2016-22983: Treatment of Data Influenced by Exceptional Events

Summary

The Environmental Protection Agency (EPA) is finalizing revisions to certain sections within the regulations that govern the exclusion of event-influenced air quality data from certain regulatory decisions under the Clean Air Act (CAA). The EPA's mission includes preserving and improving the quality of our nation's ambient air to protect human health and the environment, and the CAA and the EPA's regulations rely heavily on ambient air quality data. However, the CAA also recognizes that it may not be appropriate to use the monitoring data influenced by "exceptional" events that are collected by the ambient air quality monitoring network when making certain regulatory determinations. When "exceptional" events cause exceedances or violations of the national ambient air quality standards (NAAQS) that subsequently affect certain regulatory decisions, the normal planning and regulatory process established by the CAA may not be appropriate. This final rule contains definitions, procedural requirements, requirements for air agency demonstrations, criteria for the EPA's approval of the exclusion of event-influenced air quality data and requirements for air agencies to take appropriate and reasonable actions to protect public health from exceedances or violations of the NAAQS. It reflects the experiences of the EPA, state, local and tribal air agencies, federal land managers and other stakeholders in implementing this program over the past 10 years. These regulatory revisions, the EPA's commitment to improved communications, our focus on decisions with regulatory significance, and the expressed non- binding guidance in the preamble regarding recommendations for demonstration narrative and analyses to include in demonstration packages, protect human health and the environment while providing needed clarity, increasing the administrative efficiency of demonstration submittal process, and removing some of the challenges associated with implementing the Exceptional Events Rule. As part of the EPA's mission to protect public health, this action promulgates new requirements for mitigation plans for areas with known, recurring events. We are simultaneously using this action to provide written notification to those states with areas that are initially subject to these new requirements. In addition to finalizing revisions to the Exceptional Events Rule, the EPA is also announcing the availability of the final version of the non-binding guidance document titled Guidance on the Preparation of Exceptional Events Demonstrations for Wildfire Events that May Influence Ozone Concentrations, which applies the rule revisions to wildfire events that could influence monitored ozone concentrations.

The agency’s own summary, as published.

What this changes

Amends 2 parts of the Code of Federal Regulations — the standing rules this notice rewrites.

• 40 CFR 50 National Primary and Secondary Ambient Air Quality Standards
• 40 CFR 51 Requirements for Preparation, Adoption, and Submittal of Implementation Plans