O3
NAAQS.

VIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under section 3(f)(1) of Executive Order (EO) 12866 (58 FR 51735,
October 4, 1993), this action is an ``economically significant
regulatory action'' because it is likely to have an annual effect on
the economy of $100 million or more. Accordingly, EPA submitted this
action to the Office of Management and Budget (OMB) for review under EO
12866 and any changes made in response to OMB recommendations have been
documented in the docket for this action. In addition, EPA prepared an
analysis of the potential costs and benefits associated with this
action. This analysis is contained in the Final Ozone NAAQS Regulatory
Impact Analysis, March 2008 (henceforth, ``RIA''). A copy of the
analysis is available in the RIA docket (EPA-HQ-OAR-2007-0225) and the
analysis is briefly summarized here. The RIA estimates the costs and
monetized human health and welfare benefits of attaining three
alternative O3 NAAQS nationwide. Specifically, the RIA
examines the alternatives of 0.079 ppm, 0.075 ppm, 0.070 ppm, and 0.065
ppm. The RIA contains illustrative analyses that consider a limited
number of emissions control scenarios that States and Regional Planning
Organizations might implement to achieve these alternative
O3 NAAQS. However, the CAA and judicial decisions make clear
that the economic and technical feasibility of attaining ambient
standards are not to be considered in setting or revising NAAQS,
although such factors may be considered in the development of State
plans to implement the standards. Accordingly, although a RIA has been
prepared, the results of the RIA have not been considered in issuing
this final rule.

B. Paperwork Reduction Act

    This action does not impose an information collection burden under
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.
There are no information collection requirements directly associated
with the establishment of a NAAQS under section 109 of the CAA.
    Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal agency. This includes the time
needed to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required
to respond to a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR are listed in 40 CFR part 9.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of this rule on small
entities, small entity is defined as: (1) A small business that is a
small industrial entity as defined by the Small Business
Administration's (SBA) regulations at 13 CFR 121.201; (2) a small
governmental jurisdiction that is a government of a city, county, town,
school district or special district with a population of less than
50,000; and (3) a small organization that is any not-for-profit
enterprise which is independently owned and operated and is not
dominant in its field.
    After considering the economic impacts of this final rule on small
entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This final
rule will not impose any requirements on small entities. Rather, this
rule establishes national standards for allowable concentrations of
O3 in ambient air as required by section 109 of the CAA.
American Trucking Ass'ns v. EPA, 175 F. 3d 1027, 1044-45 (D.C. cir.
1999) (NAAQS do not have significant impacts upon small entities
because NAAQS themselves impose no regulations upon small entities).

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and Tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and Tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year. Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and to
adopt the least costly, most cost-effective or least burdensome
alternative that achieves the objectives of the rule. The provisions of
section 205 do not apply when they are inconsistent with applicable
law. Moreover, section 205 allows EPA to adopt an alternative other
than the least costly, most cost-effective or least burdensome
alternative if the Administrator publishes with the final rule an
explanation why that alternative was not adopted. Before EPA
establishes any regulatory requirements that may significantly or
uniquely affect small governments, including Tribal governments, it
must have developed under section 203 of the UMRA a small government
agency plan. The plan must provide for notifying potentially affected
small governments, enabling officials of affected small governments to
have meaningful and timely input in the development of EPA regulatory
proposals with significant Federal intergovernmental mandates, and
informing, educating, and advising small governments on compliance with
the regulatory requirements.
    This final rule contains no Federal mandates (under the regulatory
provisions of Title II of the UMRA) for State, local, or Tribal
governments or the private sector. The rule imposes no new expenditure
or enforceable duty on any State, local or Tribal governments or the
private sector, and EPA has determined that this rule contains no
regulatory requirements that might significantly or uniquely affect
small governments. Furthermore, as indicated previously, in setting a
NAAQS EPA cannot consider the economic or technological feasibility of
attaining ambient air quality standards, although such factors may be
considered to a degree in the development of State

plans to implement the standards. See also American Trucking Ass'ns v.
EPA, 175 F. 3d at 1043 (noting that because EPA is precluded from
considering costs of implementation in establishing NAAQS, preparation
of a Regulatory Impact Analysis pursuant to the Unfunded Mandates
Reform Act would not furnish any information which the court could
consider in reviewing the NAAQS). Thus, this rule is not subject to the
requirements of sections 202 and 205 of the UMRA. EPA has determined
that this rule contains no regulatory requirements that might
significantly or uniquely affect small governments.

E. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.''
``Policies that have federalism implications'' is defined in the
Executive Order to include regulations that have ``substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.''
    This final rule does not have federalism implications. It will not
have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government,
as specified in Executive Order 13132. The rule does not alter the
relationship between the Federal government and the States regarding
the establishment and implementation of air quality improvement
programs as codified in the CAA. Under section 109 of the CAA, EPA is
mandated to establish NAAQS; however, CAA section 116 preserves the
rights of States to establish more stringent requirements if deemed
necessary by a State. Furthermore, this rule does not impact CAA
section 107 which establishes that the States have primary
responsibility for implementation of the NAAQS. Finally, as noted in
section E (above) on UMRA, this rule does not impose significant costs
on State, local, or Tribal governments or the private sector. Thus,
Executive Order 13132 does not apply to this rule.

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

    Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'' (65 FR 67249, November 9, 2000),
requires EPA to develop an accountable process to ensure ``meaningful
and timely input by tribal officials in the development of regulatory
policies that have tribal implications.'' This final rule does not have
Tribal implications, as specified in Executive Order 13175. It does not
have a substantial direct effect on one or more Indian Tribes, since
Tribes are not obligated to adopt or implement any NAAQS. Thus,
Executive Order 13175 does not apply to this rule.
    Although Executive Order 13175 does not apply to this rule, EPA
contacted Tribal environmental professionals during the development of
this rule. EPA staff participated in the regularly scheduled Tribal Air
call sponsored by the National Tribal Air Association during the spring
of 2007 as the proposal was under development. EPA specifically
solicited additional comment on the proposed rule from Tribal
officials. Comments from Tribal officials on the proposed rule are
summarized in the Response to Comments document.

G. Executive Order 13045: Protection of Children From Environmental
Health & Safety Risks

    Executive Order 13045, ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies
to any rule that: (1) Is determined to be ``economically significant''
as defined under Executive Order 12866, and (2) concerns an
environmental health or safety risk that EPA has reason to believe may
have a disproportionate effect on children. If the regulatory action
meets both criteria, the Agency must evaluate the environmental health
or safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency.
    This final rule is subject to Executive Order 13045 because it is
an economically significant regulatory action as defined by Executive
Order 12866, and we believe that the environmental health risk
addressed by this action may have a disproportionate effect on
children. Accordingly, we have evaluated the environmental health or
safety effects of exposure to O3 pollution among children.
These effects and the size of the population affected are summarized in
section 8.7 of the Criteria Document and section 3.6 of the Staff
Paper, and the results of our evaluation of the effects of
O3 pollution on children are discussed in sections II.A-C of
this preamble.

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

    Executive Order 13211, ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 28355
(May 22, 2001)), requires EPA to prepare and submit a Statement of
Energy Effects to the Administrator of the Office of Information and
Regulatory Affairs, Office of Management and Budget, for certain
actions identified as ``significant energy actions.'' Section 4(b) of
Executive Order 13211 defines ``significant energy actions'' as ``any
action by an agency (normally published in the Federal Register) that
promulgates or is expected to lead to the promulgation of a final rule
or regulation, including notices of inquiry, advance notices of
proposed rulemaking, and notices of proposed rulemaking: (1)(i) That is
a significant regulatory action under Executive Order 12866 or any
successor order, and (ii) is likely to have a significant adverse
effect on the supply, distribution, or use of energy; or (2) that is
designated by the Administrator of the Office of Information and
Regulatory Affairs as a significant energy action.'' The U.S. Office of
Management and Budget has designated this rulemaking as a significant
energy action. Accordingly, EPA has prepared a Statement of Energy
Effects for this action which appears in Chapter 9 of the RIA conducted
for this rulemaking. A copy of the RIA is available in the RIA docket
(EPA-HQ-OAR-2007-0225) and the energy analysis is briefly summarized
here. The analysis estimates potential impacts of an illustrative
control strategy for the 0.070 ppm primary standard alternative on the
production of coal, crude oil, natural gas, and electricity; on energy
prices; on control technologies adopted by the electricity generating
sector; and on the mix of electricity generation. EPA believes that the
energy impacts estimated for this illustrative control strategy for the
0.070 ppm primary standard alternative are higher than those that would
be estimated for an illustrative control strategy for the primary
standard level of 0.075 ppm which was selected by the Administrator.
However, due to modeling limitations, EPA did not generate separate
estimates of the energy impacts associated specifically with an

illustrative control strategy designed for a primary standard of 0.075
ppm. It is important to note that the CAA make clear that the economic
impacts associated with attaining ambient standards are not to be
considered in setting or revising the NAAQS. Accordingly, although the
Statement of Energy Effects has been prepared, the results of EPA's
energy analysis have not been considered in issuing this final rule.

 I. National Technology Transfer and Advancement Act

    As noted in the proposed rule, section 12(d) of the National
Technology Transfer and Advancement Act of 1995 (NTTAA), Public Law
104-113, section 12(d) (15 U.S.C. 272 note) directs EPA to use
voluntary consensus standards in its regulatory activities unless to do
so would be inconsistent with applicable law or otherwise impractical.
Voluntary consensus standards are technical standards (e.g., materials
specifications, test methods, sampling procedures, and business
practices) that are developed or adopted by voluntary consensus
standards bodies. The NTTAA directs EPA to provide Congress, through
OMB, explanations when the Agency decides not to use available and
applicable voluntary consensus standards.
    This action does not involve technical standards. Therefore, EPA
did not consider the use of any voluntary consensus standards.

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

    Executive Order 12898 (59 FR 7629; Feb. 16, 1994) establishes
Federal executive policy on environmental justice. Its main provision
directs Federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies, and activities on minority populations and low-income
populations in the United States.
    EPA has determined that this final rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it increases the
level of environmental protection for all affected populations without
having any disproportionately high and adverse human health or
environmental effects on any population, including any minority or low-
income population. This final rule will establish uniform national
standards for O3 air pollution.

K. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. EPA submitted a report containing this rule and other
required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is a ``major rule'' as defined by 5 U.S.C.
804(2). This rule will be effective May 27, 2008.

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OAR-2005-0172 re: Proposed Rule--National Ambient Air Quality
Standards for Ozone. Docket No. OAR-2005-0172-4934. September 27,
2007.
National Tribal Air Association (NTAA) (2007) Letter and Comments
Sent to Docket No. OAR-2005-0172 re: Proposed Rule--National Ambient
Air Quality Standards for Ozone. Docket No. OAR-2005-0172-4169.
October 9, 2007.
Nevada Department of Conservation & Natural Resources (2007) Letter
and Comments Sent to Docket No. OAR-2005-0172 re: Proposed Rule--
National Ambient Air Quality Standards for Ozone. Docket No. OAR-
2005-0172-4173. October 9, 2007.
New Jersey Clean Air Council (2007) Letter and Comments Sent to
Docket No. OAR-2005-0172 re: Proposed Rule--National Ambient Air
Quality Standards for Ozone. Docket No. OAR-2005-0172-4119. October
9, 2007.
New York State Department of Environmental Conservation (2007)
Letter and Comments Sent to Docket No. OAR-2005-0172 re: Proposed
Rule--National Ambient Air Quality Standards for Ozone. Docket No.
OAR-2005-0172-4099. October 9, 2007.
New York State Department of Transportation (2007) Letter and
Comments Sent to Docket No. OAR-2005-0172 re: Proposed Rule--
National Ambient Air Quality Standards for Ozone. Docket No. OAR-
2005-0172-4865. October 9, 2007.
New Mexico Environment Department Air Quality Bureau (2007) Letter
and Comments Sent to Docket No. OAR-2005-0172 re: Proposed Rule--
National Ambient Air Quality Standards for Ozone. Docket No. OAR-
2005-0172-4195. October 5, 2007.
North Carolina Department of Environment and Natural Resources
(NCDENR) (2007) Letter Sent to Stephen L. Johnson re: Proposed
Rule--National Ambient Air Quality Standards for Ozone. Docket No.
OAR-2005-0172-4497. October 9, 2007.
Northeast States for Coordinated Air Use Management (NESCAUM) (2007)
Letter and Comments Sent to Stephen Johnson, Administrator re:
Proposed Rule--National Ambient Air Quality Standards for Ozone.
Docket No. OAR-2005-0172-4165. October 4, 2007.
Oklahoma Department of Transportation (2007) Letter and Comments
Sent to Docket No. OAR-2005-0172 re: Proposed Rule--National Ambient
Air Quality Standards for Ozone. Docket No. OAR-2005-0172-4365.
October 5, 2007.
Oregon Department of Environmental Quality (2007) Letter and
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National Ambient Air Quality Standards for Ozone. Docket No. OAR-
2005-0172-4014. September 20, 2007.
Ozone Transport Commission (OTC) (2007) Letter and Comments Sent to
Docket No. OAR-2005-0172 re: Proposed Rule--National Ambient Air
Quality Standards for Ozone. Docket No. OAR-2005-0172-4135. October
5, 2007.
Pennsylvania Department of Environmental Protection (2007) Letter
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National Ambient Air Quality Standards for Ozone. Docket No. OAR-
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Proposed Rule--National Ambient Air Quality Standards for Ozone.
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Air Quality Standards for Ozone. Docket No. OAR-2005-0172-4435.
October 9, 2007.
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to Docket No. OAR-2005-0172 re: Proposed Rule--National Ambient Air
Quality Standards for Ozone. Docket No. OAR-2005-0172-4409. October
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Proposed Rule--National Ambient Air Quality Standards for Ozone.
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Utility Air Regulatory Group (2007) Letter and Comments Sent to
Docket No. OAR-2005-0172 re: Proposed Rule--National Ambient Air
Quality Standards for Ozone. Docket No. OAR-2005-0172-4183. October
9, 2007.
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to Docket No. OAR-2005-0172 re: Proposed Rule--National Ambient Air
Quality Standards for Ozone. Docket No. OAR-2005-0172-4768. October
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National Ambient Air Quality Standards for Ozone. Docket No. OAR-
2005-0172-4157. October 8, 2007.
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Sent to Docket No. OAR-2005-0172 re: Proposed Rule--National Ambient
Air Quality Standards for Ozone. Docket No. OAR-2005-0172-4267.
October 9, 2007.
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yosemite.epa.gov/sab/sabproduct.nsf/
C3F89E598D843B58852570CA0075717E/$File/epec02009a.pdf.

List of Subjects

 40 CFR Part 50

    Environmental protection, Air pollution control, Carbon monoxide,
Lead, Nitrogen dioxide, Ozone, Particulate matter, Sulfur oxides.

40 CFR Part 58

    Environmental protection, Air pollution control, Reporting and
recordkeeping requirements.

    Dated: March 12, 2008.
Stephen L. Johnson,
Administrator.

0
For the reasons stated in the preamble, title 40, chapter I of the code
of Federal regulations is to be amended as follows:

PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY
STANDARDS

0
1. The authority citation for part 50 continues to read as follows:

    Authority: 42 U.S.C. 7401, et seq.

0
2. Section 50.15 is added to read as follows:

Sec.  50.15  National primary and secondary ambient air quality
standards for ozone.

    (a) The level of the national 8-hour primary and secondary ambient
air quality standards for ozone (O3) is 0.075 parts per million (ppm),
daily maximum 8-hour average, measured by a reference method based on
Appendix D to this part and designated in accordance with part 53 of
this chapter or an equivalent method designated in accordance with part
53 of this chapter.
    (b) The 8-hour primary and secondary O3 ambient air quality
standards are met at an ambient air quality monitoring site when the 3-
year average of the annual fourth-highest daily maximum 8-hour average
O3 concentration is less than or equal to 0.075 ppm, as determined in
accordance with Appendix P to this part.

0
3. Appendix P is added to read as follows:

Appendix P to Part 50--Interpretation of the Primary and Secondary
National Ambient Air Quality Standards for Ozone

1. General

    (a) This appendix explains the data handling conventions and
computations necessary for determining whether the national 8-hour
primary and secondary ambient air quality standards for ozone (O3)
specified in Sec.  50.15 are met at an ambient O3 air quality
monitoring site. Ozone is measured in the ambient air by a reference
method based on Appendix D of this part, as applicable, and
designated in accordance with part 53 of this chapter, or by an
equivalent method designated in accordance with part 53 of this
chapter. Data reporting, data handling, and computation procedures
to be used in making comparisons between reported O3 concentrations
and the levels of the O3 standards are specified in the following
sections. Whether to exclude, retain, or make adjustments to the
data affected by exceptional events, including stratospheric O3
intrusion and other natural events, is determined by the
requirements under Sec. Sec.  50.1, 50.14 and 51.930.
    (b) The terms used in this appendix are defined as follows:
    8-hour average is the rolling average of eight hourly
O3 concentrations as explained in section 2 of this
appendix.
    Annual fourth-highest daily maximum refers to the fourth highest
value measured at a monitoring site during a particular year.
    Daily maximum 8-hour average concentration refers to the maximum
calculated 8-hour average for a particular day as explained in
section 2 of this appendix.
    Design values are the metrics (i.e., statistics) that are
compared to the NAAQS levels to determine compliance, calculated as
shown in section 3 of this appendix.
    O3 monitoring season refers to the span of time
within a calendar year when individual States are required to
measure ambient O3 concentrations as listed in part 58
Appendix D to this chapter.
    Year refers to calendar year.

2. Primary and Secondary Ambient Air Quality Standards for Ozone

2.1 Data Reporting and Handling Conventions

    Computing 8-hour averages. Hourly average concentrations shall
be reported in parts per million (ppm) to the third decimal place,
with additional digits to the right of the third decimal place
truncated. Running 8-hour averages shall be computed from the hourly
O3 concentration data for each hour of the year and shall
be stored in the first, or start, hour of the 8-hour period. An 8-
hour average shall be considered valid if at least 75% of the hourly
averages for the 8-hour period are available. In the event that only
6 or 7 hourly averages are available, the 8-hour average shall be
computed on the basis of the hours available using 6 or 7 as the
divisor. 8-hour periods with three or more missing hours shall be
considered valid also, if, after substituting one-half the minimum
detectable limit for the missing hourly concentrations, the 8-hour
average concentration is greater

than the level of the standard. The computed 8-hour average
O3 concentrations shall be reported to three decimal
places (the digits to the right of the third decimal place are
truncated, consistent with the data handling procedures for the
reported data).
    Daily maximum 8-hour average concentrations. (a) There are 24
possible running 8-hour average O3 concentrations for
each calendar day during the O3 monitoring season. The
daily maximum 8-hour concentration for a given calendar day is the
highest of the 24 possible 8-hour average concentrations computed
for that day. This process is repeated, yielding a daily maximum 8-
hour average O3 concentration for each calendar day with
ambient O3 monitoring data. Because the 8-hour averages
are recorded in the start hour, the daily maximum 8-hour
concentrations from two consecutive days may have some hourly
concentrations in common. Generally, overlapping daily maximum 8-
hour averages are not likely, except in those non-urban monitoring
locations with less pronounced diurnal variation in hourly
concentrations.
    (b) An O3 monitoring day shall be counted as a valid
day if valid 8-hour averages are available for at least 75% of
possible hours in the day (i.e., at least 18 of the 24 averages). In
the event that less than 75% of the 8-hour averages are available, a
day shall also be counted as a valid day if the daily maximum 8-hour
average concentration for that day is greater than the level of the
standard.

2.2 Primary and Secondary Standard-related Summary Statistic

    The standard-related summary statistic is the annual fourth-
highest daily maximum 8-hour O3 concentration, expressed
in parts per million, averaged over three years. The 3-year average
shall be computed using the three most recent, consecutive calendar
years of monitoring data meeting the data completeness requirements
described in this appendix. The computed 3-year average of the
annual fourth-highest daily maximum 8-hour average O3
concentrations shall be reported to three decimal places (the digits
to the right of the third decimal place are truncated, consistent
with the data handling procedures for the reported data).

2.3 Comparisons with the Primary and Secondary Ozone Standards

    (a) The primary and secondary O3 ambient air quality
standards are met at an ambient air quality monitoring site when the
3-year average of the annual fourth-highest daily maximum 8-hour
average O3 concentration is less than or equal to 0.075
ppm.
    (b) This comparison shall be based on three consecutive,
complete calendar years of air quality monitoring data. This
requirement is met for the 3-year period at a monitoring site if
daily maximum 8-hour average concentrations are available for at
least 90% of the days within the O3 monitoring season, on
average, for the 3-year period, with a minimum data completeness
requirement in any one year of at least 75% of the days within the
O3 monitoring season. When computing whether the minimum
data completeness requirements have been met, meteorological or
ambient data may be sufficient to demonstrate that meteorological
conditions on missing days were not conducive to concentrations
above the level of the standard. Missing days assumed less then the
level of the standard are counted for the purpose of meeting the
data completeness requirement, subject to the approval of the
appropriate Regional Administrator.
    (c) Years with concentrations greater than the level of the
standard shall be included even if they have less than complete
data. Thus, in computing the 3-year average fourth maximum
concentration, calendar years with less than 75% data completeness
shall be included in the computation if the 3-year average fourth-
highest 8-hour concentration is greater than the level of the
standard.
    (d) Comparisons with the primary and secondary O3
standards are demonstrated by examples 1 and 2 in paragraphs (d)(1)
and (d)(2) respectively as follows:

                                  Example 1.--Ambient Monitoring Site Attaining the Primary and Secondary O3 Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Percent valid
                                                           days (within     1st Highest     2nd Highest     3rd Highest     4th Highest     5th Highest
                          Year                             the required    daily max 8-    daily max 8-    daily max 8-    daily max 8-    daily max 8-
                                                            monitoring      hour Conc.      hour Conc.      hour Conc.      hour Conc.      hour Conc.
                                                              season)          (ppm)           (ppm)           (ppm)           (ppm)           (ppm)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2004....................................................             100           0.092           0.090           0.085           0.079           0.078
2005....................................................              96           0.084           0.083           0.075           0.072           0.070
2006....................................................              98           0.080           0.079           0.077           0.076           0.060
                                                         -----------------------------------------------------------------------------------------------
    Average.............................................              98  ..............  ..............  ..............           0.075  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------

    (1) As shown in Example 1, this monitoring site meets the
primary and secondary O3 standards because the 3-year
average of the annual fourth-highest daily maximum 8-hour average
O3 concentrations (i.e., 0.075666 * * * ppm, truncated to
0.075 ppm) is less than or equal to 0.075 ppm. The data completeness
requirement is also met because the average percent of days within
the required monitoring season with valid ambient monitoring data is
greater than 90%, and no single year has less than 75% data
completeness. In Example 1, the individual 8-hour averages used to
determine the annual fourth maximum have also been truncated to the
third decimal place.

                               Example 2.--Ambient Monitoring Site Failing to Meet the Primary and Secondary O3 Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Percent valid
                                                           days (within     1st Highest     2nd Highest     3rd Highest     4th Highest     5th Highest
                          Year                             the required    daily max 8-    daily max 8-    daily max 8-    daily max 8-    daily max 8-
                                                            monitoring      hour Conc.      hour Conc.      hour Conc.      hour Conc.      hour Conc.
                                                              season)          (ppm)           (ppm)           (ppm)           (ppm)           (ppm)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2004....................................................              96           0.105           0.103           0.103           0.103           0.102
2005....................................................              74           0.104           0.103           0.092           0.091           0.088
2006....................................................              98           0.103           0.101           0.101           0.095           0.094
                                                         -----------------------------------------------------------------------------------------------
    Average.............................................              89  ..............  ..............  ..............           0.096  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As shown in Example 2, the primary and secondary O3
standards are not met for this monitoring site because the 3-year
average of the fourth-highest daily maximum 8-hour average
O3 concentrations (i.e., 0.096333 * * * ppm, truncated to
0.096 ppm) is greater than 0.075 ppm, even though the data capture
is less than 75% and the average data capture for the 3 years is
less than 90% within the required monitoring season. In Example 2,
the individual 8-hour averages used to determine the annual fourth
maximum have also been truncated to the third decimal place.

3. Design Values for Primary and Secondary Ambient Air Quality
Standards for Ozone

    The air quality design value at a monitoring site is defined as
that concentration that when reduced to the level of the standard
ensures that the site meets the standard. For a concentration-based
standard, the air quality design value is simply the standard-
related test statistic. Thus, for the primary and secondary
standards, the 3-year average annual fourth-highest daily maximum 8-
hour average O3 concentration is also the air quality
design value for the site.

PART 58--AMBIENT AIR QUALITY SURVEILLANCE

0
4. The authority citation of part 58 continues to read as follows:

    Authority: 42 U.S.C. 7403, 7410, 7601(a), 7611, and 7619.

0
5. Appendix G to Part 58 is amended as follows:
0
a. By revising section 9.
0
b. By revising section 10.
0
c. By revising section 12.
0
d. By revising section 13.

Appendix G to Part 58--Uniform Air Quality Index (AQI) and Daily
Reporting

* * * * *

9. How Does the AQI Relate to Air Pollution Levels?

    For each pollutant, the AQI transforms ambient concentrations to
a scale from 0 to 500. The AQI is keyed as appropriate to the
national ambient air quality standards (NAAQS) for each pollutant.
In most cases, the index value of 100 is associated with the
numerical level of the short-term standard (i.e., averaging time of
24-hours or less) for each pollutant. A different approach is taken
for NO2, for which no short-term standard has been
established. The index value of 50 is associated with the numerical
level of the annual standard for a pollutant, if there is one, at
one-half the level of the short-term standard for the pollutant, or
at the level at which it is appropriate to begin to provide guidance
on cautionary language. Higher categories of the index are based on
increasingly serious health effects and increasing proportions of
the population that are likely to be affected. The index is related
to other air pollution concentrations through linear interpolation
based on these levels. The AQI is equal to the highest of the
numbers corresponding to each pollutant. For the purposes of
reporting the AQI, the sub-indexes for PM10 and
PM2.5 are to be considered separately. The pollutant
responsible for the highest index value (the reported AQI) is called
the ``critical'' pollutant.

10. What Monitors Should I Use To Get the Pollutant Concentrations for
Calculating the AQI?

    You must use concentration data from population-oriented State/
Local Air Monitoring Station (SLAMS) or parts of the SLAMS required
by 40 CFR 58.10 for each pollutant except PM. For PM, calculate and
report the AQI on days for which you have measured air quality data
(e.g., from continuous PM2.5 monitors required in
Appendix D to this part). You may use PM measurements from monitors
that are not reference or equivalent methods (for example,
continuous PM10 or PM2.5 monitors). Detailed
guidance for relating non-approved measurements to approved methods
by statistical linear regression is referenced in section 13 below.
* * * * *

12. How Do I Calculate the AQI?

    i. The AQI is the highest value calculated for each pollutant as
follows:
    a. Identify the highest concentration among all of the monitors
within each reporting area and truncate the pollutant concentration
to one more than the significant digits used to express the level of
the NAAQS for that pollutant. This is equivalent to the rounding
conventions used in the NAAQS.
    b. Using Table 2, find the two breakpoints that contain the
concentration.
    c. Using Equation 1, calculate the index.
    d. Round the index to the nearest integer.

                                                            Table 2.--Breakpoints for the AQI
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                   These breakpoints                                                            Equal these AQI's
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      PM10
        O3 (ppm)  8-hour           O3 (ppm)  1-   PM2.5  ([mu]g/    ([mu]g/      CO (ppm)      SO2 (ppm)     NO2 (ppm)       AQI           Category
                                     hour \1\          m\3\)         m\3\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.000-0.059.....................  ..............        0.0-15.4         0-54      0.0-4.4     0.000-0.034        (\3\)         0-50  Good.
0.060-0.075.....................  ..............       15.5-40.4       55-154      4.5-9.4     0.035-0.144        (\3\)       51-100  Moderate.
0.076-0.095.....................     0.125-0.164       40.5-65.4      155-254     9.5-12.4     0.145-0.224        (\3\)      101-150  Unhealthy for
                                                                                Sensitive Groups.
0.096-0.115.....................     0.165-0.204  \4\ 65.5-150.4      255-354    12.5-15.4     0.225-0.304        (\3\)      151-200  Unhealthy.
0.116-0.374.....................     0.205-0.404      \4\ 150.5-      355-424    15.5-30.4     0.305-0.604    0.65-1.24      201-300  Very Unhealthy.
                                                           250.4
(\2\)...........................     0.405-0.504      \4\ 250.5-      425-504    30.5-40.4     0.605-0.804    1.25-1.64      301-400  ..................
                                                           350.4
(\2\)...........................     0.505-0.604      \4\ 350.5-      505-604    40.5-50.4     0.805-1.004    1.65-2.04      401-500  Hazardous.
                                                           500.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Areas are generally required to report the AQI based on 8-hour ozone values. However, there are a small number of areas where an AQI based on 1-hour
  ozone values would be more precautionary. In these cases, in addition to calculating the 8-hour ozone index value, the 1-hour ozone index value may be
  calculated, and the maximum of the two values reported.
\2\ 8-hour O3 values do not define higher AQI values (>= 301). AQI values of 301 or greater are calculated with 1-hour O3 concentrations.
\3\ NO2 has no short-term NAAQS, and can generate an AQI only above the value of 200.
\4\ If a different SHL for PM2.5 is promulgated, these numbers will change accordingly.

    ii. If the concentration is equal to a breakpoint, then the
index is equal to the corresponding index value in Table 2. However,
Equation 1 can still be used. The results will be equal. If the
concentration is between two breakpoints, then calculate the index
of that pollutant with Equation 1. You must also note that in some
areas, the AQI based on 1-hour O3 will be more
precautionary than using 8-hour values (see footnote 1 to Table 2).
In these cases, you may use 1-hour values as well as 8-hour values
to calculate index values and then use the maximum index value as
the AQI for O3.

[GRAPHIC] [TIFF OMITTED] TR27MR08.001

Where:

Ip = the index value for pollutantp
Cp = the truncated concentration of pollutantp

BPHi = the breakpoint that is greater than or equal to Cp
BPLo = the breakpoint that is less than or equal to Cp
IHi = the AQI value corresponding to BPHi
Ilo = the AQI value corresponding to BPLo.

    iii. If the concentration is larger than the highest breakpoint
in Table 2 then you may use the last two breakpoints in Table 2 when
you apply Equation 1.

Example

    iv. Using Table 2 and Equation 1, calculate the index value for
each of the pollutants measured and select the one that produces the
highest index value for the AQI. For example, if you observe a
PM10 value of 210 [mu]g/m\3\, a 1-hour O3
value of 0.156 ppm, and an 8-hour O3 value of 0.130 ppm,
then do this:
    a. Find the breakpoints for PM10 at 210 [mu]g/m\3\ as
155 [mu]g/m\3\ and 254 [mu]g/m\3\, corresponding to index values 101
and 150;
    b. Find the breakpoints for 1-hour O3 at 0.156 ppm as
0.125 ppm and 0.164 ppm, corresponding to index values 101 and 150;
    c. Find the breakpoints for 8-hour O3 at 0.130 ppm as
0.116 ppm and 0.374 ppm, corresponding to index values 201 and 300;
    d. Apply Equation 1 for 210 [mu]g/m\3\, PM10:

    [GRAPHIC] [TIFF OMITTED] TR27MR08.002

    e. Apply Equation 1 for 0.156 ppm, 1-hour O3:

    [GRAPHIC] [TIFF OMITTED] TR27MR08.003

    f. Apply Equation 1 for 0.130 ppm, 8-hour O3:

    [GRAPHIC] [TIFF OMITTED] TR27MR08.004

    g. Find the maximum, 206. This is the AQI. The minimal AQI
report would read:
    v. Today, the AQI for my city is 206 which is Very Unhealthy,
due to ozone. Children and people with asthma are the groups most at
risk.

13. What Additional Information Should I Know?

    The EPA has developed a computer program to calculate the AQI
for you. The program prompts for inputs, and it displays all the
pertinent information for the AQI (the index value, color, category,
sensitive group, health effects, and cautionary language). The EPA
has also prepared a brochure on the AQI that explains the index in
detail (The Air Quality Index), Reporting Guidance (Guideline for
Public Reporting of Daily Air Quality) that provides associated
health effects and cautionary statements, and Forecasting Guidance
(Guideline for Developing an Ozone Forecasting Program) that
explains the steps necessary to start an air pollution forecasting
program. You can download the program and the guidance documents at
www.airnow.gov. Reference for relating non-approved PM measurements
to approved methods (Eberly, S., T. Fitz-Simons, T. Hanley, L.
Weinstock., T. Tamanini, G. Denniston, B. Lambeth, E. Michel, S.
Bortnick. Data Quality Objectives (DQOs) For Relating Federal
Reference Method (FRM) and Continuous PM2.5 Measurements to Report
an Air Quality Index (AQI). U.S. Environmental Protection Agency,
research Triangle Park, NC. EPA-454/B-02-002, November 2002) can be
found on the Ambient Monitoring Technology Information Center
(AMTIC) Web site, http://www.epa.gov/ttnamti1/.

 [FR Doc. E8-5645 Filed 3-26-08; 8:45 am]

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