Emergency notices and public service announcements during heat waves often advise people without air conditioning at home to spend several hours a day in shopping centres, libraries and other air-conditioned public spaces. This concern is due to the increased risk of heat exhaustion, dehydration and the very serious condition known as heat stroke that results from excessive exercise or the body's inability to cool itself quickly when faced with extreme heat.
According to the Centres for Disease Control and Prevention, heat-related illness caused more deaths in the United States from 1979-1999 than hurricanes, lightning, tornadoes, floods, and earthquakes combined. In 2001, 300 deaths were caused by excessive heat exposure, and many more people suffer from less severe heat-induced illnesses each year. Although hydration, shade and clothing choice can affect how the body will fare in the heat, air conditioning is considered to be the primary preventive measure in reducing deaths due to extreme heat, especially among seniors and infants.
Besides keeping you cool, air conditioning also reduces humidity in your home, thereby reducing the growth of mold and mildew, which is a serious health hazard. However, if your unit is oversized for the space it is trying to cool, it will reduce the temperature and then turn off before the appropriate level of humidity has been removed from the room. An improperly installed or oversized air conditioner will actually encourage the growth of mold, and an air conditioning system that is contaminated will become a breeding ground and distribute the pollutants throughout the home.
People who spend prolonged periods of time in air conditioned homes or offices may be more prone to colds and viruses, and those who suffer from arthritis or neuritis will experience more severe symptoms in an air conditioned room. The move from a very hot environment to a chilled air conditioned home can also put undue stress on the body. Although your air conditioning can keep your body temperature under control, be careful not to overuse the unit—too much too often can weaken your body's ability to cope with hot temperatures, possibly resulting in a more severe illness when you do meet with the heat.
On the flip side of the positive personal health benefits of air conditioning, there are broader environmental health concerns. Weigh the positive and negative aspects of a given model to ensure that the environment won't pay a high price for your comfort.