Introduction: Air pollution is one of the greatest environmental risk to health. Ambient air pollution accounts for an estimated 4.2 million deaths per year due to stroke, heart disease, lung cancer and chronic respiratory diseases. 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. The aim of this study is to describe the Ulaanbaatar air quality related to briquettes usage during cold seasons. Material and Methods: We used ecological research design in this study. Quantitative data about air quality of Ulaanbaatar city during the cold seasons (Oct, Nov, Dec, Jan, Feb, Mar, Apr) in 2018-2020 years were analyzed from Department of air quality. These 5 indicators such as sulfur dioxide, nitrogen dioxide, particles (PM_2.5, PM₁₀) and carbon monoxide were selected for statistical analysis. The SPSS-20 software was used to analyze the data. Ethics: The methodology was approved by the Medical Ethics Sub-Committee of the Ach medical university on 5^th of February, 2021. Results: The average sulfur dioxide, nitrogen dioxide concentrations in the air have increased in October 2019–April 2020 compared to the previous five years. But carbon oxide, particular matter concentrations have decreased in the selected years. Sulfur dioxide (p <0.0001), nitrogen dioxide (p =0.001), PM₁₀(p <0.0001), and PM_2.5 (p <0.0001) are differentiated before and after the use of improved fuels by Wilcoxon signed rank test. However, the CO content did not differ from that of the briquette’s consumption (p =0.412). Conclusions During the cold seasons, the concentration of sulfur dioxide and nitrogen dioxide has increased in air of Ulaanbaatar after used briquettes, while the concentration of particulate matter has decreased during the cold seasons.