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EPA Issues Final State Plans Rule to Ensure Attainment of the Standards for Ground-Level Ozone

Requirements Provide Additional Flexibility to Develop State Plans and Regulatory Relief from International Emissions

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WASHINGTON  — Today, the U.S. Environmental Protection Agency (EPA) released its final state implementation plan (SIP) Requirements Rule for implementing the 2015 National Ambient Air Quality Standard (NAAQS) for ground-level ozone. These requirements apply to states and tribes with nonattainment areas as well as the 13 northeastern states that currently comprise the Ozone Transport Region. This rule will assist our state and tribal partners in developing their implementation plans to meet the 2015 ozone standards, while providing the greatest flexibility possible.

“This final rule grants states the flexibilities they need to incorporate factors that are often outside their control, such as international air pollution, so they can meet the 2015 ozone standards and continue our nation’s tremendous clean air progress,” said EPA Acting Administrator Andrew Wheeler. “By working with states to provide greater regulatory certainty, we are helping them improve air quality, protect public health, and enhance economic growth.”

Today’s final rule follows President Donald Trump’s April 2018 Memo, Promoting Domestic Manufacturing and Job Creation – Policies and Procedures Relating to Implementation of Air Quality Standards, which directs EPA to ensure efficient and cost-effective implementation of air quality standards under NAAQS and regional haze programs of the Clean Air Act. For example, consistent with the President’s memorandum, the final rule clarifies that states can take advantage of Clean Air Act tools for regulatory relief for areas, including those areas that are not on the border, which could meet ozone standards but for international contributions outside of their control.

Recognizing that protecting air quality is a shared responsibility of EPA and our state, local, and tribal partners, EPA will continue to work closely with our partners to control ozone pollution and protect public health. To assist states, local agencies, and tribes, the rule clarifies EPA’s interpretation of applicable statutory provisions and outlines additional flexibilities to meet 2015 ozone standards.

In order to provide certainty to co-regulators, EPA has also committed to provide these implementation tools as quickly as possible after a NAAQS is revised. Since the Clean Air Act Amendments of 1990, this is the fastest that EPA has finalized a SIP requirements rule for a revised ozone NAAQS.

The final rule also maximizes flexibility and builds upon past EPA practice in provisions related to demonstrations for attainment and reasonable further progress, pollution sources outside of a nonattainment area, trading provisions for pollutants that react to form ozone, and SIP timing.

While tremendous progress has been made in reducing criteria pollutants– combined emissions of six key pollutants dropped by 73 percent since the 1970s and emissions of nitrogen oxides, the key precursor for ground-level ozone, fell by more than 40 percent in the last ten years– background and international air pollution contribute significantly to air quality issues under increasingly stringent standards. EPA is committed to maximize flexibility for Clean Air Act tools for regulatory relief. EPA projects that the vast majority of areas in the United States will attain the 2015 ozone standards by the early 2020s.


The Clean Air Act (CAA) requires EPA to set National Ambient Air Quality Standards (NAAQS) for pollutants that are common in outdoor air, that are considered harmful to public health and the environment, and that come from numerous and diverse sources. Periodically, the standards are reviewed and may be revised. EPA most recently revised the standards for ozone on October 1, 2015.

When EPA establishes a new NAAQS or revises an existing NAAQS, it sets in motion two major actions aimed at ensuring that air quality throughout the country meets those standards:

  1. EPA must designate areas as meeting (attainment) or not meeting (nonattainment) the standard (EPA completed those designations for the 2015 ozone standard this past summer); and
  2. CAA requires states to develop State Implementation Plans (SIPs): a general plan to attain and maintain the NAAQS in all areas of the country, and a specific plan to attain the standards for each area designated nonattainment for a NAAQS.

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