have been claimed in the United States over the past fifteen years by heat than by all other extreme weather events—lightning, tornadoes, floods, and hurricanes—combined (CDC, 2002). He cited an editorial in the New England Journal of Medicine, published just a few months after the Chicago disaster, which states that compared to other kinds of disasters that kill far fewer people, the heat wave in Chicago was forgotten almost as soon as the weather changed (Kellermann and Todd, 1996).

More heat-related deaths occur in cities than in rural areas because stored heat dissipates slower in urban areas. This is due to the density of brick and stone buildings, paved streets, and tar roofs that store heat and radiate it like a slowly burning furnace to create a “heat island.” The worst heat disasters, in terms of loss of life, occur in large cities when a combination of four factors occurs for a period of several days:

• high daytime temperatures

• high humidity

• warm nighttime temperatures which prevent dissipation of stored daytime heat

• abundance of sunshine, which can increase the heat index by 15°F

Examined independently these atmospheric conditions may be of little consequence. However, in combination they can create an urban environment where infrastructure stores heat and continually releases it throughout the night until the next day, when more heat will be absorbed for the cycle to continue until temperatures drop.

Socioeconomic problems are risk factors for susceptibility to heat-related illness. Klinenberg pointed out that understanding the relationship between neighborhood conditions and vulnerability can help cities target their responses to those areas with populations that may be hit the hardest. For example, lower-income individuals may not have air conditioning or may hesitate to turn it on due to cost. Often they live in high-crime areas and may be afraid to open the