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Ozone Data Exceptional Event Flag Demonstrations

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

(Esta página en español. / This page in Spanish.)

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 website.

Current Exceptional Event Proposals

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

How to Submit a Comment

TCEQ posted this demonstration for written public comment on May 24, 2023. All comments received or postmarked by 5:00 PM Central Standard Time on June 24, 2023 will be submitted to the Environmental Protection Agency along with the final demonstration. No public hearing will be held for this action.

Comments on the demonstration should be emailed to, with a subject line containing “Houston area ozone Exceptional Event Demonstration 2022.”

Or mail comments to:

TCEQ Air Modeling and Data Analysis Section (Attn: Erik Gribbin)
P.O. Box 13087
Austin, TX 78711-3087