Seasonal and annual variations in air concentrations of Pb, Cd and PAHs in Cairo, Egypt.

A study is presented concerning the degree and extent of air pollution by cadmium, lead and polycyclic aromatic hydrocarbons (PAHs) in atmospheric particulates of an urban area (El-Abasya) in Cairo, Egypt. The average yearly and seasonal concentrations are presented. The correlation coefficients between metals, and between metals and suspended PAHs are also reported. Statistical analysis showed seasonal and annual variations. Concentrations of PAHs, Pb and Cd were higher in winter than those measured at other times in the study area. The concentration of lead decreased by 40% from 3.36 microg(-3) in 1994 to 2.4 microg m(-3) in 1997 in consequence of the reduction of the Pb concentration in leaded gasoline fuel. The average cadmium concentrations showed significant decrease in 1997. The sum of the concentrations of PAHs was higher during the winter season 1997 (14.79 ng m(-3)) than in summer (7.53 ng m(-3)) and a highly significant difference was observed between the two seasons. In addition, the ratio of benzo(a)pyrene [B(a)P] to Pb was higher in winter than in summer, suggesting the contribution of a non-vehicular source of lead. The levels of lead observed are higher than those recorded in various other parts of the world.