One of the most actual problems in monitoring of the atmosphere is the recognition of chemical composition and microphysical characteristics of atmospheric aerosol impurities. In the present work the opportunities of lidar system based on multifrequency pulsed chain chemical DF laser (λ = 3.6 - 4.2 μm) are considered from this point of view. With the purpose of working-out of the requirements to the primary performances of lidar system, model experiments are executed as to the problem of recognition of aerosol impurities in the atmosphere with the use of DF-laser radiation lines. The obtained results and their analysis are presented in the paper.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.