Question

Dust falls on Chicago at a rate of 65mg m^-2 day^-1. Major metallic elements in the dust include Al, Mg, Cu, Zn, Mn, and Pb.³ Pb accumulates at a rate of 0.03mg m^-2 day^-1. How many metric tons (1 metric ton = 1000kg) of Pb fall on the 535 square kilometers of Chicago in 1 year?

Thanks!