A high rate of lead fallout around two secondary lead smelters originated mainly from episodal large-particulate emissions from low-level fugitive sources rather than from stack fumes. The lead content of dustfall, and consequently of soil, vegetation, and outdoor dust, decreased exponentially with distance from the two smelters. Between 13 and 30 percent of the children living in the contaminated areas had absorbed excessive amounts of lead (more than 40 micrograms per 100 milliliters of blood and more than 100 micrograms per gram of hair) as compared with less than 1 percent in a control group. A relationship between blood and hair was established which indicated that the absorption was fairly constant for most children examined. It seemned that the ingestion of contaminated dirt and dusts rather than "paint pica" was the major route of lead intake. Metabolic changes were found in most of 21 children selected from those with excessive lead absorption; 10 to 15 percent of this group showed subtle neurological dysfunctions and minor psychomotor abnormalities.

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A high-volume Andersen sampler has been used to measure particle size distributions for atmospheric Pb, Br, and Cl at urban control sites and near secondary lead refineries in Toronto, Canada. Bromine and Cl were measured by instrumental neutron activation analysis, while Pb was determined both by absorption spectrophotometry and by instrumental photon activation analysis. The Pb aerosol near roadsides was predominantly submicrometer in size, whereas elevated Pb concentrations in the vicinity of the refineries were attributed mainly to increases in Pb associated with larger particles which settle more rapidly. The strong correlation between Pb and Br from automobile emissions allowed an indirect estimate of nonautomotive Pb in the atmosphere near the refineries. Chlorine, although also associated with automobile emissions, appears to be derived from several additional sources. The localized contamination of residential areas, which has resulted from refinery emissions, emphasizes the importance of particle size considerations in establishing air quality standards.An increasing amount of information on the multielement content of urban aerosols has led several investigators to deduce possible trace element sources and to estimate the relative importance of such sources to ambient air quality (1-3). The additional information provided by particle size sampling done in conjunction with multielement trace analysis greatly increases the possibility of source identification, occasionally allowing one to distinguish between different sources of the same element. This has been clearly demonstrated by Martens et al. (4), who have used aero-