Complaints to regulatory agencies about air quality are frequently about odours. This is in part due to the increased encroachment of urban areas on agricultural and industrial operations that were
originally in isolated areas. The impact of odours can range from mere detection, to an irritating nuisance or, at high enough concentrations, a health risk.
Managing odours to minimize these effects on the public is a challenging task. Odourous substances are often a mixture of different gases. This makes it extremely difficult to determine
and measure the sources of the odours, much less try to control their emissions.
In addition, odour detection varies greatly with each individual. The sensation of an odour that is “annoying” is
subjective. For example, some find the smell of a bakery pleasant, while others find it nauseating. The issue is further complicated by other factors beyond the odour itself — such as
the frequency of odour detection, duration, intensity and offensiveness of the odour.