EVS-EN 13725:2022

This document specifies an objective method for the determination of the odour concentration of a gaseous
sample using dynamic olfactometry with human assessors. The document also specifies a method for the
determination of the odour emission rate from stationary sources, in particular:
a) point sources (conveyed or ducted emissions);
b) active area sources (e.g. biofilters).
The primary application of this document is to provide a common basis for evaluation of odour emissions.
When this document is used for the determination of the odour concentration or the odour emission rate
of stationary source emissions, the other relevant European Standards concerning stationary source
emissions apply, in particular EN 15259 and EN ISO 16911-1, especially when measurements have to
comply with the relevant European Directives concerning industrial air emissions.
Even so, the analysis/quantification step of the measurement method described in this document (i.e. the
determination of the odour concentration of an odorous gas sample, without respect to the origin of the
sample itself) may be fully applied in many cases not related with industrial emission sources (e.g. the
measurement of the mass concentration at the detection threshold of odorant substances, the
determination of effectiveness of deodorising systems for indoor air). In those latter cases, the
requirements in this document concerning the measurement planning and the sampling of stationary
sources may be ignored or adapted.
This document is applicable to the measurement of odour concentration of odorous gas, mixtures of
odorants of defined composition and undefined mixtures of odorants in air or nitrogen, using dynamic
olfactometry with a panel of human assessors being the sensor. The unit of measurement is the European
odour unit per cubic metre: ouE/m3. The odour concentration is measured by determining the dilution
factor required to reach the detection threshold. The odour concentration at the detection threshold is by
definition 1 ouE/m3. The odour concentration is then expressed in terms of multiples of the detection
threshold. The range of measurement is typically from 101 ouE/m3 to 107 ouE/m3 (including pre-dilution).
The field of application of this document includes:
1) the measurement of the mass concentration at the detection threshold of odorants in g/m3;
2) the determination of the SROM value of secondary reference odorant gas, in mol;
3) the measurement of the odour concentration of mixtures of odorants in ouE/m3;
4) the measurement of the odour emission rate from point sources and active area sources, including predilution during sampling;
5) the sampling of odorous gases from emissions of high humidity and temperature (up to 200 °C);
6) the determination of effectiveness of mitigation techniques used to reduce odour emissions.
The determination of odour emissions requires measurement of gas velocity to determine the volume
flow rate.
The field of application of this document does not include:
i. the measurement of odours potentially released by particles of odorous solids or droplets of odorous
fluids suspended in emissions;
ii. the measuring strategy to be applied in case of variable emission rates;
iii. subjective methods for the sensory measurement of the relationship between odour stimulus and
assessor response above detection threshold (perceived intensity);
iv. subjective methods for the sensory measurement of hedonic tone (or (un)pleasantness) or assessment
of annoyance potential;
v. direct measurement of odour exposure in ambient air. For this measurement purpose field panel
methods exist which are the subject of EN 16841-1;
vi. direct olfactometry, including field olfactometry;
vii. static olfactometry;
viii. measurement of the odour identification (recognition) threshold;
ix. the determination of odour emission rate from volume sources, such as fugitive emissions from
buildings;
x. the determination of odour emission rate from passive area sources.
Although the ultimate application of odour concentration measurement is aimed at reducing odour
nuisance, the relation between emissions, dispersion, exposure and annoyance is not within the scope of
this document. The relation between measured odour concentrations and odour emissions according to
this standard and the occurrence of odour nuisance is highly complex. It is profoundly influenced by the
atmospheric processes determining the dispersion of odours, the quality of the odour (hedonic tone) and
finally by the receptor characteristics of those exposed to the odour. These receptor characteristics not
only vary strongly between individuals, but also in time within one individual.