Identification of lead compounds in urban air

Abstract

IN the current controversy over the toxicity of environmental lead, one point still at issue is the efficiency of respiratory uptake of urban lead aerosol. The rate at which lead passes into the blood is a function of the particle size and the solubility of the deposited lead. Although data on the aerodynamic particle size distribution of urban lead aerosol are plentiful, little is known of the chemical nature, and thus solubility, of the lead and so this has hampered studies of respiratory uptake. Several analytical studies of fresh auto exhaust have been reported¹, but Ter Haar and Bayard² have shown that rapid changes occur after emission into the atmosphere. Although these workers characterised the major components of aged lead aerosol, limitations of the electron microprobe techniques which they used have been pointed out by Heidel and Desborough³, and considerable doubt must attach to the structural assignments. Using two techniques to enrich the lead fraction of urban aerosol, we have now identified the major components by X-ray powder diffraction (XRD).