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Ozone Data Exceptional Event Flag Demonstrations

Demonstration documents supporting the proposed exceptional event flags for ozone data.

Exceptional events are unusual or naturally occurring events that affect air quality and are not reasonably controllable or preventable. States can request that the United States Environmental Protection Agency (EPA) exclude air quality monitoring data affected by an exceptional event from consideration in determining the attainment or nonattainment status of a National Ambient Air Quality Standard (NAAQS). The demonstration documents below were developed in support of the Texas Commission on Environmental Quality’s (TCEQ) proposed exceptional event flags.

Exceptional event regulations and guidance are provided on EPA's Treatment of Air Quality Data Influenced by Exceptional Events Exit the TCEQ website.

Current Exceptional Event Proposals

There are no proposed exceptional events at this time.

Approved Exceptional Events

El Paso Ozone Exceptional Event: June 21, 2015

Exceptional Events Demonstration Document for the University of Texas El Paso (CAMS 12) Monitoring Site

EPA Concurrence Letter to TCEQ

Previously Proposed Exceptional Events

Dallas-Fort Worth Exceptional Event: August 16, 17, and 21, 2020

The TCEQ identified natural and human-caused wildfire events in Colorado and California that led to high concentrations of ozone at the Grapevine Fairway monitor in the Dallas-Fort Worth area on August 16, 17, and 21, 2020. The exceptional event demonstration package below describes the technical analyses that support the TCEQ’s conclusion and EPA's response.