Lead in the ambient air and blood specimens of children in Helsinki.

Ambient air lead concentrations have been measured in Helsinki since 1978. The mean concentrations at various stations reached maximum values in 1980, being then 209-1150 ng/m3. From 1980 to 1991 the concentrations decreased to one-eighth (335-41 ng/m3) at the three stations where measurements were made continuously. Concomitantly the estimated annual lead emissions in Helsinki decreased from 78 to 9 tons, mainly owing to the reduced emissions of lead in exhaust gases from road traffic. The mean concentration of lead in the blood of children in day-care centres was 46 micrograms/l in 1983 and 30 micrograms/l 5 years later. Similar concentrations were found in blood samples from a day-care centre beside a street with heavy traffic and in those from an area with less traffic.