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printreg, September, 2001
Re: Odor Regs and Testing


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From: William Bertele (wbertele@voicenet.com)
Date: Tue, 18 Sep 2001 07:36:07


Most states have some form of recognition of odors as pollution even if not malodors. I note that you have many responses regarding state regs, but none concerning testing. 

A. D. Little has written several papers on the subject of odor testing by hoods and odor panels. There is also an ASTM odor panel syringe dilution test method. These test methods establish statistically that there is an odor DILUTION RATIO that a significant portion of the population (odor panel) will not detect an odor. This gives us a sense of the magnitude of the odor and the degree of corrective efforts required.

 The dilution ratio is also an important piece of data for input into a computer dispersion model for predicting the downwind potential for odorous impact. This analysis is usually used to confirm odorous impact and to determine a stack height that would avoid significant odorous impact at a receptor site, some distance from the stack. 

For a specific odorous gas, e.g. an odorous hydrocarbon, simple VOC sampling and analysis can be performed to determine the concentration in ppmv. This concentration can then be compared to published odor detection thresholds, e.g. A.D. Little. This concentration could also be inputted in a computer dispersion model predicting the downwind potential concentration. This concentration can be compared to published odor detection threshold values. Again, this analysis is usually used to confirm odorous impact and to determine a stack height that would avoid significant odorous impact at a receptor site of interest some distance from the stack.

 I'm not sure there is an answer to the question "Can testing determine the cause of the odor". Usually knowledge of the process and materials will reveal the odorous compounds at the source. Sampling and analysis of the gas stream at the source for the identity of the components can also be performed.

 If the intent of the question is to determine where an odor, that is impacting on a receptor site, is coming from, then meteorological methods would be employed, e.g. wind vane & anemometer, published historical meteorological data etc.



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