Selective Detection of Hazardous Indoor VOCs Using Metal Oxide Gas Sensors

Abstract

A strategy for detecting and identifying trace levels of hazardous volatile organic compounds (VOCs) in indoor air is presented. A metal oxide semiconductor gas sensor in temperature cycled operation is used to detect formaldehyde, benzene and naphthalene in ppb and sub-ppb concentrations with a varying background of ethanol with concentrations of up to 2 ppm. Measurement results from a laboratory device have been compared with an integrated sensor system designed for use in field tests. We found that gas emissions from the system itself are an important issue. The emissions have been identified and quantified using analytical methods in order to derive design rules for a proper field test system. However, the results show that selective detection of VOCs in the ppb range is possible even with an intensive background of various VOCs, although sensitivity is reduced compared to the ideal laboratory case.