Investigation of Particulate Air Pollution of a University Classroom: Indoor-outdoor Relationships

Abstract

This study aimed to investigate PM₂.₅ pollution and air physical parameters in the university classroom and to address the relationships between indoor and outdoor during a high-polluted period. We selected the classroom 310 of the General Science Building, Faculty of Science, Chulalongkorn University as a study area. We measured PM₂.₅ concentration, temperature, relative humidity, and air velocity, at 1-minute intervals, inside and outside the classroom in the afternoon during January–February 2020. We divided the data into four groups by class activity (no class or having a class) and air quality index (healthy or unhealthy), and then performed statistical analysis. The results showed that the Group 3 “having a class on an unhealthy day” data had the highest 1-minute average PM₂.₅ concentrations for both inside and outside the classroom (44.40 ± 7.04 μg/m³ and 56.75 ± 6.57 μg/m³ respectively), while the Group 1 “no class on a healthy day” data had the lowest 1-minute average concentrations for both environments as well (14.78 ± 1.29 μg/m³ and 20.27 ± 4.19 μg/m³ respectively). Moreover, PM₂.₅ inside the class showed a statistically significant moderate-to-high correlation to PM₂.₅ outside the classroom, with a positive direction, but statistically significant low-to-moderate correlations to temperature, relative humidity, and air velocity, with uncertain directions (p < 0.05). This pattern was also found when perform the statistical analysis with the 1-hour average data.