Cooperative Evaluation of Techniques for Measuring Diesel Exhaust Odor Using the Diesel Odor Analysis System (DOAS)

The CRC-APRAC CAPI-1-64 Odor Panel was formed in 1973 to assess an instrumental measurement system for diesel exhaust odor (DOAS) developed under CRC-APRAC CAPE-7-68 by Arthur D. Little, Inc.

Four cooperative studies were conducted by nine participating laboratories using common samples. The objectives of these studies were to define the DOAS system variables and to validate and improve the sampling and collection procedures. A fifth study, serving as a review of each analysis step, showed that analysis of common derived odorant samples could be conducted within acceptable limits by the participating laboratories. Three in-house sampling system design and operating parameter studies were conducted simultaneously with the cooperative work. The combined findings from the in-house and cooperative studies led to a tentative recommended procedure for measuring diesel exhaust odor.

During the course of these cooperative tests the variability of odor measurements improved from 0.6 TIA to 0.2 TIA units, well within the ability of the human nose to detect differences in Total Intensity of Aroma (TIA).