OSH Answers Fact Sheets

How does working in a hot environment affect a worker's health and safety? Whether work is done indoors in a hot smelting plant or outdoors in the summer months, heat exposure can be dangerous. Workers who are exposed to extreme heat or work in hot environments may be at increased risk of heat stress. Very hot environments can increase your internal body temperature several degrees above the normal temperature of 37°C, overwhelming your body's natural cooling systems and leading to a variety...

What is heat stress? "Heat stress" is the "net [overall] heat load to which a worker may be exposed from the combined contributions of metabolic heat, environmental factors, and clothing requirements. As the heat stress approaches human tolerance limits, further increases may lead to unacceptable heat strain and the possibility of heat-related disorders." [Reference: 2025 TLVs and BEIs: Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices....

How can I measure occupational heat stress exposure? Feeling hot or cold depends on: Air temperature. Relative humidity of the air. The presence of hot or cold objects in the surrounding area. Presence of air movement (breeze, ventilation). Physical exertion. Clothing. Various methods of measuring occupational heat exposure combine these environmental factors to obtain a single number as a measure of overall heat load. The most used measure in the workplace is the wet bulb globe temperature...

Do workers have rights? Yes. Every person employed in Canada has the right to a safe work environment. In each jurisdiction, the Occupational Health and Safety Act (or equivalent) is based on the internal responsibility system (IRS). The internal responsibility system requires that everyone at or associated with the workplace takes responsibility for their own health and safety and the health and safety of those around them. This shared responsibility for health and safety includes employers,...