Heat domes. Heat waves. The dog days of summer. B.C. has seen its share of record-setting temperatures the last few summers, and this puts some workers at risk of injuries related to heat stress.

By Marnie Douglas

As temperatures rise, both workers and employers need to be aware of the risks and implement measures to keep themselves and their workplaces safe.

Sweating on a hot day cools your body down, but if you work in a hot environment, whether it's outdoors or indoors, this might not be enough. If your body heats up faster than it can cool itself, you experience heat stress, and this can lead to serious heat disorders, explains Jeanette Campbell, WorkSafeBC senior occupational hygienist.

If not recognized and treated early, heat stress can lead to heat exhaustion and heat stroke. And heat stroke can result in cardiac arrest and/or other serious injuries.

Heat stress can come from working outdoors in the hot sun in industries such as construction, farming, and forest firefighting. Or it can occur indoors, particularly in boiler rooms, pulp and paper mills, industrial laundries, and restaurant kitchens.

Three main factors that contribute to heat stress

1. The environment. Air temperature, radiant heat, air movement or flow, and relative humidity affect the body's response to heat. Radiant heat sources can be found indoors and outdoors — indoor sources include boilers and commercial ovens, and outdoor sources include the sun and forest fires. Radiant heat can also be reflected from surfaces such as roofs. If the air temperature is hotter than skin temperature, it can warm your body, and high humidity can make it harder for you to cool down.
2. The work. The harder you work, the more heat your body produces. Heat stress can occur at lower air temperatures if the work is physically demanding.
3. The worker. Some people respond differently to heat than others. Poor hydration, lower physical fitness levels, and obesity, as well as some medical conditions and prescription drugs, make people more susceptible to heat. Acclimatization is a physiological adaption that improves your body's ability to tolerate heat. This process takes time (about seven days) and exposure to heat while working at a consistent pace. Just as acclimatization can be acquired, it can also be lost in a relatively short period of time.

In addition, certain personal protective equipment – for example, turnout gear worn by firefighters or disposable coveralls worn by asbestos abatement workers — can affect the body's ability to cool itself.

What can be done to avoid heat stress

To prevent heat-stress injuries, WorkSafeBC requires employers to conduct heat-stress assessments. In preparation for summer, employers should develop a heat-exposure control plan after identifying jobs, occupations, and areas where workers are at risk of developing heat-related disorders.

This plan must include an approach for monitoring temperature and other factors in the work environment, as well as controls that will be implemented when conditions get too hot.

Engineering controls such as air conditioning, spot cooling, and shielding should be introduced first. Depending on the conditions, administrative controls (for example, work-rest cycles or scheduling work during cooler parts of the day) and personal protective equipment may also be required.

"Employers must train workers about heat-related disorders and their signs and symptoms," Campbell explains. "It's key that employees are trained on what to look for and to watch for these signs and symptoms in themselves and their co-workers."

Employers can also do the following:

• Understand that outdoor thermal conditions may change throughout the day. Be aware and adaptive.
• Empower workers to speak up when they feel it's unsafe to work in a heated environment.
• Get workers involved in choosing safety measures for their specific work situation.
• Ensure first aid coverage and emergency procedures are in place.

To reduce the effects of heat when you work, you should:

• Drink plenty of cool water (one glass every 20 minutes).
• Wear light-coloured, loose-fitting clothing made of breathable fabric, such as cotton.
• Take rest breaks in a cool, well-ventilated area that are long enough to cool the body.
• Do hard physical work during the coolest parts of the day (typically before 11 a.m. and after 3 p.m.).
• Know your personal risk factors, such as medications and any pre-existing conditions.
• Check yourself and your co-workers for signs and symptoms of heat disorders.

For more information

Learn more on our Heat stress webpage. You can also read Preventing Heat Stress at Work or watch Sun Safety at Work on WorkSafeBC's YouTube channel.

This information originally appeared in the Summer 2023 issue of WorkSafe Magazine. To read more or to subscribe, visit WorkSafe Magazine.