EPA Releases Tools to Assist Air Agencies in Exceptional Events Demonstrations

EPA Releases Tools to Assist Air Agencies in Exceptional Events Demonstrations

June 26, 2026

WASHINGTON - Today, U.S. Environmental Protection Agency (EPA) released three enhanced user-friendly tools to help state, local, and Tribal air agencies expedite, develop, and prepare demonstrations of exceptional events. One of the tools, an update to the AirNow Fire and Smoke Map, is being issued in conjunction with the U.S. Forest Service. Exceptional events are unusual or naturally occurring events outside an air agency's control, such as wildfires, that affect air quality. Under Section 319(b) of the Clean Air Act (CAA) and EPA's Exceptional Events Rule (EER), air quality monitoring data from these events may be excluded in certain regulatory determinations regarding the National Ambient Air Quality Standards (NAAQS).

EPA developed these tools to reduce burdens on state, local, and Tribal agencies, to streamline the identification of monitoring data affected by an exceptional event, and to increase transparency for the public. By doing so, EPA's partner air agencies can effectively implement the EER, while freeing up valuable time and resources to focus on providing clean air based on emission sources within their control.

"We have heard loud and clear from our state, local, and Tribal partners about the difficulties surrounding exceptional events demonstrations and frustrations with being penalized for emissions that are out of their control," said EPA Assistant Administrator for Air and Radiation Aaron Szabo. "These three tools will greatly reduce burdens faced daily by our air partners as EPA continues to work on our revision to the Exceptional Events Rule."

"Together with EPA, the Department of Agriculture is creating ways to cut through the burden of understanding wildfire-driven air quality impacts," said Department of Agriculture Under Secretary of Agriculture for Natural Resources and Environment Michael Boren. "Under President Trump's leadership, states, Tribes, and local agencies can spend less time sorting wildfire smoke data and more time supporting the prescribed fire work that protects communities. The U.S. Forest Service is leading the way with these updates to the Fire and Smoke Map."

In response to requests from local, state, and Tribal air agencies, EPA has:

• Updated the Expedited Modeling of Burn Events Results (EMBER) Tool to expand support for ozone demonstrations resulting from exceptional events. The tool now provides information on ozone impacts and levels from domestic, Canadian, and Mexican fires at U.S. ozone monitoring locations from 2021-2025.
• Created a new tool called the HYSPLIT Trajectory Tool for Exceptional Events to provide users with quick access to trajectories, smoke plumes, and fire locations. This tool will reduce computational burdens and ensure uniformed assessments across the board. The tool uses National Oceanic and Atmospheric Administration's Hazardous Mapping System smoke polygons to identify when transported smoke may have influenced conditions at the monitoring site.

Further, EPA and the U.S. Forest Service have jointly:

• Launched a new historic version of the AirNow Fire and Smoke Map to provide past map conditions by date and time, giving additional context for fine particulate matter (PM2.5) measurements. The map combines PM2.5 air quality measurements from permanent and temporary monitors and sensors with wildland fire locations and satellite smoke plume observations. Air agencies will be able to access and use downloadable map images as supporting evidence.

Background

Air quality monitoring data that meets the criteria for exceptional event exclusion may be removed from the data sets used by EPA in making certain regulatory determinations.

Exceptional events demonstrations are prepared by local, state, and Tribal air agencies, and include information about specific days where air quality levels were impacted by exceptional events. This helps EPA determine if there is sufficient evidence to meet the criteria for data exclusion under the CAA and the EER.