Continuous, in situ monitoring of air, water and land quality is fundamental to most environmental applications. Low cost and non-invasive chemical sensor arrays provide a suitable technique for in situ monitoring. Their ability and performance under realistic conditions is discussed in this paper. Published studies report promising results despite a number of limitations that are associated with both the technology itself and its application in ever changing ambient conditions. Early investigations include the analysis of single substances as well as odour and wastewater organic load monitoring. Reported applications typically highlight the sensitivity of the currently available sensors to changes in temperature, humidity and flow rate. Two types of approaches are recommended to deal with these effects: either working under fixed experimental conditions or measuring the external parameters to numerically compensate for their change. The main challenge associated with the use of non-specific sensor arrays lies in establishing a relationship between the measured multivariate signals and the standards metrics that are traditionally used for quality assessment of gas mixtures. For instance, odour monitoring requires calibration against olfactometric measurements while investigations of wastewater samples still need to be correlated with organic pollution parameters such as BOD, COD or TOC. On the other hand, results obtained in the field have demonstrated how sensor arrays can be readily used as simple alarm devices or as early warning systems based on a general air/water quality index.

Abstract. The e-nose technology has enormous potentialities for in site monitoring of malodors. However a number of limitations are associated with the properties of chemical sensors, the performances of the signal processing and the realistic operation conditions of environmental field. From the experience of the research group in the field, the metal oxide based gas sensors (Figaro type) are until now the best chemical sensors for long term application, more than one year of continuous working in the field. To be usable for malodors measurement in the field, the e-nose has to deal with the lack of long term stability of these sensors. The drift and the sensors replacement have to be considered. In order to appraise the time evolution of the sensors and the effect on the results of an electronic nose, experimentation has been performed during three years on two identical sensor arrays. The two arrays contain the same six Figaro sensors and are in the same sensor chamber of the e-nose system. Both arrays have worked continuously during three years without break.

Abstract. The e-nose technology has enormous potentialities for in site monitoring of malodors. However a number of limitations are associated with the properties of chemical sensors, the performances of the signal processing and the realistic operation conditions of environmental field. From the experience of the research group in the field, the metal oxide based gas sensors (Figaro type) are until now the best chemical sensors for long term application, more than one year of continuous working in the field. To be usable for malodors measurement in the field, the e-nose has to deal with the lack of long term stability of these sensors. The drift and the sensors replacement have to be considered. In order to appraise the time evolution of the sensors and the effect on the results of an electronic nose, experimentation has been performed during three years on two identical sensor arrays. The two arrays contain the same six Figaro sensors and are in the same sensor chamber of the e-nose system. Both arrays have worked continuously during three years without break.

Abstract:The paper presents a review of several studies on the detection of microbial volatile organic compounds (MVOCs) considered as indicators of fungal contamination. As fungi produce specific profiles, or fingerprints of volatile compounds, the electronic nose technology is a very promising opportunity for rapid and non costly detection of fungi in buildings. E-noses are able to distinguish between mouldy and non-mouldy samples, and also to recognise certain species of fungi. However, two limiting factors may appear decisive for employment of electronic noses in indoor fungi detection: low concentrations of MVOCs and presence of interfering substances in indoor environments.

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