The paper discusses the results of experimental studies of chemical, microphysical and optical properties of atmospheric aerosol in different natural and climatic conditions of Mongolia. The main factor in the formation of the component composition of aerosols are anthropogenic emissions, whose proportion in the urban atmosphere (Ulan-Bator, Sukhbaatar) is significantly higher than at stations in arid regions where regional sources of emissions are associated with mining enterprises, road transport and terrigenous dust. The data of long-term observations AERONET at the station Dalanzadgad were used for analyze of the seasonal, annual variations of AOD in the Gobi Desert. It is established that high transparency of the atmosphere is observed (τ<sub>0.5</sub>=0.09) with a maximum in spring and summer (τ<sub>0.5</sub>=0.15) and a minimum in winter (τ<sub>0.5</sub>=0.04).
The paper presents the results of studies of air mass and smoke aerosol transport using the HYSPLIT, NAAPS models and data of remote sensing CALIPSO during the forest fires in 2016 in Baikal region. In June 2016 the homogeneous filling of the atmosphere by smoke aerosol over the Baikal region up to 2 km was observed. It is revealed that in the spectra of particle size distribution the large particles of the submicron aerosol fraction with a diameter exceeding 200 nm are observed, typical for smoke particles. The results of trajectories calculation have shown that in June influence of local fire on air quality in Ulan-Ude was observed under the general northwest transport of a smoke aerosol, in July downwind was mainly from the Irkutsk, Krasnoyarsk and the Yamalo-Nenets regions.