In fact, the highest asthma- related hospital discharge rates were in central, northern and western areas of the City of Milwaukee. In 1994, the population of Milwaukee County was 938,105. Although Wisconsin does not represent the states with the highest asthma prevalence, it truly demonstrates that asthma correlates with urban environments. Urbanization or the development of the land is literally making people sick. This is mostly due to urban sprawl and the urban heat island.
Urban sprawl is the term for automobile-oriented cities.
The term urban heat island is used to describe cities that generate large amount of heat due to motor vehicles, factories, furnaces, air conditioners, and lights. Trapped pollutants and heat create a dust dome. As a result, any thing within the city overheats, so more energy is used to cool down the area, and pollution increases. Asthma is obviously one of the chronic influences of pollution. Automobiles expel exhaust, which contains nitrogen oxide, and reacts with hydrogen chloride and sunlight to form ozone a component of photochemical smog.