When Is It Too Hot To Work?

Heat records are falling all over the world and there is little relief at night because nighttime temperatures are not dropping like they used to.  If you work outside or in a hot environment such as a steel mill, kitchen, bakery or even an unairconditioned office you are in uncharted thermal territory.

Your body must maintain a fairly constant temperature (around 37 Celsius).  If your body temperature gets too high because of internally generated heat from physical activity, radiant heat from the environment (such as the sun or large ovens in a bakery) or contact with hot air or other materials, it tries to cool itself and if it cannot, heat exhaustion or heat stroke can occur. 

One of the main ways the body cools it self is through the evaporation of sweat.  If your sweat cannot evaporate because of the large amount of moisture in the air (humidity) you can easily overheat.  That is why the humidity of the air is so important when discussing heat stress.

Everyone has a different tolerance to heat stress. This is affected by age, fitness and specific medical conditions and personal adaptation to the heat.   If you work in a hot environment continuously for several weeks you will become more proficient at working in the heat (acclimatized). 

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The legislative requirements regarding work in the heat vary by province. Some provinces have no maximum heat exposure limits while others such as British Columbia have specific regulations.

Let’s try to keep it simple!
Working in the heat can be deadly! All the Canadian Provinces have the requirement that the employer take reasonable precautions for the safety of the worker. And workers across Canada have the right to refuse unsafe work.  If you feel faint, lightheaded, uncoordinated or ill at any time let your boss know and rest in a cool airconditioned area if possible. Heat stress can quickly escalate to heat stroke which can put your life in danger. Even if you feel fine check in with the other people in your area to make sure they are okay. Drink plenty of water while working and continue to drink water even when you are off work to make sure your internal water supplies are topped up for the next day.

Let’s get a little more complex now.  The most accepted heat guideline in the world is from the American Conference of Industrial Hygienists (ACGIH).  So, this is the best guideline to follow at work however, this is tricky to use because you need a Wet Bulb Glove Temperature Gauge (WBGT) and a consultant to measure it for you.  

A simple way of assessing workers exposure to heat stress has been developed in Ontario. The scale uses the Humidex which is a Canadian innovation which uses the temperature and the humidity to create a number that reflects the perceived temperature.  Any levels above 30 will lead to discomfort for healthy adults and safety measures such as taking frequent breaks that increase in time with increasing temperature and the drinking of plenty of water.  At levels above 40 all unnecessary activity should be stopped.

See the Occupational Health Clinics for Ontario Workers for a great humidex calculator that also gives some basic safety measures to follow when the temperature gets hot.

How do you keep cool when the heat is on?  Let us know.

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