Energy & Environment

EPA rejects Texas’ plan to lower ozone levels in Houston, Dallas areas

The Environmental Protection Agency, in a ruling issued this month, said the federal agency will intervene if Texas does not do more to reduce ozone levels in the state’s two largest metropolitan areas. The Houston and Dallas regions have been out of compliance with federal standards for more than a decade.

Houston does not meet US EPA limits for ozone pollution
Dave Fehling/Houston Public Media
Houston does not meet US EPA limits for ozone pollution

The Environmental Protection Agency (EPA) wants Texas to do more to lower ozone levels in the state's two largest cities, with the federal agency indicating this month it is prepared to intervene and issue sanctions if the Texas Commission on Environmental Quality (TCEQ) does not adopt more stringent control measures.

In a ruling published last week in the Federal Register, the EPA said it rejected the contingency measures outlined in a 2020 proposal submitted by the TCEQ. At issue is the Houston and Dallas regions' longstanding noncompliance with federal ozone standards under the Clean Air Act.

If Texas does not submit an acceptable ozone-reducing plan for those metropolitan areas by November 2025, the EPA said a federal plan will be implemented and those areas could lose out on federal highway funding. If 18 months pass without an approved state plan, the EPA said it could require more offsetting emissions reductions in the Houston and Dallas areas, which would curb the expansion of pollution-causing industry.

"We welcome that rejection, because it means you've got to go back to the drawing board, you've got to try again, you have to do things that are much more transformational than just business as usual," said Jennifer Hadayia, the executive director of local nonprofit Air Alliance Houston. "We hope the outcome of that will be great change, and not just voluntary change. We hope there will be mandatory changes, use of all the best pollution-control practices and a reimagination of how we design transportation systems to reduce car emissions, so that we will come out of non-attainment finally with ozone pollution. But none of that is going to happen unless the EPA pushes back and says, ‘Nope, Texas, you must do better."

A spokesperson for the TCEQ, the environmental agency for Texas, said Tuesday it did not have a comment on the Oct. 3 ruling by the EPA. Hadayia and Daniel Cohan, an atmospheric scientist and associate professor of environmental engineering at Rice University, both said it is likely that Texas will file a lawsuit against the EPA over the ruling, like the state has done before in similar instances.

The EPA's ruling stems from Texas' failure to meet the federal ozone limit in 2008 of 75 parts per billion – the Dallas and Houston areas had values of 77 and 78, respectively, at that time – and the federal threshold was lowered in 2015 to 70 parts per billion. And while the federal standards have become more stringent, Cohan said ozone levels in the Houston region have been increasing since 2014 after a decades-long trend of declining.

Based on preliminary data for the three-year measuring period ending in 2023, Cohan said he expects ozone levels in the Houston region to be 83 parts per billion.

Ozone, or smog, is largely the product of emissions by vehicles as well as industrial facilities, such as refineries, with nitrogen oxide in the air reacting with volatile organic compounds. Heat and sunlight contribute to the presence of ozone, which can be harmful to health by making it harder to breathe and exacerbating lung diseases and other health conditions.

"We're not going in the right direction," Hadayia said. "We are only getting worse."

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In its ruling, the EPA said the TCEQ proposed contingency measures that are already in place, such as the gradual shift from traditional gasoline-powered automobiles to electric vehicles. Such measures would have been acceptable before a 2022 court ruling that determined the contingency measures needed to be more proactive and intentional, according to the EPA.

The EPA ruling also said the TCEQ argued it should not be required to submit an implementation plan regarding the 2008 ozone levels because the state's status with the federal agency subsequently changed from "serious" non-attainment of the ozone standard to "severe." The standard became more strict in 2015.

Other metro areas in the U.S., including Sacramento, California, also have long been noncompliant with federal ozone standards, according to information provided by the EPA.

“Rarely have sanctions been imposed, and when they have, they've been short-lived,” the federal agency said in a statement. “EPA routinely works with states to meet Clean Air Act requirements to protect health and the environment, and will continue to work with Texas toward this goal.”

Cohan said there's "a lot we can do" in the Houston area to try to meet or at least approach the most recent ozone standard, but he also said it figures to be challenge from a scientific standpoint, because large cities tend to have relatively high levels of ozone. And because a variety of chemicals and environmental factors contribute to the formation of ozone, Cohan said it would take a dramatic decline in emissions to make much of a difference in the short term.

"It's a very thorny problem facing air quality regulators," Cohan said. "Even if you do all that you can, it's very hard to get smog quite as low as we wish it would be."