Measuring the external health cost of particulate matter from road traffic and other sources in Stockholm, Sweden.

This paper measures the external health cost due to emissions from different sources in the Stockholm area using the Impact pathway approach. The estimated health impact is the result of detailed dispersion modelling with high spatial resolution. We make separate calculations for the impact that occur within the Stockholm area, the surrounding region and the rest of Europe. The pollutants considered are combustion and secondary particulate matter (PM) from the burning of fuels and also road wear (non-exhaust PM) that makes a large contribution to measured concentrations of PM locally in Stockholm. We also investigate the influence of assumptions made regarding the exposure-response functions used in these calculations since PM of different origin are expected to have different health impacts. According to the results road traffic makes important contributions to the external health cost both on a local and a regional scale compared to other sources. This is in part due to emissions being released in close proximity to where people live but also because of the amount of pollutants emitted. Although non-exhaust PM makes a large contribution to local population exposure within Stockholm the external health cost is relatively small which is due to other health impact being relevant for this emission source. Residential heating also makes an important contribution to exposure and external health cost on a local scale while power plants have a large influence regionally.