These are just 2 of the estimated 220 people in Canada and the U.S. who die annually from Heat Stress.

But the worse is yet to come if global climate change makes our summers hotter. Toronto Public Health predicts that heat related deaths will rise from 20 each year to 300 annually by the year 2020.

Workers in a wide range of industries will be affected, with Bakeries and Food manufacturing being high on the list along with smelters and foundries. Outdoor workers such as roofers and road crews will also be at risk.

Some workers are more vulnerable than others to heat stress. Those not acclimatized to high temperatures are more likely to suffer from heat related disorders. Older workers, workers with heart or lung disease, diabetes, obesity and individuals taking certain drugs are also at higher risk.

It takes a worker 5 to 10 days to acclimatize to higher temperatures.  When acclimatized the body will begin to sweat at lower temperatures and reduce heat load faster. Unfortunately, the sudden arrival of sweltering heat in Southwestern Ontario does not allow for acclimatization and leaves workers more susceptible to heat related illnesses.

There are a variety of health affects related to very hot work environments.

Heat Stroke is the most serious consequence. It occurs when the worker’s own body temperature regulation fails and the body’s temperature rises. Signs and symptoms include hot and dry skin that is red or spotted, mental confusion, delirium, convulsions or unconsciousness. If heat stroke is not treated immediately, permanent damage to organs or death can result.

Heat Exhaustion is caused by the loss of large amounts of fluids by sweating. A heat-exhausted worker will still sweat but suffer some or all of the following symptoms: extreme weakness, dizziness, headache, nausea, vomiting, muscle cramps and breathlessness.

Heat Cramps are sharp muscle spasms that occur in those people that sweat large amounts in the heat and drink lots of water, but do not adequately replace the loss of salt. Sports drinks can help with this problem.

Heat stress can also trigger other safety problems. Fogged up safety glasses, sweaty palms, dizziness and a lack of mental alertness can increase the risk of accidents.

From a legal standpoint workers in this province cannot fall back on labour laws when it gets hot. Ontario does not have specific regulations governing heat exposure and resulting heat stress. In the absence of any law, the Ministry of Labour (MOL) applies Threshold Limit Values (TLV’s) for heat stress outlined by the American Conference of Governmental Industrial Hygienists (ACGIH). The MOL inspector will use these TLV’s to enforce the Ontario Health & Safety Acts general duty clause, which requires employers to take every reasonable precaution to protect the worker.

ACGIH Heat Stress Guideline: The heat stress guide uses a Wet Bulb Globe Thermometer. The WBGT will read environmental factors that lead to heat stress. The WBGT reads Wet bulb, Dry bulb and Vernon Globe temperature with:

Examples of permissible heat exposure