detection threshold

Dynamic olfactometer

A device which mixes neutral gas (odourless air) with odourous gas in specified ratio by flowrate and delivers mixture to an outlet for analysis.  The analysis involves a selected panel…

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EN 13725 – YES/NO Mode

The assessor is asked to evaluate gas presented from a specific port and to indicate if an odour is perceived ( YES/NO). The assessor is aware that in some cases…

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EN 13725 – Forced Choice Mode

The assessor is presented with two or more ports, of which one presents the stimulus and the other(s) neutral gas.The location of the stimulus in consecutive presentation is randomly distributed…

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Exposure

Exposure is a combination of the amount of a pollutant in the air and the amount of time that person stays in the presence of a pollutant. Exposure determines the…

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Federal Clean Air Act (FCAA)

A federal law passed in 1970 and amended in 1974, 1977 and 1990 which forms the basis for the national air pollution control effort. Basic elements of the act include…

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Hazardous Air Pollutants (HAPs)

Pollutants released into the atmosphere as particles and volatile organic compounds (VOCs) — including the known carcinogens of benzene and toluene — from a variety of sources such as vehicle…

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Individual threshold

The detection threshold for an individual where an odour elicits a physiological response. Individual thresholds will vary from person to person as their ability to perceive certain smells are different….

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Odour unit

The odour unit is a unit of measure of odour concentration.  It is defined as follows: American and Australian Odour Unit (OU) One odour unit is a dimensionless number where…

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Particulate Matter (PM)

Tiny solid or liquid particles that are suspended in air. Particulate matter is produced from a wide variety of sources like natural and human-caused, large and small. They are comprised…

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Recognition threshold (RT)

The odour concentration where 50 % of the population can recognize and identify what the odour sample represents. Not to be confused with the Detection Threshold (DT), where the RT…

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