What term describes finely divided solid materials that present a fire or explosion hazard when dispersed in air?

• A. Mist
• B. Fumes
• C. Smoke
• D. Dust

Answer: (D)

Finely divided solid materials that can form a cloud in air and ignite or explode are called dust. When these tiny solid particles become suspended, they create a combustible mixture that can ignite from a spark or heat and spark a rapid explosion, especially in confined spaces. Mist is liquid droplets in air, not solids; fumes are airborne particles formed from vaporized material and are often toxic or irritant; smoke comes from burning and is about combustion byproducts, not a general dust explosion hazard. Dust best fits the description because it specifically refers to solid particulates that pose a fire or explosion risk when dispersed in air.