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Heat-related Health Effects

Extreme heat causes the most weather-related deaths in the CARA region, with Pennsylvania leading the other CARA states in numbers of reported fatalities.

Heat-Related Fatalities in the CARA Region 1998-2002
Source: NOAA's National Hazard Statistics
  1998 1999 2000 2001 2002
Connectictut         1
Delaware 1 4      
Maryland 2 15   5 50
Massachusetts   2      
New Jersey   28   2 2
New York   33   4  
Pennsylvania 15 88 17 28 42
Rhode Island          
Virginia   1      
Washington, D.C.   3      
Total 18 174 17 39 95

Heatstroke is the cause of death most clearly attributable to heat waves, and the bulk of heat-related fatalities reported are due to heatstroke and dehydration. The linkage between environmental temperature and heatstroke is clear. Prolonged exposure to high temperatures can overcome the body’s cooling mechanisms and cause the internal temperature to rise. Heatstroke is associated with body temperatures of 105 °F (40.5 °C) or above.

Some other causes of death are observed to increase following heat waves, such as heart attacks, diabetes, and stroke, but are not reported as heat-related. In people with chronic illnesses that involve the circulatory system, such as high blood pressure, heart disease, circulatory diseases, diabetes, and kidney diseases, the body’s efforts to cool itself put stress on already-impaired systems, leading to acute episodes. Diseases that impair mental functions or mobility such as Alzheimer’s disease and Parkinson’s disease are also risk factors.

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CDC's Emergency Preparedness and Response - Extreme Heat

Unusual heat waves are considered more lethal than customary heat waves, so populations in the northeast and midwest United States are believed to be more vulnerable than people in the south. The explanation for this is that people accustomed to the heat adapt their behaviors to compensate for it (clothing, activity level, cooling strategies) and know how to avoid dangerous conditions like dehydration. Still, heat-related deaths occur every year in the south as well as the north.

Urban populations are the most vulnerable to heat-related medical problems, particularly, the elderly, the poor, young children, the mentally ill, and people who aren’t fluent in English. People in these categories often are less aware of the potential dangers of heat and ways to reduce their risk level. Cities are known to be “heat islands,” which means they are hotter than surrounding areas and there is less cooling during the night. Temperatures inside closed buildings and vehicles can exceed ambient temperatures, and poor ventilation can interfere with normal body cooling. Vulnerable populations (homeless, impoverished, elderly) tend to live in cities. These factors make urban areas particularly prone to health problems from excessive heat.

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