Rusting is the process in which of iron in the presence of moisture and air form a layer of a brownish substance called rust. Both air and moisture are necessary for rusting of iron objects. Due to the presence of the sea, In coastal areas, there is more moisture in the air. But, in the desert, there’s a scarcity of water and hence the air is nearly dry with respect to coastal area. This is the reason why rusting is faster in coastal areas than in deserts.