Exposures to Particulate Air Pollution and Nitro-Polycyclic Aromatic Hydrocarbons among Taxi Drivers in Shenyang, China

Exposures to particulate matter (PM) of both 10-2.5 mu m (PM(10-2.5)) and below 2.5 mu m (PM(2.5)) were measured for a cohort of taxi drivers in Shenyang, China, during August 2007. PM samples were collected inside and outside the taxi during the drivers' workshifts, and also inside the drivers' homes when they were off-shift. Ambient PM samples were also collected at a stationary location in Shenyang. Elemental carbon (EC) and organic carbon (OC) were also measured in PM collected on quartz filters inside the taxis as well as at the stationary site. Concentrations of three nitro-polycyclic aromatic hydrocarbons (NPAHs), 1-nitropyrene (1NP), 2-nitropyrene (2NP), and 2-nitrofluoranthene (2NFI), were determined in extracts of the PM samples by using a 2D-HPLC-MS/MS method. The 2NP and 2NFI concentrations did not change substantially with sampling location, but the 1NP concentrations were much higher in samples collected inside and outside the taxis as compared with sampling locations that were more removed from traffic. Concentration ratios of specific NPAHs were used to assess the atmospheric conditions in Shenyang during the sampling period. The relatively high ratios of 2NFI/1NP (similar to 8-50) indicate an important contribution from secondary NPAH formation to ambient NPAH levels, especially for the nontaxi samples. The ratios of 2NFI/2NP (2.5-4.3) indicate that 2NFI is primarily formed via the hydroxyl-initiated reaction.