Air odor threshold

The air odor threshold in healthy subjects is approximately 250 ppm (Utell et al. 1997). During a clinical study with exposures at 250, 500, or 1,000 ppm, subjects were asked to record their responses to any perceived odor. At 250, 500, and 1,000 ppm, one, two, and three of eight subjects, respectively, noticed the odor. A subject that responded at 250 and 500 ppm did not notice the odor at 1,000 ppm. In all cases, the odor was rated as mild, which was defined as noticeable but not annoying. 

Clear, colorless to pale yellow-brown, watery, volatile liquid with a sweet, irritating or pungent odor resembling peach pits, onions, or garlic. Evaporates quickly when spilled. Turns dark on exposure to air. Odor threshold concentrations of 1.6 and 8.8 ppmv were reported by Stalker (1973) and Nagata and Takeuchi (1990), respectively. 

Colorless to yellow scales with an unpleasant odor. Turns red on exposure to light and air. Odor threshold of 0.14 ppm was reported by Buttery et al. (1988). 

White to yellow crystals or rhombic needles with an unpleasant odor. Becomes purplish-red on exposure to air. Odor threshold concentrations were 140-290 pg/m (quoted, Keith and Walters, 1992). 

In your laboratory refrigerator (5°C) you store pure cyclohexane that you use for extracting organic trace contaminants from water samples for subsequent analysis by gas chromatography. Among the compounds of interest is tetrachloroethene (also called perchloroethene or PCE). One day you realize that somebody is using tetrachloroethene in the laboratory. In fact, you can even smell the compound in the air (odor threshold values 0.03 - 0.1 mg-L-1). You are worried that your cyclohexane is contaminated, particularly, because you have realized that the bottle was not well sealed in the refrigerator. Calculate the concentration of PCE in the air that, at 5°C, would be sufficient to produce an equilibrium PCE concentration in the cyclohexane of 1 jig-fiL l, which you would consider to be a problem for your analysis. 

Table 35.1 Permissible Exposure Levels (PEL) and Air Odor Thresholds (AOT) (in ppm) for Volatile Organic Compounds120,211...

L. J. van Gemert and A. H. Nettenbreiger, Compilation of Odor Threshold Values in Air and Water, National Institute for Water Supply, Voolburg, the... 

The odor threshold for detection of ethyleneimine is 2 ppm. The maximum permissible concentration of ethyleneimine in the air at the place of work is 0.5 ppm (as specified in statutory regulations in the United States (374) and in Germany (375)). Animal experiments have shown ethyleneimine to be both carcinogenic (376) and mutagenic (377) (Table 2). 

The odor threshold of carbon disulfide is about 1 ppm in air but varies widely depending on individual sensitivity and purity of the carbon disulfide. However, using the sense of smell to detect excessive concentrations of carbon disulfide is unreHable because of the frequent co-presence of hydrogen sulfide that dulls the olfactory sense. 

The first element, dynamic dilution, provides a reproducible sample for each panelist. The system must minimize the loss of the odorant to the walls of the delivery apparatus, provide clean dilution air of odor-free quality, maintain a constant dilution ratio for the duration of a given test, and have no memory effect when going from high to low concentrations or switching between odorants of different character. The type of mask or port and the delivery flow rate have been found to influence the response of panelists in determining odor threshold and intensity. 

Engineering Considerations To effect the good engineering design of an activated carbon adsorption system, it is first necessary to obtain information on the following the actual cubic feet per minute (ACFM) of air to be processed by the adsorber, the temperature of gas stream, the material(s) to be absorbed, the concentration of the material to be adsorbed, and if the intended application is air pollution control such as odor control - then the odor threshold of the material to be adsorbed. In addition, data is needed on the presence of other constituents in the gas stream, and whether or not solvent recovery is economical. 

Health Hazards Information - Recommended Personal Protective Equipment U.S. Bu. Mines approved toxic dust mask chemical goggles rubber gloves neoprene-coated shoes Symptoms Following Erqrosure Inhalation produces slight toxic effects. Contact with eyes irritates eyes and causes skin rash General Treatment for Exposure INHALATION remove to fresh air. EYES wash with water for 20 min. call a physician. SKIN wash with water Toxicity by Inhalation (ThresholdLimit Value) Data not available Short-Term Exposure Limits Data not available Toxicity by Ingestion Grade 2 oral rat LDjq 820 mg/kg Late Toxicity Data not available Vapor (Gas) Irritant Characteristics Data not available Liquid or Solid Irritant Characteristics Data not available Odor Threshold Data not available. 

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