Updated ‘Toxic Ten’ ranking reveals Allegheny County’s most-toxic air polluters

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PITTSBURGH – Here’s a top ten list no one wants to head. Allegheny County has a new #1 air polluter, according to the PennEnvironment Research & Policy Center’s updated “Toxic Ten” report. The report, co-authored with researchers from Frontier Group, found Allegheny County’s worst ten industrial polluters collectively released 1.4 million pounds of toxic air pollution in 2021. The toxic chemicals spewed into the air include benzene (a carcinogen), chromium (a form of which is a carcinogen and respiratory irritant) and manganese (a neurotoxin). U.S. Steel’s Clairton Coke Works topped the list, in part because of its increased emissions of hydrogen sulfide, benzene and hydrogen cyanide.

“PennEnvironment’s latest review of the ‘Toxic Ten’ shows that these facilities churned out a whopping 80% of all toxic air pollution reported by facilities in Allegheny County,” said Zachary Barber, the clean air advocate with PennEnvironment Research & Policy Center. “If our local leaders rein in the Toxic Ten, we could make significant headway in reducing unhealthy air pollution in the Pittsburgh region.”

Other Toxic Ten facilities this year include:

  • ATI Flat Rolled Products, the second-most-toxic emitter in the county, which has polluted for two decades despite never receiving its legally-required Clean Air Act operating permit;
  • Neville Chemical, which was fined $62,000 following a chemical leak that allowed nearly 25,000 pounds of volatile organic compounds and nearly 1,000 pounds of hazardous air pollutants to escape into the air over the course of just five hours in 2021;
  • Thermal Transfer Corp, which led Allegheny County for reported emissions of chromium.

The full rankings, along with an interactive map and detailed histories and emissions data for each facility, is available on PennEnvironment Research & Policy Center’s website.

“I love this great city, and it’s not acceptable that a handful of industrial polluters are making it less healthy and less attractive to businesses and new residents,” said Rep. Dan Frankel, who serves as majority House Health Committee Chairman. “Under-regulation of polluters is a health issue, a workers’ issue and an economic issue.”

PennEnvironment Research & Policy Center recommends setting stronger, health-protective emission limits; increasing permitting fees; imposing stricter fines on companies emitting illegal pollution; and improving pollution monitoring.

These recommendations were also included in the group’s recently released Green Allegheny Issue and Policy Agenda, created by some of the region’s top environmental policy experts to direct local officials on ways to protect Allegheny County’s environment. This is critical, as Allegheny County is set to elect its first new County Executive since 2011. 

“As an emergency physician and now legislator, I recognize the relationship between environmental quality and public health,” said State Representative Arvind Venkat. “Highlighting these facilities is a way to understand how best to target our resources to help the wider community in Allegheny County.”

The Toxic Ten report was compiled using industry-reported data from the U.S. Environmental Protection Agency’s (EPA) Toxic Release Inventory for facilities in Allegheny County in 2021. The pollution releases were then weighted for their toxicity using the EPA’s Risk-Screening Environmental Indicators (RSEI) Hazard model. With a toxicity-weighted measure for each facility,  PennEnvironment Research & Policy Center was able to compare facilities that emit different types of pollution.


PennEnvironment Research & Policy Center is dedicated to protecting our air, water and open spaces. We work to protect the places we love, advance the environmental values we share, and win real results for our environment. For more information, visit www.pennenvironment.org/center.


Frontier Group is a non-profit, non-partisan public policy organization that provides information and ideas to build a healthier, more sustainable America. For more information, visit www.frontiergroup.org.