Safety Insights

Dangers of Heat Stress: What to Know About Hot Work Sites

If you’re working at what’s known as a “hot” work site, you should always be aware of the dangers of heat stress and what it can do to you.

hot work site is a location where any combination of air temperature, humidity, radiation and wind speed exceeds a wet bulb globe temperature (WBGT) of 79°F (26°C).

These factors can help you define a hot work site:

  • High air temperatures
  • High surface temperatures
  • High humidity
  • Relatively low air movement

These could be outdoor surface areas where excavation or construction is taking place, indoor facilities where there are smelters or furnaces or deep underground mines where the rocks are giving off extreme heat.

Human bodies generate a significant amount of heat, especially when strenuous movement is involved. The higher the humidity is where you’re working, the more dangerous the area becomes.

Heat stress refers to the total heat-related load on the individual from all natural and man-made sources. If this heat load is not reduced or eliminated, workers can suffer from mild to dangerous heat-related disorders and illnesses.

The objective of controls in a hot work site is to keep workers’ body core temperatures from rising above 100°F (38°C).

Excessive heat gained by the human body must be offset by adequate periods of heat loss. The methods of reducing heat fall into these three categories:

  • Engineering controls
  • Administrative controls and work practices
  • Personal protective clothing and equipment


  • To learn more about how to reduce heat stress in mining, go here.
  • To see what CORESafety Module #13 has to say about occupational health hazards, including heat stress, go here.
  • To explore why CORESafety may be right for your mining operation, go to
Social media & sharing icons powered by UltimatelySocial