The U.S. Steel plant where two workers were killed and 10 injured in an explosion on Monday had a history of chemical accidents — but it was one of hundreds of high-risk chemical facilities that were recently hidden from the public after demands from the chemical industry.

The Trump administration, at the behest of the powerful chemical lobby, has been working to gut oversight of so-called Risk Management Program facilities, chemical plants that are considered at the highest risk of deadly explosions. In April, two months after an explicit request from industry, Trump’s Environmental Protection Agency (EPA) scrubbed a tracking tool listing such facilities from its website.

Clairton Coke Works, the U.S. Steel plant near Pittsburgh that erupted in black smoke on Monday, is one such facility. Deemed high risk by environmental regulators, the plant, which manufactures materials used in steel production, is subject to various risk management requirements under the Clean Air Act aimed at preventing chemical fires.

The plant has a history of chemical accidents involving ammonia, a reactive chemical, public records show. From 2017 to 2022, it received 32 formal enforcement actions from the EPA, according to the agency’s enforcement records, the most of any facility of its kind covered under Risk Management Program regulations during that time period.

That included “high-priority” violations of the Clean Air Act, the records indicate, which could relate to the release of pollutants or problematic chemical safety procedures. It’s unclear what led to these past violations or what caused Monday’s explosion.