On April 22, 2026, two workers were killed and more than 30 others sought medical care following a toxic hydrogen sulfide (H2S) release at the Catalyst Refiners, Inc. facility in Nitro, West Virginia. The incident occurred during the cleaning and decommissioning of process equipment — a non-routine activity that required the mixing of chemicals that generated H2S gas inside an occupied building.
The H2S release resulted from the unintended mixing of nitric acid with a proprietary cleaning agent called M2000A during decommissioning of a tank. The chemical reaction between these two substances generated toxic hydrogen sulfide gas inside the building where multiple employees were working. The gas rapidly incapacitated workers who were exposed, and the enclosed building environment allowed concentrations to build to fatal and injurious levels before evacuation could be completed.
The CSB opened an investigation. The investigation is examining the chemical hazard identification process for the decommissioning activity, H2S monitoring and alarm systems, the adequacy of confined space and toxic gas controls during decommissioning, and the facility process safety management system. The incident highlights the specific and often underappreciated chemical hazards of decommissioning and cleaning activities.
This incident traced to breakdowns across 5 PSM elements (PHA · SOP · HOW · MI · TRN). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.