CSB Cites Combustible Dust Hazard in Update on Fatal Nebraska Explosion

The U.S. Chemical Safety and Hazard Investigation Board (CSB) has released an update on its investigation into the fatal July 29, 2025, explosion and fire at the Horizon Biofuels facility in Fremont, Nebraska. According to the CSB, the incident resulted in the death of three people — an operator and his two young daughters.

Preliminary findings point to a combustible wood dust explosion, described in a statement by CSB chairperson Steve Owens as a “well-known — and completely avoidable — hazard in wood processing.” The agency said its ongoing work will examine facility design, dust handling and control systems, site operating practices and regulatory oversight. More than a month after the incident, the structurally compromised plant reportedly remains unsafe to enter, reported the agency, further hindering their investigation.

As part of its investigation, the CSB said the blast occurred after a sudden release of dust or smoke from the tower was followed by flames and a larger secondary explosion, which caused significant structural damage and fires that smoldered for weeks. The operator and his children were in the facility’s breakroom when the explosion occurred, trapping them inside the burning, collapsed structure. CSB board members emphasized that the investigation will identify root causes and share lessons to prevent future incidents.

The Fremont facility produces wood fuel pellets from wood waste and also supplies animal bedding. In early August, Chemical Processing reported on CSB’s decision to launch a formal investigation into the tragedy, which echoed long-standing agency concerns about combustible dust hazards.

The CSB is an independent, nonregulatory federal agency tasked with investigating chemical incidents and making safety recommendations to industry and regulators such as OSHA and EPA.

Chemical Processing has long covered combustible dust safety and prevention efforts. Most recently, we hosted a Combustible Dust Roundtable webinar to share insights from experts on managing hazards, strengthening safeguards and protecting workers across combustible solids processing industries.