1. Introduction
Separation distances to protect the neighbourhood from odour
annoyance can be obtained from dispersion models. Such models
predict the ambient odour concentration on an hourly or halfhourly
basis. This time series of concentration values allows a
calculation of the percentage of the time in a year during which the
threshold odour concentration will be exceeded. This can be
compared to a tolerated exceedence probability depending on the
land-use category. Usually, separation distances between an odour
source and the nearby residential area are calculated depending on
wind direction, e.g. in 10 increments. Combinations of threshold
odour concentrations and tolerated exceedence probabilities are
called odour impact criteria. An overview of various national odour
impact criteria can be found in Sommer-Quabach et al. (2014).
Two pre-requisites are necessary to run this procedure: a
transformation of the mean values calculated by the models to
short-term concentrations relevant for human odour perception,
and the appropriate meteorological input, i.e. representative wind
and stability information for the site under investigation.
For Austria, to determine the short-term peak concentrations
required for the assessment of odour perception, the authors
developed a peak-to-mean approach depending on atmospheric
stability; this algorithm is used in the Austrian Odour Dispersion