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A nonlinear mathematical model is proposed and analyzed to study the removal of primary and secondary air pollutants by precipitation in the atmosphere. The atmosphere, under consideration, consists of four interacting phases i.e. the rain droplets phase, the primary pollutants phase, the secondary pollutants phase and the combined phase of these pollutants absorbed in the rain droplets. The dynamics of these phases is governed by the ordinary differential equations with source, nonlinear interaction, conversion and removal terms. The proposed model is analyzed qualitatively using stability theory of differential equations. It is shown that under appropriate conditions, the pollutants can be removed from the atmosphere significantly and the removed amount would depend upon the rate of introduction of primary pollutants, rate of formation of secondary pollutants, rate of precipitation, rate of absorption and rate of falling rain droplets on the ground. Finally, computer simulations are performed to investigate the dynamics of model system. The results obtained in the paper are found to be in line with the experimental observations published in the literature. [ABSTRACT FROM AUTHOR]