A Review of 20 Years of Standardization of Odor Concentration Measurement by Dynamic Olfactometry in Europe

Twenty years of development of standards for odor concentration measurement in Europe are reviewed.Issues covered are the development of instruments, standards, and guidelines for methodology and calculation of odor concentration as well as validation of results through interlaboratory comparisons.National efforts led to an initiative in the technical committee CEN/TC264 Air Quality of the Committee Européen de Normalisation (CEN) to draft a European standard.The final draft was validated by an international interlaboratory comparison in 1996.This validation showed that the strict performance criteria set for repeatability, reproducibility, and accuracy (assessed for an n-butanol standard) were attainable by laboratories using two modes of presenting odor samples to assessors (singlestimulus and forced-choice) that were included in the standard.An agreed-upon reference value for the European odor unit was set at 1 ou E /m 3 ≡ 40 ppb/v n-butanol.This value is attained by a strict protocol for panel selection, which has been the main contributing factor in improving the reproducibility of olfactometry.The notion that the panel should be representative of the general population was explicitly IMPLICATIONS A sizable proportion of environmental complaints are raised due to odors.Environmental odor management requires tools to quantify, regulate, and enforce odor emission limits.The application of olfactometry has been hampered by a lack of reproducibility and traceability of results.The introduction of air quality guidelines for odors in Europe in the mid 1980s has prompted further standardization of olfactometry and validation through interlaboratory comparisons.The most recent development is the drafting of a standard for dynamic olfactometry by the European standardization organization CEN (in Brussels).This standard was validated in a large scale interlaboratory comparison in 1996 and is expected to become mandatory in the European Union in 1998.abandoned, recognizing that this proposition was not tenable using small panels of a practical size of five to eight assessors.The validation demonstrated that the CEN draft method, expected to be introduced in 1999, can guarantee reliable and reproducible results, which are effective in supporting the implementation of effective odor abatement policies in the member countries of the European Union.