Evaluation of SO2 and NO2 concentration levels in Vilnius (Lithuania) using passive diffusion samplers

The method of passive diffusion samplers has been used for evaluation of SO2 and NO2 concentration levels in the Lithuanian capital Vilnius. It was analysed about 70 diffusion tubes twice per 4 seasons during 1995–1996 for each component, thus about 600 samplers were exposed and analysed including control parallel sampling. The measurement results show that the SO2 concentrations levels depend mainly on heating and exhibit average values 7–13 μg/m3 for warm and 17–23 μg/m3 for cold seasons. The NO2 average rates depend strongly on traffic (sampling place) and are highest in crossroads (52–82 μg/m3) and lowest at the background-suburban level (9–16 μg/m3).