According to statistics from the Centers for Disease Control and Prevention , an average of 384 people die from heat every year. Heat can be especially deadly in large urban areas that can become heat islands. Brick buildings, asphalt streets, and tar roofs store heat and radiate is like a slow burning furnace.
Temperatures can be several degrees hotter in the city than in nearby suburbs and rural areas.
In these situations, the elderly, infants, and young children, and people with chronic health problems are most at risk. The body cools itself by sweating because the evaporation of moisture has a cooling effect. High humidity reduces this evaporation and hinders the body's effort to cool itself. The dew point temperature is a much more useful measure of the moisture content of the atmosphere than the commonly used relative humidity. During summer in Illinois, dew point temperatures in the 50s are generally comfortable.