Assessment and regulation of odour impacts

Decades of experience support the inclusion of odours in the list of contaminant types that must be regulated by government. In many jurisdictions, odour impacts are regulated under the nuisance provisions of common law. However, the explicit conditions that establish whether a nuisance condition exists are not easily defined. Due to this shortcoming, there is a need to introduce objectivity into odour impact assessments and odour limits. While individual responses to odours are highly variable and can result in a variety of effects, generally the impacts of odours arise from a variety of interacting factors, collectively known as FIDOL: frequency, intensity, duration, offensiveness, and location. In view of the need to prevent or mitigate such impacts, an approach to odour regulation is proposed in which the protection of the public from odour impacts is accomplished based on the FIDOL approach. This involves the introduction of an objective odour limit, as follows: “Facilities that are identified as sources of potentially offensive odours shall ensure that the 10-min average concentration of odour resulting from all sources at the facility and determined in accordance with accepted procedures, shall be less than 1 odour unit 99.5% of the time at the most impacted sensitive receptor”. It is argued that the proposed limit would provide the public with an understanding of the degree of protection from odours that is to be provided through regulations and would provide industries with a basis for designing their facilities to minimize impact at the design stage. Such limits would also provide industries with benchmarks against which they can gauge their success at preventing or mitigating odour impacts and for evaluating the effectiveness of odour control technologies.