Millions of Texans are advised to limit vehicle use this Monday due to air quality alerts from the National Weather Service. These alerts affect areas like Dallas-Fort Worth, Houston, Galveston, and Brazoria, indicating that atmospheric conditions may lead to increased ozone levels, a harmful air pollutant.
Steps to Reduce Ozone Pollution
Residents can minimize ozone pollution by:
- Carpooling, walking, or biking
- Bringing lunch from home
- Avoiding drive-through lanes
- Conserving energy
- Ensuring vehicles are properly maintained
Understanding Ozone Action Days
Ozone Action Days are announced based on periods when regions are more prone to high ozone levels. Forecasts are made by assessing if concentrations will meet or exceed the EPA’s AQI Level Orange threshold. This evaluation requires historical weather data, ozone monitoring, and models from Texas Commission on Environmental Quality (TCEQ) meteorologists. Alerts are then communicated by the National Weather Service.
What Is Ozone?
“Ozone is a secondary pollutant, meaning it’s not emitted directly from sources, but is formed through chemical reactions,” explained AccuWeather meteorologist Brandon Buckingham.
These reactions need sunlight and heat, making warmer months more susceptible to ozone formation. When air stagnates, pollutants are not dispersed, causing ozone levels to rise. Ozone exists in two main forms: stratospheric, which acts as a protective shield from ultraviolet rays, and ground-level, produced by chemical reactions between nitrogen oxides and volatile organic compounds in sunlight.
Ground-level ozone exposure poses risks particularly to those with asthma, children, older adults, and outdoor workers. It can lead to coughing, throat irritation, breathing difficulties, inflamed airways, increased infection risk, and worsen lung conditions like asthma, emphysema, and chronic bronchitis.
How the EPA Measures Air Quality
The EPA measures air quality using the Air Quality Index (AQI), a scale from 0 to 301+, categorizing air quality as:
- Green—Good (0 to 50): Air quality is satisfactory with minimal risk.
- Yellow—Moderate (51 to 100): Air quality is acceptable but may affect sensitive individuals.
- Orange—Unhealthy for Sensitive Groups (101 to 150): Sensitive groups may experience health effects, though the public is less likely to be affected.
- Red—Unhealthy (151 to 200): Some public members may experience health issues. Sensitive groups could face more serious effects.
- Purple—Very Unhealthy (201 to 300): A health alert signifies increased risk for everyone.
- Maroon—Hazardous (301 and higher): Emergency conditions likely affect everyone.
Updated on 5/25/2026, 5:30 a.m. ET with additional information.