With Memorial Day only weeks away, the official start of summer is just around the corner. But hot, sticky weather often raises questions for employers concerned about workplace safety when the temperature rises. For example, if your facility gets quite hot, is there a maximum temperature at which employees must be sent home?

Neither state law nor federal OSHA regulations set a specific maximum temperature that should be considered injurious to employees' health. However, a temperature that gets high enough to cause heat-related illness or physical injury would run afoul of an employer's general duty to provide employees with a workplace free from recognized hazards.

If you anticipate that your worksite might get unusually warm, consider implementing the following practices suggested by OSHA:

  • Allow workers to get used to hot environments by gradually increasing exposure. Begin with 50% of the workload and time spent in the hot environment and gradually build up to 100%.
  • Provide workers with plenty of cool water in convenient, visible locations near the work area.
  • Remind workers to drink small amounts of water frequently to stay hydrated.
  • Reduce the physical demands of the job through the use of mechanical devices or by assigning extra workers.
  • Monitor weather reports daily and reschedule jobs with high heat exposure to cooler times of the day.
  • Schedule frequent rest periods in shaded or air-conditioned areas.
  • Monitor workers who wear personal protective equipment, which can trap heat close to the body.
  • Train employees and supervisors to recognize and prevent hazards leading to heat stress.

Engineering controls that can reduce indoor temperatures include providing reflective shields to redirect radiant heat, insulating hot surfaces, and decreasing water vapor pressure by sealing steam leaks and keeping floors dry. The use of fans to increase air speed over workers will improve heat exchange between the skin surface and the air, unless the air temperature is higher than skin temperature.

Heat stroke is the most serious heat-related health problem. Signs include confusion, loss of consciousness, and seizures. Workers experiencing heat stroke typically have a body temperature above 104 degrees and may stop sweating. Heat stroke is a medical emergency that can result in death; call 911 and get help immediately.

Heat exhaustion is the next most serious heat-related health problem. Symptoms include headache, nausea, dizziness, weakness, irritability, confusion, thirst, heavy sweating, and a body temperature above 100 degrees. Workers with symptoms of heat exhaustion should be taken to a clinic or emergency room.

For more information, consult the OSHA technical manual on preventing heat stress.