What causes heat stress?

Heat stress occurs when the body can’t cool itself adequately via sweating.

The key things that cause heat stress are:

  • air temperature (how hot the air is around us)
  • humidity (the moisture content of the air) in the outdoor environment or workplaces, such as laundries and mines
  • amount of air movement or wind speed
  • radiant temperature of surroundings such as the sun or other sources, including furnaces, ovens and working under a metal roof
  • clothing being worn including protective clothing such as overalls, coveralls and suits worn during insecticide spraying
  • type of the physical activity being done, and the length of time it is done for
  • physical fitness of the worker (including whether a worker is used to working in a hot environment or has any pre-existing conditions – eg overweight, heart/circulatory diseases, skin diseases or use of certain medicines).
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