# Air Quality Assessment of a School in an Industrialized Area of Southern Italy
## 3 Results and Discussion
### VOC Distribution in the Different School Areas Investigated and Their Temporal Variability  
Table 2 shows the concentrations of toluene, ethylbenzene, and xylenes, calculated as average values over the entire monitoring period, compared to the average value reported in the literature for school environments. Moreover, for a better visualization of this comparison, the reader can observe Figure S6 in the Supplementary Materials. The measurements show that concentrations of volatile organic compounds in the investigated school were, on average, lower than those reported in the literature for other schools [1,14,15]. It is worth noting that, for alkylbenzenes and halogen VOCs, reference values were not available. In particular, in the case of benzene, toluene, and xylenes, a comparison was made with the determinations for schools in the European Union [14]: we found that average indoor concentrations of toluene and xylenes were less than shown in the European schools, while average indoor concentration of Benzene was larger than reference levels. In the case of ethylbenzene, on the other hand, a comparison was made with an average value relating to a study carried out in Australian schools [15]. In our study, the ethylbenzene average indoor concentrations were less than values found in the Australian schools. Furthermore, the values determined in the present study are also lower than what has been reported for the same pollutants in other places such as public buildings [16] or homes [17]. It is important to note that there are no limits or threshold values for these pollutants in indoor environments. In contrast, the average concentrations of benzene far exceed the average value of 0.98 \(\upmu\)g/m\({}^{3}\) reported in the literature. Despite this, it doesn't exceed the limit of 5 \(\upmu\)g/m\({}^{3}\) imposed by the European Union for outdoor environments to protect health. In addition to being above the European average, benzene concentrations were higher than those of the other BTEXs, while it is worth noting that benzene is usually the lowest among the BTEXs present. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**VOC** & **C\({}_{\text{average, indoor}}\)** **Galatina (\(\upmu\)g m\({}^{-3}\))** & **Standard Deviation \(\pm\) (\(\upmu\)g m\({}^{-3}\))** & **C\({}_{\text{reference}}\) (\(\upmu\)g m\({}^{-3}\))** \\ \hline Toluene & 0.81 & 0.09 & 4.44 1 \\ Ethylbenzene & 0.08 & 0.02 & 3.00 2 \\ Alkylbenzenes & 0.29 & 0.09 & - \\ Xylenes & 0.18 & 0.04 & 2.64 1 \\ Halogen VOCs & \textless{}0.1 & - & - \\ Benzene & 1.94 & 0.47 & 0.98 1 \\ \hline \hline \end{tabular}  
* [PERSON] et.al., 2011. 2 [PERSON] et.al., 2016.  
\end{table} 
Table 2: Indoor average concentration and reference values for main VOCs investigated. Figure 2: Indoor and outdoor TVOCs concentration profiles over the period 18–24 February (classroom 4E and its balcony, respectively). Figure 3 shows the values of all determined VOCs averaged over the entire monitoring period for the five environments studied. Benzene is always the pollutant present in the highest concentration, and the highest value was found on the balcony facing classroom 4E. Taking into account that the I/O ratio for benzene is less than 1 (see Table 3), an outdoor source can be assumed for this pollutant, as discussed further on in the text. Alkylbenzenes show I/O ratios always around 1 for all locations, confirming their low variability. This suggests that there are no indoor sources for this class of pollutants, and that the concentrations found indoors are due to penetration from outdoors. Xylenes have higher I/O ratios for B1 and B2, i.e., the two bathrooms, and this could be related to emissions due to the use of specific cleaning products, smoking and/or cosmetics, although it is difficult to say this precisely. In Figures 4-6, the trends of the different VOCs are reported for three of the examined environments (the balcony, the corresponding classroom, and one of the bathrooms) as average values calculated for each monitoring period (as reported in Table 1).