Portable novel micro-device for BTEX real-time monitoring: Assessment during a field campaign in a low consumption energy junior high school classroom

Abstract A novel micro-device was deployed during an indoor field campaign to validate and demonstrate its ability to highlight rapid changes of atmospheric BTEX concentrations. The field campaign was carried out in a junior high school recently built respecting the thermal regulation of 2005 and equipped with a modern ventilation. BTEX concentrations were continuously measured using the novel micro-device and a commercial analyzer for two weeks during the winter holidays, both operating with a time resolution of 10 min. Toluene appeared to be the major VOC inside the investigated classroom. Its concentration varied between 1 and 18 ppb and was strongly correlated with the room ventilation status. This latter was partially programmed to mimic the school period. In order to compare the efficiency of the ventilation with natural ventilation, the windows were opened for 1 h when the ventilation was OFF. In all tested conditions, the toluene concentrations measured with our new micro-device were in very good agreement with those provided by the commercial BTEX analyzer. In addition, punctual short calibrations were performed during the campaign for both instruments (after 4 days and 9 days). Results showed that our micro-GC was more stable (gap less than 15% after 9 days) while the commercial analyzer required regular calibrations because of the loose of 60% of its sensitivity after 9 days of continuous operation. Therefore, our micro-device, of about 3 kg and fully controlled by homemade software, appears to be suitable to monitor BTEX concentrations higher than 1 ppb in near real time.