Spatial distribution of fine particulate matters in urban school classrooms during high-concentration events in South Korea

Abstract The assessment of indoor fine particulate matter (particularly PM 1.0 ) in classrooms is a recent concern due to its negative effects on the health and performance of young students, most of whom spend 6–8 h per day in schools. A field investigation of 20 urban schools with uncontrolled classroom conditions found that the hourly average concentrations of PM 2.5 and PM 1.0 in 20 classrooms ranged from 6.5 μg m −3 to 36.9 μg m −3 and 4.3 μg m −3 to 27.4 μg m −3 , respectively. The ratios of indoor to outdoor (I/O) concentrations were 0.46 to 1.32 for PM 2.5 and 0.43 to 0.97 for PM 1.0 . The size-based ratios of fine-to-coarse (F/C) were 0.46 to 0.88 for PM 1.0 /PM 2.5 in indoor environments and 0.57 to 0.93 outdoors. During high-concentration events caused by yellow dust and heavy local smog, the F/C ratio (PM 1.0 /PM 2.5 ) in the classroom was 0.22 and 0.93, respectively, and the respective I/O values for PM 2.5 and PM 1.0 were 0.68 and 0.60. These findings can inform the development of school guidelines for managing the health of young students.