On May 24, 2022, the EPA published proposed state implementation plan (SIP) disapproval notices for air quality plans submitted by California, Nevada, Utah, and Wyoming.
In each case, the Agency cited that the state failed to adequately address compliance with the 2015 8-hour ozone National Ambient Air Quality Standards (NAAQS).
If the proposed disapprovals are finalized, each state will have 2 years to submit revised acceptable SIPs or be placed under a federal implementation plan (FIP) to address the relevant interstate transport requirements.
The “good neighbor” or “interstate transport” provision of the NAAQS requires that each state’s SIP contain adequate provisions to prohibit emissions from within the state from significantly contributing to nonattainment or interfering with maintenance of the NAAQS in other states. This requirement is part of the broader set of “infrastructure” requirements, which are designed to ensure the structural components of each state’s air quality management program are adequate to meet the state’s responsibilities under the Clean Air Act (CAA).
The 2015 8-hour ozone NAAQS lowered both primary and secondary standards to 0.070 parts per million (ppm).
To evaluate interstate transport provisions in a SIP, the EPA utilizes a four-step framework that includes:
- Identify monitoring sites that are projected to have problems attaining and/or maintaining the NAAQS (i.e., nonattainment and/or maintenance receptors).
- Identify states that impact those air quality problems in other (i.e., downwind) states sufficiently such that the states are considered “linked” and therefore warrant further review and analysis.
- Identify the emissions reductions necessary (if any), applying a multifactor analysis, to eliminate each linked upwind state’s significant contribution to nonattainment or interference with maintenance of the NAAQS at the locations identified in Step 1.
- Adopt permanent and enforceable measures needed to achieve those emissions reductions.
In March 2023, the EPA proposed an FIP impacting 26 states under the good neighbor provision of the CAA. That proposal contained implications for industrial nitrogen oxide (NOx) sources.
To avoid the FIP, each state must submit an approved SIP. Now that these four states’ SIPs are proposed as unacceptable by the EPA, each state must submit a revised SIP.
It is not clear at this time whether these states will simply resubmit; challenge the EPA findings; or, during the rulemaking process, attempt to find exemption from the good neighbor requirements.
A state’s nonattainment status is clearly bad for attracting new business and revenue.
Through comments, appeals, and even litigation, nonattainment status battles can drag on for years. Texas is a good example.