An emerging application of electronic noses in the environmental field concerns the real-time measurement of odour concentration at plants fencelines. One advantage related to the continuous monitoring of odour emissions from the plant, is that the setting of “warning” thresholds for the odour concentration offers useful indications for the plant management: the real-time signaling of the threshold exceedance enables the instantaneous identification of plant malfunctions, thereby allowing rapid intervention and thus preventing odour events at receptors. In Italy, there is an increasing number of new and existing plants for which the IOMS installation at plant fenceline is prescribed in the permits. Thus, the need arises to have specific quality programs capable to ensure the reliability of IOMS outcomes. In this context, this paper presents a case study, in which a procedure for the verification of IOMS quantification capability was applied in the field.