New understanding of miniaturized VOCs monitoring device: PID-type sensors performance evaluations in ambient air

Abstract

With low-cost sensors getting more attention in network monitoring, whether volatile organic compounds (VOCs) sensors are easily serviceable in ambient air monitoring is debatable. Evaluations of performance are necessary to provide a comprehensive understanding of commercially available sensor devices at present. In this paper, 17 photo-ionization detectors (PID) based VOC sensor devices have been evaluated through both laboratory and field tests, sensor were primarily from Alphasense and Baseline. The results exhibited the average level of all participating devices and the influence of the humidity on the results has been discussed in detail. Good linearity (R2>0.93), repeatability (<10 %), and quick response time (T80<1 min) over the target gases in the laboratory have been revealed. The average of intra-best two devices correlation (R) is 0.68 and correlations (R2) with reference data are 0.5∼0.8 for one third of devices in the field tests. However, the accuracy is not as robust as flame ionization detector (FID). In summary, PID-type VOC sensor devices are capable of providing useful information in some application scenarios. The features of quick response and good accuracy at high concentrations are recognized as pollution indicators. Devices with good consistency, correlation and stability are appropriate for investigating the regional VOCs pollution distribution using network monitoring.