In 1992, at the demand of the European Committee for Standardization (Comite europeen de normalisation CEN) a working group was formed to develop a standard method to determine odour concentrations using dynamic olfactometry. Two years later a draft CEN Standard was presented and in 1995 the working group decided to validate these Standard by an international ringtest. In the summer 1996, 19 European participants realized olfactometry tests using the developed CEN Standard . The procedures of the ringtest are presented in the proceeding and n-butanol was used as odour source as its concentration can be measured and identical samples could be sent to the participant laboratories. The CEN Standard as the guideline VDI 3881 (Germany) provides precise description of the common olfactometric methods but it also gives quality requirements. Testing of all the elements of the Standard (dilution equipment calibration, panel selection and odour threshold measurement) was done in the “European Interlaboratory Comparison Olfactometry”.
Panel selection is an important part in the CEN Standard as it has an important impact in the results obtained.

Olfactometry is an important tool in the determination of odour intensity of a specific source particularly when the emissions are constituted of many different compounds which can’t be chemically analyzed as a whole and as the determination of the concentration of one or two components can’t give significant information of the odour level of the mix. However olfactometry is a complicated process and the results depend greatly in the respect of specific procedures. The CEN Standard were developed so the used of a standard method could allow comparisons between laboratories and in time. This method could then be used to compare or develop odour control methods, products or policies through out Europe and elsewhere if the Standard is used.