Preliminary Mobile Air Monitoring Results

Published on September 17, 2025

Allegheny County Health Department Shares Preliminary Mobile Air Monitoring Results Following Clairton Coke Works Explosion

PITTSBURGH – The Allegheny County Health Department (ACHD) has monitoring results from Mobile Air Units provided by Carnegie Mellon University (CMU) and Pennsylvania’s Department of Environmental Protection (DEP) that were stationed in the Mon Valley shortly after the Clairton Coke Works explosion in August.

No immediate health risks were measured by any of the instruments including DEP and CMU’s mobile monitoring or ACHD’s stationary monitoring.

DEP monitoring equipment in the area showed short-term exposure limits did not exceed U.S. Environmental Protection Agency (EPA) standards.

CMU data is still undergoing final processing and quality assurance checks from its mobile monitoring of fine particulate matter (PM 2.5) and black carbon on August 15, 2025. Preliminary results showed no specific “hot spots” tied to the explosion and were generally consistent with data from ACHD’s regulatory monitoring network. CMU will submit the finalized data to ACHD, and ACHD will review and post the information on its website.

As part of broader efforts to understand pollutant levels near the Clairton Coke Works, ACHD and its partners detected compounds, including hydrocarbons and air toxics known to be associated with coke production. These compounds have been observed previously through fence line and permanent monitors and are included in the annual emissions inventories for the Clairton facility.

DEP did measure concentrations of air toxics such as formaldehyde, ethyl benzene, and xylene at the fence line, but those concentrations were only observed for a brief time period and were mostly undetectable throughout most of the testing periods. These findings could indicate health risks, but ACHD is continuing to evaluate the DEP report and other data to determine if there are any potential issues.

ACHD will provide additional updates as more information becomes available.

###

The Allegheny County Health Department's mission is to protect, promote, and preserve the health and well-being of the more than 1.2 million people who call Allegheny County home.

Media inquiries may be directed to Ronnie Das,
Public Information Officer for the Health Department,
at ronnie.das@alleghenycounty.us or by phone at 412-578-7991.