Automobile exhaust can bring about Pb pollution to soils and trees along expressway

which can be decreased by green belts to some extent.However

fewer reports are available on this subject.The Pb concentration of soil and tree leaf sampled from roadside were measured and present situation of Pb pollution along expressways in Shandong province was studied.Also

the Pb attenuation by green belt was evaluated for different afforestation mode.The results showed that the pollution existed in roadside soil along expressway

which mainly within 50 m.The positive correlation was found between Pb pollution and traffic vehicle density

which might be used to indicate expressway pollution.The Pb concentration of tree leaf from inner side of green belt was increased by Pb pollution.Large traffic vehicle density resulted in heavier Pb pollution on green trees along expressway.The Pb attenuation by green belt varied much depending on afforestation mode.Green belt with too big width was not ideal to decrease Pb pollution.