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The United States Environmental Protection Agency (EPA) is proposing to approve portions of Arkansas’ state implementation plan (SIP) addressing the 2015 ozone National Ambient Air Quality Standards (NAAQS).

The SIP provides for implementation, maintenance, and enforcement of the 2015 NAAQS such that the state’s responsibilities under the Clean Air Act are fulfilled.

EPA is also proposing to approve updates to Arkansas’ environmental regulations that incorporate the most recent federal ozone standards.

The proposed approval was published in the Federal Register on June 30, 2020. Public comments may be filed on the proposal and are due on or before July 30, 2020.

A primary component of a NAAQS SIP is that it contain provisions prohibiting significant contributions to interstate transport of the target pollutant. In its proposed approval of Arkansas’ 2015 ozone NAAQS SIP, EPA is not evaluating three out of four prongs of the interstate transport component of the state’s submittal. Rather, EPA states those measures will be addressed in forthcoming separate actions.

Arkansas and other states are primarily responsible for ensuring attainment and maintenance of Clean Air Act NAAQS once EPA has established them. Each state is therefore required to formulate, subject to EPA approval, SIPs designed to achieve each NAAQS. The SIPs will contain the measures and actions the state proposes to undertake to attain each NAAQS.

The SIPs are in theory dynamic documents which the state can choose to change as it continues to determine the appropriate means of attaining or maintaining the various NAAQS. The SIP and subsequent revisions must be reviewed and approved by the EPA if the criteria set forth in Section 110 of the Clean Air Act are met. A change in a NAAQS may require revision in the SIP. The SIPs and/or revisions must be adopted pursuant to public notice and hearing and include various substantive requirements such as:

• The emissions and the control measures that will be used by the state
• Schedules and timetables for compliance
• The means used to monitor and analyze data on ambient air quality
• The permitting procedure controls used for stationary sources
• The enforcement procedures used

A copy of EPA’s proposed approval may be accessed here.