ÖNORM EN 13725

This European Standard specifies a method for the objective determination of the odour concentration of a gaseous sample using dynamic olfactometry with human assessors and the emission rate of odours emanating from point sources, area sources with outward flow and area sources without outward flow. The primary application is to provide a common basis for evaluation of odour emissions in the member states of the European Union. This European Standard is applicable to the measurement of odour concentration of pure substances, defined mixtures and undefined mixtures of gaseous 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 European Standard includes: the measurement of the mass concentration at the detection threshold of pure odorous substances in g/m3; the measurement of the odour concentration of mixtures of odorants in ouE/m3; the measurement of the emission rate of odorous emissions from point sources and surface sources (with and without an outward flow), including pre-dilution during sampling; the sampling of odorants from emissions of high humidity and temperature (up to 200 °C); the determination of effectiveness of end-of-pipe devices used to reduce odour emissions. The characterisation of odour emissions requires detailed measurement of the gas velocity, that shall be performed according to the relevant standards included in the normative references. This European Standard is not applicable to: the measurement of odours potentially released by particles of odorous solids or droplets of odorous fluids suspended in emissions; the measuring strategy to be applied in case of variable emission rates; the measurement of the relationship between odour stimulus and assessor response above detection threshold; direct measurement of hedonic tone (or (un)pleasantness) or direct assessment of potential annoyance; field panel methods; measurement of recognition thresholds; EN 13725:2003 (E) + AC:2006 (E) 5 measurement of identification thresholds. Although the ultimate application of odour measurement is in reducing odour nuisance, the relation between measured thresholds of odour 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 characteristics not only vary strongly between individuals, but also in time within one individual. The relation between emissions, dispersion, exposure and annoyance is not within the scope of this European Standard.