This video lecture from Environmental Chemistry (F.Sc. second year Chemistry) covers nitrogen oxides, sulfur oxides and hydrocarbons. This lecture is a continuation of the previous lecture on primary atmospheric pollutants. The natural and artificial sources are discussed for several of these pollutant gases. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.