Lead concentration in Teheran's atmosphere

Aerosol Pb pollution in Teheran was repeatedly measured at nine crossroads in the city from April to November 1976. The mean value of atmospheric Pb in the city was 3.6 μg m^?3. The average values obtained for the Pb in the air of the crossroads were close to each other except in the southern parts of the city where it was higher. Stagnation of motor vehicles and higher dustfall may have a role in this increase. Since industrial Pb pollution is not significant in Teheran, it was concluded that the contamination by Pb in the city is mainly from gasoline consumption.