Magazine article Occupational Hazards

Don't Overlook the Hazards of Heat Stress: If the Dangers of Heat Stress Are Well Known, Why Do Workers Keep Getting Hurt, or Even Killed, by the Heat?

Magazine article Occupational Hazards

Don't Overlook the Hazards of Heat Stress: If the Dangers of Heat Stress Are Well Known, Why Do Workers Keep Getting Hurt, or Even Killed, by the Heat?

Article excerpt

Heat stress is a common, yet often ignored hazard in the workplace. While it is widely recognized that heat stress can pose a serious health hazard to workers, employers may not realize that working in hot environments also increases safety risks.

Research conducted by the National Institute for Occupational Safety and Health (NIOSH) shows that work in hot environments is linked with lower mental alertness and physical performance, and subsequently, more injuries. Factor in elevated body temperature and physical discomfort and it's easy to see how workers can divert their attention from hazardous tasks and overlook common safety procedures.

Sources of heat stress range from the hot summer sun to the body heat generated inside a hazardous material suit worn during the cleanup of a toxic chemical spill. While often considered a summer or southern states problem, many companies need to take precautions throughout the year regardless of where they are located.

Heat-Related Slips

The safety hazard of heat stress is overlooked partly because the "accidents" that result from it are often not properly recorded, according to Mike Wurm, vice president of engineering at Oconomowoc, Wis.-based Quest Technologies Inc., a manufacturer of industrial hygiene and safety instrumentation. To illustrate the issue, Wurm recounts an episode that occurred at a heat stress meeting in California he attended.

"One guy stood up and said, "I've been in construction 9 years and no one ever died from heat stress,'" Wurm recalled. "But then someone asked him how many slips and falls his company had during 100-degree days that were recorded as non-heat-related 'accidents.' The fellow sat down and had nothing more to say."


Loren Tapp, M.D., a medical officer at NIOSH, agreed. "If a person trips or breaks an ankle, there's not an emphasis on finding out if the person was heat-stressed," she said. "There needs to be more awareness about that."

Monitoring the Heat

Wurm and Tapp both say that awareness of heat stress is growing. "We see growth in our business," said Wurm. Tapp added, however, that even where the problem is recognized, many companies "have a long way to go as far as training employees to work in heat, surveillance and medical screening."

Medical screening of workers can help identify those who are more vulnerable to heat stress, such as workers who are older, overweight or taking medications that affect their ability to handle exertion in hot weather.

Tapp recommends employers monitor hot environments by using a wet bulb thermometer, which will provide the wet bulb globe temperature (WBGT).

"Use of WBGT is essential, because it allows you to measure not just the air temperature, but humidity in the air, radiant heat and wind velocity," said Tapp. All four factors are crucial in determining the risk of heat stress. The level of work activity, plus the clothes and the condition of the employee, are additional factors that must be considered.

The American Conference of Government Industrial Hygienists (ACGIH) uses WBGT in its threshold limit value (TLV) for heat exposure. Research confirms that WBGT mirrors how hot a person will become in any given environment, according to Thomas Bernard, vice chair of ACGIH's TLV physical agents committee.

"People have looked at bio-physical models of heat exchange, and they find that WBGT behaves much as a human behaves," said Bernard, a professor at the College of Public Health in the University of South Florida. …

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