Characterizing Particle Number Size Distributions and Source Contribution for Public Elementary School Classrooms in Bangkok
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Abstract
This study provides crucial information on indoor air pollution in public elementary schools in Bangkok, highlighting the substantial impact it has on the health and learning conditions of students, particularly in view of the city's rapidly urban expansion. The research examines particle size distributions (PSD) in four urban schools using the scanning mobility particle sizers (SMPS) and the optical particle sizers (OPS) to cover particle size range of 10 nm to 10 microns. Measurement covered class hours on weekdays and experiments on the weekends. Throughout the study, outdoor particle number concentration (PNC) was significantly higher than indoor levels.
On weekdays, the indoor 1-hour mean PNC at Site S4 reached 23,182 cm⁻³ as a highest level among others, classified as a High PNC level according to WHO good practice guidelines. This suggests substantial internal sources, inadequate ventilation, and the impact of nearby traffic and school activities. Similarly, during weekend measurements, Sites S1 and S3 also reached High PNC levels, with concentrations of 27,663 cm⁻³ and 29,534 cm⁻³, respectively. Peaks in PNC were directly linked to the use of cleaning products containing volatile chemicals, underlining the pronounced impact of these activities on indoor air quality. The weekday indoor particle number size distribution (PNSD) exhibited a single-mode distribution, significantly influenced by routine class activities and student movements. Over the weekend, the indoor PNSD across all sites showed fluctuations corresponding to various experimental setups involving changes in ventilation and cleaning activities. This study underscores the necessity of strategic indoor air quality management in schools, aiming to reduce exposure to high PNCs, improve indoor air quality in classrooms, and provide better educational settings for children in increasingly urbanized regions. Effective strategies might include enhanced ventilation, controlled cleaning practices, and real-time monitoring of PNC and PNSD to maintain a healthy educational environment.
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References
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