In the Flemish legislation, no odour assessment framework is implemented, despite that odour-related permit applications require the inclusion of an odour impact study. For livestock farming, odour emission factors, derived from olfactometric measurements (ouE), are widely used. Contrastingly, the available assessment tools, based on earlier odour impact research, utilize sniffing measurements (se).
To allow comparison between the two units of odour, it is assumed that 1 ouE equals 1 se. For most groups of livestock animals with a rather constant growth cycle (e.g. pigs), this comparison is deemed valid and suitable for evaluating the odour impact. However, the theoretical assessment of broiler chicken emissions can be questioned, as the olfactometric emission factor of 0.33 ouE/s.animal results in almost no odour impact.