Diurnal and annual variation of the sensation distance of odour emitted by livestock buildings calculated by the Austrian odour dispersion model (AODM)

The diurnal and annual variation of distances for different odour thresholds is investigated by the dynamic Austrian odour dispersion model (AODM) consisting of an emission module, a dispersion module, and a module to calculate instantaneous odour concentrations. The effect of daily variations in odour production, ventilation rates and indoor air temperature are included in impact assessments. The ambient half-hour odour concentrations calculated by a regulatory Gaussian plume model are transformed to instantaneous values representative for the duration of a single breath by an attenuation function decreasing the peak-to-mean ratio with increasing wind velocity, stability, and distance from the source. The resultant distances for different odour thresholds and their dependence on meteorological parameters are investigated and discussed in detail, focussing on the distance for the detection limit, 1 OU m−3, the so-called sensation distance. The results suggest a stronger dependence of the sensation distance upon variation in meteorological conditions than diurnal and annual variations in odour emission rates.