CSB Releases Video on Fatal 2017 Didion Dust Explosion

The U.S. Chemical Safety and Hazard Investigation Board (CSB) released a new safety video on its investigation into the fatal combustible dust explosions and fires at the Didion Milling facility in Cambria, Wisconsin, that occurred May 31, 2017.

Five employees were killed and 14 others were injured in the incident, which destroyed the facility and caused more than $15 million in property damage, according to the CSB. The video, titled “Deadly Dust: Explosions at Didion Milling,” includes an animation of the events leading to the incident and commentary from CSB officials and investigators.

Didion Milling operates agricultural processing facilities in Wisconsin. At the Cambria dry corn mill, corn kernels were ground into smaller components for use in a range of corn-based products. The grinding process also produced dust, and the CSB found that both the product and the dust were combustible.

According the CSB investigators, a “smoldering nest” of dust inside the corn grinding process ignited, triggering an explosion within milling equipment and fires that spread through the facility, followed by secondary explosions in other mill buildings.

The agency issued its final investigation report in December 2023. The new video highlights five of the 13 key safety issues identified: process hazard recognition, dust hazard analyses, fugitive dust management, process safety leadership and regulatory coverage of combustible dust. It also outlines safety recommendations made to Didion Milling, the National Fire Protection Association and the Occupational Safety and Health Administration (OSHA).

The CSB noted that since 2006, it has called on OSHA to develop a comprehensive combustible dust standard for general industry. The agency said OSHA has not yet issued such a rule.

CSB board member Sylvia Johnson said in a statement, “The CSB has been calling for a comprehensive standard on combustible dust for many years to help prevent tragic, deadly incidents like the one at Didion from continuing to occur. Robust regulation is absolutely essential to keep these incidents from happening in the future.”