The effect of the change in air inflow velocity has been investigated at the opening of the malodor emission source to determine its influence on the Complex odor concentration. Both the Complex odor collection efficiency and concentrations were measured according to the change in airflow velocity. When the air inflow velocity was 0.1 m/s, it was observed that some of the generated gas streams were diffused to the outside due to low collection efficiency. In contrast, only the increased gas collection volume up to 0.5 m/s showed no substantial reduction of the Complex odor concentration, which indicates an increase in the size of the local exhaust system as well as the operation cost for the Complex odor control device. When the air inflow velocity reached 0.3 m/s, the Complex odor concentrations not only were the lowest, but the odorous gas could also be collected efficiently. The air inflow velocity at the opening of the malodor emission source was considered the key factor in determining the gas collection volume. Therefore, based on the results of this study, an optimal air inflow velocity might be suggestive to be 0.3 m/s.

This study is a summary of the complex odor proficiency testing method using the air dilution sensory method conducted for the last 7 years. Results of the homogeneity and stability test were obtained from the measurement of the standard sample for identifying the range of measurable concentration so that the complex odor proficiency testing method was established through processing the manufactured standard sample and distribution method. Standard samples were prepared using a large Teflon bag after being homogeneously mixed inside a Teflon bag. Also, a distributing container was selected with a polyester aluminum bag in order to avoid samples of the best condition from being contaminated during transport as well as being exposed to invasive odor from a sampling bag. Test results revealed that the mixture of toluene and m-Xylene was most appropriate for this proficiency testing method to the homogeneity and stability of the testing method. In addition, DMS and DMDS were the optimized samples at the outlet area. As a result, the standard method was established to address the analysis quality management to the mixed odor inspection agencies in Korea.

Since 2011, proficiency test for the air dilution olfactory method started in Korea for the evaluation of the authorized odor inspection agencies’ analysis skill. For this purpose, sulfur compounds of PTMs (proficiency test materials) were made and investigated for the application to the proficiency test as a complex malodor sample. Time stability and homogeneity between samples were analysed for the PTM which was made with 10 ppm of DMS and 10 ppm of DMDS. As the results, the stability of sample concentration with GC analysis was shown around 6%RSD through the time of 6~48 hr. In addition, dilution number during the same test period appeared almost stable, less than 6%RSD in air dilution olfactory method. The reproducibility results of four laboratories showed very similar results except one lab which was caused by the elder panel characteristics.