Dallas Air quality today

What is ozone, and how does it form over Dallas-Fort Worth?

Ground-level ozone is a harmful gas and the main ingredient in smog ^[5]. It is not released directly into the air ^[5]. It forms when nitrogen oxides and volatile organic compounds, two kinds of pollution, react in sunlight ^[5]. The American Lung Association likens its effect to a sunburn of the lungs ^[1].

The Texas Commission on Environmental Quality, the state air agency, says high ozone in the area usually comes on hot, sunny, dry days with slow winds from the southeast ^[3]. Slow, shifting winds that circle air back over the region can make it worse ^[3]. Ozone tends to build first near the city center and is then carried north and northwest, where the highest levels are usually measured ^[3].

Where does the pollution come from?

The state agency names vehicles, large power plants and industrial processes as the nitrogen oxide sources that matter most for the area's air ^[3]. Two monitors placed beside busy highways, in Dallas and Fort Worth, record some of the highest nitrogen oxide levels, which the agency says shows how much vehicle exhaust matters ^[3].

For volatile organic compounds, the agency found four main groups ^[3]. One was isoprene, a natural compound given off by trees and plants ^[3]. Two were linked to oil and gas extraction ^[3]. The fourth was linked to many industrial activities and to motor vehicle exhaust ^[3]. The agency notes that one suburban monitor sits downwind of the city and of oil and gas production in the Barnett Shale ^[3].

Not all of the ozone is made locally. From 2012 through 2022, ozone carried in from outside the region made up about 68 percent of the ozone on high ozone days, the agency estimated ^[3]. Ozone made in the area made up about 27 to 32 percent ^[3].

When is ozone worst in Dallas?

The state agency says high ozone can happen any time from March through October ^[3]. High ozone days come most often from April through June and again from August through October, with a dip in July ^[3]. The agency says the July dip comes from a high-pressure system that brings cleaner air from the Gulf of Mexico in midsummer ^[3].

During the ozone season, the highest hourly ozone usually comes in the mid to late afternoon ^[3]. The EPA's AirNow guide says ozone is generally worse in the afternoon and early evening ^[6].

How does Dallas compare with other US cities?

In the American Lung Association's 2026 State of the Air report, based on 2022 to 2024 data, the Dallas-Fort Worth metro area ranked 9th worst in the US for ozone ^[1]. Denton County, its worst county, averaged 27.8 unhealthy ozone days a year and got an F grade ^[1]. In the 2025 report, the area ranked 10th worst, with 25.5 days a year ^[1].

The area also has fine particle pollution, tiny bits of soot from sources such as diesel engines, coal-fired power plants and wildfires ^[1]. In the 2026 report, it ranked 22nd worst in the US for year-round particle levels, up from 30th worst in the 2025 report ^[1]. Dallas County got a failing grade because its levels were above the federal standard ^[1]. For short spikes in particles, the area ranked 137th worst ^[1].

What is being done about ozone in Dallas-Fort Worth?

When an area does not meet a national air quality standard, the EPA calls it a nonattainment area ^[5]. In October 2015, the EPA lowered the ozone standard to 0.070 parts per million ^[2]. In 2018, nine counties, including Dallas, Tarrant, Collin and Denton, were rated as not meeting it ^[2]. The EPA moved the area to a stricter class, moderate, in 2022, and to serious in June 2024 ^[2]. The deadline to meet the standard is August 3, 2027 ^[2].

Under an older standard from 2008, set at 0.075 parts per million, a 10-county area was rated severe in October 2022, with a deadline of July 20, 2027 ^[2]. In April 2024, the state agency adopted a plan for that standard, including changes to state rules that control volatile organic compounds and nitrogen compounds ^[4]. In March 2025, it adopted a plan for the 2015 standard that includes a review of available pollution controls and of the vehicle inspection program ^[4].

There has been progress. From 2012 through 2022, the area's ozone figure used to judge it against the standard fell about 11.5 percent ^[3]. Over the same years, nitrogen oxide emissions fell 26 percent and volatile organic compound emissions fell 32 percent ^[3]. The agency says cutting nitrogen oxides is likely to do more for the area's ozone than cutting volatile organic compounds ^[3].

How to protect yourself in Dallas

Check the Air Quality Index, or AQI, before planning time outside, and watch for Ozone Action Days ^[6]. When the AQI is unhealthy, choose a less intense activity, take more breaks, or move your activity indoors, where ozone levels are usually lower ^[6]. Because ozone is usually worse in the afternoon and early evening, plan outdoor activities for the morning ^[6].

People most at risk from ozone include people with lung disease such as asthma, children and teenagers, older adults, and people who are active outdoors, including outdoor workers ^[6]. People with asthma should follow their asthma action plan ^[6]. In extreme heat, staying inside with the windows closed and no air conditioning may be dangerous; go somewhere with air conditioning or find a local cooling center ^[6].

You can also help cut ozone by driving less, not letting your engine idle, not spilling fuel when you fill up, and using low-VOC paints and cleaning products ^[6].