Indoor air quality study among the households of Ulaanbaatar, Mongolia

Abstract

Abstract This study was conducted to compare whether the indoor air pollutants had changed in 2020 compared to 2019 in accordance with the raw coal use ban. A total 295 households and 10 family health centers were recruited from 6 districts of Sukhbaatar, Bayangol, Chingeltei, Songinokhairkhan, Khan-Uul and Bayanzurkh districts of the Ulaanbaatar city. The average 24-hour concentration of fine particles is 102.7 µg/m3 in total households, which is 2.1 times higher than the Mongolian air quality standard. The average concentration of PM2.5 which was measured in 2019, when the raw coal usage was available, is decreased by 40 percent (from 176.1 µg/m3 to 105.7 µg/m3) compared to the year of 2020 when improved fuel usage was introduced. Particulate matter pollution varied significantly by dwelling and heating types. The concentration of indoor PM2.5 was relatively high (128.4-150.2 µg/m3) in gers and houses with traditional stoves, whereas it was low (81.2–86.3 µg/m3) in gers and houses with improved stoves. PM2.5 concentrations varied diurnally in gers, houses and apartments with peak concentrations from 07:00 to 11:00 in the morning (68–96 µg/m3) and from 18:00 to 20:00 in the evening (71-85.5 µg/m3). PM2.5 concentrations varied by district, with relatively low concentrations in Khan-Uul and Sukhbaatar districts (87.9 µg/m3) as compared to households in Songinokhairkhan and Bayanzurkh districts (108.1 µg/m3). The average 24-hour concentration of carbon monoxide was 17.6 ± 9.2 mg/m3 in gers and houses, which is 2.5 times higher than the WHO recommended level with higher concentrations in houses than in gers. Compared to the winter of 2019 (176.1 µg/m3), the mean concentration of PM2.5 was measured as 105.7 µg/m3 (40% lower) in gers/houses who used refined/improved "Good" fuel in Jan-Feb of 2020. Thus, indoor PM2.5 concentration in gers and houses had decreased significantly (p < 0.05) in winter when improved fuels usage was introduced.