Definition by OSHA
Combustible particulate solid that presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations, regardless of particle size or shape.
Nearly 300 explosions have injured or killed over 800 American workers since 1980. The explosion at an Imperial Sugar Plant in 2008 which killed 14 people and injured over 40 caused the House of Representatives to pass a bill demanding a federal standard based on existing NFPA standards.
After the billed stalled in the Senate, OSHA reissued a National Emphasis Program (NEP) with the purpose to inspect facilities in industries where frequent or catastrophic combustible dust events have occured. OSHA has since inspected over 1,000 firms for combustible dust. Of the firms visited, 87% have received citations. PPE violations are the third most common category.
Flash Fire Hazard
Combustible Dust events include a Flash Fire Hazard. A Flash Fire is a rapidly moving flame front with a duration typically less than 3 seconds in any single location, can propagate through a facility as shock waves create dust waves ahead of the flame front.