Houston, Galveston, and Brazoria Are Under an Ozone Action Day This September 25. Children, Older Adults, People with Asthma, and Those Engaged in Intense Outdoor Activity Are More Sensitive to Ozone.
Updated on September 25, 2026.
HOUSTON, Texas — Houston and other areas of southeast Texas are under an air quality alert this Friday, September 25 due to atmospheric conditions that favor the formation of elevated ground-level ozone.
The Ozone Action Day covers the areas of Houston, Galveston, and Brazoria and remains in effect for this Friday. The forecast conditions could push air quality to levels considered unhealthy for sensitive groups.
The risk does not mean that everyone will experience respiratory problems, nor that the entire region will have the same ozone concentration throughout the day. An Ozone Action Day is a forecast issued when conditions may favor ozone levels reaching or surpassing the orange category of the Air Quality Index.
Children, Older Adults, and People with Asthma Are More Sensitive to Ozone
Ground-level ozone can irritate the airways and aggravate lung diseases such as asthma.
Among those at greatest risk are children, older adults, people with asthma or other lung diseases, and those who work or exercise for prolonged periods outdoors.
When air quality reaches the orange category, or “Unhealthy for Sensitive Groups,” the recommendation is to reduce prolonged or intense outdoor exertion and move those activities, when possible, to earlier or later times of the day.
Ozone can cause coughing, throat irritation, shortness of breath, and difficulty breathing deeply. It can also worsen asthma symptoms and other respiratory diseases.
The Air Quality Alert Continues Through Friday Night
Conditions will continue to be favorable for the formation of elevated ozone on this Friday.
Houston will also remain in the 90 °F range, while southeast Texas enters a relatively dry period. The chances of rain during the day are focused primarily over Gulf waters.
Warm, sunny days with light winds can promote the accumulation of ozone near the surface.
The National Weather Service recommends that sensitive individuals limit outdoor activities to early or late times of the day while the alert remains active.
Ground-Level Ozone Forms From Pollutants and Sunlight
Unlike the ozone in the upper atmosphere, which protects the Earth from some ultraviolet radiation, ground-level ozone is a pollutant.
It is not emitted directly. It forms through chemical reactions between nitrogen oxides and volatile organic compounds in the presence of sunlight.
Vehicles, industrial facilities, power plants, gasoline vapors, and other processes can contribute pollutants that participate in those reactions.
Reducing Car Travel Can Help Limit Ozone Formation
During an Ozone Action Day, environmental authorities recommend reducing activities that add pollutants to the air.
Options include carpooling, limiting unnecessary car trips, avoiding idling vehicles while parked, conserving energy, and keeping vehicles in good condition.
Air quality conditions can change during the day. The EPA’s AirNow system allows checking the updated Air Quality Index for Houston.
The ozone alert is expected to last through Friday night, September 25.
