“…In some cases, performance evaluation tests of the sensors have been conducted at high VOCs concentrations (Morsi et al, 2013, Spinelle et al, 2017Liu et al, 2019); however, good responses at much lower concentrations, around the average values that can be expected indoors/outdoors in reality, are being pursued (Bastuck et al, 2018;Choi et al, 2019;Nazemi et al, 2019). On the other hand, some sensors have been only calibrated for a specific compound (Hori et al, 2013). In this last case, as the sensitivity of the sensor will be different depending on the kind of VOC, the results obtained using a sensor calibrated with a single compound may differ from reality depending on the VOC content of the sample (Hori et al, 2013).…”