Emissions of odour constitute a variety of chemical compounds that can be odorous or non-odorous. Each odorous chemical (odorant) has a particular odorant characteristic and detection threshold, unique and specific to that compound. Within an odour matrix the compounds present will interact to form the overall (global) odour; in much the same way as a perfume is composed of many fragrance types. The combination of odorants and non-odorants is complicated by chemical interactions (to form additional species) and the mechanism of combination; it is not simply a matter of addition, for the global odour can be more or less than the sum of the individual components. The management of odorous emissions must first begin with a comprehensive chemical characterisation of the emission in order to identify the key contributors causing the odorous annoyance. This will enable effective odour management to reduce the emission impact; however identification of the nuisance chemicals at the source may differ from those potentially reaching a local receptor; it is therefore imperative that both the source emission be understood and the potential reaction pathways of these chemicals.
