Which of the following is NOT listed as an engineering control for thermal stress?

• A. Dilution ventilation
• B. Active cooling
• C. Shielding
• D. Personal protective equipment

Answer: (D)

Understanding how thermal-stress controls are categorized. Engineering controls are measures that modify the workplace or environment to reduce heat exposure: dilution ventilation lowers ambient heat and contaminants, active cooling removes heat from the space or worker, and shielding blocks radiant heat paths. Personal protective equipment, by contrast, protects the worker without changing the environment—it’s worn to reduce heat gain or exposure but does not alter the heat source. Because PPE doesn’t modify the environment or heat source, it is not an engineering control. In practice, engineering controls are prioritized to reduce hazard at the source, with PPE used as a supplementary measure when additional protection is needed.