Precision of Olfactometry and Odor Testing Results

Olfactometry is a precise testing method. How precise depends on the quality assurance / quality control (QA/QC) statistics associated with the laboratory’s results. The European Olfactometry testing standard, EN13725:2003, provides a formalized method for monitoring the performance of panel members (assessors) and test results. This is accomplished through testing with the standard odorant 1-butanol (n-butanol). Olfactometry precision can be understood through four different variance values: 1. specific panel variance, 2. within panel variance, 3. inter-panel variance, and 4. inter-laboratory variance. Inter-laboratory studies have shown standard deviation of log threshold values as high as 0.30 and individual laboratories have shown inter-panel standard deviations of 0.10 and within panel standard deviations as low as 0.05. This paper defines the four types of variances and shows how the precision of odor panel results can be expressed as analogous to a group of assessors determining sound level within ±1dB in 95 % of the cases. This paper will present these different measures of precision with test data and examples of applications of how this information can be utilized by various stakeholders