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CSP question for October 21, 2026

The CSP question of the day for Wednesday, October 21, 2026, on combustible dust hazards. Pick an answer to see the explanation and its source.

CSP Domain 6: Occupational Health and Applied Science

A plant buys a sugar-based powder and a lab report classifies it as a weak explosion. After the plant switches to a finer grind of the same material with lower moisture, a manager wants to keep using the earlier classification for the new lot without further review. According to OSHA's guidance, what is the best response?

Show answer and source: OSHA 3371-08, Hazard Communication Guidance for Combustible Dusts (2009), PDF p. 6

Answer: D. Treat the earlier class as sample specific and check whether the new particle size and moisture change it.

OSHA's guidance says the actual class is sample specific and depends on traits such as particle size or moisture. A finer, drier lot may differ from the tested sample, so the class should be rechecked. The class is not fixed by the material name, does not automatically jump to the top, and is not erased by moisture.

On the job

A plant engineer at a pharmaceutical tablet facility receives a new lot of excipient powder milled finer than the lot that went to the lab. The earlier test result had assigned an explosion class, but OSHA's guidance says that class is sample specific and depends on traits like particle size or moisture. The engineer holds the old class as unconfirmed and requests testing on the new lot before updating the hazard communication materials.

Study aid, not site-specific safety advice. The official rule controls.

Answer D comes from

OSHA 3371-08, Hazard Communication Guidance for Combustible Dusts (2009), PDF p. 6(opens osha.gov in a new tab)
“The actual class is sample specific and will depend on varying characteristics of the material such as particle size or moisture.”

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