Assessing the Impact of Outdoor Air Pollutants Affecting the Indoor Air Quality (IAQ) in Naturally Ventilated Classrooms of Public School Buildings in the Philippines ^†

Despite policies and efforts aimed at improving air quality in the Philippines, indoor air quality remains a critical issue in naturally ventilated public school classrooms in highly urbanized cities. In tropical urban cities, where educational facilities often lack proper ventilation systems, students and teachers are exposed to outdoor air pollutants infiltrating classrooms from high-traffic roads and nearby construction activities. This research employs a mixed-method approach that integrates empirical measurement using air quality sensors and perception assessment through ANOVA-gathered structured surveys. Such methods reveal a significant correlation between elevated particulate matter (PM_2.5, PM₁₀), carbon dioxide (CO₂), and humidity concentrated inside the classroom and increased indoor exposure levels, which affect discomfort and health-related symptoms among students and staff, such as irritation and respiratory issues. These results underscore the urgent need for architectural, climate-responsive strategies and improved environmental monitoring. Furthermore, this study aspires to reinforce policy reforms that will enhance indoor air quality (IAQ) in public educational school buildings, supporting the UN Sustainable Development Goals (SDG 3, 4, 11, and 13) by framing indoor air quality (IAQ) as a foundation of health equity, educational equality, and resilient public infrastructures.