Which of the following statements about flammable dust clouds is true?

• A. They cannot explode
• B. They can explode with great force
• C. They explode only at high humidity
• D. They require a catalyst

Answer: (B)

Flammable dust clouds are hazardous because when dispersed as a fine, combustible cloud in air, they can ignite and burn rapidly. If ignition occurs in a confined or semi‑confined space, the rapid burning produces a high overpressurization, creating a powerful explosion. That’s why dust explosions can unleash great force and cause serious damage.

Humidity doesn’t govern the possibility in a way that limits it to high levels; in fact, moisture often dampens powders and can reduce explosibility, so the idea that explosions only happen at high humidity isn’t correct. And a catalyst isn’t required for these explosions—the ignition can come from a spark, flame, or hot surface, with no catalyst needed.