Lead (Pb) . Major sources of Pb pollution are exhaust gases
of petrol engines, which account for nearly 80% of the
total Pb in the air. Soils located near Pb mines may contain
high as 0.5% Pb content. Apart from minerals, sources of
Pb are pesticides, fertilizer impurities, emissions from
mining and smelting operations, an atmospheric fall out
from the combustion of fossil fuels.