Exposure to nitrogen oxides and other air pollutants from automobiles

We have conducted an epidemiological study to investigate the association between exposure to automobile exhaust and respiratory health. Three zones were selected in Tokyo according to expected exposure levels. Zone A is within 20 meters from the roadside of major roads with heavy traffic. Zone B is 20-150 meters away from the roadside of the same road. Zone C is the residential district in a suburb of Tokyo. Zone A, which was nearest to the roads, had the highest mean levels of personal exposure to nitrogen dioxide for housewives, followed by Zone B and Zone C. Ambient levels of nitrogen oxides, and mass concentrations, polycyclic aromatic hydrocarbons and mutagenicity of suspended particulate matter were higher at the roadside within Zone A. A cross-sectional study of respiratory symptoms and repeated examinations of pulmonary function were also performed in each zone. These results suggest that exposure to automobile exhaust may be associated with respiratory symptoms. Nevertheless, pulmonary function didn't show consistent differences over all examinations. We should have further analyses about a decline of pulmonary function with age.