Sign up for The Brief, The Texas Tribune’s daily newsletter that keeps readers up to speed on the most essential Texas news.

Twelve Texas counties have recently exceeded federal air quality standards for particulate matter, commonly known as soot. But Texas environmental regulators are proposing that only four of them be required to take action to improve their air quality.

In its proposal to exclude eight counties from stricter federal pollution rules, the Texas Commission on Environmental Quality cited either bad air monitoring data or "exceptional events” — unusual or naturally-occurring events that can temporarily affect air quality such as wildfires, dust storms or emissions from outside the state.

The agency looked at air quality data from 2021-23 and proposed that four counties — Dallas, Harris (which includes Houston), Tarrant (Fort Worth), and Bowie (Texarkana) — be declared out of attainment with new federal air standards. But it’s recommending that eight other counties — Travis (which includes Austin), Montgomery (Conroe), Kleberg (Kingsville), Harrison (Marshall), Ellis (Waxahachie), Webb (Laredo), Hidalgo (McAllen) and Cameron (Harlingen and Brownsville) — be allowed to avoid the tougher standards.

Last year, the U.S. Environmental Protection Agency slashed the level of particulate matter permitted in the air from 12 to 9 micrograms per cubic meter annually, marking the first update to the standard since 2012. It was one of the most ambitious parts of the Biden administration’s environmental agenda.

Particulate matter comes from diesel engines, wildfires, construction site dust, coal-fired power plants and other industrial sources. Some researchers have labeled particulate matter the deadliest form of air pollution.

The new standards came in response to growing evidence of the severe health impacts associated with particulate matter, which can penetrate deep into the lungs, aggravating respiratory issues and increasing the risk of premature death.

State agencies are responsible for enforcing the federal standards. The TCEQ initially determined that all 12 counties exceeded the new standards, then dropped the number to four in a new assessment released in November.

“I was surprised when TCEQ claimed so many exceptional event days,” said Neil Carman, a former TCEQ investigator who is now clean air director for the Sierra Club in Texas. “I thought more counties would fall under nonattainment.”

Harris County, home to much of the state’s massive petrochemical industry, has the highest particulate matter levels in the state at 12.5 per cubic meter on average over three years, followed by Cameron, Bowie and Dallas counties.

Cameron County, on the Texas-Mexico border, was removed from the nonattainment list because TCEQ determined its air quality levels were heavily influenced by international emissions, including wildfires and agricultural burns in Mexico and Central America. Similarly, Kleberg County, which includes Kingsville, was excluded due to particulate matter from Saharan dust and smoke.

TCEQ also ruled out Harrison, Travis, Hidalgo and Webb counties using the exceptional events rule. For Ellis and Montgomery the agency cited bad air quality data.

Nonattainment designations trigger stricter controls on pollution sources, including technologies that clean and filter out particulate matter. It also requires states to develop plans for achieving compliance. Adopting measures to reduce soot can be costly for industries and local governments.

Industry groups have argued that wildfires and other events out of their control are major soot generators that have elevated levels in many areas. They also said the new EPA soot rules would make it difficult to obtain permits for new projects and hinder economic growth.

TCEQ’s three commissioners must approve the recommendations, then the agency must submit its proposal to the EPA by Feb. 7. The EPA can reject or modify the state’s proposal and may designate additional counties as out of attainment.

Texas regulators are taking input from the public on its recommendations until Jan. 21.

Is agency properly using exceptions?

Experts and advocates argue that TCEQ often improperly uses “exceptional events” to let counties avoid stricter regulations, making it harder to hold them accountable for improving air quality.

“If you take exceptional events out, how do you 100% know where the spike came from? What if it happened to be the same day a polluter was polluting?” said Jennifer Hadayia, executive director of the environmental nonprofit Air Alliance Houston.

“We know twice a year there are going to be fireworks. That's a given. We know generally a couple times a year Saharan dust will exist. That's a given,” she added. “So … if the intent is to accurately represent air quality, and then take steps to truly improve air quality, then we have to consider that those things are going to happen.”

Richard Richter, a TCEQ spokesperson, said the agency’s use of exceptional events is consistent with federal regulations and guidance.

For example, TCEQ identified 25 days between 2021 and 2023 when Harrison and Travis counties experienced particulate matter spikes from prescribed fires, Saharan dust (which regularly drifts across the Atlantic Ocean to North America), fires from Mexico and Central America, high winds and fireworks.

Daniel Cohan, an associate professor at Rice University, said that with Donald Trump returning to the White House, the EPA might be less likely to push back on the TCEQ’s recommendations.

“TCEQ may be hoping that the Trump administration will be more lenient in letting counties off the hook for their high pollution,” Cohan said.

Once designations are finalized, Texas will have two to three years to develop a compliance plan, which will also require EPA approval.

Inadequate air monitoring

While Texas has one of the largest air monitoring networks in the U.S., with 215 sites, only 54 of them measure particulate matter. Hadayia and other environmental advocates said this leaves many counties, including those with significant pollution sources, without air quality monitoring.

For example, Fort Bend County lacks a monitor to measure particulate matter despite being home to W.A. Parish Generating Station — the largest coal-fired power plant in Texas. A Rice University study in 2019 estimated that the plant emitted enough pollution to cause 178 premature deaths annually.

Yet the county was ruled as “unclassifiable” by the TCEQ because it does not have an air monitor and there’s no data to determine whether the area meets the new particulate matter standard — so industries in the county won’t have to implement any new restrictions to meet the standard.

Hadayia and others argue that more monitoring by TCEQ is essential to protecting public health.

“If we’re not putting protections in place, how will we ever bring air quality to healthy levels?” she said.

Williamson County, north of Austin, has the state’s largest number of quarries — open-pit mines for stone, sand, and gravel that release particulate matter — but has no particulate matter monitors, said Christina Schwerdtfeger, chief technical officer for the Coalition for Responsible Environmental Aggregate Mining. According to the TCEQ’s air monitoring database, the three air monitors in Williamson County measure pollutants other than particulate matter.

“[TCEQ] can’t just act like an ostrich with your head in the sand and say, well, we don’t have any data. We don’t know,” Schwerdtfeger said.

TCEQ said the agency determines the locations of air monitors based on population trends, the number of emission sources in a region, and air quality complaints by residents. The agency added that its statewide air monitoring network exceeds the number of monitors required by federal regulations.

Disclosure: Air Alliance Houston and Rice University have been financial supporters of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.

This article originally appeared in The Texas Tribune at https://www.texastribune.org/2025/01/15/texas-particulate-matter-air-pollution-rule-epa/.

The Texas Tribune is a member-supported, nonpartisan newsroom informing and engaging Texans on state politics and policy. Learn more at texastribune.org.