1. Model used in « Source Apportionment of Airborne Particulate Matter in the UK » [Stedman et al., Receptor modelling of PM 10 concentrations at a UK national network monitoring site in central London, Atmospheric environment (35) 297-304 (2000)] PM 10 = A * [NOx urban](surrogate of PM from local combustion) +B * [SO 4 rural] (surrogate of secondary regional PM ) +C (other PM : crustal material, marine aerosol,…) Statistical model of PM10 origin in the urban atmosphere UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 27th session, Oslo, 13-15 May 2002

2. Location of cities (blue) and rural SO4 monitoring stations (red) UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 27th session, Oslo, 13-15 May 2002

3. Clermont-Ferrand : comparison between model and observations UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 27th session, Oslo, 13-15 May 2002

4. Clermont-Ferrand : variability of local and regional contributions to ambient PM UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 27th session, Oslo, 13-15 May 2002

5. Paris : seasonnality of local and regional contributions to ambient PM UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 27th session, Oslo, 13-15 May 2002

6. Overview of local/regionalcontributions for four cities Clermont-Ferrand Caen Paris 12èmeVitry-sur-Seine (Paris suburban) UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 27th session, Oslo, 13-15 May 2002

7. Refined model for PM apportionment in a Suburban Paris site Both PM10 and PM2.5 being available at Vitry (suburban Paris), a more refined apportionment model has been applied, identifying specifically the contribution of coarse particles (construction, road abrasion, brake and tyre wear, construction, mineral dust,...). This contribution amounts to 36% of ambiant PM10. Mean unexplained PM10 concentration is below 1 µg/m3 The « local combustion » and « regional PM », as identified by the model, are almost enterely in the PM2.5 size range. For this suburban Paris site, the share of « local combustion » in PM2.5 ambiant concentration is higher than that for PM10 (70% for PM2.5 versus 50% for PM10).

8. Refined model for PM apportionment in a Suburban Paris site : results for PM10.

9. Refined model for PM apportionment in a Suburban Paris site : results for PM2.5

10. Some concluding remarks Both local sources and regional concentrations are important to explain ambiant PM10 concentration in the cities studied here. Local combustion involved through: -Transport : primary PM, secondary PM from NOx and VOC emissions. -Heating : the case of Paris in winter ?? The share of local combustion increases when considering PM2.5 instead of PM10 for the case in suburban Paris studied. UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 27th session, Oslo, 13-15 May 2002