Whether inside or outside a building, working in the heat can represent a health and safety risk for workers doing physical tasks. 

To prevent serious heat-related injuries which can prove fatal, the Commission des normes, de l'équité, de la santé et de la sécurité du travail (CNESST) advises employers to identify, correct and control the risks surrounding working in the heat and to adopt a procedure to adequately prepare their workplace for heat episodes.

The CNESST has recorded seven fatalities and over 500 occupational injuries attributed to working in the heat since 2002. Men aged between 20 and 54 are mostly affected and account for 78 per cent of total injuries and all recorded fatalities.

Signs and symptoms

The main signs and symptoms of a heat-related illness are dehydration and discomfort such as heat stroke which can cause dizziness, loss of balance, loss of consciousness and in some circumstances, even death. Incoherent speech and unusual fatigue are also signs to watch out for.

The first signs of a heat-related illness can be subtle but a person's condition can quickly worsen. At the first sign of heat-related discomfort, the first-aid attendant and a supervisor should be notified so that they can take appropriate action.

Preventive measures

Employers must put in place various preventive measures before heat-related incidents occur to ensure safe working conditions especially during heat episodes.

A good practice is to establish a procedure providing for technical controls (such as an air-conditioned shelter and adequate water supply) and administrative measures (such as alternating work and rest periods and reducing the pace of work), training and information, as well as the wearing of clothing and the use of equipment adapted to work in the heat.

The CNESST recommends employers consult the guide La planification des travaux en prévision des vagues de chaleur.

Workers must apply the preventive measures and pay particular attention to their employees' general condition and that of their colleagues.

The main preventive measures to be applied are as follows:

- Adjust the pace of work according to the temperature; 
- Give workers lighter work loads during the hottest periods and postpone non-essential physical tasks until later in the day or when it's cooler; 
- Provide a sufficient number of breaks and ensure they are taken in cool, air-conditioned areas (shelters, air-conditioned trailers) or in the shade; 
- Provide workers with an adequate quantity of fresh water and ensure they have access to it and drink it (at least one glass or more every 20 minutes or more, as recommended by the "Corrected Air Temperature" utility); -Monitor workers' symptoms; 
- Inform all workers - current, new, temporary and student supervisors - of the risks, preventive measures, signs and symptoms of heat illness, and how to provide first aid.

For more information, visit the CNESST website at cnesst.gouv.qc.ca/heat.