Different setback estimation models for animal production farms have been developed in European countries and some states and provinces in North America. Five setback models, based on empirical, combination of empirical and odour measurement, or odourdispersion calculation, were compared for various sizes of swine farms. The setback distances generated by different models were found to fall into a wide range. The Minnesota OFFSET model gave the occurrence frequency of faint odour at various distances away from an odour source and produced different setback distances according to odour annoyance free frequencies from 91 % up to 99%. The Ontario MDS-II model and the Austrian model generated low setback distances that were close to OFFSET'S setbacks at the 91 and 94% levels, however, the Austrian model did not consider outdoor manure storage units. The Purdue model produced medium setback distances similar to 94 to 97% annoyance free level of the Minnesota OFFSET model. Finally, the Williams and Thompson model (W-T model), from the Warren Spring Laboratory in England, gave setbacks similar to OFFSET 98% odour annoyance free distance. The relative results from the models and the methods used by them to calculate setback distance should be helpful tolocal government officials or designers when choosing a model to use for land use guidelines or specific case studies. kw:odour; setback distances; air dispersion model; livestock; distances; séparatrices; modèle de dispersion; élevage
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