Abstract
Indoor air quality is associated with academic performance and harmful health effects on students and teachers who participate in the classroom. Outdoor sources always contribute to classroom air quality. This study aims to estimate the amounts of indoor and outdoor pollutants and the influence of outdoor sources on open-air classrooms in a school located in the city. A health risk assessment was applied to assess the non-carcinogenic risk to students and teachers from exposure to the pollutants in the classroom. The concentrations of indoor NO2 ranged between 46.40 and 77.83 µg/m3, which is about 0.8 times that of outdoor NO2. A strong correlation and a high indoor/outdoor (I/O) ratio (>0.5) without a source, indicated that indoor NO2 is significantly influenced by outdoor sources. The range of indoor PM2.5 concentrations was 1.66 to 31.52 µg/m3 which was influenced by meteorological conditions. The indoor PM2.5 concentrations were affected by both indoor and outdoor sources. Although the level of indoor air pollutants met the official standard, the young children were exposed to indoor air pollutants which were above the recommended limits to human health with regard to the hazard index (HI) of 1.12. Instant measures such as regularly cleaning the classrooms, zoning the students, and installation of solid and vegetation barriers are recommended to reduce the daily dose of pollutants affecting students in open-air classrooms.
Highlights
Since this study collected NO2 by using passive sampling for 24 h, the 24 h NO2 quality standard of New Zealand, Japan, South Korea, and Kuwait were selected for comparison instead of the 1 h and annual concentrations which are indicated in the World Health Organization (WHO) and Thailand air quality standards
This study found that the concentrations in the rainy season were approximately 0.8 times those of the summer season
This study estimated the concentration of indoor air pollutants (NO2 and PM2.5 ) and the influence of outdoor pollutants on an open-air classroom with a ceiling fan and natural ventilation
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Indoor air quality is the quality of air within and around buildings including homes, schools, and offices. It greatly influences human wellbeing because people spend most of their time indoors. The World Health Organization (WHO) reported that 3.8 million people die annually from exposure to indoor air pollution. Respiratory diseases, heart disease, and cancer are associated with indoor air quality [1,2]
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