Levels of ozone pollution in San Antonio are expected to spike to harmful levels and remain that way for the rest of the week, according to air quality forecasts. 

The Texas Commission on Environmental Quality has declared ozone action days in San Antonio for Wednesday and Thursday, largely because of regional weather patterns. The state agency is predicting that pollution will stay at levels considered “unhealthy for sensitive groups” through Saturday. 

Ozone forms when air pollution from power plants, industrial sites, and vehicle exhaust reacts with volatile chemicals from sources like gasoline and paint in the presence of sunlight. The pollutant has been tied to chronic lung conditions such as asthma, and high enough levels can cause severe symptoms.

The poor air quality comes on the heels of a cold front that’s bringing cooler-than-average summer temperatures to much of Texas, which should, in theory, promote better air quality, not worse. But local conditions and regional wind patterns actually are making higher ozone levels more likely, Brian McGovern, a TCEQ spokesperson, explained in an email.

For San Antonio, high temperatures are likely to remain in the 90s, “which is plenty warm enough to contribute to efficient ozone production,” McGovern said. After the cold front departs, a ridge of high pressure is expected to remain over Texas that will result in sinking air, light to moderate winds, and clear skies, “all of which are conducive for ozone formation,” he said. 

McGovern said that some of this ozone will be blowing in from elsewhere. 

“Continental air from the central and southern plains is expected to filter in behind the cold front,” he continued. “This area had been experiencing high pressure, light winds, and hot temperatures, all of which contribute to the elevated ozone background levels that are now being transported into Texas.”

Dallas-Fort Worth, Houston, Austin, and El Paso also are expected to have high ozone levels this week, according to the TCEQ. 

San Antonio’s ozone issues have drawn more attention recently after the EPA last July declared the city’s long-term ozone levels too high to meet federal health standards. The designation has brought stricter state and federal scrutiny on San Antonio’s air quality, though so far it has not brought the kind of onerous regulations that some have feared. 

This week’s high ozone levels could hamper the region’s ability to meet specific clean air standards by the December 2020 deadline, which would place more stringent regulations on business and transportation planners.

However, those who will feel the most immediate effects of this week’s ozone spike will be “children and especially children with respiratory conditions; the elderly and adults with lung diseases,” said Adelita Cantu, an associate professor of nursing at UT Health San Antonio. 

“The impact of breathing ground-level ozone for a number of days includes chest pain, coughing, sore throat, [and] airway inflammation,” Cantu said in an email. “Longterm, it could result in lung damage. And most importantly, it can exacerbate existing health problems asthma, emphysema, chronic bronchitis, and cardiac issues, particularly for people that work outdoors.”

Cantu said avoiding ozone impact means staying indoors and limiting outside activity. 

“For students, this may increase school absences,” she said. “For all age groups, this may increase visits to providers and emergency rooms and hospital admissions.

“It is important that our policymakers understand that ground-level ozone is what we call an ‘upstream issue’ that ‘downstream’ causes many health problems for all ages. If we can focus more on the curbing the upstream issue, we will have more success downstream.”

Since the EPA’s designation last year, San Antonio’s Metropolitan Health District has taken the local lead on addressing ozone problems.

Ricardo Ambriz, a senior management analyst for Metro Health, said all residents can help keep ozone levels lower this week by changing their driving and fueling behaviors to keep more ozone-forming emissions out of the air. 

First, reduce the amount of time vehicles are idling, Ambriz said in an email. 

“Idle reduction can take many forms, such as walking into restaurants instead of using the drive-through,” he said. “This can also mean more efficient planning when running errands or better still, postponing unnecessary errands to a future date. People should also consider mass transit options like using the VIA bus system or car- or van-pooling.”

Second, wait to refuel until after 6 p.m., when the sun begins to sink. 

“Everyone can help limit the amount of gasoline vapors reacting with sunlight by filling up near sunset or by waiting until after an ozone action day to fill up,” Ambriz said. 

Ambriz said that Metro Health also is engaging in several programs aimed at lowering Bexar County’s overall ozone levels. These include working with a team at Bexar County’s Public Works Department to encourage construction workers to idle their equipment less. 

Metro Health also is trying to encourage businesses to help reduce emissions by getting their employees to drive and idle less, he said. 

Brendan Gibbons is a former senior reporter at the San Antonio Report. He is an environmental journalist for Oil & Gas Watch.