1. WHAT IS MISSING IN THE SOURCE APPORTIONMENT OF PM? Dick Derwent rdscientific, Newbury APRIL Workshop, Imperial College London April 23 rd 2010 This work was supported by ALE Defra under contract AQ0704 ‘Modelling of Tropospheric Ozone’

2. SOURCE ATTRIBUTION OF PM 2.5 FOR A BIRMINGHAM CITY CENTRE SITE Yin and Harrison (2008). Atmos. Environ. 42, 980-988

3. A DYNAMIC TREATMENT OF ORGANIC PM A Spectrum of Volatility for Organic Compounds Increasing volatility Decreasing volatility methane, bp -182.5 o gasesliquidssolids α-pinene, mp -50 o anthracene, mp 217 o Non-volatile Highly volatile

4. A DYNAMIC TREATMENT OF ORGANIC PM Volatile Organic Compounds VOCs Highly volatile 0.13 mb Emissions as vapours VOCs CO, H 2 O oxidation Low volatility oxidation products Secondary Organic PM evaporation condensation NAEI has 663 species and 248 sectors Master Chemical Mechanism with 12,723 reactions Pankow absorptive partitioning solvents glues spirits

5. A DYNAMIC TREATMENT OF ORGANIC PM Non-volatile Organic Compounds Non-volatile solids Emissions as vapours Primary Organic PM condensation due to elevated temperatures Handled by NAEI and EMEP? Large PAHs

6. A DYNAMIC TREATMENT OF ORGANIC PM What happens in the middle? Intermediate Volatility Organic Compounds IVOCs 0.13 mb Increasing volatilityDecreasing volatilityEmissions as vapours IVOCs CO, H 2 O Low volatility oxidation products oxidation Secondary Organic PM small PAHs, (naphthalene) alkanes, (hexadecane) phenols due to elevated tempeatures

7. A DYNAMIC TREATMENT OF ORGANIC PM What happens in the middle? Semi-Volatile Organic Compounds SVOCs Increasing volatility Decreasing volatility IVOCsNon-volatiles Emissions as vapours due to elevated temperatures condensation Primary organic PM SVOCs evaporation condensation CO, H 2 O Low volatility oxidation products oxidation Secondary organic PM PAHs, fluoranthene alkanes, pentacosane Biomass burning Wood-burning

8. A DYNAMIC TREATMENT OF ORGANIC PM What are we missing? VOCsIVOCsSVOCsNon-VOCs VOCs LVOPs Secondary Organic Matter IVOCs CO, H 2 O Primary Organic Matter SVOCs CO, H 2 O 0.13 mb

9. WHAT IS MISSING IN THE SOURCE APPORTIONMENT OF PM? Focus on organic PM fraction Attention is required on IVOCs and SVOCs Chemical mechanism and emissions data are required Need extensions to existing approaches and not radically new methods Acknowledgements to Michael Jenkin and NAEI team.