CSB Launches Investigation of Nitrogen Oxide Releases, Provides Update on Givaudan Explosion
The U.S. Chemical Safety and Hazard Investigation Board (CSB) recently launched an investigation into two releases of nitrogen oxide gas at facilities owned by Austin Powder, a provider of products and services to the mining industry. No injuries were reported in either incident.
According to Austin Powder, on Nov. 24, 2024, the first release resulted from a malfunction during startup at the company’s nitric acid plant in Greene County, Tennessee. The company attributes the second incident, which occurred June 11, 2025, at a facility in Vinton County, Ohio, to an “unanticipated chemical reaction” in a storage tank containing nitric acid, forming a large plume of nitrogen oxide gas. Local officials evacuated residents within a three-mile radius around the facility as well as hundreds of residents in nearby Zaleski, Ohio. Media reports indicate that the Federal Aviation Administration also temporarily restricted flights surrounding the facility.
“We are concerned that incidents involving nitric acid have occurred at two facilities owned by Austin Powder in less than seven months,” said CSB Chairperson Steve Owens. “While fortunately no one was injured in either incident, we want to ensure that they do not continue to happen.”
CSB also provided a new update on its investigation of the November 2024 explosion at Givaudan Sense Colour in Louisville, Kentucky, which injured five workers, two fatally, and damaged nearby homes and businesses. Operators at the facility were directed to adjust pressure and temperature setpoints in a batch reactor, leading to excessive pressure that ruptured the vessel. According to CSB, testing confirmed that the materials in the reactor could have led to a runaway reaction and explosion even under normal operating limits. The agency’s investigation of the incident is ongoing.
More information about the Austin Powder and Givaudan Sense Colour investigations is available from the CSB website.