The United States Environmental Protection Agency (“EPA”) published a September 20th Federal Register notice approving portions of the Arkansas State Implementation Plan (“SIP”) submittal that addresses a Clean Air Act requirement that:
. . . SIPs address the potential for interstate transport of air pollution to significantly contribute to nonattainment or interfere with maintenance of the 2012 fine particulate matter (PM2.5) National Ambient Air Quality Standard (NAAQS) in other states.
See 83 Fed. Reg. 47569.
EPA determined that emissions from Arkansas sources do not contribute significantly to nonattainment in, or interfere with maintenance by, any other state with regard to the 2012 PM2.5 NAAQS.
The process EPA is describing involves Section 110 of the Clean Air Act. Section 110 requires that the states assume primary responsibility for assuring attainment and maintenance of the NAAQS once EPA has established them. Each state is therefore required to formulate, subject to EPA approval, an SIP designed to achieve each NAAQS. The SIPs will contain the measures and actions the state proposes to undertake to attain each NAAQS. These measures or actions must be enforceable through state regulations.
The states are generally free to make their own choices as to how they will attain the NAAQS through their SIPs. Further, 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 EPA if the criteria set forth in Section 110 are met. A change in a NAAQS may require a revision in the SIP. The SIP and/or revisions must be adopted pursuant to public notice and hearing.
EPA states that Arkansas submitted a SIP on March 24, 2017, addressing the CAA requirement that the SIPs account for potential interstate air pollution significantly contributing to nonattainment or interfering with maintenance of the 2012 PM2.5 NAAQS in any other state.
EPA states it is also approving the portion of the Arkansas’s previous SIP submittal that:
. . . revise the definition of NAAQS in Regulation 19, Chapter 2, and revised the entry for “Particle Pollution, PM2.5 ” in Regulation 19, Appendix B.
A copy of the Federal Register notice can be downloaded here.