The study proposed to document, under various weather conditions (wind direction, velocity, temperature and humidity) and times of the year, at what distances odours from six existing larges hog operations are detectable. In addition, it was our intent to delineate the odour plume so as to provide useful information in locating future hog facilities; in providing scientific evidience to refute unsubstantiated odour complaints; and, to evaluate odour controlling effectiveness of various types of manure storages; wind screens (trees or wind break(s) or terrian features. Six (6) large facilities within the hog producing area of southern Manitoba were included in the study; two in relatively flat terrian with few or no trees; two in relatively flat terrian with considerable bush; and, two in relatively rolling terrian preferably one with few or no trees and one with considerable bush. Because olfactory senses are possibly still the best and most oftern used indicator of the relative strength of odours, we coose to use a two-person ‘odour-panel” to rate the relative strength of a particular odour on a scale of zero to ten. Public roads and municipal maps were useful in siting studies for lareg hog operations. Unfortunately, winds in Manitoba and for that matter most places can be experienced out of any direction; and, as a result odours from a large hog facility might be experienced at various strengths anywhere 360 degrees of the facility. With this in mind, however, these data combined with wind data for a particular location should be useful in explaining theprobability and frequency that neighbours might anticipate odours from a planned hog facility