Quantification of general population exposure to nitrogen dioxide in Sweden

Based on an empirical statistical calculation method for air quality assessment, the URBAN model, a method for quantifying the general population exposure of different ambient air pollutants on a national level has been developed. However, this study has focused on NO2, a pollutant closely related to traffic emissions and hence to the exposure of air pollution in cities. The advanced numerical model, TAPM (The Air Pollution Model) was used to improve the ventilation factor by using the output parameters mixing height and wind-speed respectively, for calculating new ventilation parameters with high time and spatial resolution (1 month and 1x1 km (2x2 km for the northern inland)). A comparison between monthly averages of measured and calculated NO2 concentrations shows a fair accordance. The results from the urban modelling show that in 1999 the majority of people in Sweden, 40%, were exposed to yearly mean concentrations of NO2 between 10-15 µg/m3. Another 40% were exposed to less than 10 µg NO2/m3, and only about 5% of the Swedish inhabitants experienced exposure levels of NO2 above 20 µg/m3.