Is It Too Hot to Work?

The Ministry of Labour (MOL) provides the following direction on temperature in the workplace (click here for link):

“Is there an acceptable temperature range for workplaces, either hot or cold?

In a health care facility or an industrial establishment, such as a factory, store, shop or office, the regulations set a minimum temperature of 18 °C, subject to some exemptions for things like work outdoors or in freezers.

The construction projects regulation specifies a minimum of 27 °C for underground change rooms [Section 260 (3) (d)], a maximum of 38 °C for work chambers [Section 384], and where work is done in compressed air, the provision of a medical lock with a minimum of 18 °C [Section 357] and maximum of 27 °C [Section 380].

There are no set minimum or maximum temperatures for other workplaces. Nevertheless, because either extreme heat or cold may be a hazard, temperature is a legitimate issue in determining workplace safety. A particular concern is heat stress.”

However, there are varying schools of thought on the level at which work should be stopped due to heat in non-construction workplaces (which have their own regulations). Generally, workplaces that are not air-conditioned or are located outside should use the following levels to determine when or if work should be stopped:

**Humidex refers to the combination of heat and humidity levels to determine how hot it “feels”.

  • Humidex of 30 to 33 Employees are warned to monitor for signs of Heat Stress and are encouraged to drink water.
  • Humidex of 34 to 37 Employees are warned to monitor for signs of Heat Stress and encouraged to increase water intake during heat breaks. Employees should be given a 5-minute break every hour. Consideration should be given to bringing work to areas that are air conditioned.
  • Humidex of 38 to 39 Employees are warned to monitor for signs of Heat Stress and are instructed to drink a bottle of water during heat breaks. Employees should only be permitted to work 45 minutes per hour. Heat breaks should be taken in areas that are air conditioned. Consideration should be given to bringing work to areas that are air conditioned.
  • Humidex of 40 to 42 Employees are warned to monitor for signs of Heat Stress and are instructed to drink a bottle of water during heat breaks. Employees are only permitted to work 30 minutes per hour. Heat breaks should be taken in areas that are air conditioned wherever possible. Consideration should be given to bringing work to areas that are air conditioned.
  • Humidex of 43 to 44 Employees are restricted to 15 minutes of work per hour during this period. Consideration should be given to stopping work – employees may be sent home and/or the next shift might not be scheduled.
  • Humidex of over 45 – Stop work!

Other Resources:

Canadian Center for Occupational Health & Safety

http://search.ccinfoweb.ccohs.ca/ccohs/jsp/search/ccohs.jsp?QueryText=heat+stress&MaxDocs=500&ResultStart=1&SortSpec=Score+desc&hTab=0

Air Quality Ontario (Smog & Heat Alerts)

http://www.airqualityontario.com/