This article explains how to prevent heat stroke, dehydration, heat exhaustion, skin cancer and other hot weather hazards. When the mercury rises, so does the risk of injury and illness. Uncomfortable workers are less focused on the task at hand. Dehydrated workers are more prone to fatigue and poor coordination. And workers with heat stroke actually can die if they don't receive immediate hospitalization. Such diverse consequences of hot weather jobsites can be minimized and prevented with simple education. Informed workers will know how to prepare appropriately for a day's labor in hot weather; maintain their core body temperature as low as possible throughout the day; and identify signs of and treat heat-induced problems (in themselves and others). Serious health problems, such as heat stroke, heat exhaustion, and skin cancer, can be prevented by simple precautions. Less life-threatening difficulties, such as muscle cramps and heat rashes, which reduce productivity and alertness, can be prevented just as easily. The inability to cool off fast enough puts abnormal stress on a person's body; if a person's core body temperature rises even a few degrees above its normal 98.6 degrees, results range from dizziness to death. Physical exertion exacerbates heat stress, so construction workers who do not cool down enough and keep working risk succumbing to some form of heat stress, which can manifest itself as any or all of the following problems (listed in descending order of severity): heat stroke, heat exhaustion, heat cramps, mental or physiological strain, and heat rash. An effective heat stress program features heat stress measurement, a proper work-rest regimen, and training on the signs and symptoms of heat stress and proper protective clothing. Workers should be allowed to become acclimated to the heat for at least one week. Heat stroke is the most serious health problem associated with work in hot environments, and it happens when a worker's temperature regulatory system backs down. If medical help is not sought immediately, the victim can die or suffer permanent brain damage. Symptoms include hot dry skin that is red or spotted, a high temperature, and/or feelings of confusion. Victims may also suffer from delirium or convulsions and may lapse into unconsciousness. First-aid efforts should concentrate on lowering the body temperature--by loosening tight clothing, moving the person to the shade, wiping the skin with cool water, and fanning him or her with anything available (such as a piece of cardboard). It's also good to massage arms and legs vigorously to maintain circulation until the paramedics arrive. Heat stroke usually requires hospitalization of several days.