Guideline for work in HOT ENVIRONMENTS

  HOT ENVIRONMENTS AND THE HUMAN BODY

 The human body functions best within a narrow internal temperature range of 36 to 38 degrees Celsius. Above or below this range, the body's temperature control center in the brain goes to work and will cause shivering to keep warm or perspiration to keep cool. As the surrounding air warms, the body pumps more blood to the skin and increases sweat production. In this way the body loses heat, to balance the heat gain. When the heat gain becomes more than the body can lose, body temperature begins to rise and may lead to a heat-related illness.

SOURCES OF HEAT GAIN AND HEAT LOSS

  Metabolic heat - the body's own internal heat, generated by the breakdown of food to form energy. The greatest energy users, and therefore internal heat producers, are muscles. Hard work in a hot environment contributes to the body's heat load.

 Conduction - the direct transfer of heat to the body by direct contact with a warm object. Generally, an almost insignificant source of heat when considering heat gain to the body.

 Convection - the exchange of body heat with the surrounding air that comes into contact with the skin. If the moving air is cooler than the body temperature, it will cool the body; if warmer, it will increase the heat load. Air speed is an important factor in heat loss or gain.

 Radiation - the transfer of heat to the body through air from a hot source, for example, a furnace, an oven, or the sun. This is an important factor as, again, heat is lost from the body only if the surrounding air is cooler than the body

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