Table 3.

Examples of application of electronic nose instruments for evaluation of air odour quality in a vicinity of municipal processing plants.

Application	Type	Level of Advancement	Results Expressed in Odour Concentration Units	Comparision with Olfactometry	Sensors	Data Processing	Reference
NETWORK
Indoor/outdoor air quality	prototype	Advanced in-situ experiments	No	No	MOS	Neural Processing Blocks (NPB)	[43]
Odour dispersions modelling	commercial	In-situ implementation	Yes	Yes	Odotech’s system, OdoWatch	mapping	[44]
Pulp and paper industry	prototype	Calibration of electronic noses network	No	No	MOS	ANN	[77]
Odour monitoring	prototype	In-situ implementation	No	Yes	MOS	cluster analysis, mapping	[78]
Assessment of odour annoyance near a compost facility.	prototype	Advanced in-situ experiments	Yes	Yes	MOS	DFA, PLS	[79]
Monitoring of odours from a composting plant	commercial	Advanced in-situ experiments	Yes	Yes	EOS, Sacmi Group, Imola, Italy (MOS)	kNN	[80]
Monitoring odour emissions from an oil & gas plant	commercial	Advanced experiments in model condition	Yes	Yes	EOS Ambiente, Sacmi Group, Imola, Italy (MOS)	not provided	[81]
PORTABLE
Landfills odour monitoring	prototype	Improvement of electronic nose in field studies	No	No	MOS	DA, PCA, MLR, PCR, PLS	[82]
Outdoor air quality	prototype	Basic in-situ experiments	No	No	MOS, EC	mapping	[83]
Odour measurement around: compost facilities, printing houses, paint shops, wastewater treatment plants, rendering plants, settling ponds of sugar factories	prototype	Basic in-situ experiments	No	No	MOS	DA, PCA	[84]
Unpleasant and potentially harmful odours in urban areas, likely coming from residential waste containers	prototype	Basic in-situ experiments	No	No	MOS	mapping	[85]
Farm odour	prototype	Advanced in-situ experiments	Yes	Yes	MOS	ANN	[86]
Asphalt odour patterns in hot mix asphalt production	commercial	Basic experiments in model condition	No	No	Cyranose 320, Smiths Detection Inc., Edgewood, MD, USA (CP)	Polar plots, PCA	[87]
ROBOTS & DRONES
Air Quality	prototype	Basic experiments in model condition	No	No	MOS	mapping	[88]
Localizing gas emission sources on landfill sites	prototype	Advanced experiments in model condition	No	No	MOS	Polar plots & mapping	[62]
Air Quality	prototype	Basic experiments in model condition	No	No	MOS	mapping	[89]

ANN—Artificial Neural Network; CP—Conducting Polymer; DA—Discriminant Analysis; DFA—Discriminant Function Analysis; kNN—k-Nearest Neighbours; MOS—Metal Oxide Semiconductor; MLR—Multiple Linear Regression; PCA—Principal Component Analysis; PCR—Principal Component Regression; PLS—Partial Least Squares.