Hazmat Division 4.3 hazard?

• A. Oxidizers
• B. Dangerous when Wet
• C. Flammable Solids
• D. Spontaneously Combustible

Answer: (B)

Division 4.3 hazards are materials that become dangerous when they come into contact with water. When moisture touches these substances, they can release flammable or toxic gases and may ignite or explode, so treating water exposure as a critical risk is essential. That’s why “Dangerous when Wet” is the right descriptor: it directly communicates the special danger that moisture introduces for these chemicals.

Other options point to different hazards. Oxidizers are substances that accelerate combustion and are typically handled as a separate hazard class. Flammable solids refer to solids that can ignite or contribute to a fire on their own, not specifically because they react with water. Spontaneously combustible materials ignite without an external ignition source, often due to exposure to air or moisture, which is a different danger profile from water-triggered reactions.