Performances and limitations of electronic gas sensors to investigate an indoor air quality event

• The performance of multisensor arrays to monitor an indoor event have been assessed.
• The sensor response has been successfully confronted to analytical measurements.
• Due to low selectivity, the quantitative analysis of VOC mixtures is difficult.
• As a case study, the effect of a green wall on indoor pollution has been estimated.

Indoor air quality (IAQ) receives an increasing attention because of long-term occupancy of confined environments with high specific pollutant concentrations, especially volatile organic compounds, inducing a risk for human health. Standard air quality instruments are not adapted for long-term continuous real-time monitoring of these environments, and a promising alternative resides in using electronic gas sensors, which are miniature and low-cost devices capable to detect air pollutants, even at low concentrations.The present study focuses on IAQ monitoring with electronic gas multi sensor systems, as well as with typical indoor air analyzers in a 40 m3 experimental room. The suitability of electronic gas sensors to monitor pollution events in indoor environments, characterized by transient concentrations of VOCs, has been characterized by simultaneous injections of acetaldehyde, acetone, formaldehyde, toluene and o-xylene. The impact of a green wall structure in the room has been assessed by the reduction of residual pollutant and higher decay of injected oxygenated VOCs than in the empty room. It has been shown that electronic gas sensor response show a good correlation within the analyzer measurements, both for injected VOC concentrations and their decay. Indeed, these systems provide relevant information for air treatment control system and detection of indoor air quality events, in the case of simple gas matrixes, however realistic complex matrixes are poorly monitored by electronic gas sensors selected in this study. This limitation could be overcome by increasing the number of sensitive sensors to indoor air specific composition.

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