Odour impact criteria to avoid annoyance

Abstract

To determine separation distances between odour sources and residential areas to avoid odour nuisance and complaints by the residents, odour impact criteria OIC have to be adopted by the responsible authorities. There is a wide variety of OIC used for this purpose, which differ by the odour concentration threshold (between 0.12 ouE m and 10 ouE m), the averaging period (hourly or instantaneous) and by the tolerated exceedance probability of the adopted threshold (between 0.1% and about 35% of the time). There are two groups of OIC used in various jurisdictions: the first one with a low odour concentration threshold and a high tolerated exceedance probability (e.g. Germany); and the second group with a high odour concentration threshold and a low tolerated exceedance probability (e.g. Ireland). The modelled direction-dependent separation distances (using OIC which are supposed to offer the same protection level) can vary significantly. The OIC of the second group, considering higher ambient odour concentrations, show a much lower sensitivity to site-specific meteorological data. Therefore, a higher tolerated exceedance probability seems more appropriate for the determination of OIC. Even if the similarity of separation distances by various OIC could be determined, the direction-dependent separation distances differ considerably for the same protection level for a certain receptor type, e.g. rural residential properties.