Additional Information on Heat-Related Illness and Prevention

Heat Exhaustion

Heat exhaustion is the body’s response to an excessive loss of the water and salt contained in sweat. Those most prone to heat exhaustion are elderly people, people with high blood pressure and people working or exercising in a hot environment.

Warning Signs of Heat Exhaustion Include:

What to Do

Heat Stroke (Life Threatening)

Heat stroke occurs when the body becomes unable to control its temperature: the body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Heat stroke can develop within minutes or hours. Heat stroke can cause death or permanent disability if emergency treatment is not given. Treatment includes rapidly lowering the person’s body temperature followed by intensive supportive care.

Warning Signs of Heat Stroke Vary But May Include:

What to Do

How To Prevent Heat-Related Illness

Use of Fans for Cooling

In order for a fan to be effective, the skin surface must be moist. When the skin surface is moist, moving air removes heat from the skin as the moisture evaporates. Unfortunately, when a person begins to develop heat stroke, they stop sweating. In addition, elderly persons may not sweat due to poor heat regulation messages sent out by their brain centers. If a fan is to be effective, the skin must be moist either with sweat, or with dampened clothing, or with moisture added by rubbing wet cloths over the skin surface.

Although fans are less expensive to operate, they may not be effective as indicated above, and may even be harmful, when temperatures are very high. As the air temperature rises, air flow is increasingly ineffective in cooling the body until finally, at temperatures above about 100° F (the exact number varies with the humidity) increasing air movement actually increases heat stress. More specifically, when the temperature of the air rises to about 100° F, the fan may be delivering overheated air to the skin at a rate that exceeds the capacity of the body to get rid of this heat, even with sweating, and the net effect is to add heat rather than to cool the body. The widespread distribution of fans, often practiced in the past as a heat-relief measure, thus appears unlikely to be particularly effective in preventing major heat-related health effects when temperatures are very high. The better alternative by far when the temperature soars is to use an air conditioner if one is available or to seek shelter in an air-conditioned building.