PAH exposure through air, water, soil, and food sources occurs on a regular basis for most people. Routes of exposure include ingestion, inhalation, and dermal contact in both occupational and non-occupational settings. Some exposures may involve more than one route simultaneously, affecting the total absorbed dose (such as dermal and inhalation exposures from contaminated air). All non-workplace sources of exposure such as diet, smoking, and burning of coal and wood should be taken into consideration.