Particulate pollution in Ulaanbaatar, Mongolia

The World Health Organization (WHO) listed the air pollution in Ulaanbaatar (Mongolia) among the top 5 cities with the worst air quality in the world. Air quality in the winter season reaches highs of 750 μg/m³ for daily average fine particulates (PM) due to increased coal combustion and lower mixing heights (<200 m), coupled with the city’s geography surrounded by mountains, which further restricts the vertical and horizontal dispersion of the pollutants. The annual average concentrations in 2010–2011 ranged 136?±?114 μg/m³ (the WHO guideline for fine PM is 10 μg/m³). The single largest source of particulate pollution in Ulaanbaatar is coal and biomass combustion in households and heat-only boilers, followed by power plants. In this paper, we present sector-specific emissions for 2010 accounting for 62,000 tons of fine PM, 55,000 tons of sulfur dioxide, and 89,000 tons of nitrogen oxide emissions. The inventory is spatially disaggregated at 0.01° resolution on a GIS platform for use in a chemical transport model (ATMoS). The modeled concentrations for the urban area ranged 153?±?70 μg/m³, when overlaid on gridded population, resulted in estimated 1,000–1,500 premature deaths per year due to outdoor air pollution. This study also highlights the linkages between indoor and outdoor air pollution. In these harsh temperate conditions, with 50 % of the emissions originating from Ger households, they are as big a health risk for indoor air quality as they are for outdoor air quality. Any intervention improving combustion efficiency or providing clean fuel for these stoves will have a combined benefit for indoor air quality, outdoor air quality, and climate policy. The analysis shows that aggressive pollution control measures are imperative to protect the population in Ulaanbaatar from excess exposure levels, and implementation of control measures like the introduction of heat efficient stoves, clean coal for heating boilers, and urban transport planning will result in significant health benefits, which surpass any costs of institutional, technical, and economic interventions.     

An assessment of air pollution and its attributable mortality in Ulaanbaatar, Mongolia

Epidemiologic studies have consistently reported associations between outdoor fine particulate matter (PM_2.5) air pollution and adverse health effects. Although Asia bears the majority of the public health burden from air pollution, few epidemiologic studies have been conducted outside of North America and Europe due in part to challenges in population exposure assessment. We assessed the feasibility of two current exposure assessment techniques, land use regression (LUR) modeling and mobile monitoring, and estimated the mortality attributable to air pollution in Ulaanbaatar, Mongolia. We developed LUR models for predicting wintertime spatial patterns of NO₂ and SO₂ based on 2-week passive Ogawa measurements at 37 locations and freely available geographic predictors. The models explained 74% and 78% of the variance in NO₂ and SO₂, respectively. Land cover characteristics derived from satellite images were useful predictors of both pollutants. Mobile PM_2.5 monitoring with an integrating nephelometer also showed promise, capturing substantial spatial variation in PM_2.5 concentrations. The spatial patterns in SO₂ and PM, seasonal and diurnal patterns in PM_2.5, and high wintertime PM_2.5/PM₁₀ ratios were consistent with a major impact from coal and wood combustion in the city’s low-income traditional housing (ger) areas. The annual average concentration of PM_2.5 measured at a centrally located government monitoring site was 75 μg/m³ or more than seven times the World Health Organization’s PM_2.5 air quality guideline, driven by a wintertime average concentration of 148 μg/m³. PM_2.5 concentrations measured in a traditional housing area were higher, with a wintertime mean PM_2.5 concentration of 250 μg/m³. We conservatively estimated that 29% (95% CI, 12–43%) of cardiopulmonary deaths and 40% (95% CI, 17–56%) of lung cancer deaths in the city are attributable to outdoor air pollution. These deaths correspond to nearly 10% of the city’s total mortality, with estimates ranging to more than 13% of mortality under less conservative model assumptions. LUR models and mobile monitoring can be successfully implemented in developing country cities, thus cost-effectively improving exposure assessment for epidemiology and risk assessment. Air pollution represents a major threat to public health in Ulaanbaatar, Mongolia, and reducing home heating emissions in traditional housing areas should be the primary focus of air pollution control efforts.