Heat stress
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Heat stress happens when our bodies heat up faster than they cool down, and it can lead to serious health effects. Although sweating cools our bodies down naturally, this might not be enough for workers in hot environments. Employers are responsible for managing the risk of heat stress in the workplace.
- How workers are exposed
- The risks for workers
- Measuring the risk
- How to protect workers
- Resources
How workers are exposed
There are three main causes of heat stress:
| The environment |
|
| The work |
|
| The worker |
|
The risks for workers
Employers should train workers to be aware of these early signs of heat stress in themselves and others:
- Excess sweating
- Muscle cramps
- Weakness, fatigue, and dizziness
- Nausea
Heat stress can also result in reduced physical and mental ability. This in turn can lead to an increased risk of workplace incidents.
If heat stress is not recognized and treated early, it can lead to heat disorders, such as heat exhaustion or heat stroke. Signs and symptoms include:
- Agitation and confusion
- Increased or irregular heart rate
- Decreased consciousness and awareness
- Seizures
Measuring the risk
If your workers may be exposed to heat conditions, you need to assess the potential for heat stress.
There are four methods to determine whether workers are exposed to harmful heat conditions:
- Using the Humidex method
- Using the wet bulb globe thermometer (WBGT) method
- Measuring body temperature
- Measuring heart rate
Which method you use depends on the conditions of your workplace. Use the Heat stress screening tool to help you select the appropriate method. You can also refer to the publication Methods for Measuring Heat Strain or Stress.
If you find that workers are at risk of heat-related illness, you need to develop and implement a heat stress exposure control plan. See OHS Guidelines G7.29-5 for more information.
How to protect workers
The most effective way to reduce the risk of heat stress is to eliminate the source of exposure. If that’s not possible, there are other risk controls to use.
Risk controls
-
1
Elimination or substitution
If you can eliminate the heat hazard or substitute a safer process away from the heat source, this is the most effective control. This could include:
- Cancelling or postponing the work until heat conditions improve
- Moving the work to a cooler environment
- Replacing highly strenuous work with less strenuous activities
-
2
Engineering controls
Making physical modifications to facilities, equipment, and processes can reduce worker exposure to heat. Some examples of engineering controls:
- Automating work
- Installing air conditioning
- Improving ventilation
- Insulating or covering hot surfaces to reduce radiant heat
- Installing shields and barriers to protect workers from heat
- Reducing humidity
-
3
Administrative controls
Changing work practices and work policies, awareness tools, and training can limit the risk of heat stress. Examples include:
- Rescheduling work to avoid the hottest parts of the day or times of the year
- Implementing work-rest cycles
- Having workers rotate work between hotter and cooler environments
- Providing cool-down areas for workers to rest and recover with access to cool water
-
4
Personal protective equipment (PPE)
PPE is not an effective control for heat stress in most cases, and wearing some types of personal protective clothing can actually increase heat stress. Heat-reflective clothing or cooling suits may be appropriate in some situations.
See the resources below and the OHS Guidelines for more information.
Resources
Preventing Heat Stress at Work
This booklet provides a basic overview of risk factors that increase the chances of experiencing heat stress, how to prevent heat stress, and how to recognize and treat heat-related illnesses.
Whether...
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Heat stress screening tool
Working in a hot environment can cause heat stress, which can lead to serious health problems. Employers can use this interactive tool to help evaluate when workers may be at risk of heat stress and...
Title
Methods for Measuring Heat Strain or Stress
When workers are exposed to hot or humid conditions, employers need to measure heat stress. This book outlines four methods for measuring heat stress to protect workers. It also explains when each method...
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Sun Safety at Work: Workers
Outdoor workers are up to 3.5 times more likely than indoor workers to develop skin cancer and are at a higher risk of experiencing heat stress. This video illustrates the dangers of sun exposure and...