(TNS) — It’s the question asked by every fenceline community after an industrial accident: As the dust settles, what dangers linger in the air?

Mon Valley residents and environmental groups were hoping that would become clearer when U.S. Steel’s Clairton Coke Works, along with all the other coke-making facilities in the country, was required to install fenceline air monitors and fix problems that became obvious as a result of that monitoring.

The requirements were part of a U.S. Environmental Protection Agency rule on hazardous air pollution at coke ovens and integrated steelmaking facilities, finalized in 2024. The rule called for fenceline monitoring to begin this year.

But the Trump administration delayed its implementation by two years and signaled that it may revise or revoke the rule altogether.

“That means people in Clairton and the broader Mon Valley could once again be left in the dark about the toxic air that we are breathing,” said Qiyam Ansari on Thursday during a news conference organized by the Environmental Integrity Project, a national non-profit, which filed a lawsuit against the EPA earlier this month.

Mr. Ansari is executive director of Valley Clean Air Now, a Glassport-based organization that partnered with Carnegie Mellon University and the Environmental Integrity Project to monitor the air around Clairton for benzene, a known carcinogen, over an 18-month period beginning in December 2021.

For part of that time, U.S. Steel was also monitoring these emissions on its fenceline. It was asked to do so on a short-term basis by the EPA as the federal agency was crafting its emission rules for coke ovens and integrated steel facilities.

Coke is a product made from baking coal at very high temperatures. It is used to make iron and steel.

The results of that monitoring showed that average concentrations of benzene on the fenceline exceeded the emission rate set by the 2024 rule for such facilities that would trigger the company to take action.

“Based on six months of data, Clairton Coke Works is currently 10 times over EPA’s proposed action level, so the proposed fenceline standard could have a huge impact on improving air quality for residents that live downwind from the plant,” the Environmental Integrity Project wrote in a report tracking such data, released on Thursday.

Mr. Ansari put it more bluntly: “Rolling back these protections would lock us into a cycle of fear, illness and environmental injustice, and it would tell communities like mine that our health is expendable.

“Fenceline monitoring is the bare minimum of what justice requires.”

U.S. Steel, in a statement, said that “Mon Valley Works has never been fined for exceeding the benzene emissions standards set forth by federal, state or county laws and regulations under which we operate. That is a direct result of U. S. Steel Mon Valley Works’ extensive industrial hygiene programs that continuously monitor benzene and other chemicals, and the safety and environmental performance work of our more than 3,000 dedicated Mon Valley employees, many of whom live and raise their families in surrounding communities.”

There are various standards for benzene emission limits. The company’s air permit, which is administered by the Allegheny County Health Department, allows Clairton to emit up to 62 tons of benzene during any rolling 12-month period. Other benzene standards are set by the U.S. Occupational Health and Safety Administration for worker exposure inside the plant.

Lessons from Beaver County

A fenceline monitoring system, the type required in the 2024 EPA regulations, wouldn’t have yielded real-time data in the immediate aftermath of the coke oven explosion that rocked Clairton on Aug. 11, killing two employees and leaving at least 10 injured.

As communities around the Shell petrochemical complex in Beaver County have learned over the past few years, that kind of data takes time.

The Shell facility in Potter Township, which turns ethane, a natural gas liquid, into ethylene and then into lentil-sized plastic pellets, installed fenceline monitors as part of a settlement with environmental groups. Its system is modeled on what the EPA already requires to be installed at oil refineries.

Shell’s sprawling campus has four monitors that run continuously and record a total concentration of volatile organic compounds in short increments. To get more details about the specific chemicals being emitted, a passive system of sorbent tubes is also placed around the perimeter.

The air that collects in those tubes over a two-week period is sent to a lab for analysis. By the time it’s made public, typically about a month later, it includes a breakdown of the chemicals and their concentrations in the sample. This is the same methodology used by both U.S. Steel and the Environmental Integrity Project during their Clairton monitoring projects in previous years, and is what would be required by the now-delayed federal rule.

That kind of data is helpful to alert the company of a problem that might require attention. It is also useful for tracking pollution over time and is sometimes employed in legal filings or to inform rule making.

But it’s not an instant warning system.

That’s why Germaine Patterson, who lives near the Clairton plant and who felt her body shake from the blast last week, called for an alert system.

“The county told community members to shut their windows, to keep their doors closed, don’t come outside,” Ms. Patterson said on Thursday.

These are “good precautions,” she said, “however, we’re in August. It’s hot. You know, the pollution that is outside is always in the home, and so it’s not always safe to be indoors.”

The Allegheny County Health Department, which oversees Clairton’s air emissions, sent mobile air units out into the area last week. So far, the authorities have said they have not detected elevated pollution levels.