Heat Stress (NIOSH Criteria) questions for the ASP
ASP11 Domain 6: Industrial Hygiene and Occupational Health (6.4.c Thermal stressors). 3 free questions below. Every answer quotes and links the regulation paragraph it rests on.
Regulations covered
- NIOSH, Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments (Pub. 2016-106) NIOSH Heat Criteria Document
Text pulled from the eCFR, current as of .
Question 1
A utility contractor is sending a crew back to a boiler-room maintenance job after a long break. Industrial hygiene measurements show combined environmental and metabolic heat of 1-hour TWA that is above the Recommended Alert Limit (RAL) but below the Recommended Exposure Limit (REL) for the work. Every crew member is healthy and wearing conventional one-layer clothing. The crew has NOT been working in hot environments recently and is not acclimatized. Which conclusion is correct?
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Answer: C. The exposure should be controlled because non-acclimatized workers should not be exposed to heat greater than the RAL
The guidance states that healthy workers who are not acclimatized should not be exposed to combinations of metabolic and environmental heat greater than the applicable RALs. The REL applies to acclimatized workers, so using it for this crew would be wrong.
Answer C rests on
NIOSH, Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments (Pub. 2016-106), PDF p. 34(opens ecfr.gov in a new tab)“against heat) healthy workers who are not acclimatized to working in hot environments are not exposed to combinations of metabolic and environmental heat greater than the applicable RALs, given in Figure 8-1.”
Question 2
A plant has a hot indoor finishing area where a worker has done only light assembly tasks for several months. The supervisor proposes moving this worker to an outdoor loading dock on a sunny day, reasoning that the worker has been 'working in the heat' for months and is fully acclimatized. Which assessment is most consistent with the NIOSH guidance?
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Answer: B. The worker is likely not acclimatized for outdoor work, because light indoor work does not produce the acclimatization needed for the added solar heat load.
The guidance says acclimatization depends on the total heat stress experienced, so light indoor work will not prepare a worker for the added heat load of the sun or for harder work. Fitness gives only partial acclimatization, so it does not replace heat exposure.
Answer B rests on
NIOSH, Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments (Pub. 2016-106), PDF p. 64(opens ecfr.gov in a new tab)“Thus, a worker who does only light work indoors in a hot climate will not achieve the level of acclimatization needed to work outdoors with the additional heat load from the sun or to do harder physical work in the same hot environment indoors.”
Question 3
A roofing laborer weighs 82.0 kg at the start of a hot shift and 81.1 kg at the end, after sweating heavily. No fluids were taken during the shift. Using the standard rule of thumb for converting weight loss to body water loss, about how much water does this worker need to replace?
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Answer: C. About 900 mL
The standard's rule of thumb is that each 0.45 kg of body weight lost equals about 450 mL of body water. The 0.9 kg loss is two such increments, so about 900 mL must be replaced. The other figures misapply that 1 kg to 1 L-type conversion.
Answer C rests on
NIOSH, Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments (Pub. 2016-106), PDF p. 60(opens ecfr.gov in a new tab)“A rule of thumb is that a 0.45-kg (1.0-lb) decrease in body weight represents a 450-mL (15.2-oz) decrease in body water in extracellular and intracellular compartments that needs to be replaced by consumption of water.”
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