Indoor and outdoor monitoring of volatile organic compounds in school buildings: indicators based on health risk assessment to single out critical issues.

Children are more sensitive to pollutants than adults and yet they spend large amounts of time in school environments where they are exposed to unknown levels of indoor pollutants. This study investigated the concentrations of the most abundant volatile organic compounds (VOCs) in eight naturally ventilated school buildings in Italy. The schools were chosen to include areas with different urbanization and traffic density characteristics in order to gather a more diverse picture of exposure risks in the different areas of the city. VOCs were sampled for one week in the presence/absence of pupils using diffusive samplers suitable for thermal desorption inside three classrooms at each school. The samples were then analyzed with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). In addition, outdoor measurements were carried out in the yard at each school. VOC identification and quantification, and indoor/outdoor concentration plots were used to identify pollutant sources. While some classrooms were found to have very low VOC levels, others had a significant indoor contribution or a prevalent outdoor contribution. High concentrations of terpenes were found in all monitored classrooms: a-pinene and limonene were in the range of 6.55-34.18 µg/m3 and 11.11-25.42 µg/m3 respectively. Outdoor concentrations were lower than indoors for each monitored school. Indicators based on health risk assessment for chronic health effects associated with VOCs (either carcinogenic or non-carcinogenic) were proposed to rank sites according to their hazard level.