Sammanfattning
Model calculations have been performed to estimate the effects of emissions in Stockholm on the population exposure to particulate matter (PM) outside the city. The impacts of five different emissions were investigated: Road traffic exhaust, split into Light Duty Vehicles (LDV) and Heavy Duty Vehicles(HDV), Sea Traffic, Power Plants and Residential Heating. The emissions from non-exhaust (mainly road wear due to use of studded tyres) were also treated, in addition to combustion sources. The uncertainties in the emission estimates for Residential Heating using biomass (wood) are very large but it seems that it is an important PM source in Stockholm. In this report two estimates of the emissions have been used. In the lowest estimate, which seems more realistic, the contribution to population exposure of directly emitted combustion particles from residential heating is of similar magnitude (37%) as the contribution from road traffic exaust (42%). For all sources, except Sea Traffic, the total population exposure to combustion PM is much larger within Stockholm than outside; for shipping the total exposure is about as large outside the city as within. For all sources, except residential heating, the secondary inorganic aerosol (SIA) exposure is higher than the combustion particle exposure. Non-exhaust particles dominate the total impact on PM10 exposure, contributing about 60-70% to the total exposure, due to all the studied sources in Stockholm. The calculated population exposure due to the wear particles is to a very large extent (87%) occurring within the Greater Stockholm area.