A new study from the Centers For Disease Control and Prevention suggests guidelines may need to be revised to protect outdoor workers from heat.
Researchers examined 25 heat-related cases investigated by the Occupational Safety and Health Administration from 2011 to 2016.
They found that the current OSHA threshold of 91 degrees may be too high and that a heat index of 85 degrees could be hazardous for some workers.
The study identified outdoor workers wearing non-breathable clothing, as well as those who have not been climatized to high temperatures, are especially at risk.
The researchers suggest employers develop a schedule to climatize workers to hotter temperatures and train supervisors to look for symptoms of heat stress.