Impact of traffic emissions on local air quality and the potential toxicity of traffic-related particulates in Beijing, China.

OBJECTIVE

Air-borne particulates from different sources could have different physicochemical properties and inflammatory potentials. This study aims to characterize the chemical compositions and the toxicity of ambient particulate matter (PM) associated with traffic emissions.

METHODS

The concentrations of trace elements, organic carbon (OC), elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) in PM2.5 and PM10 were measured in samples collected at sites in Beijing, China. Their toxic effects on the pulmonary system of rats were investigated. Biochemical parameters (LDH, T-AOC, TP) and inflammatory cytokine(IL-6, IL-1, TNF-a) levels were measured in the lungs of rats exposed to traffic-related PM. Oxidative damage was observed. PM samples were taken from a near road site and an off road site in summer time in 2006.

RESULTS

The concentrations of the USEPA priority pollutant PAHs in both PM10 and PM2.5 were higher (299.658 and 348.412) at the near road site than those (237.728 and 268.472) at the off road site. The similar trend was observed for the concentrations of trace elements in PM. Compared to coarse particles (PM10), fine particles (PM2.5) have a greater adsorption capacity to enrich toxic elements than inhalable particles. Decrease in antioxidant capacity and an increase in the amount of lipid peroxidation products in rat lung tissues was observed.

CONCLUSION

The findings of the present study suggest that the differing inflammatory responses of PM collected from the two road sites might have been mediated by the differing physicochemical characteristics.