Assessment of indoor air quality in classrooms of secondary high schools in Ulaanbaatar city

Abstract

Background: Air pollution is a global crisis that specifically affects the population of developing countries including pregnant women, children and the elderly. For instance, fine particulate matter (PM2.5) is associated with type II diabetes, cognitive development of children and even affects mental health. In addition, it is estimated that at least 20 percent of newborn deaths worldwide are caused by air pollution. Aim: An assessment of indoor air quality and air pollutant sources in the classrooms of secondary high schools. Materials and Methods: We conducted this study in 2022 through the cross-sectional study design. We selected 69 classrooms of 10 secondary high schools in Ulaanbaatar city. Results: Total of 59 classrooms had mechanical ventilation, of which 44 ventilators were operated, while 15 were non-operated. The average air temperature in the classrooms was 22.6°C. The air temperature did not reach 18°C in 9 (11%) classrooms, while in 51 (64%) classrooms it exceeded 22°C. The 8-hour average indoor concentration of PM2.5 particles in the classrooms was 113.4 μg/m3 (minimum value 10.8 μg/m3, maximum value 431.4 μg/m3). In terms of season, the average concentration of indoor PM2.5 particles was 62.3±30.8 μg/m3 in April to May while in winter (November to December) it was 113.6±88.7 μg/m3 in 2022, which shows a statistically significant difference (p=0.0057). Conclusion: In 54 (91.5%) classrooms, the frequency of air exchange was not met specified in “Illustrated Code of Hygiene and Infection Protection for Education and Training Institutions”. The average indoor PM2.5 concentration is about 1.2 times higher than the recommended level in spring and 2.3 times higher in winter, respectively. Fine particle pollution is particularly increasing in winter time.