Millions of Texans have been urged to cut down on vehicle use this Monday. The National Weather Service issued air quality alerts for areas including Dallas-Fort Worth, Houston, Galveston, and Brazoria. The alerts warn that atmospheric conditions may lead to high ozone levels, a harmful air pollutant.
Actions for Residents
Residents can help lower ozone pollution by adopting these practices:
- Carpooling
- Walking or biking
- Bringing lunch from home
- Avoiding drive-through lanes
- Conserving energy
- Maintaining vehicles properly
These areas face Ozone Action Days, times when elevated ozone levels are expected. Forecasts look at whether levels could meet or exceed the EPA’s AQI Level Orange threshold. This threshold is defined as an eight-hour average of 71 parts per billion or a one-hour average of 125 ppb.
Forecasting Methods
The Texas Commission on Environmental Quality (TCEQ) uses historical weather data, ozone monitoring, and predictive models to decide when to issue an Ozone Action Day. They work with the National Weather Service to issue alerts.
Understanding Ozone
“Ozone is a secondary pollutant, meaning it’s not emitted directly, but formed through chemical reactions,” said AccuWeather meteorologist Brandon Buckingham. “These reactions need sunlight and heat, making them more common in warmer months. Stagnant air lets pollutants accumulate, leading to unhealthy ozone levels.”
Ozone, also known as smog, forms in the atmosphere. There are two types: stratospheric and ground-level. Both have the same chemical structure. Stratospheric ozone exists naturally in Earth’s upper atmosphere, protecting from the sun’s harmful ultraviolet rays. Ground-level ozone forms from chemical reactions between oxides of nitrogen and volatile organic compounds when exposed to sunlight.
The Environmental Protection Agency (EPA) notes that those most at risk from ground-level ozone include people with asthma, children, older adults, and those who spend significant time outdoors.
Health Risks from Ozone Exposure
Ozone exposure can lead to various respiratory issues. It can cause coughing and sore throats, make deep breathing difficult, and result in pain when inhaling deeply. It may inflame and harm airways, increase infection risks, worsen lung conditions, and trigger more frequent asthma attacks.
Measuring Air Quality
The EPA uses the Air Quality Index (AQI) to gauge air quality across America. The AQI ranges from 0 to 301+, rating air quality levels from good to hazardous:
- Green—Good (0 to 50): Satisfactory air quality with no risk.
- Yellow—Moderate (51 to 100): Acceptable air quality; some risk for sensitive individuals.
- Orange—Unhealthy for Sensitive Groups (101 to 150): Health effects possible for sensitive groups.
- Red—Unhealthy (151 to 200): Health effects possible for some; more serious for sensitive groups.
- Purple—Very Unhealthy (201 to 300): Health alert; increased risk for everyone.
- Maroon—Hazardous (301 and higher): Health warning of emergency conditions; high risk for all.
Update, 5/25/2026, 5:30 a.m. ET: This article includes additional information.
Limited Interest in Arctic National Wildlife Refuge Oil Auction 
Confronting the Truth Behind Sustainability Buzzwords in the Food Industry 
The Aftermath of Santa Rosa Island’s Fire 
Largest Seizure of Illegal Cockroaches in Australia 
Flesh-Eating Fly Returns to the United States Causing Concern 
Australia’s Largest Seizure of Exotic Invertebrates: Over 100,000 Cockroaches Confiscated