BROMINE - LEAD RATIOS IN AIRBORNE PARTICLES FROM URBAN AND RURAL SITES

Air particulate samples were collected from one urban and two rural sites in NW England. Regression of Br and Pb showed the elements to be virtually uniquely associated at all sites, but with a lower ratio of Br/Pb in the town than at rural sites. All the Br/Pb ratios were below that assumed to characterize fresh exhaust and it is suggested that this is due not only to loss of Br, but more substantially to the collection of either resuspended street dust or re-entrained exhaust deposit emissions. Evidence for this was found in size-fractionated samples. Further evidence came from studies of the lead speciation. In contrast, a second urban site, at Ellesmere Port, showed evidence for Br loss in measurements of gaseous and particulate Br.