Characteristics of indoor air quality and source Identifications of Pollutants in schools of Taiwan

摘要

Inhalation exposure to indoor pollutants in schools is a health concern for children. The main purposes of this study were to measure pollutant levels (volatile organic compounds (VOCs), carbonyls, CO, C02, 03, PM10 and PM2.5) in indoor/outdoor air at schools and to evaluate the contributions of indoor and outdoor sources to indoor air concentrations using mass balance model and receptor model. In the first stage of the study, fifty schools were selected for short-term air monitoring according to population density and industrial development in the study areas. Results reveal that the indoor air qualities in natural ventilated classrooms were mostly affected by the penetration of outdoor pollutants. Air pollutants such as VOCs and carbonyls emitted from indoor sources would accumulate in the seldom used classrooms. The indoor VOCs levels for schools located near industrial areas were higher than that of the schools located in the densely populated areas. Six schools were selected for more detailed evaluation. The results indicated that the school TVOCs levels in summer and in fall were similar, while PM2.5 levels in fall were usually higher than that in summer. Indoor PM2.5 and 03 were lower than that in outdoors, which suggest the indoor PM2.5 and 03 were mainly contributed by outdoor sources. Higher C02 levels were found in fall season because the windows were closed due to the high PM2.5 outside. Receptor models were used to identify and quantify the major sources contributing to VOCs and PM2.5 indoors. Results from receptor model revealed that indoor VOCs were mainly contributed by vehicles exhaust and indoor sources, while major indoor PM2.5 sources were crustal materials and vehicles exhaust.