Measurements of hedonic tone of odour from animal production facilities

Pleasantness or hedonic tone of an odour is closely connected to human reactions and is at least interesting regarding odour impact, setback models and dispersion modelling as a complement to normally used concentration and intensity. In order to measure hedonic tone of odour from pig, poultry and milk production facilities, 16 persons, university staff and students, were engaged as panel members. Odour samples of n-butanol and perfume were also analysed. The panel may have similarity to a rural population since many of the panel members are used to the environment in animal houses and the others have a background in horticulture and landscaping. At the sites collected and bagged odour samples were analysed regarding odour concentration (OUg/m(3)). By the help of an olfactometer the samples were diluted and presented to the panel at various concentrations. Each panel member noted the pleasantness/unpleasantness rating for each concentration from low up to high. Approximate odour thresholds for n-butanol were measured for each panel member. Correlation between odour concentration (OUE/m(3)) and hedonic tone was studied. This correlation was also studied regarding individual odour thresholds and panel member characteristics and experiences. As expected, quite high variation of pleasantness rating was found for each concentration. On average the hedonic tone of odour from pig, poultry and cow houses decreased from slight unpleasant to more unpleasant by concentration, however, at some concentrations it was rated slight pleasant by some individuals in the panel.