Indoor and Outdoor Monitoring of Volatile Organic Compounds in School Buildings: Indicators Based on Health Risk Assessment to Single out Critical Issues

Abstract

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: α-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.

Indoor Air Quality Assessment and Study of Different VOC Contributions within a School in Taranto City, South of Italy

“…The I/O ratio can be used to highlight the presence of important indoor emission sources or outdoor emission sources when it is very high (I/O > 5) or very low (I/O < 0.2) respectively. In order to understand whether VOC sources were located in indoor or in outdoor air, the indoor concentration values for each pollutant were plotted against the corresponding outdoor value and five different I/O ranges were defined [8]. I/O ratios are commonly used to highlight the presence of important indoor emission sources.…”

“…Terpenes are odorous compounds mainly used to give pleasant fragrance in particular in cleaning products [8,[28][29][30]. The high levels of 2-butoxyethanol in classrooms and in the corridor, …”

“…Terpenes are odorous compounds mainly used to give pleasant fragrance in particular in cleaning products [8,[28][29][30]. The high levels of 2-butoxyethanol in classrooms and in the corridor, were probably due to the fact that this compound is used as a solvent for many commercial products such as detergents, paints, adhesives, coatings, inks and products for personal care [31,32].…”

“…In these spaces, a number of factors influence good air quality including the number of inhabitants, activities conducted inside the classrooms and insufficient ventilation, aggravated by the poor construction and maintenance of many school buildings [8,9]. Among pollutants, volatile organic compounds (VOC) are considered important parameters for the assessment of air quality in indoor and outdoor environments because of their ubiquitous presence and their significant impact on the environment and human health [3,10].…”

“…A modest number of studies have examined VOC in school's indoor air [8,[11][12][13]. Usually the organic compounds in these environments tend to be lower in the spacious and well ventilated classrooms with a low occupancy ratio [14], whereas accumulation of pollutants occurs when doors and windows remain closed for long periods of time in order to maintain thermal comfort, especially in winter.…”