SUPPLEMENTARY INFORMATION:

1. General Information

Where can I get information related to this action?

Docket: The EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2022-0313. All documents in the docket are listed on the https://www.regulations.gov website. Although listed in the index, some information may not be publicly available, e.g., Confidential Business Information or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy. Publicly available docket materials are available electronically through https://www.regulations.gov.

Agency website: A list of the additional areas subject to mitigation plans is found on the website that contains information related to exceptional events at: https://www.epa.gov/​air-quality-analysis/​treatment-air-quality-data-influenced-exceptional-events-homepage-exceptional.

II. What is the purpose of this action?

In keeping with the EPA's mission to protect public health and consistent with the principles included at the Clean Air Act section 319(b)(3)(A), the 2016 Exceptional Events Rule (Rule) promulgated new regulations requiring states to develop mitigation plans for areas with historically documented or known seasonal exceptional events. Using air quality monitoring data contained within the Air Quality System (AQS) for the period January 1, 2013, through December 31, 2015, the EPA initially identified 29 areas required to submit mitigation plans within 2 years of the effective date of the Rule.^[1]

Further, the 2016 Exceptional Events Rule states that as areas become subject to the mitigation plan requirements, the Administrator will notify the states in writing. However, the Rule did not establish a specific process for providing notice to states with areas newly identified as being subject to mitigation plan requirements. This action establishes a process for providing that notice and fulfills our obligation to identify additional areas with recurring events of the same type and pollutant. Table 1 contains a list of the newly identified areas subject to mitigation requirements. Generally, areas subject to the mitigation requirements have experienced three events or three seasons of events of the same type and pollutant in a 3-year period. For purposes of this analysis and notification, the EPA evaluated rolling 3-year periods for January 1, 2016, through December 31, 2020. A detailed description of the process the EPA followed to identify these areas and a summary of required components of a mitigation plan are included in a background document placed in the docket for this rulemaking titled, “Additional Areas Subject to Mitigation Plan Requirements in 40 CFR 51.930(b).”

Within 2 years of being notified that they are subject to the mitigation plan provisions within the 2016 Exceptional Events Rule, air agencies responsible for ensuring air quality for the areas identified in Table 1 shall submit mitigation plans to the applicable EPA Regional Administrator. Consistent with the 2016 Exceptional Events Rule, after this 2-year timeframe, if an air agency has not submitted the required mitigation plan, the EPA will not concur with an air agency's request to exclude data that have been influenced by an event of the type that is the subject of a required mitigation plan. An air agency may submit a mitigation plan in advance of, or as part of, an exceptional events demonstration submission of the same event type and pollutant as the focus of the mitigation plan.

The discussion of the mitigation plan components is included in the preamble to the 2016 Exceptional Events Rule ^[2] and 40 CFR 51.930(b)(2) identifies the required components for each mitigation plan. A discussion of mitigation plan components is also included in the background document placed in the docket for this rulemaking.

87 FR 29045