Road traffic, NO2 exposure and respiratory function among children (VESTA study)

Within the multicentre VESTA case-control study on childhood asthma and traffic air pollution, we studied the association between the respiratory function and NO2 personal exposures or intensity of traffic close to homes and schools. The relative contribution of different indoor and outdoor emission sources on personal NO2 exposures was also assessed. The respiratory function (forced expiratory volume in one second - FEV1 - and peak expiratory flow rate - PEFR) was measured with a One-Flow tester(R) NO2 personal exposure was measured using passive Ogawa samplers that were worn during 48 hours by study participants, aged four to 14 years old. Exposure to traffic exhausts was assessed through an index based on a time-weighted average of traffic density to road distance ratios. The most influential variables that predicted NO2 personal exposures were the traffic index, use of a gas cooker at home and background ambient air pollution, with variable associations across cities (model R-2 rank from 0.33 to 0.67). No association was found between the respiratory function and the levels of NO2 personal exposure; FEV1 or PEFR values, however, were associated with the traffic index, in two out of four cities. These results suggest that cumulative exposure to traffic exhausts may alter the respiratory function of children.