Beat heat-related dangers with aggressive education, monitoring

Summer heat requires intervention

Heat stress is a year-round threat to workers in some industries, but the summer heat extends the threat to many more. Some occupational health programs are taking the threat seriously and incorporating specific programs to protect workers from heat exhaustion and heat stroke.

Because the summer months always bring an increased risk to local workers, heat-related problems are a concern at St. Luke’s Occupational Health Services in South Sioux City, NE. Most employers are eager to protect workers from heat, but that takes a lot of education, says Kirk Koithan, DO, occupational medicine staff physician for the program.

"This is an issue that employers can understand well, but we have to educate them about heat exhaustion and heat stroke, and how to prevent them," Koithan says. "We conduct meetings here to educate employers and encourage them to pass the information on to the employees at the work site."

Employer education includes explaining the differences between simple discomfort, heat exhaustion, and heat stroke. The program uses a chart to show the different symptoms and different responses. (For a sample of a chart outlining the differences, see p. 93.) Koithan and his staff then explain different ways to combat heat problems, including workplace policies that encourage workers to take frequent rest breaks and drink fluids. Employers also learn about possible engineering controls such as increased ventilation in buildings and cooling garments.

The more expensive high-tech solutions that cool workers with special garments tend not to be as popular as other options, Koithan says. But that is partly because his clients do not include many manufacturers with extremely hot working conditions such as a foundry. (For a summary of high-tech cooling options, see related story, p. 95.) Rather, the program’s clients are typical employers in a wide range of manufacturing businesses.

The federal Occupational Safety and Health Administration in Washington, DC, does not have a rule specifically addressing heat stress, but the "general duty clause" requiring a safe workplace can be used to penalize employers who subject workers to unreasonable heat or fail to provide adequate precautions. Also, any heat problem severe enough to require medical attention is a reportable event.

The average manufacturing employee has a generally good understanding of the dangers of heat, says Dwanna Zyla, RN, COHN, occupational health nurse with Memorial/Sisters of Charity Health Network in Houston. Zyla works full-time as an on-site nurse at Lyondell-Citgo Refining Company, also in Houston. The petroleum refining plant employs 1,300 people.

Despite their general understanding that heat can be dangerous, workers sometimes lack the details that can be important. All of the employees at the refinery attend an education session each year on the dangers of heat stress, with an emphasis on symptoms and factors that can predispose people to problems in the heat.

"They often don’t factor in things like whether they’re on medication that will make them sensitive to heat and sun or whether they were drinking the night before," Zyla explains. "Even if they didn’t get drunk, they might have consumed enough alcohol to dehydrate them, and that will make them more susceptible to heat the next day. They know that it’s dangerous to stay in the heat too long, but they don’t think about things like that."

Health conditions contribute to heat stress

Health conditions that can make a worker more susceptible to heat stress include poor conditioning, obesity, skin disease, dehydration, low blood pressure, cardiac disease, alcohol intake, older age, recent illness, and sleep deprivation. Medications that can increase the risk include diuretics, laxatives, antihistamines, some blood pressure medicines, and sedatives.

(For another physician’s advice on how to assess workers for risk of heat stress, see related story, p. 94.)

The occupational health staff at the oil refinery also watch for any workers who have had trouble with heat stress in the past, and they may be prohibited from activities that would put them at high risk again. Anyone who has been pulled off the job because of heat stress must be evaluated by the on-site physician, and anyone who must be treated at a hospital is likely to be prohibited from future work that would expose them to high heat. The occupational health staff also might disallow heat work for workers with certain factors that would make them susceptible to heat stress, such as age or certain medical conditions. The heat prohibition can be permanent, or it can be temporary.

Stress tests eliminate susceptible workers

At WNJ WorkMed, the occupational health program of Wilson N. Jones Regional Health System in Sherman, TX, occupational medicine director Lilly Ramphal-Naley, MD, MPH, advises employers to use baseline stress tests to weed out workers who may be unable to withstand extreme heat. There is no standard for testing workers for sensitivity to heat, so Ramphal-Naley depends on a three-minute step test that challenges the worker’s pulse and blood pressure.

The three-minute step test requires the worker to exercise vigorously on a step for three minutes, and then the pulse and blood pressure are measured. Workers who are overly stressed by the exercise probably will not fare well in extreme heat, she says. (For the testing protocol used at WNJ WorkMed, see procedures, p. 91.)

Not all workers must be screened for heat susceptibility — only those who may work in hot conditions. But for many workplaces that includes the entire work force. The step test protocol should not eliminate that many employees. In most workplaces, 5% will be excluded from high-heat work, Ramphal-Naley says.

To be most effective, the baseline measurements should be combined with wet bulb monitoring at the work site. Wet bulb monitoring is a method of measuring both the heat and humidity to get an accurate assessment of how much workers will be stressed. The method requires a health professional, so many employers are unable to do wet bulb monitoring at their work sites. The baseline measurements alone, however, still will provide a good measure of protection.

"We had one employee last year who had a near syncope episode because of heat, and I didn’t know that when I screened him with the step test this year," recalls the doctor, who has been with the program for only six months. "His blood pressure shot way up and he failed the test. So I turned to the safety officer and said he shouldn’t work in a hot environment. He said, ‘Funny you should say that.’"