Findings and Recommendations from the Joint NIST – AGA Workshop on Odor Masking

Published

November 1, 2011

Author(s)

Thomas J. Bruno, Nancy Rawson, Ali Quaraishi

Abstract

Since the days of the alchemist, the observation that some substances have a smell while other substances do not has been a source of fascination. The sense of smell, or olfaction, is our least understood sense, however it is important for many human functions, including digestion, food selection and hazard avoidance. The detailed explanation of why individual chemicals (called odorants) might have a particular smell is still elusive. The situation with mixtures of odorants is even more complex and interesting. A number of distinct odorant mixture phenomena have been documented. Odorant suppression (sometimes called masking), conjugation and cross-adaptation are among a collection of such phenomena. They are related to the differential effects that one odorant species will have when mixed with another. Masking is a term that describes situations in which one odorant can overpower the sensation of another. There may be profound technological implications in a number of industrial sectors, most prominently in the fuel gas sector. Here, masking is suspected when the odorant that is added to natural gas can be detected by analytical instrumentation, but cannot be properly detected by an observer with a normal sense of smell. Note that this phenomenon is distinct from odor fade, which more properly describes a decrease in the concentration of an odorant rather than a decrease, disappearance or qualitative change in the perception of the odor in the absence of a change in absolute concentration. Anecdotal descriptions of masking events in the natural gas industry have persisted for over a decade, with the frequency of such events on the rise. Pursuant to the philosophy that the technological problem cannot be addressed until the basic science is understood, NIST, in collaboration with the American Gas Association (AGA), sponsored a workshop that brought together olfactory scientists and natural gas operations personnel in an effort to achieve a common unders

Citation

Journal of Research (NIST JRES) - 116.026

Report Number

116.026

NIST Pub Series

Journal of Research (NIST JRES)

Pub Type

NIST Pubs

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DOI Link

Keywords

Cross-adaptation, odorant conjugation, odorant masking, Zwaardemaker pair

Citation

Bruno, T. , Rawson, N. and Quaraishi, A. (2011), Findings and Recommendations from the Joint NIST – AGA Workshop on Odor Masking, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/jres.116.026 (Accessed April 19, 2024)