
The Houston Health Department has joined the chorus of voices opposing the proposed expansion of TPC Group's petrochemical plant in the East End, saying that residents nearby already face high levels of toxic air pollution.
TPC Group has applied for air permits to expand its production of butadiene, a highly explosive gas that is also a known carcinogen. It's used to make synthetic rubber products like car tires.
An analysis of air monitor data from last year shows that 1,3 butadiene levels in the area downwind of the plant are already high, according to the Houston Health Department.
“It’s a really big problem, because the concentrations are so high that they’re posing a risk by themselves without expanding the facility,” said Loren Hopkins, the city’s chief environmental scientist.
The department analyzed data from the Milby Park and Cesar Chavez air monitors. The average 1,3 butadiene levels in 2021 at the Milby Park monitor were about 2 parts per billion – a significant increase from 2020 and 2019 when average levels were less than 1 ppb.
The Texas Commission on Environmental Quality considers concentrations above 9 ppb to pose a long-term health risk. But other states have implemented lower screening levels, such as California, where exposure to concentrations above 1 ppb is considered a long-term health risk.
It's also above federal health screening levels for cancer. The 2021 concentrations at the Milby Park monitor equate to a cancer risk of an additional 5.4 cases per 100,000 people, according to the EPA cancer risk screening level. And that's just from the one air pollutant.
"This is just from 1,3 butadiene so when you add together the other hazardous air pollutants these people are being exposed to it’s definitely of concern," Hopkins said.
There are other sources of 1,3 butadiene pollution in the area – such as the adjacent Goodyear facility – and Hopkins said the fact that we don't know what caused the high levels last year is concerning.
"Something went wrong in 2021. And so the question is, why did it go wrong? When you look at it, it wasn’t during the (winter) freeze, the highest month was May," Hopkins said. "Without understanding the source or having a plan to remedy it, it doesn’t seem in the best interest of the community to expand."
In a statement, the TCEQ said it wouldn't be investigating the cause since the levels are still below what the agency considers to be harmful.
"The monitoring data available from the Milby Park automated gas chromatograph demonstrates that the concentrations of chemicals emitted by TPC group (and by other nearby facilities) are not at levels that are expected to cause acute or chronic health effects from exposure," the agency said in a statement, adding that TPC is on its air reconnaissance route and is observed regularly.
The agency also said though TPC plans to increase its production of butadiene, there will be an overall decrease in 1,3 butadiene emissions due to the implementation of updated pollution control technology.
Some of the calculations for this alleged emissions reduction, however, are in a confidential permit file not available to the public.
Environmental groups have already taken issue with the company's calculations for how it will reduce nitrogen dioxide, another harmful air pollutant that forms smog.
Based on TCEQ’s modeling, the agency said the plant expansion won't have adverse health impacts on nearby residents.
"If the TPC group complies with their air permits, the surrounding community should not experience concentrations of emitted chemicals that could cause adverse health or welfare effects," the agency said.
But environmental groups say TPC regularly violates environmental standards and has a history of chemical fires and excess pollution.

In November 2019, a massive explosion at the butadiene processing unit at TPC's Port Neches facility rocked the surrounding neighborhood, damaging homes and causing a mandatory evacuation.
The Houston plant has also had its share of incidents over the years, including a fire in 2018 and a flaring incident in 2020 that sent a plume of black smoke into the air. The Houston plant has also been in violation of the Clean Air Act for the past 3 years, according to federal data.
"This plant shouldn’t be located where it is," said Gabriel Clark-Leach, a senior attorney with the Environmental Integrity Project. “It’s a dangerous plant. It’s an aging plant. It’s a poorly maintained plant. It breaks down frequently. The chemicals it releases during those breakdowns are carcinogenic, and they’re also explosive.”
The Environmental Integrity Project has filed a contested case hearing on behalf of the Sierra Club and Air Alliance Houston, which means the air permit application will undergo a legal proceeding in front of an administrative law judge. Those hearings are set to take place in June, according to Clark-Leach.
He also sees the plant expansion as an environmental justice issue since the majority of residents near the plant are low-income and Latino.
A TPC representative said the company’s application to expand in Houston meets health and environmental standards set by the state and highlighted the effort the facility has made to reduce emissions since 2004.