Tips for preventing heat stress.

Heat stress is a health and safety hazard that many employers must be especially aware of in the summer months.

According to the Occupational Safety and Health Administration (OSHA), there are four environmental factors that affect the amount of stress a worker can tolerate in a hot work area. These include:

* temperature;

* humidity;

* radiant heat (such as from the sun or a furnace);

* air velocity.

Personal characteristics such as age, weight, fitness, medical condition and acclimatization also are important to the level of stress an individual may feel.

Foundries have many locations where temperatures, due to radiant heat, are high enough to cause heat stress in exposed individuals. Prominent sources of such radiant heat are melting furnaces, metal transfer ladles, holding furnaces, pouring lines, shakeout, casting sorting areas, core ovens and annealing ovens. Sometimes the heat generated at these sources can be intense enough to affect adjacent work areas. There are also jobs, such as chipping, grinding and degating, that aren't commonly thought of as "hot" but which require a great deal of physical effort. Under conditions of high relative humidity and high temperatures (summer conditions), workers performing these jobs may suffer heat-related illnesses.

Warning Signs

In an article from Safety+Health magazine, Thomas Adams, professor of physiology at Michigan State Univ., East Lansing, Michigan, cautions people not to rely on complicated calculations, measurements of body or environmental temperatures, or personal protective equipment. Rather, he says, look for the many warning signs of heat-related disorders. These include:

* visible sweating;

* increased heart rate;

* clumsiness or confusion;

* unexplained irritability;

* flu-like symptoms.

Heat-Related Disorders

OSHA outlines five types of heat-related illnesses that employers and employees should be aware of:

* Heat rash may occur in hot and humid environments where workers' skin surfaces are constantly bathed in perspiration. When extensive, or complicated by infection, heat rash may impair a worker's performance or even result in temporary total disability, according to OSHA. Heat rash can be prevented by resting in a cool, dry place and allowing the skin to dry.

* Fainting may be a problem if a worker is unacclimatized to heat and if the worker simply stands still in the heat. Victims usually recover after a brief period of lying down. Moving around, rather than standing still in the heat, usually will reduce the possibility of fainting.

* Heat cramps - painful muscle spasms - occur when workers drink sufficient water but don't replace their bodies' salt loss. Cramps may occur during or after exertion and can be relieved by drinking salted fluids.

* Heat exhaustion results from fluid loss due to perspiring and affects workers who fail to drink enough fluids, take in enough salt, or both. A worker with heat exhaustion still perspires but experiences extreme weakness or fatigue, giddiness, nausea or headache. The victim has clammy and moist skin, a pale or flushed complexion, and a body temperature that is normal or slightly elevated. OSHA says the victim should rest in a cool place and drink salted liquids. Severe cases involving victims who vomit or lose consciousness require medical treatment.

* Heat stroke is the most serious heat-stress illness because it can be fatal if not treated promptly. Heat stroke is caused by the body's failure to regulate its core temperature; perspiring stops and the body is no longer able to rid itself of excess heat. Signs of heat stroke include (1) mental confusion, delirium, loss of consciousness, convulsions or coma; (2) a body temperature of 106F or higher; and (3) hot, dry skin that may be red, mottled or bluish. Prompt first aid can prevent injury to the brain and other vital organs that may occur from heat stroke. Medical help should be summoned. While waiting for help to arrive, move the victim to a cool area, soak his or her clothing with cool water and fan vigorously to increase cooling.

Preventive Measures

According to OSHA, most heat-related problems can be prevented so that the risk of developing heat-stress symptoms is reduced. The agency recommends the following basic practices:

* Acclimatization to heat through short exposures followed by longer periods of work in a hot environment.

OSHA recommends that new employees and workers returning from an absence of two or more weeks have a five-day period of acclimatization.

* Engineering controls, including general ventilation and spot cooling by local exhaust ventilation at points of high heat production are helpful but will not reduce the radiant heat reaching workers. Radiant heat can be controlled by lowering the surface temperature of heat sources; by placing a shield between the worker and the heat source; and by providing a reflective booth, which may need tempered air.

* Drinking water helps prevent heat-related disorders and as much as one quart per hour per worker should be available at the work site.

* Training Supervisors to detect early signs of heat stress in workers, and training first-aid workers to recognize and treat heat-stress disorders is essential. It is also imperative that workers be informed of the names of trained personnel.

* Educating employees to be aware of the need to replace fluids and salt lost through perspiring and to recognize the signs of dehydration, exhaustion, fainting, heat cramps and heat stroke is vital.

Workers are subject to exercise-induced heat stress year-round, regardless of the weather. With basic training and awareness, many heat-related disorders can be avoided.