A combustible dust explosion hazard may exist in a variety of industries, including: food (e.g., candy, sugar, spice, starch, flour, feed), grain, tobacco, plastics, wood, paper, pulp, rubber, furniture, textiles, pesticides, pharmaceuticals, dyes, coal, metals (e.g., aluminum, chromium, iron, magnesium, and zinc), and fossil fuel power generation.
Regulatory citations
Note that some State-Plan States have adopted different standards applicable to combustible dusts.
OSHA’s General Duty Clause: Section 5(a)(1) of the OSH Act requires employers to “furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees.”
Key definitions
- Combustible dust: A 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.
- Deflagration: The rapid combustion caused by a sufficient quantity and concentration of dispersed dust particles being exposed to a flame. When deflagration occurs in a confined area such as a building, room, vessel, or process equipment, the resulting pressure can cause an explosion.
- Dust explosion pentagon: The five main factors that contribute to a dust explosion: oxygen, heat, fuel (the dust), dispersion, and confinement.
Summary of requirements
- Follow the specific OSHA requirements for your operations and industry.
- List the possible sources of dust in the workplace and areas of accumulation. Check safety data sheets (SDSs) for the materials used in the facility that might become combustible dust under normal operations.
- Ensure working surfaces are designed to minimize the buildup of dusts.
- Follow good housekeeping programs to prevent the buildup of dust, emphasizing regular cleaning of floors and horizontal surfaces (e.g., pipes, hoods, ledges, and beams).
- Use grounding, bonding, and other methods to dissipate any electrostatic charge that could be generated while dust moves through ductwork.
- Ensure electrically-powered devices (e.g., vacuum cleaners) and equipment are approved for the hazard classification for Class II locations.
- Select and use powered industrial trucks (e.g., forklifts) that are approved for combustible dust locations.
- Comply with the company’s Hot Work Permit program.
- Smoke only in designated areas.
- Install and maintain dust-containment systems, if necessary, and ensure they do not allow fugitive dusts to accumulate in the work area.
- Do not locate dust collectors inside buildings (with some exceptions).
- Install separator devices to remove foreign materials capable of igniting combustible dusts.
- Direct explosion venting away from employees.
- Train employees to recognize and prevent the hazards associated with combustible dust.
- Develop a facility emergency action plan and train employees on it.
- Properly mark and maintain emergency exit routes.
