Hazmat Division 4.2 hazard?

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

Answer: (A)

Division 4.2 covers materials that can ignite on their own due to self-heating in air. The term Spontaneously Combustible describes substances that may ignite without an external ignition source because their oxidation generates heat fast enough to reach ignition temperature. That’s why it’s the best fit for this hazmat division. For example, oily rags or certain metal powders can heat up and ignite without a spark. In contrast, Flammable Solid belongs to the 4.1 category and requires an ignition source to start burning. Dangerous when Wet refers to substances that release flammable or toxic gases when in contact with water (4.3). Oxidizers are a different hazard class that support combustion but aren’t defined as spontaneously combustible themselves.