Washington, D.C., June 13, 2025 — The U.S. Chemical Safety and Hazard Investigation Board (CSB) has opened an initial investigation into the June 11 release of toxic nitric acid and nitrogen oxide gas at the Austin Powder Company’s Red Diamond facility, a commercial explosives manufacturing plant near McArthur in Vinton County, Ohio. The CSB is deploying an investigator to the site to begin fact-finding efforts surrounding the incident.
According to state officials, the release occurred after "an unknown contaminant" entered a 5,000-gallon tank containing nitric acid and purportedly caused a chemical reaction that released nitrogen oxide gas. A large, brownish-colored plume of the gas covered the facility and much of the surrounding area. Local officials ordered an evacuation of a 3-mile radius around the facility, and hundreds of residents in the nearby community of Zaleski also were later evacuated. Additionally, local media reported that the Federal Aviation Administration temporarily restricted flights for a 30-nautical-mile radius surrounding the facility.
The CSB will work with other local, state, and federal officials to assess the situation and determine the CSB’s path forward.
The CSB is an independent federal agency responsible for investigating industrial chemical incidents that result—or could result—in catastrophic releases of hazardous substances. The Board conducts thorough investigations, issues safety recommendations, and advocates for preventive measures to protect workers, communities, and the environment.
Board members are appointed by the President and confirmed by the Senate. The CSB does not issue fines or citations but makes non-binding safety recommendations to companies, labor organizations, regulatory bodies, and industry stakeholders.
For more information, visit www.csb.gov or contact Communications Manager Hillary Cohen at [email protected].