PERSONAL EXPOSURE TO NITROGEN-DIOXIDE IN SWITZERLAND

Home indoor and outdoor levels, and personal exposures to NO2 were det ermined for more than 500 subjects in a subpopulation of SAPALDIA by u sing passive samplers. The overall personal NO2 average was found to b e 27 mu g m(-3), the overall indoor average 21 mu g m(-3) and the over all outdoor average 31 mu g m(-3). Personal NO2 levels ranged between the outdoor and indoor levels, with the exception of study areas with low NO2 concentrations. In the winter, the indoor/outdoor ratios were lower than in the summer. Outdoor NO2 levels were higher in winter. In some study areas, indoor NO2 levels were lower in the winter than in the summer due to reduced ventilation but this was not consistent. Per sonal NO2 concentrations were very similar during all seasons. Gas-coo king and smoking were important factors for elevated indoor and person al NO2 levels (contribution: 5 mu g m(-3), 2 mu g m(-3), respectively) . Personal exposure to NO2 correlated best with the indoor NO2 concent rations. (C) 1998 Elsevier Science B.V.