What is an ozone watch and do you need to worry about it in Dallas? Here’s what to know

Ozone season in Dallas-Forth Worth lasts the majority of the year.

Dallas drivers may have noticed flashing signs warning of an “OZONE WATCH” this week. But what exactly does that mean?

Those new to Texas or not as familiar with air quality control may not recognize or heed the alert the same way they would a thunderstorm warning or tornado watch, but it’s worth noting — especially as the “ozone season” is upon us.

Ground-level ozone is a common air pollutant that can be harmful to human health. The pollutant forms when certain organic compounds interact with sunlight and intense heat.


This month marked the first days this year on which the air quality became unhealthy for some people in North Texas, according to data kept by the North Central Texas Council of Governments. The ground-level ozone rose high enough to cause an alert in Dallas-Fort Worth on May 2 and 3 and again Wednesday and Thursday.

D-FW Weather Wise

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Isn’t the ozone something up in the sky?

Yes, but there are two very different kinds of ozone, according to the Texas Commission on Environmental Quality.


There’s stratospheric ozone, which is naturally found in the earth’s atmosphere anywhere from 6 to 30 miles above the ground. This acts as a protective layer shielding us from the sun’s ultraviolet rays.

Ground-level ozone, also called tropospheric ozone, is a pollutant that causes concern at high levels.

What is ozone season and when is it?

Ozone season lasts the majority of the year in D-FW, according to Air North Texas. March through November is when ground-level ozone levels are highest.


Weather patterns play a major role in air quality, so there’s a higher risk of pollutants such as ground-level ozone when there are higher temperatures and less wind.

Ozone levels usually rise during the day and peak in the late afternoon, according to the National Weather Service. When daylight goes away, ozone concentrations decrease.

Scientific research that’s being challenged by industries and Texas regulators has serious implications for people in North Texas, where high levels of ozone pollution are common. ( Nathan Hunsinger - Staff Photographer )

What do the colors mean in the air quality index?

  • Green: Ozone levels are low; air quality is good for everyone.
  • Yellow: Moderate ozone levels; some sensitive groups may want to reduce time spent outside.
  • Orange: Unhealthy ozone levels for sensitive groups; all sensitive groups should reduce the amount of time spent outside.
  • Red: Unhealthy ozone levels for all; everyone should reduce time spent outside and sensitive groups should avoid it if possible.
  • Purple: Very unhealthy ozone levels; the general public may feel serious effects.
  • Maroon: Most serious rating, indicating hazardous ozone levels; the entire population is likely to be affected.

Who is considered sensitive to air pollutants such as ozone?

According to the Texas Department of Environmental Quality, sensitive groups include people with lung disease such as asthma; older adults; children and teenagers; and people who are active outdoors.

Particle pollution in the air has been linked to health problems such as coughing and wheezing, according to the Environmental Protection Agency. Sometimes the impacts are more extreme, leading to asthma attacks or strokes.

Is there a way to check the air quality online?

You can check the air quality and see if there are any warnings at or the Texas Commission on Environmental Quality website.


Can I do anything to improve the air quality?

Some of the steps Air North Texas recommends taking to improve air quality can be done at home or during your commute. Those include:

  • Taking public transit when possible. Only drive when necessary, and if multiple people are headed the same direction, carpool or use ride-sharing if you can.
  • Don’t let your engine idle if you can help it.
  • Turn off your lights and appliances when you’re not using them.
  • Set your air conditioning at a conservative range and try not to crank it up when you’re home.
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