Which of the following is an engineering control for thermal stress?

• A. Dilution ventilation
• B. Shielding
• C. Active cooling
• D. All of the above

Answer: (D)

Engineering controls reduce heat exposure by changing the environment or removing heat, not by relying on workers to manage it. Dilution ventilation works by circulating and replacing hot air with cooler air, lowering the ambient temperature and heat load. Shielding provides a barrier to radiant heat sources, so workers absorb less radiant energy. Active cooling directly removes heat from the environment or from individuals, using systems like air conditioning or cooling garments. Since each method targets a different way heat affects workers, all of these options are engineering controls for thermal stress.