Background:
Cardiovascular disease (CVD) are the leading cause of death globally. A major contributor to CVD mortality and morbidity is ambient air pollution (AAP) exposure. The AAP level in the capital city of Mongolia is considerably higher than the World Health Organisations air quality guideline. The main source of AAP is related to the traditional houses where people burn raw and processed coal for heating and cooking purposes. Although several studies have reported the association between AAP and CVD outcomes worldwide, scientific evidence in Mongolia is lacking. The purpose of this study is to evaluate associations between air pollution and CVD mortality in Ulaanbaatar.

Methods:
We collected air pollution and meteorological data from the Centre for Environmental Monitoring and mortality data from the Health Development Centre between January 2014 and December 2021. Six criteria air pollutants were measured at 15 monitoring stations, including particulate matter with an aerodynamic diameter ≤ 2.5 µm and ≤ 10 µm (PM2.5 and PM10), nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3) and carbon monoxide (CO). An ecological time-series analysis was applied to examine the relationship between exposure and outcome variables.

Results:
The highest concentrations of AAP, except ozone, were reported in winter. The average concentration of PM2.5, PM10, NO2, SO2, O3 and CO were 118.2±73.8 µg/m3, 219.8±119.6 µg/m3, 76.1±20.3 µg/m3, 71.9±52 µg/m3, 21.9±19.8 µg/m3, 1.8±1.07 mg/m3 respectively. A total of 33,931 deaths were identified, most of which occurred during cold seasons. In a multiple pollutant model, PM2.5, PM10 and SO2 were significantly correlated (P-value<0.05) with CVD death, accounting for seasonal variations after adjusting other pollutants.

Conclusion:
This research found evidence of a positive association between short-term exposure to PM2.5, PM10 and SO2 and CVD mortality. These study findings provide evidence-based information for further research and policymakers to reduce current air pollution level in Mongolia.