Abstract: After studing the plumbum orgin in Total Suspended Particulates(TSP) of the ambient air of Changchun urban district， the results show that 94.8% of plumbum in TSP of the ambient air come from the vehicle exhaust. The forecasted and tested plumbum contents in TSP of the ambient air of the main t raffic line after using lead-free gasoline show that after using lead-free gasoline, there is a great decline of plumbum content in TSP of the ambient ai r and a difference between the two results.

Key words: plumbum, lead-free gasoline, vehicle exhaust