Comparison of different approaches for odour impact assessment: dispersion modelling (CALPUFF) vs field inspection (CEN/TC 264)

Odour impact assessment has become an important environmental issue. Different approaches can be used in order to evaluate the odour impact on receptors, and therefore to regulate it. Among the different possible regulation approaches, the use of dispersion modelling is suggested or required by several national or regional legislations. The wide diffusion of this approach is probably due to the fact that odour dispersion modelling is relatively cheap and results are easily understandable. Another kind of approach attempts to evaluate the odour impact directly in the field relying on a panel of trained human assessors (field inspection). The growing importance of this odour impact assessment method is proved by the current draft of a European Standard (CEN/TC 264), which defines two different methodologies of field inspection: grid measurement and plume measurement. In this study two different approaches were compared, i.e. odour dispersion modelling and field inspection by plume measurement (with specific adaptation for the studied site), the latter consisting in using a panel of examiners for determining the absence or presence of odour downwind relative to the source, in order to evaluate the plume extent. The comparison was based on application of both methods to the assessment of the odour impact of a plant for the composting of sludge from an Italian food industry. The results show that the odour impacts assessed by the two strategies turned out to be quite comparable, thus indicating that, if opportunely applied, both approaches may be effective and complementary for odour impact assessment purposes.