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Philos Trans R Soc Lond B Biol Sci

Title:		Human odour thresholds are tuned to atmospheric chemical lifetimes
Author(s):		Williams J; Ringsdorf A;
Address:		"Max Planck Institute for Chemistry, Hahn-Meitner Weg 1, 55128 Mainz, Germany"
Journal Title:		Philos Trans R Soc Lond B Biol Sci
Year:		2020
Volume:		20200420
Issue:		1800
Page Number:		20190274 -
DOI:		10.1098/rstb.2019.0274
ISSN/ISBN:		1471-2970 (Electronic) 0962-8436 (Print) 0962-8436 (Linking)
Abstract:		"In this study, the odour thresholds (OT) and atmospheric lifetimes (AL) were compared for a suite of volatile organic compounds. It was found that odour threshold, as determined by the triangle bag method, correlated surprisingly well with atmospheric lifetime for a given chemical family. Molecules with short atmospheric lifetimes with respect to the primary atmospheric oxidant OH tend to be more sensitively detected by the human nose. Overall the correlation of odour threshold with atmospheric lifetime was better than with mass and vapour pressure. Several outliers from the correlations for particular chemical families were examined in detail. For example, diacetyl was an outlier in the ketone dataset that fitted the trend when its more important photolysis lifetime was included; and similarly, the relatively low odour threshold of carbonyl sulfide (OCS) was interpreted in terms of uptake by vegetation. The OT/AL relationship suggests that OH rate constants can be used as a first-order estimate for odour thresholds (and vice versa). We speculate that the nose's high sensitivity to chemicals that are reactive in the air is likely an evolved rather than a learned condition. This is based on the lack of dependence on ozone in the aliphatics, that the anthropogenically emitted aromatic compounds had the worst correlation, and that OCS had a much lower than predicted OT. Finally, we use the OT/AL relationships derived to predict odour thresholds and rate constants that have not yet been determined in order to provide a test to this hypothesis. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'"
Keywords:		Atmosphere *Environmental Monitoring Humans Odorants/*analysis Smell Volatile Organic Compounds/*analysis/classification atmospheric lifetime evolution odour threshold olfaction volatile organic compounds (VOCs);
Notes:		"MedlineWilliams, Jonathan Ringsdorf, Akima eng England 2020/04/21 Philos Trans R Soc Lond B Biol Sci. 2020 Jun 8; 375(1800):20190274. doi: 10.1098/rstb.2019.0274. Epub 2020 Apr 20"