By Yosie Saint-Cyr 

Various health studies and other forms of research indicate that heat stress is a set of conditions where the body is under stress from overheating. Conditions include heat exhaustion, heat cramps, heat stroke and heat rash and symptoms include profuse sweating to dizziness, to cessation of sweating and collapse. High temperatures, heavy workloads, and the type of clothing worn can induce heat stress. Other heat stress factors are also significant. In addition to temperature, increased relative humidity, decreased air movement or lack of shading from direct heat (radiant temperature) can all increase the potential of heat stress.

Employees who experience heat stress may at first be confused or unable to concentrate, followed by more severe symptoms such as fainting and/or collapse. Employers must ensure supervisors/managers and employees are aware and know how to deal with heat stress when it occurs in the workplace. Heat stress may be a health and safety hazard found in the workplace, and employers must insure they have identified it as a possible health and safety issue and implemented measures to control this specific hazard.

If an employee does show heat stress symptoms, move them to a cool, shaded area, give him or her water and immediately contact the supervisor and first aid attendant (if one is available) while following procedures in the health and safety policy in respect to heat stress and first aid.

Several Workers’ Compensation Board or Occupational Health and Safety divisions of the Ministry of Labour have developed health and safety guidelines to assist employers in preventing and dealing with heat stress. The guides will provide steps to identify and control heat stress, including each type of heat stress, their cause, symptoms, treatment and prevention. Links to these guidelines can be found below. Other steps supervisors can take to prevent heat stress are as follows:  

• Have a policy in place dealing with working in hot weather and/or hot environments 
• Establish a schedule for work and rest periods during hot days and for work in hot environments 
• Allow time for employees to adjust to hot weather and/or job environment when possible; it often takes up to one week for an employee to become acclimated to a hot environment 
• Adjust the work schedule, if and when possible 
• Assign heavier work on cooler days or during the cooler part of the day 
• Reduce the workload, if and when possible 
• Increase the use of equipment on hot days to reduce physical labour 
• Train supervisors/managers and employees to recognize signs and symptoms of heat stress disorders and be prepared to give first aid, if necessary 
• Select appropriate employees to work on hot days and/or in hot environments. Some employees are more likely to have heat disorders than others depending on their health and/or physical makeup. Avoid placing “high risk” employees in hot work environments for extended time period (“high risk” individuals are those that suffer from cancer, lung or kidney disease, diabetics, those experiencing high blood pressure or under certain medication) 
• Understand that individual employees vary in their tolerance to heat stress conditions 
• Have employees pace work, taking adequate rest periods (in shade or cooler environment) 
• Use adequate fans or ventilation and cooling especially when wearing personal protective equipment (PPE) 
• Have employees wear appropriate personal protective equipment (PPE) 
• Have employees wear light coloured, loose (unless working around equipment with moving parts) clothing 
• Keep employees, work area, and equipment shaded from direct heat where possible (i.e., wear a hat in direct sunshine) 
• Have employees drink plenty of water; provide water to your employees; in hot environments the body requires more water than it takes to satisfy thirst 
• Ensure procedures for first aid are in place and accessible to all employees, and include steps to deal with heat stress

Links to health and safety guidelines available online:

• Best Practice – Working Safely in the Heat and Cold, Alberta (in PDF)
• Worksafe BC – Heat Stress Guide (in PDF)
• Summer Heat or Thermal Conditions: Hot and Cold Conditions at Work – Saskatchewan Labour Department
• Risk Alert, Working outdoors, do you have everything under the sun – New Brunswick (in PDF)
• The Hazard of Heat – Newfoundland and Labrador (in PDF)
• Heat Stress Hazard Alerts – Nova Scotia Labour and Workforce Development
• Heat Stress (Health and Safety Guidelines) | Ontario Ministry of Labour
• Preventing Heat Stress – Ontario WSIB
• Québec CSST – Prévention des coups de chaleur (in French only)
• Sun Safety Prevention (in PDF) and Guide to Prevention of Heat Stress at Work (in PDF) – WCB Prince Edward Island
• Worker Discomfort in Increased Temperatures – Bulletin 133 (in PDF) – Manitoba Safe at Work

Yosie Saint-Cyr, LL.B., is managing editor at HRinfodesk.com–Canadian Payroll and Employment Law News. 

Originally published in HRinfodesk–Canadian Payroll and Employment Law News and Developments June 2009.

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