Dynamic olfactometer airflow variation in determining odor dilutions-to-threshold

Primary, sample, and supplemental airflow rates were measured for one year on two dilution levels through a dynamic olfactometer to determine airflow rate variation and calculated dilution variation. Levels 3 and 9 were chosen to be monitored for variation because they lie at the 25% and 75% dilution levels in the range of one to 12. Sample and supplement airflow rates were significantly different when measured at the beginning and end of each session. In general, sample airflow rates increased, while supplemental airflow rates decreased during the session. Calculated dilutions (using a constant 9.4 L/min) decreased 2.6% and 1.0% from session beginning to session end for Levels 3 and 9, respectively. Using the measured primary airflow rates caused main effects of time (before/after the session) for calculating odor dilutions to become nonsignificant. Information from this study indicates that daily measuring of sample, supplemental, and primary airflow rates is needed to precisely calculate dilutions-to-thresholds for odor determination. In addition, constant attention and maintenance of the olfactometer is needed to ensure the instrument is working properly.