Site of 2017 Combustible Dust Explosions Implements CSB Recommendations

Didion Milling Inc., the company whose Cambria, Wisconsin, facility was the site of a deadly fire and series of explosions in May 2017, has implemented all of the safety recommendations issued by the Chemical Safety and Hazard Investigation Board, CSB announced last week. Initiated by combustible dust, the explosions killed five employees, injured 14 others, destroyed the facility, and resulted in more than $15 million in damage.

CSB’s investigation report on the incident, published in 2023, found that Didion had not recognized or addressed hazards posed by combustible dust and that the interconnections between processes at the facility “allowed explosions and propagations to go unmitigated.” CSB further found that Didion did not perform a dust hazard analysis and that the safety culture at the facility encouraged workers to regard smoldering fires as routine, affecting their ability to recognize potential hazards. The 2023 report described nine recommendations from CSB to Didion to help improve safety at its facility.

According to a CSB news release, “Didion has worked cooperatively with the agency since August 2025” to address its recommendations and has made changes to include developing a comprehensive dust management program and installing engineered safeguards appropriate for the combustible dust hazards at its Cambria facility. CSB notes that Didion has also provided documentation demonstrating that it has improved its continuity of operations, emergency response, and personal protective equipment programs as well as performed a dust hazard analysis with the assistance of a third party.

Some recommendations stemming from this investigation—three from CSB to OSHA—remain open. For example, CSB calls on OSHA to promulgate a standard for all industries that handle combustible dust, a recommendation it first made in 2006. CSB also urges OSHA to develop a program that would trigger follow-up inspections at facilities where combustible dust hazards have been identified but there is insufficient evidence as to whether the hazards have been abated. 

More information about CSB’s investigation of the incident at Didion’s Cambria facility, including a full list of its recommendations, is available from the agency’s website.