Causes and sources of heat stress
Understanding heat stress
Environmental factors
Understanding heat stress
Heat stress occurs when heat is absorbed from the environment faster than the body can get rid of it. Several factors may contribute to heat stress, such as the type of work activity, the surrounding air temperature/humidity level, and the physical condition of the individual (he/she may be new to the job or new to Queensland).
Our bodies maintain a fairly constant internal temperature even though they may be exposed to varying environmental temperatures.
To keep internal body temperatures within safe limits in hot conditions, the body has to get rid of excess heat - and it does this by evaporating sweat and varying the blood flow to the skin. These responses are controlled by the brain and usually occur when the blood exceeds 37 degrees centigrade.
Factors that may contribute to heat-related health problems at work include:
- inadequate cooling off or rest periods
- insufficient water consumption
- climatic conditions (such as low air movement, high humidity levels and high air temperature)
- inappropriate clothing
- individual factors that may cause dehydration (such as poor diet, vomiting, diarrhoea or alcohol and caffeine consumption)
- individual medical conditions that may cause heat stress (such as heart problems, diabetes or hypertension)
- individual medication that may affect the body's temperature regulation
- an individual's age, general physical fitness and weight
Environmental factors
Environment and seasonal factors that can contribute to heat problems:
- high air temperatures
- radiant heat from hot objects such as machinery
- radiant heat from working outdoors in the sun
- higher relative humidity levels
- low air movement
Various engineering controls are effective for reducing heat in workplaces. Examples include:
- reducing the body's metabolic heat production using automation and mechanisation of tasks
- reducing radiant heat emissions from hot surfaces and plant e.g. by insulation and shielding
- using ventilation and air-conditioning
- humidity reducing methods e.g. install a dehumidifier (seek engineering advice)
- creating some shade (tarp, umbrella) or at least find a tree for outdoor workers' rest breaks.
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