Diesel Exhaust Odor Measurement Using Human Panels

A technique for measuring the intensity of diesel exhaust odor using a human panel has been developed and evaluated. While the ratings obtained are primarily useful for comparative tests, the degrees of difference which can be shown to be significant is sufficiently small to make the procedure adequate for practical use.

The panelists were selected on the basis of superior olfactory ability and trained to rate the odor of diluted diesel exhaust against a series of 12 odor intensity standards contained in plastic bottles. The exhaust was diluted at the engine exhaust pipe and flowed dynamically through the presentation system in order to maintain its quality and intensity. The panelists were exposed to the diluted exhaust in a 1/2 cu ft sniff box for approximately 5 sec. The test programs of observations used were statistically designed. The resulting data were analyzed for significance of differences and confidence limits were determined.