Comparative receptor modelling study of airborne particulate pollutants in Birmingham (United Kingdom), Coimbra (Portugal) and Lahore (Pakistan)

Samples of airborne particulate matter have been collected in three cities in different parts of the world. In Birmingham, U.K. and Coimbra, Portugal, samples were of PM10 whilst in Lahore, Pakistan, total suspended particulates were collected. The samples have been analysed for a wide range of metallic constituents, black carbon and organic carbon, and the soluble ions, SO42−, NO-, Br-, Cl− and NH4+. A receptor modelling study has been conducted for data from each city using Principal Component Factor Analysis followed by multi-linear regression analysis in order to provide quantitative insights into the sources of specific chemical components and total particulate matter (or PM10) in the three cities. This methodology, applied separately to coarse and fine fractions in the samples collected in Birmingham and Coimbra, reveals between four and six source categories according to location and size fraction, and whilst the sites in Birmingham and Coimbra in northern and southern Europe, respectively, show considerable similarities, there are large contrasts with Lahore with its dryer climate and poorly controlled pollution sources. A detailed intercomparison has been conducted into the source attributions for lead and for PM1O/TSP. In the case of lead, the source attributions in Birmingham are shown to correspond closely to the national atmospheric emissions inventory. Large differences between the cities in source contributions are seen in the case of PM,o/TSP, with soil dust estimated to contribute 62% of total suspended particulate matter in the atmosphere of Lahore, but contributing much less in Birmingham and Coimbra where road traffic emissions comprise a substantial percentage of the total.