SEARSMONT, Maine — Two volunteer firefighters died and 11 others were injured after an oxygen-limiting silo exploded during a fire at a Maine lumber mill. The 20-by-60-foot silo contained kiln-dried wood shavings and residual sawdust. Neither facility employees nor responding firefighters recognized that the silo was oxygen-limiting or that its contents posed a combustible dust explosion hazard. Crews directed water through an opening into the silo’s base for more than 30 minutes. At approximately 11 a.m., firefighters heard a “whoosh” as smoke rapidly vented from the top, and the silo launched into the air as fire erupted below it. NIOSH’s investigation highlights the need for hazard-specific preplans, disciplined accountability and tactics designed for oxygen-limiting silos. Recommendations for fire departments include:

• Train members to identify silo type and contents before beginning suppression.
• Do not direct water or foam into an oxygen-limiting silo. 
• Establish command, accountability and hazard-zone control at the start of the incident.
• Develop written pre-incident plans for high-hazard occupancies.