Ulaanbaatar, the capital city of Mongolia, has occasionally been considered the most polluted city in the world. Approximately 46% of the population resides in Ulaanbaatar, and over half of the population living in ger (traditional yurt dwelling) areas consumes raw coal, which leads to an increase in ambient air pollutants. The Government of Mongolia took a series of actions to reduce air pollution; one was the ban on the consumption of raw coal beginning on 15 May 2019. In this study, improvement in particulate matter (PM) air quality was shortly studied by assessing the hourly data for the last six years, from January 2014 to February 2020. The analysis exhibited a major improvement in PM concentrations during the 2019-2020 winter in Ulaanbaatar. The average PM concentrations clearly exhibited a decreasing trend in November 2019-February 2020 compared to the previous five years. The maximum PM 2.5 and PM 10 concentrations were reduced to 46% and 55%, respectively, compared to the mean maximum values of the previous five years. The most prominent occurrence frequency of PM concentrations shifted to a lower concentration range. Although a PM pollution reduction was seen during the 2019-2020 winter, further air quality improvement can be obtained by taking a set of multiple actions with accurate planning management.

To accurately study aerosol distribution and composition, continuous observations are required from satellites, networks of ground-based instruments and dedicated field experiments. AERONET Sun-photometer has been used to make measurements of solar radiation and aerosol properties in arid Gobi desert region of Mongolia, Dalanzadgad (43.57722° N, 104.41917° E, and 1470 m above the sea level) site in Mongolia since February 1997. We have analyzed Aerosol Optical Thickness (AOT), and derived Angstrom exponent acquired by an AERONET Sun-photometer at Dalanzadgad. Monthly means computed from quality-assured daily means, seasonal trends are presented and discussed. Spring and early summer has the maximum seasonal average AOT and minimum seasonal average appears in winter of 2002-2003. Monthly average Angstrom exponents are indicates that aerosol mixtures of both coarse and fine mode particles, specially dust aerosol pattern over Dalanzadgad dominantly in spring. This presentation addressed to the aerosol optical properties over arid and semi-arid regions of Mongolia that observed from representative sites of the Global AERONET Sun-photometer and SKYNET Sky Radiometer measurements.