Working up a sweat may be healthy for a short spell in the gym, but it can be dangerous if you’re doing hard physical labor over a full shift during the dog days of summer, says the United Auto Workers’ Safety and Health Department.

Sweating is normally good because that’s how your body tries to maintain a stable internal temperature. But sweating is effective only if the humidity level is low enough or air is moving across your skin and if body fluids and salt are adequately replaced.

Here are danger signs you should be on the lookout for this summer:

Heat exhaustion is the first stage of heat illness. Symptoms: feeling extremely weak, giddy, nauseous, or headachy; clammy and moist skin and pale or flushed complexion. Your body temperature could be normal or slightly higher.

Treatment: Resting in a cool place and drinking an electrolyte solution, drinks that quickly restore potassium, calcium, and magnesium salts. Severe cases of heat exhaustion, involving vomiting or fainting, require medical treatment.

Heat stroke is the most serious health problem for workers in hot environments. It occurs when the body’s mechanisms can no longer regulate internal temperature. Symptoms: stopping sweating while doing strenuous labor, mental confusion, temperature of 106 degrees or higher, and hot dry skin that may be pale, red, mottled or bluish.

Treatment: Unless treated promptly, heat stroke victims can die. While waiting for medical help, you should move the victim to a cool area and soak him or her with cool water. Fanning vigorously can increase cooling, too. UAW offers these recommendations:

  • Cases of any heat illness should be reported to your medical department. Insist these cases be recorded on your employer’s injury log to document the problem areas and provide evidence for improved ventilation.
  • Worksite walk-through reviews assure that ventilation and air movement equipment is working, with properly functioning air make-up units, properly installed and positioned cooling fans, clean ventilation fans, and clean air filters.
  • Workers in hot environments should also be provided with ice, cool liquids, regular monitoring, additional relief, and available medical staff trained to treat heat stress.

A good OSHA publication entitled "Protecting workers in hot environments" is available at Fact_data/FSNO95-16.html.