Abstract
The performance of on-site measurements by dynamic olfactometry using a mobile laboratory with online measurements was compared with delayed olfactometric analysis carried out by two external laboratories using the same kind of olfactometer as the mobile laboratory. All sampling and analyses were performed according to CEN 13725:2003, and analyses at the external laboratories were carried out within 24 hours of sampling. Sampling was not performed at the mobile laboratory, since the olfactometer was connected directly to the source with a heated sampling tube. In total, results for 120 odour measurements, representing four different types of pig housing or mitigation systems, were compared.
Due to the direct connection between the olfactometer and the source in the mobile laboratory, there was no time delay or other effects (e.g. sampling bags, temperature or condensation) that could affect the results. The number of panellists used in the mobile laboratory was lower than that used in one of the two external laboratories. The results for each sample were compared in order to evaluate the overall performance of the three laboratories with regard to concentration levels and variance.
The study shows a statistically significant difference between the results from the three laboratories. The variance in the mobile laboratory with online measurements was lower than that in the two laboratories using delayed olfactometry, and most of the difference was due to day-to-day variance.
