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Indoor Air Quality in Tacloban City Public Schools: Assessment of PM2.5, PM10, and CO2 Levels and Infrastructure Design Implications

Abstract

This study assessed indoor air quality (IAQ) in selected public school classrooms in Tacloban City, Philippines by measuring particulate matter (PM2.5 and PM10) and carbon dioxide (CO2) concentrations and examining their relationship with building profile, ventilation characteristics, and environmental exposure. A quantitative descriptive cross-sectional design was employed in three public schools with similar DepEd/DPWH standard classroom building designs but different proximity to road and traffic sources. One typical classroom per floor was monitored, where available, from 07:00 to 18:00 using calibrated Temtop M2000 air quality monitors placed indoors and outdoors. Data were analyzed using descriptive statistics, indoor-outdoor ratios, Kruskal-Wallis tests, estimated air-change rates based on CO2 decay, and Spearman correlation analysis. Results showed that mean PM2.5 concentrations ranged from 7.76 to 10.43 ug/m3, remaining below the WHO 24-hour guideline of 15 ug/m3. Mean PM10 concentrations ranged from 34.56 to 46.51 ug/m3, with short-term exceedances observed in several classrooms and one mean value slightly above the WHO guideline of 45 ug/m3. Mean CO2 concentrations ranged from 431.91 to 617.85 ppm, indicating generally adequate ventilation, although minor short-term exceedances occurred in two classrooms. PM2.5 indoor-outdoor ratios below 1.0 indicated strong outdoor influence with indoor dilution, while some PM10 ratios above 1.0 suggested indoor dust resuspension. Kruskal-Wallis tests showed no significant floor-level differences for PM2.5, PM10, or CO2. Correlations between CO2 and particulate matter were weak to moderate and non-significant. The findings indicate that naturally ventilated classrooms can maintain acceptable CO2 and PM2.5 levels under observed conditions, but PM10 variability requires attention to dust control, traffic-source exposure, ventilation pathways, and routine IAQ monitoring. Evidence-based policy and infrastructure recommendations are proposed to support healthier school environments in tropical urban settings.