What Are Effects of Severe Heat Waves?

A heat wave is a weather condition in which temperatures are abnormally high for an extended period of time, usually a few days to a week or more. A heat advisory is issued when temperatures are expected to be higher than tolerable for aged people or people with diseases. If the heat is expected to be accompanied by humidity, an excessive heat warning is issued. In excessive heat warnings a heat index number is given; this number represents the temperature that it feels like due to the humidity.

Death

• Death can occur during a heat wave, especially in people whose heart or health is weak or compromised by disease. Usually the heat includes humidity and wears a body down beyond its tolerance. In a normal year about 175 Americans die due to the pressures heat causes the body. In the 40 years from 1936 to 1975, nearly 20,000 people in the United States died due to heat and solar radiation. In the 1980 heat wave, 1,250 people died, and in the 1995 heat wave, there were 1,000 heat-related deaths in the Midwest and East Coast.

Sunstroke

• Sunstroke or heatstroke is a life-threatening condition. It is evidenced by symptoms such as cramps, spasms and nausea, which indicate that the body’s thermostat is not working. Body temperature can rise high enough to cause brain damage, and death can occur in fewer than 10 minutes if medical help is not given. Sunstroke is highly likely for weak and aged people when the temperatures reach 130 degrees Fahrenheit or higher. When the temperature is 105 to 130, sunstroke is likely with prolonged exposure. Even when temperatures are 90 to 105, sunstroke can occur with prolonged exposure or physical activity.

Dehydration and Respiratory Problems

• Where the humidity is low, the most common human response to a heat wave is dehydration. A human can lose as much as one-half gallon of water every 10 minutes when exposed to direct sunlight in temperatures 90 degrees and above. Dehydration can happen slowly so that the dangers are not apparent until it is too late. People in cities are at great risk because of stagnant atmospheric conditions that trap pollutants. Breathing these added pollutants can trigger respiratory problems. The elderly, young children and sick people are most at risk.

Heat Exhaustion

• Overexposure to extreme heat is the most common cause of heat exhaustion; it is especially dangerous for young children and the elderly. Heat exhaustion is a mild shock. The symptoms are heavy sweating, weakness, cold and clammy skin, weak pulse, fainting and vomiting. This condition occurs most often to people who have been working or exercising in warm, humid temperatures. Heat exhaustion will worsen if not treated. The body temperature will continue rising and a heatstroke may result.