Analysis and interpretation of measurements of suspended particulate matter at urban background sites in the United Kingdom

Monitoring of atmospheric particulate matter as PM 10 commenced in the UK in 1992, and by 1995 16 national network stations sited at urban background locations were reporting data. The concentrations conform closely to log normal distributions and statistical properties of the data are reported. The data have been analysed for relationships to other pollutants, and close correlations with carbon monoxide (CO) and nitrogen oxides (NO X) are observed for much of the time at all sites for which adequate data are available. These analyses indicate the importance of vehicle-emitted PM 10 as a contributor to atmospheric concentrations and confirm the ratio of PM 10 to carbon monoxide emissions from road traffic indicated by the national and London inventories. Analyses of data from Leeds have shown an occasional impact of power station emissions on urban PM 10. In comparison to the primary sources of PM 10, secondary sulphates and nitrates show less small scale spatial variability, but a mapping of data from the European Monitoring and Evaluation Programme (EMEP) indicates a gradient across the UK with the highest concentrations in the south and east of the country. Secondary particulate matter does not appear to be a major contributor to urban concentrations in winter episodes, although there are indications that it can be important during summer photochemical episodes. The correlations of PM 10 and meteorological parameters for the Edinburgh site are also reported. Overall, the data indicate that three source categories contribute substantially to PM 10 at UK urban sites: vehicle exhaust emissions, secondary sulphates and nitrates, and resuspended surface dusts and soils.