Heat in indoor workplaces

Heat events

Heat events, or heatwaves, involve high temperatures and sometimes high humidity. These events are usually hotter than the seasonally normal temperatures for a region. B.C. is experiencing an increase in average summer temperatures and extremely hot days. As the climate changes, heat events are expected to become hotter, more frequent and longer lasting.

Heat events can affect anyone’s health. Unusually high heat can have serious negative health effects, and some people are at greater risk. 

Wildfires can occur at the same time as heat events and create conditions for exposure to wildfire smoke and extreme heat. For information about monitoring air quality and reducing exposure, refer to Wildfire smoke and workplace air quality.

Heat stress

Heat stress occurs when a person is exposed to conditions that cause their core body temperature to exceed 38°C or 100°F. Normal core body temperature is 37°C or 98.6°F. Depending on the work environment, the body adapts and maintains its normal temperature by sweating and increasing blood flow to the skin. These responses help prevent body temperature from rising.

Several factors are considered when assessing heat safety for employees:

• Temperature

• Humidity

• Level of physical exertion

• Duration of effort

• Adaptation in a hot environment

Heat stress and heat-related illnesses can occur when the body overheats from prolonged exposure to high temperatures.

People at greater risk of heat stress are the elderly, pregnant people and people with chronic health conditions. They may not realize when their core body temperature is rising. People with mobility difficulties may need additional help to keep cool.

People leaders and employees should know how to recognize heat stress and heat-related illness. Review Health checks during extreme heat events for information about recognizing heat stress and taking appropriate action. Take immediate action to cool down if you or someone you are caring for shows signs of heat stress.

Steps to ensure a heat-safe workplace

People leaders and employees can take steps to reduce heat in indoor workplaces and help employees remain comfortable during heat events.

1. Check the HVAC system

• Make sure the heating, ventilation and air-conditioning system is operating and functioning properly

• Work with your facilities management team and CBRE if you have concerns 

• During prolonged or extreme heat events, air-conditioning settings and hours of operation may need to be modified

• Work with your facilities management team and CBRE if the building is not cooling to its normal temperature

2. Minimize cooling loss and heat gain

• Do not prop open exterior doors that allow hot air to enter and cool air to escape

• Turn off unnecessary or heat-generating equipment

• Leave internal office doors open, where possible, to improve air distribution, including overnight

• Block sunlight by closing blinds and window coverings

• If security requirements allow close blinds before leaving at night

• If blinds cannot be closed at night, cover east- and south-facing windows when first arriving at the workplace in the morning

3. Use individual fans appropriately

• Small individual fans may be used to improve personal comfort in smaller offices and meeting spaces

• Consider fan placement to prevent respiratory droplets and aerosols from being directed toward other people

  • For example, do not place fans where they will direct droplets and aerosols downwind toward others

• Where possible, arrange devices so that airflow moves down from the ceiling

4. Use portable air conditioners appropriately

Portable air conditioners may be necessary in buildings with inadequate cooling systems. They may also be used in buildings that otherwise have adequate mechanical ventilation. When using a portable air conditioner:

• Direct the airflow away from people

• Do not arrange seating directly in front of the unit

A workplace without mechanical ventilation or air conditioning may be cooled using natural ventilation and fans. Continue to consider fan placement when using these measures.

5. Take personal measures

• Drink plenty of water without added salt throughout the day, including before, during and after work

• Wear loose, lightweight clothing where appropriate 

When indoor temperatures exceed the acceptable range

In workplaces without functioning mechanical air conditioning or other effective cooling methods, heat events can create a risk of heat stress. Most employees working in offices are in public service buildings with mechanical ventilation and air conditioning. Based on WorkSafeBC requirements, buildings with mechanical ventilation should maintain an indoor temperature between 23°C and 27°C during the summer, depending on the humidity level.

For office work involving light or sedentary duties, work may continue when the temperature exceeds 27°C, but heat-mitigation measures must be put in place.

Workplaces involving moderately or heavily physically demanding work, or heat-generating processes such as laboratories or workshops, may require mitigation measures at a lower temperature and a heat exposure control plan.

If the workplace remains above the acceptable temperature range after preventive measures have been taken, other options may include:

• Working from another office

• Working from home, if the home is sufficiently cool

When indoor temperatures exceed the acceptable range, follow the indoor air quality guidance, including what is too hot or too cold information to assess the concern and determine the appropriate next steps. Employees working remotely who experience high and unsafe temperatures at home should work from their assigned office or work location to access air conditioning. 

People leaders who believe that their workplace may need heat-mitigation measures and a heat exposure control plan can request help assessing the workplace environment and the tasks being performed. Contact a BC Public Service Agency occupational safety specialist by submitting a service request through AskMyHR. Choose service category Workplace Safety and sub-category Other Issues and Inquiries.