Heat-related deaths are one of the deadliest weather-related health outcomes in the United States.

WHAT IS HEAT-

RELATED ILLNESS?

Heat-related illness, also called hyperthermia, is a condition resulting from exposure to extreme heat where the body becomes unable to prop- erly cool, resulting in a rapid rise in body temperature. The evaporation of sweat is the normal way to remove body heat, but, when the humidity is high, sweat does not evaporate as quickly. This, in turn, prevents the body from releasing heat quickly. Prompt treatment of heat-related illnesses with aggressive fluid replacement and cooling of core body temperature is critical to reducing illness and preventing death.

HEAT EXHAUSTION

Exposure to excessive heat can directly or indirectly cause some illnesses and can exacerbate many preexisting conditions, such as heart and respiratory disease. Of the heat-related illnesses, heat exhaustion and heat stroke are the most serious. The symptoms of heat exhaustion include:

• Muscle cramping

•Fatigue

• Headache

• Nausea or vomiting

• Dizziness or fainting

Ironically, a patient with heat exhaustion often might have cool and moist skin, indicating that the body’s ability to cool itself is still present, but the patient’s pulse rate is fast and weak, and breathing is rapid and shallow.

HEAT STROKE

If untreated, heat exhaustion may progress to heat stroke. Heat stroke is a serious, life-threatening condition characterized by the following symptoms:

• A body temperature greater than 103°F (39.4°C)

• Red, hot, and dry skin (no sweating)

• Rapid, strong pulse

• Throbbing headache

• Dizziness

• Nausea

• Confusion

• Unconsciousness

Very high body temperatures can damage the brain or other vital organs. In severe cases, the problem can progress to multiple organ system failure and death.

While heat-related illnesses and deaths are prevent- able, many people still succumb to illness caused by extreme heat each year. In addition to the actual air temperature and a person’s underlying health issues, environmental factors, such as humidity, can contribute to hyperthermia, as can strenuous physical activities in hot conditions. Buildings and other parts of the man-made environment can also increase the health risks of heat waves.

RISK FACTORS FOR HEAT-RELATED

ILLNESS AND DEATH?

NON-ENVIRONMENTAL RISK FACTORS

People at greatest risk for heat-related illness include infants and children up to 4 years old; people 65 years of age and older; people who are overweight or have existing medical conditions, such as diabetes and heart disease; people who are socially isolated; and the poor. However, even young and healthy individuals can succumb to heat if they participate in strenuous physical activities during hot weather. Other behaviors also put people at greater risk, such as drinking alcohol and taking medications that impair the body’s ability to regulate its temperature or that inhibit perspiration.

ENVIRONMENTAL RISK FACTORS

Exposure to temperatures much hotter than those to which the population is accustomed can make people more vulnerable to heat-related illnesses and death. This applies especially to populations living in the midwestern and northeastern United States, where temperatures are typically cooler, and many buildings are not equipped with air conditioning. Increased risks posed by heat waves (generally, three or more consecutive days with

at least 90°F [32°C] heat) can be exacerbated by features of the man-made environment, including limited access to transportation, medical care, and cooling centers.

The man-made environment also can lead to what is called the ‘urban heat island effect,’ in which urban centers are significantly warmer than their surrounding rural areas, even in the absence of a heat wave. This occurs because urban areas have much more concrete and asphalt, which absorb more of the sun’s energy.

Source: Centers for Disease Control and Prevention