Odor Concentration Farmstead odors always occur as mixtures of odorants. It is difficult and expensive to measure the concentration of each odorant in a sample. Instead, odor scientists measure the concentration of odors as a whole by grabbing a sample and presenting it to a panel of trained sniffers. The sample is diluted with odorless gas until half of the panel can no longer smell anything. When 50 percent of the sniffers can no longer detect an odor, we say the sample has been diluted to the detection threshold .
Detection threshold is similar to detection level discussed in the previous sections.
Detection threshold is the detection level of a mixture of odorants at the conditions given in the experiment. The ratio of odorless gas to sample is called the dilution factor. Dilution factor is a good measure of odor concentration. For example, an air sample taken from inside a dairy barn is diluted 100 times until half of the people on a panel could no longer detect an odor. Other odor threshold standards do not state odor concentration in odor units per volume.