FACT SHEET
FINAL RULE: IMPLEMENTATION OF THE 2015 NATIONAL AMBIENT AIR QUALITY
STANDARDS FOR OZONE: NONATTAINMENT AREA STATE IMPLEMENTATION PLAN
REQUIREMENTS
ACTION
• On November 7, 2018, the U.S. Environmental Protection Agency (EPA) issued final requirements
that apply to state, local, and tribal air agencies for implementing the 2015 National Ambient Air
Quality Standards (NAAQS) for ground-level ozone. EPA revised both the health-based and
welfare-based standards for ozone on October 1, 2015.
• These requirements apply to states and tribes with nonattainment areas, and states in the Ozone
Transport Region (OTR). The OTR includes: Connecticut, Delaware, the District of Columbia,
Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode
Island, Vermont, and Virginia.
• This final rule is largely an update to the implementing regulations previously promulgated for the
2008 ozone NAAQS, and the EPA is retaining without significant revision most of those provisions
to implement the 2015 ozone NAAQS.
• This final rule addresses a range of nonattainment area and OTR state implementation plan (SIP)
requirements for the 2015 ozone NAAQS, including requirements for:
o attainment demonstrations;
o milestone compliance demonstrations to address reasonable further progress requirements;
o planning and implementation deadlines for reasonably available control technology (RACT);
o reasonably available control measures;
o consideration of pollution sources within a state but outside of a nonattainment area for
purposes of attainment planning;
o optional ozone NAAQS trading provisions for pollutants that react to form ozone, which
would allow either volatile organic compounds (VOC) or oxides of nitrogen (NOx)
emissions reductions to satisfy nonattainment New Source Review permitting emissions
offset requirements for VOC or NOx emissions increases;
o the timing of required SIP submissions, and compliance with emission control measures in
the SIP; and
o emissions inventories and emissions statements.
• In this final rule, the EPA is maintaining its existing approach to evaluating potential impacts of
international transport of ozone and ozone precursors under the Clean Air Act (CAA) section 179B.
This final rule also clarifies that a demonstration prepared under CAA section 179B could consider
emissions emanating from North American or intercontinental sources and is not restricted to areas
adjoining international borders.
• This final rule also provides discussion of additional requirements and policies, including: (1)
managing emissions from wildfires and wildland prescribed fires; (2) transportation conformity and
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general conformity; (3) contingency measures; (4) background ozone; and (5) additional policies for
achieving emissions reductions.
• In the proposed rule, EPA also sought comment on two alternative approaches for revoking the 2008
ozone NAAQS for all purposes and, where applicable, establishing anti-backsliding requirements.
EPA intends to address any revocation of the 2008 ozone NAAQS, and potential anti-backsliding
requirements, if any, in a separate future rulemaking.
BACKGROUND
• Ozone is formed from NOx and VOC in the presence of sunlight. Cars, trucks, buses, engines,
industries, power plants and products, such as solvents and paints are among the major manmade
sources of ozone-forming emissions. Exposure to ground-level ozone pollution is linked to a variety
of significant health problems.
• Ozone levels are most commonly elevated in the warm summer months, when hot sunny days make
it more likely that ozone will form. But this isn't always the case. In parts of the western United
States with high levels of local VOC and NOx emissions and unique meteorological conditions,
ozone levels have been high when snow is on the ground.
• The CAA directs the EPA to set and review air quality standards for common pollutants known as
"criteria pollutants," which the agency has identified based on their likelihood of harming public
health and welfare. The EPA established air quality standards for ozone in 1979. The EPA
subsequently revised the ozone standards in 1997, 2008 and 2015 based on the most recently
available scientific studies at the time.
o In October 2015, the EPA revised the ozone NAAQS from 75 parts per billion (ppb) to
70 ppb to ensure the protection of public health and welfare.
• After the EPA establishes or revises an air quality standard, the agency follows a process by which
states recommend area designations {i.e., as nonattainment, attainment, or unclassifiable) to the EPA.
The EPA then evaluates their recommendations (and air quality data and other factors) prior to
making its proposed and final determinations regarding area designations.
• Implementation of the NAAQS is a shared responsibility of the EPA, states and tribes. This final rule
interprets the requirements of the CAA in a manner that ensures public health protection is achieved
by meeting the 2015 ozone standards, while giving the EPA's partners flexibility to reduce
administrative burdens, where possible.
• States, and in some cases local agencies or tribes, are the primary implementers of the NAAQS.
They are responsible for developing and submitting to the EPA implementation plans that meet the
nonattainment planning requirements of the CAA. To assist states, local agencies and tribes, the
EPA promulgates implementation rules to clarify its interpretation of applicable statutory provisions.
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FOR MORE INFORMATION
• To download a copy of the final rule from the EPA website, go to: https://www.epa.gov/ozone-
pollution/implementation-2015-national-ambient-air-qualitv-standards-naaqs-ozone-state.
• Additional information on the ozone nonattainment areas is available on the EPA Green Book at
https://www.epa.gov/green-book/green-book-8-hour-ozone-2015-area-information.
• For more information on the final rule, contact Robert Lingard at (919) 541-5272 or
lineard.robert(a),epa.gov; or Butch Stackhouse at (919) 541-5208 or stackhouse. butch®,eya.gov.
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