Working in extreme heat puts stress on a person’s cooling system. When heat is combined with other stresses such as hard physical work, loss of fluids, fatigue or some medical conditions, it may lead to heat-related illness, disability and even death.
As a general consideration, all persons working in these situations need to be prepared for the possibility of bodily stress due to extreme heat or cold.
Anybody working in extreme heat may face these risks. In Ontario, heat stress is usually a concern during the summer. This is especially true early in the season, when people are not used to the heat. It is important to understand the symptoms and take preventative measures against heat related stresses in order to function effectively in such conditions.
The employer should implement a heat stress prevention program that establishes:
worker training in the hazards, health effects and prevention of heat related illness;
criteria or monitoring method (e.g. acting on heat wave or alert notices by Environment Canada or calculating humidex from temperature and humidity measurements);
a monitoring/sampling plan (e.g. when, where and what to measure or monitor);
responses or preventative measures (e.g. increase frequency of breaks, reduce the work pace and workload, avoid working in direct sunlight, schedule heavy work for cooler part of day, wear hat and sun screen outdoors, etc.);
a water supply plan and encourages hydration (e.g. at least 1 cup every 20 min.); and
first aid and emergency responses, including monitoring of worker symptoms, and investigating incidents of health-related illnesses.
How We Cope with Heat
People are always generating heat and passing it to the environment. The harder a body is working, the more heat it has to lose. When the environment is hot, humid or has a source of radiant heat (i.e. a large lighting setup, a furnace, or the sun) a person must work harder to get rid of the heat. If the air is moving (for example from fans or wind) and it is cooler than the body temperature, it is easier for a person to pass heat to the environment.
Workers on medications or with pre-existing medical conditions may be more susceptible to heat stress. These workers should speak to their personal physicians about work in hot environments.
It should be noted that heat stroke is a medical emergency and as a result requires immediate medical attention (an ambulance should be called).
Other risk factors for developing heat strain besides medical conditions and certain medications are age, gender, past history of heat illness and use of PPE or heavy clothing such as costumes.