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Pollution and Pollutants
Published in Paul Mac Berthouex, Linfield C. Brown, Chemical Processes for Pollution Prevention and Control, 2017
Paul Mac Berthouex, Linfield C. Brown
The odor detection threshold is the lowest concentration of odorant that will elicit a response in a given percentage (usually taken as 50%) of a population without reference to odor quality. A different threshold is the minimum concentration that is recognized as having a characteristic odor quality. Odor character is how the substance smells; descriptors included fishy, nutty, creosote, turpentine, rancid, sewer, and ammonia. Hedonic tone describes how pleasant or unpleasant the odor is.
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Published in Jeff Kuo, Air Pollution Control Engineering for Environmental Engineers, 2018
The odor detection threshold is the lowest concentration of an odorant that is perceivable by the human sense of smell. The thresholds cannot be accurately detected; they are measured through extensive tests using human subjects instead. The threshold values can be quite different; for example, 100 ppm for methanol and 0.0021 ppm for trimethylamine (C3H9N)
Odour Testing Methods and Regulatory Norms
Published in G. Thilagavathi, R. Rathinamoorthy, Odour in Textiles, 2022
Anton P. van Harreveld, Rajal Shinkre, Carmen Villatoro, Charlotte Tournier, Saisha Naik
The perception of odour is triggered when odour-active chemical compounds (odorants) in the textile product interact with olfactory receptor cells located in our nasal cavity. Some odorants can be perceived while others are not, because their concentration is below the olfactory detection threshold. The minimal concentration necessary to allow detection of the odour of a chemical compound is expressed as the odour threshold value (OTV). The odour detection threshold is the lowest concentration of a certain odour compound that is detectable by the human sense of smell. In practical terms, this is a very variable value, because human olfactive sensitivity varies over a wide range. That is why the determination of a reproducible OTV requires a large panel of observers (e.g., n > 10) in order to obtain a stable mean value. This uncertainty due to inter-individual variation has been reduced by making OTVs traceable to an agreed reference stimulus, in the EN13725 European olfactometry standard. The revised 2021 edition of this standard includes a standard procedure to determine OTVs, as Secondary Odour Reference Mass (SROM), traceable to the European Reference Odour Mass (EROM), defined for the primary reference odorant n-butanol. The olfactory relevance of a specific odorant in an odorous gas can be expressed by dividing its mass concentration by its odour detection threshold value (OTV). This calculation results in the Odour Activity Value, which is an estimate of the specific odour concentration for that particular odorant in an aroma composition. This concept was first introduced by Patton and Josephson (Patton and Josephson 1957) and led to the definitions of aroma value (Rothe and Thomas 1963) and odor unit (ou) (Guadagni et al. 1966). To know the ‘olfactory stimulus weight’ of perception of an odorant, the Odour Activity Value (OAV) is often used. This is calculated from the abundance of that odorant molecule (or mass concentration) divided by the odour detection threshold, or Odour Threshold Value (OTV).
Recovery in sensory-enriched break environments: integrating vision, sound and scent into simulated indoor and outdoor environments
Published in Ergonomics, 2019
Brid Sona, Erik Dietl, Anna Steidle
The ambient scents should be induced above odour detection threshold, but below odour identification. A question with open-response format indicated that in the control group (group without induced scents), no participant reported smelling a significant scent. One person in the control group (4.3%) perceived a general fresh fragrance, which signals that the odour neutralizer that was applied in the control group successfully removed any unpleasant scents. In the two scented conditions, 18 subjects (36.7%) mentioned that they could smell a scent (63.3% did not). In the scented nature condition, participants mentioned more general smell of ‘freshness’, ‘sweet’ and ‘not known’ as well as specific smell of ‘flowery’, ‘lemon’ and ‘lavender’ which fit to the visually presented park scenario. In the scented lounge condition, participants mentioned the more general smell of ‘sweet’ and ‘not known’ as well as the specific smell of ‘sandalwood’ and ‘peach’, which are seen as typical indoor odours. Overall, the mentioned scents differed between the two scented conditions and fit rather well to the presented visual stimuli. As expected, a precise odour identification was not possible.