The benzene comes from auto exhaust, gasoline stations, industrial sources and environmental tobacco smoke. Urban areas may tend to have higher benzene levels due the greater number of industrial sources, gas stations and vehicles. Benzene gets into the indoor environment from outdoor air and from indoor sources such as cigarette smoke. Benzene has a slightly sweet odor. The type and severity of health effects depends on several factors including the amount of chemical you are exposed to and the length of time you are exposed .
Individuals also react differently to the same level of exposure.
1998 Kao, 1994. Formation and Removal of Hazardous Air Pollutants.