The Use of Receptor Modelling and Emission Inventory Data to Explain the Downward Trend in UK PM sub(10) Concentrations

Automatic monitoring of ambient PM sub(10) concentrations has been performed in the UK since 1992, and statistically significant downward trends in annual mean concentrations have been observed at a number of monitoring sites. A receptor model-based site-specific projection model has been revised in the UK to include an improved treatment of trends in secondary particle concentrations and the contribution from point-source emissions to primary PM sub(10). In this study, receptor model-based source apportionment was applied to the observed downward trend at three monitoring sites. The receptor modeling technique enabled the measured daily mean PM sub(10) concentration at a monitoring site to be divided into three components: primary combustion particles, secondary particles, and other particles assumed largely to be coarse particles. Nitrogen oxides measurements were used as an indicator for primary combustion particles, and rural sulfate measurements were used as an indicator for secondary particles. Results showed that, between 1992 and 2000, annual average PM sub(10) concentrations declined to 66 71% of the 1992 concentrations, which was attributed to reductions of approximately 50 and 30% in primary and secondary particles, respectively.