This preliminary study measured Polycyclic Aromatic Hydrocarbons (PAHs) concentrations in the
resuspendable fraction of settled dust on 39 bus lines, to evaluate the impact of engine type (gasoline and
compressed natural gas) on exposure for commuters and drivers. Benzo(b)fluoranthene(BbF) was the
predominant PAH in resuspendable fraction of settled bus dust. The concentration of total PAHs was
92.90 ± 116.00 mg/g (range: 0.57e410) in gasoline buses and 3.97 ± 1.81 (range: 2.01e9.47) in compressed
natural gas (CNG) buses. Based on Benzo[a]pyrene (BaP) equivalent concentrations for the sum
of 16 PAHs, the average daily dose (ADD) via dust ingestion and dermal contact was calculated. The ADD
of PAHs was higher for commuters and drivers in gasoline-powered buses than in buses using CNG buses.
For both short and long duration journeys, young commuters were exposed to higher levels of PAHs via
dust ingestion and dermal contact than adult commuters.