Residential PM2.5 concentrations in Ger, traditional residence in Mongolia

摘要

Aim: Significant proportion of population in Ulaanbaatar (UB), the capital city of Mongolia, is living in traditional ger home. Residents in ger can be exposed to high concentration of PM2.5 from burning coal and biomass fuels. The purposes of this study were to measure indoor PM2.5 levels in gers and determine effects of fuel combustion for cooking and heating on indoor PM2.5 level. Method: This study was conducted in 28 gers in UB in January 2016. PM2.5 concentration, temperature and relative humidity were simultaneously measured by real time monitors during daytime for about 7 hours. During the monitoring, two researchers recorded stove type, fuel type, fuel usage and the number of putting fuels into stove. Results: The average PM2.5 concentration, temperature and relative humidity in 28 gers were 208+176 ug/m3 (n=28), 23±4 °C (n=27, one home is missing due to malfunction of the monitor) and 21 ±8 % (n=28), respectively. Overall, the PM2.5 concentration was higher in the morning and then decreased constantly until late afternoon. Five temporal profiles of indoor PM2.5 concentration in 28 gers were determined (Fig 1). Average PM2.5 concentrations in the five groups were 384+171 ug/m3, 171 ±71 ug/m3, 123±56 ug/m3, 74±27 ug/m3 and 27±20 ug/m3. In the first group, indoor PM2.5 concentrations were very high and extreme peak of about 8500 ug/m3 was observed. In the second and third groups, indoor PM2.5 concentrations in the morning were 600 and 400 ug/m3 respectively and decreased gradually. In the second group, there was peak of about 1100 ug/m3 in the afternoon. In the third group, less peak was observed. In the fourth group, indoor PM2.5 concentrations in the morning were 200 μg/m3. There was peak of about 180 ug/m3 in the afternoon. In the fifth group, PM2.5 concentration was maintained below 50 μg/m3 in the afternoon. The peaks in daily profile of PM2.5 concentration were coincided with smoking, burning herbs or candle, opening stove for refueling, cooking fried food and using vacuum cleaner. Conclusions: The indoor PM2.5 concentrations in gers were very high with peak concentration up to 8500 ug/m3. However, our measurement might underestimate 24 hour exposure due to lack of monitoring during night and early morning. Further study is necessary to measure indoor concentration for 24 hours and identify factors associated with daily indoor exposure.