People's reaction to odours also varies a great deal. Persistence - a calculated relationshop between intensity and dilution. Odours entrained in building wake, poor dispersion. A siting model being proposed for Austria can be used to illustrate the factors to be considered in predicting odour protection separation distances. Dispersion factor is dominated by the regional wind patterns from the closest weather station.
Local flow is weighted more or less importantly depending on the local topography.
Distance separation is reduced. At night, air may move down a slope in a narrow layer, carrying odours longer distances. The dispersion factor is calculated by adding the weighting points to the wind frequencies for 8 wind directions. If the wind comes from a direction that promotes good dispersion, the separation distance is reduced. If the wind blows down a long slope, separation distance is increased.