: Critical condition – Call 911! Occurs when the body can no longer control its own temperature due to failure of the sweating mechanism, causing body temperature to rapidly rise. Heat Stroke can cause permanent disability or death.
Heat Cramps: Sweating depletes the body’s salt and moisture levels, causing painful cramps.
Heat Collapse (Syncope): Dehydration and lack of acclimatization can contribute to fainting or dizziness. This condition can be very serious if workers are operating machinery.
Heat Rash: Skin irritation (typically a cluster of small red blisters) caused by excessive sweating during hot, humid conditions that gives a prickling sensation.
Heat Fatigue: Typically occurs due to lack of acclimatization, leaving the worker tired and with impaired performance.
There are many different ways to measure and determine if an environment is too hot for workers. Two of the more common
means are the Heat Index and Permissible Heat Exposure TLV, providing information on when caution needs to be taken and
recommended work/rest regimens.
Permissible Heat Exposure Threshold Limit Value (TLV)
|Less than 91°
|Basic heat safety and planning
|91°F to 103°F
|Implement precautions and heighten awareness
|103°F to 115°F
|Additional precautions to protect workers
|Greater than 115°F
|Very High to Extreme
|Triggers even more aggressive protective measures
These TLV levels are based on the assumption that nearly all acclimatized, fully clothed workers with adequate water and salt
intake should be able to function effectively under the given working conditions without exceeding a deep body temperature
of 100.4°F. They apply to physically fit and acclimatized individuals wearing light summer clothing.