ODOR INDEX: AN INTEGRATION OF ODOR PARAMETERS FOR SWINE SLURRY ODORS

In the animal production industry, manure odors can be a potential nuisance to neighboring residents. A more suitable metric other than odor concentration and intensity is required to evaluate odor dispersion or to evaluate on-farm odor-reducing technologies. An odor parameter was developed to better describe odor by integrating odor concentration, odor intensity, and hedonic tone values into an odor index. In order to mathematically define the odor index, an assumption was made that the odor index is equivalent to the geometric mean of odor intensity and hedonic tone. The mathematical models for the relationships of odor intensity versus odor concentration, hedonic tone versus odor concentration, and odor index versus odor concentration were determined based on the analysis of stored pig slurry headspace odor. The models showed that odor intensity increased as a power function of odor concentration with an exponent of 0.39, while odor index and hedonic tone decreased as a power function of odor concentration with the same exponent.