Working in Hot Environments

Protecting Workers from Heat Stress

High temperature, high humidity and hard physical work can be a dangerous combination. Working in hot environments can cause heat-related illness ranging from heat cramps to heat stroke.

It is incumbent upon Supervisors to inform workers of heat stress hazards due to hot processes or hot weather and instruct them on how to control those hazards.  This includes developing hot environment safe work procedures.

EHS Bulletin - Working in Hot Environments

The Working in Hot Environments Bulletin explains how to recognize the signs and symptoms of heat stress and how to prevent them, and provides guidance to Supervisors and workers on preventing heat stress through worker awareness and the implementation of adequate control measures.

Hot Weather Response Plan

The Hot Weather Response Plan (HWRP) is a protocol for hot weather response and is intended to alert those at risk of heat-related illness to take appropriate precautions to manage heat stress due to hot weather conditions.  

General practices/controls for reducing heat exposures already in place:

▪     Workers have received information about how to prevent heat stress

▪     Workers can recognize the signs and symptoms of heat stress

▪     Workers have access to an adequate supply of cool drinking water

When developing the HWRP, Supervisors should take steps, as appropriate, to implement additional measures/controls to mitigate heat health impacts.  Controls will vary depending on the type of workplace, type of work and other factors.  Refer to the Working in Hot Environments Bulletin for information on additional measures/controls to manage heat stress induced by hot weather.

Implementation of the HWRP is triggered during any of these conditions:

humidex reaching or exceeding 35 degrees Celsius

heat wave (3 or more consecutive days with temperatures over 32 degrees Celsius)

Environment Canada Humidex Advisory (air temperature exceeding 30 degrees Celsius and Humidex exceeding 40)

A smog alert issued by the Ontario Ministry of Environment, Conservation and Parks

Heat Exposures in Indoor Work Areas

Heat exposures can occur in indoor work areas as well on campus, where there may be radiant heat sources such as cooktops or ovens in kitchens, bakeries and heat in plants or workshops.  For guidance on heat stress due to indoor radiant heat sources, contact the Occupational Hygienist at 519-824-4120 ext. 54855.

For more information or if you require assistance:

If you require assistance regarding heat stress prevention or the selection of appropriate control measures for reducing heat exposures in your work area, contact the Occupational Hygienist at 519-824-4120 ext. 54855.

Links to additional useful resources:

Managing Heat Stress at Work, Ontario Ministry of Labour, Training and Skills Development

Hot Environments – Health Effects and First Aid, Canadian Centre for Occupational Health and Safety (CCOHS)