Correlation of human olfactory responses to airborne concentrations of malodorous volatile organic compounds emitted from swine effluent

Direct multicomponent analysis of malodorous volatile organic compounds (VO Cs) present in ambient air samples from 29 swine (Susscrofa) production fac ilities was used to develop a 19-component artificial swine odor solution t hat simulated olfactory properties of swine effluent. Analyses employing ei ther a human panel consisting of 14 subjects or gas chromatography were per formed on the air stream from an emission chamber to assess human olfactory responses or odorant concentration, respectively. Analysis of the olfactor y responses using Fisher's LSD statistics showed that the subjects were sen sitive to changes in air concentration of the VOC standard across dilutions differing by approximately 16%. The effect of chemical synergisms and anta gonisms on human olfactory response magnitudes was assessed by altering the individual concentration of nine compounds in artificial swine odor over a twofold concentration range while maintaining the other 18 components at a constant concentration. A synergistic olfactory response was observed when the air concentration of acetic acid was increased relative to the concent ration of other VOC odorants in the standard. An antagonistic olfactory res ponse was observed when the air concentration of 4-ethyl phenol was increas ed relative to the other VOC odorants in the standard. The collective odora nt responses for nine major VOCs associated with swine odor were used to de velop an olfactory prediction model to estimate human odor response magnitu des to swine manure odorants through measured air concentrations of indicat or VOCs. The results of this study show that direct multicomponent analysis of VOCs emitted from swine effluent can be applied toward estimating perce ived odor intensity.