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Weekly Toolbox Talk: Heat Stress


Heat Stress 

Hot weather causes more fatalities than any other weather-related source.  Heat waves rarely are given adequate attention but in fact, they claim more lives each year than floods, hurricanes, and tornadoes combined. Heat waves are a silent killer.  Heatstroke also affects both genders equally. However, because many men are exposed to heat in the workforce, the annual death rate is 2 times higher in men than in women. 

In general, the human body cools itself by producing sweat. Sweat evaporating from the skin keeps the body cool.  Higher humidity, limited air movement, and wearing protective equipment can reduce evaporation.  Less evaporation means less cooling.  Frequent intake of liquids is necessary to prevent dehydration through loss of sweat. Plenty of cool (50ºF-60ºF) water or other cool liquids (except beverages with alcohol or high caffeine levels) should be available.  Drink small amounts frequently, for example, one cup every 20 minutes.  

Health and safety problems caused by excessive heat are called heat stress. These range from heat cramps to heat exhaustion to the most serious state, heat stroke. 


  • HEAT CRAMPS are a warning sign the body has lost too much salt through sweating.  The cramps affect working muscles, such as the legs, arms, and abdomen. Heat cramps may also occur when a person is resting.   
  • HEAT EXHAUSTION is a warning that the body’s heat control mechanism has become overworked.  Symptoms are exhaustion, dizziness and/or nausea, pale and clammy skin, rapid pulse, and low blood pressure.  Heat exhaustion may lead to heat stroke if symptoms are ignored. 
  • HEAT STROKE can be fatal. This happens when the heat loss mechanism of the body just shuts down. The person stops sweating and the body temperature goes up.  The heart pounds and the skin is hot and red. A person suffering from heat stroke needs immediate emergency medical attention. 

The best way to treat sickness is to prevent it: 

  • Drink water early and often. The body loses water through perspiration, and you need to replace it frequently. 
  • Experts recommend that you avoid using alcoholic beverages, coffee, tea or other beverages with caffeine as a fluid replacement. These types of drinks cause you to lose even more water and salt. The best defense is to drink plain water early and often. 
  • Use fans to create air movement throughout your work area. 
  • When possible, take approved / frequent rest breaks.  Immediately move to a cooler area if you feel dizzy or become nauseated. Report this to your foreman. Keep an eye on your work partner. 
  • Dress in light colors. Choose fabrics that let moisture and heat escape.  Dress in layers so you can peel off outerwear as needed as the day progresses. 

Watch for signs of heat stress in yourself and your fellow workers. Most of the time, a construction worker may not realize what is happening to them until heat sickness strikes. If signs of heat sickness do occur, help the victim to cool off by removing him to a cool place, fanning him or soaking him with cloth that has been dipped in cool water.  Give him sips of water to drink ONLY if he is conscious.