Skip to Content

Search tceq.texas.gov

Questions or Comments: amda@tceq.texas.gov

Exceptional Event Demonstrations for Ozone

Demonstration documents supporting the proposed exceptional events for ozone data.

About Exceptional Events

Definition

Exceptional events are unusual or naturally occurring events that affect air quality and are not reasonably controllable or preventable. Wildfires, prescribed fires, high winds blowing dust, dust from the Sahara Desert, fireworks to celebrate days such as July 4th, etc., can be considered exceptional events.

How They Affect Monitoring Data

States can request that the United States Environmental Protection Agency (EPA) exclude air quality monitoring data affected by an exceptional event from determining if an area met an air quality health standard . This page provides access to exceptional event demonstration documents developed by TCEQ.

EPA Regulations and Guidance

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

Draft Exceptional Event Proposals

Houston 1-Hour Ozone Exceptional Event: May 18, 2023

Public Comment Period: June 30, 2026 – August 7, 2026

TCEQ is posting this demonstration for written public comment on June 30, 2026. For your comment to be submitted to the EPA along with the final demonstration, it must be e-mailed by 5:00 p.m. CDT on August 7, 2026, or it must be postmarked by August 7, 2026.

Submit comments on the demonstration to amda@tceq.texas.gov, with the subject line “2023 1-Hour Ozone Exceptional Events Demonstration” or mail the comments to:

TCEQ Air Modeling and Data Analysis Section
MC 164
P.O. Box 13087
Austin, TX 78711-3087.

Finalized Exceptional Event Demonstrations (Submitted to EPA)

Houston Ozone Exceptional Events: June 20, September 13, September 21, and October 8, 2022

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

El Paso Ozone Exceptional Event: June 21, 2015

Houston Exceptional Event: August 26, 2011