Complaints about odours in the ambient air are a frequently expressed form of criticism, particularly with regards to industrial facilities located in the immediate vicinity of residential areas.

They are often made when the odour nuisance has become so acute that it is considered necessary for the company to react or even for the responsible public authority to intervene. In this scenario, the industry emitting the odours has not taken actions to prevent the emissions. Everyone would probably agree on that this should be avoided as much as possible.

However, the absence of odour complaints does not necessarily indicate the absence of odour nuisance in the neighbourhood. Being a good neighbour implies interacting, integration, taking care of your vicinity and perceiving potential problems at an early stage before nuisance becomes annoyance.

Depending on the industry or installation, residents may be annoyed and feel endangered even if the odour nuisance is not to be classified as considerable because the exposure limits are not exceeded. Take also into account that continuing complaints and the experience of nuisance can be the effect of several non-olfactory factors, such as worries about facility’s harmful effects on health (real or not), appreciations of the public authority’s capacity to monitor a facility, or perceptions of further impairments from the facility (e.g. noise and dust).

The WHO considers in the evaluation of sensory effects a nuisance threshold level as the concentration at which not more than a small proportion of the population (less than 5%) experiences annoyance for a small part of the time (less than 2%). At first sight, this definition seems to be quite strict. But so is the WHO’s definition of health: a state of complete physical, mental and social wellbeing and not merely the absence of disease or infirmity. Take into consideration that nuisance threshold levels for odorous substances therefore are well below exposure levels that have direct adverse effects on health.

Therefore, if the industry cannot lower odour emission levels, still there is the possibility to work on person related or context related influence factors that might interfere with the perception of odours and nuisance response. It might be as simple as talking to your neighbour, creating confidence and establishing channels of communication. Surveys and repeated questioning might help to determine annoyances parameters within the assessment of odours, hopefully helping to avoid having to process odour complaints or even having to manage odour conflicts.

By Gerhard Schleenstein, odour engineer expert from Ecotec.