Evaluation of air quality programs for a combination of source categories.

The contribution of air pollution from car traffic. home heating and industry to the population exposure in Oslo is determined by calculations based upon data for emission and dispersion. The calculations are carried out in a km2 -grid with special calculations for roads with high traffic and for large point sources. Based on data for pollution advection into each km2, on local contribution and on the concentrations close to streets with high traffic, estimates are made of the cumulative spatial distribution of pollution within each km2. The number of people living in each km2 combined with the spatial concentration distributions are used to summarize the population exposure to 24 hour mean episodic concentrations values.