Numerous factors affect the amount of stress a worker faces in a hot work area. Temperature, humidity, radiant heat (such as from the sun or a furnace) and air velocity are environmental factors, but, perhaps most important to the level of stress an individual faces in a hot space are personal characteristics, such as age, weight, fitness, medical condition and acclimatization to the heat.

New, individual cooling technology is now available that can overcome these environmental and personal factors, which may lead to heat-induced fatigue.

According to the National Institute for Occupational Safety and Health, the body reacts to high external temperature by circulating blood to the skin, which increases skin temperature and allows the body to give off its excess heat through the skin. However, if the muscles are being used for physical labor, less blood is available to flow to the skin and release the heat.

Sweating is another means the body uses to maintain a stable internal body temperature in the face of heat. However, sweating is effective only if humidity level is low and conditions permit evaporation, and if fluids and salts lost are adequately replaced.

When the body cannot dispose of excess heat, it will store it. When this happens, the body’s core temperature rises and the heart rate increases. As the body continues to store heat, the individual begins to lose concentration and has difficulty focusing on a task, may become irritable or sick and often loses the desire to drink.

Of course, there are many steps a person might take to reduce the risk of heat stress, such as moving to a cooler place, reducing the work pace or load, or removing or loosening some clothing. When these options are not practical, something else has to happen. Passing out from heat exhaustion or heat stroke is not acceptable, especially in the middle of a job.

Sometimes you just can’t cool the space enough to protect workers. That’s when it’s time to turn to engineering and/or administrative controls. That’s what Rick Shafer did, when he discovered a way to keep doctors comfortable in the operating room.

After the discovery of AIDS in the 1980s, the protective clothing that operating room personnel turned to was causing doctors to overheat during long surgeries. Shafer, an orthopedic salesman at the time, sought a way to keep doctors cool, since warm temperatures in the OR are believed to help prevent patient hypothermia, reduce infection rates and reduce post-operative cardiac and other adverse events.

Shafer developed a vest that would cool the skin by circulating cold water through tubing sewn to an undershirt. In 1994, the first Cool Shirt vest appeared in an operating room, and Shafer has been keeping doctors cool ever since.

Also a racecar driver for 20 yeas, Shafer soon turned his focus to racing, knowing the type of clothing drivers must wear, and the heat generated in the cockpit of a race car. Now president of Cool Shirt, which makes personal cooling systems for surgeons, race car drivers, football players, other athletes and industrial workers, Shafer concentrates on raising awareness of the effects of body temperature on performance and why it’s important to keep the body cool, especially when under extreme duress.

NASA has found that when people are exposed to temperatures of 95ºF or more for extended periods, they can make up to 60 mistakes per hour, said Shaver. “What does that mean when you’re driving a race care, or operating on someone,” asked Shafer.

Heat Disorders

Heat stroke, the most serious health problem for workers in hot environments, is caused by the failure of the body’s internal mechanism to regulate its core temperature. Sweating stops and the body can no longer rid itself of excess heat.

Signs include: (1) mental confusion, delirium, loss of consciousness, convulsions or coma; (2) a body temperature of 106ºF or higher; and (3) hot dry skin which may be red, mottled, or bluish. Victims of heat stroke will die unless treated promptly.

While awaiting medical help, the victim must be removed to a cool area and his or her clothing soaked with cool water. He or she should be fanned vigorously to increase cooling. Prompt first aid can prevent permanent injury to the brain and other vital organs.

As with most ailments, prevention is better than treatment, and most heat-related health problems can be prevented or the risk of developing them reduced.

To that end, Shafer’s shirt covers 30 to 40 percent of a worker’s body and is designed to cool the blood next to the skin so that the normal blood flow reaches the organs that need it most under duress. Workers can be kept cool for six to seven hours at a time via a system that runs cool water through 50 feet of medical grade capillary tubing stitched to the front and back of a shirt that has four cooling zones. The system features an internal pump in a cooling unit that contains ice and water and gets to the shirt through an eight-foot hose.

Shafer’s Cool Shirt is being used and endorsed by numerous racecar drivers, including some on the NASCAR circuit, but perhaps its best endorsement came from being worn by deceased driver and actor Paul Newman, who, by all accounts, knew something about being cool.