Texans Urged to Cut Vehicle Use Amid Air Quality Concerns

The National Weather Service has issued air quality alerts advising millions of Texans to limit vehicle use on Monday. These alerts cover the Dallas-Fort Worth area along with Houston, Galveston, and Brazoria, due to predicted elevated ozone levels.

Ozone, a harmful air pollutant, is expected to rise due to specific atmospheric conditions. Residents are encouraged to reduce ozone levels by taking practical steps like carpooling, walking or biking, bringing food from home, avoiding drive-through services, conserving energy, and maintaining vehicle upkeep.

The concept of Ozone Action Days relates to periods when regions are likely to see increased ozone concentrations. The forecasters use historical weather data, ozone monitoring, and models to determine these periods. An Ozone Action Day is declared if concentrations anticipate meeting or surpassing the Environmental Protection Agency’s (EPA) Air Quality Index (AQI) Level Orange threshold, reflecting an eight-hour average of 71 parts per billion or a one-hour average of 125 ppb.

The Texas Commission on Environmental Quality (TCEQ) meteorologists analyze past weather patterns, ozone data, and predictive modeling to make these evaluations. When an Ozone Action Day is declared, coordination with the National Weather Service is established to issue alerts effectively.

Understanding Ozone

Ozone, deemed a secondary pollutant, forms through chemical reactions rather than direct emissions. AccuWeather meteorologist Brandon Buckingham explained, “These reactions require sunlight and higher temperatures, which makes warmer months more prone to ozone formation.” Stagnant air prevents pollutant dispersion, allowing ozone to accumulate to unhealthy levels.

Ozone occurs in two categories: stratospheric and ground-level. While it’s chemically identical in both forms, stratospheric ozone naturally assembles in the upper atmosphere. It acts as a protection against ultraviolet rays from the sun. Ground-level ozone, influenced by reactions between nitrogen oxides and volatile organic compounds under sunlight, is considered harmful.

The EPA highlights that those vulnerable to ground-level ozone exposure include individuals with asthma, children, older adults, and people frequently outdoors, such as outdoor workers. Exposure may lead to coughing, sore throat, breathing discomfort, airway inflammation, increased infection vulnerability, and aggravated lung issues like asthma.

EPA’s Air Quality Index (AQI)

The EPA utilizes the Air Quality Index (AQI) to gauge air conditions in the U.S., ranging from 0 to 301+, describing air quality from good to hazardous based on health risks.

• Green—Good (0 to 50): Air quality is satisfactory with minimal pollution risks.
• Yellow—Moderate (51 to 100): Acceptable air quality, though sensitive individuals might face some risks.
• Orange—Unhealthy for Sensitive Groups (101 to 150): Health effects possible for sensitive individuals but unlikely for the general public.
• Red—Unhealthy (151 to 200): Health effects possible for the general public, with sensitive groups facing more significant risks.
• Purple—Very Unhealthy (201 to 300): Health alert; heightened risks for everyone.
• Maroon—Hazardous (301 and higher): Emergency health condition warning; broader public impact expected.

Update, 5/25/2026, 5:30 a.m. ET: This article includes expanded information.