Hot man pouring water on his own head

When Is It Too Hot To Work?

Heat records are falling all over the world. Heatwaves are coming more often and are more deadly than ever. 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 territory.

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Make sure everyone at your company knows the signs and symptoms of heat exhaustion and heat stroke and how to keep cool.

Even in a heatwave your body must maintain a fairly constant temperature (around 37 Celsius or 98.6 Fahrenheit ).  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 Country, State and Province. Some Jurisdictions have no maximum heat exposure limits while others such as British Columbia, Canada have specific regulations.

How Can I Tell If I Am At Risk of Heat Stroke?

One simple method that does not require environmental monitoring and that measures your individual response to the heat involves measuring your heart rate. It has been found that when your heat rate remains above the value obtained by the calculation – 180 minus your age – for several minutes you are at increased risk of a heat illness. Slow down for a few minutes or take a break in a cool area. If you work in the heat get a smart watch. Smart watches that measure your heart rate are readily available and inexpensive. Soon your smart watch will be able to tell you when you are at risk of heat stroke but until then keep it simple

Let’s try to keep it simple!
Working in the heat can be deadly! The United States, Europe and Canada all have the requirement that the employer takes reasonable precautions for the safety of the worker. All workers across Canada, the United States and Europe 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 shaded or air-conditioned area. Heat stress can quickly escalate to heat stroke, putting your life in danger. Please check in with the other people in your area to ensure 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 Globe 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. At this level safety measures such as taking frequent breaks that increase in time with increasing temperature and the drinking of plenty of water should be put in place.  At humidex levels above 35 a hot weather plan should be implemented. 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.

If you work outside in the heat, you may also be exposed to the cold in the winter. Check out “When Is It Too Cold to Work.”

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

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