Air particulate matter pollution in Ulaanbaatar, Mongolia: determination of composition, source contributions and source locations

Abstract

Ulaanbaatar, the capital city of Mongolia is subject to high air particulate matter pollution episodes during winter and during dust storm events in spring and autumn that have severe implications for the health of the exposed population. This paper presents the results of fine (PM2.5) and coarse (PM10–2.5) particulate matter monitoring in Ulaanbaatar from 2004 to 2008 and receptor modelling to determine the sources contributing to particulate matter pollution. Ion Beam Analysis was used to determine elemental concentrations in the two size fractions and black carbon was measured with a light reflectance device. Mass contributions to ambient particle concentrations from emission sources were estimated by positive matrix factorisation and air mass back–trajectory analysis was used to assess probable source locations. The results show that crustal matter sources are the primary contributors to the coarse particle fraction. Combustion sources (coal combustion, biomass burning, and motor vehicles) dominate the fine fraction of particulate matter in the Ulaanbaatar airshed, primarily from local emission sources but forest fires to the north can be a significant contributor to biomass burning concentrations at times. Analysis of seasonal differences showed that coal combustion processes were largely responsible for fine particle air pollution episodes during winter. Temporal trends show an increase in the coal combustion contributions over the monitoring period. We suggest that this is linked to the increase in the Ulaanbaatar population and a consequent increase in the use of coal for power generation and domestic heating purposes.