Non-SS-SO4 contributed from 14 to 31% to PM2.5 and 0.8 to 6.8% to PM2.5 − 10. NO3 contributed from 1.1–18% to PM2.5 and 3.7–14% AZD0530 to PM2.5 − 10; NH4 7.9–9.3% to PM2.5 and 0.06–2.7% to the PM2.5 − 10 fraction. The model simulations from this study show that the share of ship originated sulphur particles in the modelled total sulphur along BS coastlines in 2010 was around 5% in the northern BS, 5–10% along the Polish coast, 2–5% along the Lithuanian coast, 10–20% north of Stockholm and Turku and along the coast of the eastern GoF, 20–30% on the Swedish coast south of Stockholm and in the south-west corner of Finland; it exceeds

30% only in the coastal areas of the Danish Straits. The share of the modelled ship originated SO4 concentration of the total PM2.5 on BS coastlines thus varies from 0.3% to 12%, being approximately < 9% along most (> 90%) of the coastline and < 5% on ca 70% of the BS coastline. If the aerosol chemical composition

of Sillanpää et al. (2006) is used, only 0.15–6% of the total NU7441 purchase PM mass < 10 μm along the BS coastline is BS ship-originated sulphate. This percentage declines sharply with distance from the sea, so in the BS region the contribution of ship originated SO4 concentrations to PM concentrations is on average very low, and their contribution to the mortality caused by PM concentrations in air should also be low. The mortality caused by sulphur originating from Baltic Sea ship-emissions was most likely overestimated when the sulphur directive was enacted. The quantitative magnitude of the sulphur-emission effect on mortality should be re-evaluated. The work will continue in that all PM emissions of BS ships STK38 will be modelled, because they produce the majority of the health problems caused by shipping traffic. I would like to thank Robin King, Curtis

Wood and Peter Senn for suggesting language corrections and the unknown reviewers for their useful comments. The deposition and surface concentration fields will be made available for environmental impact studies through the FMI open data web service interfaces for geospatial data. “
“Urban environments are characterised by a significant percentage of impervious surfaces (such as roads, pavements and roofs), a reduced area of natural sinks and a large number of pollution sources (Parikh 2005). The impervious surfaces alter the natural hydrology because they do not permit rain and snowmelt to infiltrate into the soil as at natural sites; this water thus contributes a significant proportion to the surface runoff. Urban surface runoff can carry a considerable amount of impurities, sometimes comparable to that of municipal wastewaters (Chouli 2007). Storm runoff discharges from urban areas can give rise to various adverse effects in receiving water quality: deposition of contaminated sediments (Marsalek 2005), increased toxicity due to pollutants from traffic (Roger et al., 1998 and Han et al.