A report from activities in TRAPART and IMPORT. EMFO funded projects

Optimal air pollution abatement strategies aiming at minimizing health effects, requires knowledge of the impact on people’s health of different sources and different compounds. Both local sources and non-local (e.g. long-range transported air pollutants) need to be considered. TRAPART ("Traffic related particles relative and absolute impact on quantifiable health endpoints") focussed on health effects due to exposure of local traffic related sources and IMPORT ("Comparing health effects due to local and regional pollution in Stockholm") has focussed on health effects due to exposure of non-local sources. In this report we present calculations of the exposure and discuss the different source contributions. Health assessments will be presented in separate reports. Exposure to long-range transported (LRT) particulate components was estimated using an Eulerian, three-dimensional, chemistry and transport model covering Europe (the MATCH model developed by SMHI). Daily mean contributions due to emissions from different sectors in different parts of Europe were estimated. Calculations were made for 7 years (1997-2003). One of the largest contributors to LRT particulate exposure is the secondary inorganic aerosol (SIA). SIA is formed by emissions of nitrogen oxides (NOx) and sulphur oxides (SOx), which are emitted mainly from road traffic, energy production and shipping. SIA is also due to emissions of ammonia (NH3) mainly from agricultural activities. Another contributor to the LRT aerosol exposure is primary emitted particles mainly from road transport, shipping and other combustion processes. According to the emission inventory used here most SOx (46% of total emissions) and primary PM (ca 50%) is emitted in eastern Europe, whereas western Europe is the largest source region for NH3, NOx, non-methane volatile organic carbon (NMVOC) and carbon monoxide (CO). For primary PM the largest contribution to the population exposure in Sweden was estimated to be due to emissions in Sweden; 40%, 44% and 48% for elemental carbon (EC), organic carbon (OC) and inorganic compounds (IPM), respectively as averages for 1997-2003. Primary PM emissions in eastern and western Europe contribute with between 11% and 21% to EC, OC and IPM. Eastern and western European emissions make the largest contributions to secondary organic aerosols. For sulphate (SO2-4) the largest contributor is eastern Europe (28 %), but western Europe (23 %) and international shipping (22 %) are also large contributors. For nitrate (NO3-) western Europe is the largest contributor (32 %). For ammonium (NH+4) western Europe is also the largest contributor (30 %), but the contribution from eastern Europe (25 %) and Sweden (21 %) is also important. Hence, for secondary inorganic aerosols the largest emitters of precursor gases also contribute most to population exposure in Sweden, whereas for primary PM Swedish emissions are only a few percent of total emissions, but they are the most important for the exposure.