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Climate Change is a Threat to Health: Heat-Related Illnesses

As the average global temperature increases, heat waves will become more frequent, more intense, and longer-lasting.

Exposure to extreme heat can have lethal consequences.  Extreme or long-lasting heat can override the body's ability to cool itself by circulatory changes and sweating. The consequences may range from heat rash and heat cramps to heat exhaustion and heat stroke.

Severe cases of heat stroke may result in death.

The heat wave that struck Europe in the summer of 2003 claimed the lives of more than 70,000 people especially those most vulnerable with chronic heart or lung disease. It was a tragic example of what may occur more frequently as global warming continues.

If a heat wave of similar magnitude were to occur in the United Sates, heat-related deaths would surge to more than five times the current national average. 

More frequent and intense heat also has other major health consequences. Long-lasting bouts of heat exacerbate stress and symptoms of mental illness, increase chance of dehydration, harm agriculture and the food supply, and increase ground-level ozone, which can inflict serious respiratory and cardiovascular harm. Many forms of violence increase with heat.

The elderly, infants and children, and people suffering from chronic illness are especially vulnerable to heat-related illness, as their bodies are less capable of coping with the stress of excessive heat.

The urban poor are also more vulnerable as cities are hotter than surrounding country; they may not be able to afford the relief of air conditioning, which becomes necessary when the temperature exceeds about ninety degrees and especially when there is no cooling at night.

To learn more about heat-related illnesses, download PSR's Heat Factsheet (PDF), our PowerPoint presentation and our video on Heat Impacts on Health.