Each year more people in the U.S. die from extreme heat than from hurricanes, lightning, tornadoes, floods, and earthquakes combined. Just in the workplace alone, in 2001, excessive heat exposure caused 24 worker deaths and 3,135 occupational injuries and illnesses involving days away from work. These numbers were up slightly from the previous year. Even with these kinds of numbers, state and federal agencies report that heat-related illnesses are vastly under recognized and under-reported.
The purpose of this safety topic is to make employers and employees aware of the symptoms and dangers associated with the various heat illnesses and the measures that can be taken to prevent heat stress. Therefore, as we head into the hottest days of summer, you are encouraged to talk about this important topic
and also review the OSHA data on the subject by clicking on http://www.osha.gov/Publications/osha3154.pdf.
Environmental and Personal Factors
The following four factors affect the amount of stress a worker faces in a hot work area.
3. Radiant Heat (such as from the sun or a furnace)
4. Air Velocity
Personal factors are very important in determining the level of stress an individual faces. They are:
4. Medical Condition
5. Acclimatization to the Heat
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 temperature in the face of heat. However, sweating is effective only if the humidity level is low enough to permit evaporation and if the fluids and salts lost are adequately replaced.
If 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 fluids. The next stage is most often fainting and death is possible if the person is not removed from the heat stress.
Heat Disorders Click on http://www.osha.gov/Publications/osha3154.pdf. to review important information and facts published by OSHA on heat exhaustion and heat strokes.
Preventing Heat Stress
1. A variety of engineering controls including general ventilation and spot cooling by local exhaust ventilation at points of high heat production may be helpful. Shielding is required as protection from radiant heat sources. Cooling fans can also reduce heat in hot conditions. Eliminating heat sources such as steam leaks may help. Reduce manual labor by using power tools or material handling equipment. Personal cooling devices or protective clothing are other ways to reduce the hazards of heat exposure for workers.
2. Work practices such as providing plenty of drinking water, as much as a quart per worker per hour, at the workplace can help reduce the risk of heat disorders. Training first aid workers to recognize and treat heat stress disorders and making the names of trained staff known to all workers are essential. Employers should also consider an individual worker’s physical condition when determining his or her fitness for working in hot environments. Older workers, obese workers and personnel on some types of medication are at greater risk.
3. Alternating work and rest periods with longer rest periods in a cool area can help workers avoid heat stress. If possible, heavy work should be scheduled during the cooler parts of the day and appropriate protective clothing provided. Supervisors should be trained to detect early signs of heat stress and should permit workers to interrupt their work if they are extremely uncomfortable
4. Acclimatization to the heat through short exposures followed by longer periods of work in the hot environment can reduce heat stress. New employees and workers returning from an absence of two weeks or more should have a period of acclimatization. This period should begin with 50 percent of the normal workload and time exposure the first day and gradually build up to 100 percent.
5. Employee education is vital so that workers are aware of the need to replace fluids and salt lost through sweat and can recognize dehydration and the various heat disorders. Workers should also be informed of the importance of daily weighing before and after work to avoid dehydration.
Most heat-related problems can be prevented or the risk of developing them reduced by following these recommendations for preventing heat stress.