Controls and general actions to minimize heat stress
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Educate and train workers
Employers must provide adequate training and education to all workers at risk of heat stress, their immediate co-workers, and their supervisors. Training should include the following information:
- How heat stress develops
- Personal factors
- How to prevent heat stress
- How to recognize signs and symptoms for different stages of heat stress
- What workers should do if they, or co-workers, develop a heat-related illness
Provide drinking water
The body naturally sweats to cool itself. Sweating can use up a significant amount of fluid, which must be replaced continuously throughout the workday. If fluid is not regularly replaced, workers will become dehydrated, increasing their risk of heat stress.
Employers are required to provide an adequate supply of cool drinking water, close to the work area for workers exposed to heat.
- Workers should drink about two glasses (about 0.5 litres) of water before starting work in a hot environment and one glass every 20 minutes throughout the workday.
- In very hot environments, or where sweating is profuse, even more water may be required.
- Suitable drinks include tap water, mineral water, and fruit juices.
- Fluids do no need to be iced; cooled drinks between 10 °C and 15 °C are adequate.
- Eating fresh fruits also helps to replace lost fluids.
Workers must not wait until they are thirsty to replace fluids.
Engineering controls
If elimination is not practicable, engineering controls are the most effective and preferred means to reduce excessive heat exposure. The following are some examples of engineering controls:
For indoor workplaces:
- Automate tasks to reduce worker exposure to heat or reduce workload
- Cover or insulate hot surfaces to reduce radiant heat
- Install shielding between workers and radiant heat sources
- Provide air conditioning or increased ventilation to remove hot air
- Provide fans for spot cooling (Caution: Fans may interfere with local exhaust ventilation and may not be effective at high temperatures)
- Where humidity is high, use dehumidifiers or reduce the sources of moisture (e.g., cover water baths, drains, leaky steam valves)
For outdoor workplaces:
- Use power tools or other equipment to reduce workload
- Install and maintain air conditioning in equipment cabs
- Provide shade to workers (e.g., erect canopies or tarps)
- Provide temporary cooling spaces (e.g., tents or trailers with portable air conditioning)
- Provide misting station where humidity is low and where safe to do so
- Provide fans for spot cooling (Caution: Fans may not be effective at high temperatures or may interfere with contaminant control)
Administrative controls
If engineering controls are not practicable, administrative controls must be considered. Examples of administrative controls include:
- Determine and implement appropriate work-rest cycles to allow adequate time for workers to cool down.
- Schedule work to minimize heat exposure.
- Assign workers to work in pairs or groups to monitor for signs and symptoms of heat stress.
- Provide adequate supervision.
- Determine acclimatization status of workers and implement a plan to acclimatize workers.
- If appropriate, have workers wear light-coloured, loose-fitting clothing made of breathable fabric.
- Post heat stress warning signs where heat exposure limits may be exceeded.
Personal protective clothing and equipment
Specialized heat-protective clothing:
- May be required in extremely hot environments when the risk of heat stress is not adequately controlled by other methods
- May be used in moderately hot environments to allow longer work periods between breaks
- Should be worn only by properly trained workers following manufacturer's instructions
A proper assessment of all heat sources is required to determine if any specialized clothing would be effective in reducing heat stress.
The clothing's effectiveness must be monitored through physiological measurements.
Precautions such as close supervision should be maintained until the effectiveness of the clothing is known.
Temperature-controlled clothing
Examples of temperature-controlled clothing include:
- Air- or water-cooled suits
- Ice-cooled waistcoats
There may be practical limitations on the use of such equipment.
Anti-radiant heat or reflective clothing
This clothing:
- May be necessary where there is excessive radiant heat from hot surfaces
- May include aprons, jackets or suits
- Provides little or no protection from high air temperatures unless the clothing is also temperature controlled
See Preventing Heat Stress at Work for additional controls and actions.
Have questions about heat stress? Call us at 604.276.3100 (or toll-free at 1.888.621.7233).
Have a technical issue with this tool? Call us toll free at 1.888.855.2477 or email ehelp@worksafebc.com