A Slow Burning Furnace

Most heat-related deaths occur in cities. Large urban areas become "heat islands". Brick buildings, asphalt streets, and tar roofs store heat and radiate it like a slow burning furnace. Heat builds up in a city during the day and cities are slower than rural areas to cool down at night. The amount of sunshine is an important contributing factor in urban heat waves. In addition, the stagnant atmospheric conditions associated with a heat wave trap ozone and other pollutants in urban areas. The worst heat disasters, in terms of loss of life, happen in large cities when a combination of high daytime temperatures, high humidity, warm night time temperatures, and an abundance of sunshine occurs for a period of several days.

There are also socioeconomic problems that make some urban populations more at risk. Many people in cities don't have air conditioning. Some that do have air conditioning hesitate to turn it on. Some residents in high crime areas, especially the elderly, are afraid to open windows or go out to cooling shelters. As neighborhoods change, some older residents become isolated because of cultural, ethnic and language differences.

Other Potential Heat-Related Problems

• High demands for electricity can result in black outs or brown outs.
• Buckling of pavement.
• Loss of water pressure due to opening of fire hydrants in urban areas.
• Stagnant atmospheric conditions that occur with heat waves are also favorable for trapping ozone and other pollutants in urban areas.
• Pets and livestock can suffer from prolonged exposure to excessive heat.
• Vehicles may overheat.