Odeurs & Nuisances
Glossary
ASTM E679-04 Standard
"Standard Practice for Determination of Odor and Taste Thresholds By a Forced-Choice Ascending Concentration Series Method of Limits”
American standard describing the measurement method for characterizing effluent emissions.
Atmospheric dispersion
The evolution in time and space of a pollutant or combination of pollutants (aerosols, gases, dust, odor, etc.) emitted under given conditions in the atmosphere.
Modeling tools are used to numerically simulate the dispersion of pollutants. The three main types of models are Gaussian, Eulerian and Lagrangian. The latter model offers an excellent correlation of forecasts with the perception of residents, even in the case of more complex topographies.
Channeled source
Emission source coming from a conduit
Exemple : stack
Detection threshold of the panel
Dilution factor at which the sample has a 0.5 probability of being detected in test conditions
Diffuse source
Source which has defined dimensions (mostly surface sources) but not a defined airflow.
E.g. fields after spreading, compost pile
Dynamic olfactometry
Measuring the response of panelists to olfactory stimuli generated by a dynamic olfactometer. This is a device in which a sample of odorous gas is diluted with a neutral gas at various known ratios and then presented to panelists.
Electronic nose
Measuring instrument used to detect, discriminate and quantify odors and volatile chemical compounds. The odor fingerprint of the sample is scanned using different detection technologies. A statistical analysis software processes and interprets the measures according to the type of information sought: quantitative models, quality control charts, etc.
EN 13725 Standard
“Determination of odour concentration by dynamic olfactometry”
European standard defining olfactometry measurement methods
European odor unit per m3 (ouE.m-3)
Amount of odorant(s) that, when evaporated into 1 cubic metre of neutral gas at standard conditions, elicits a physiological response from a panel (detection threshold) equivalent to that elicited by one European Reference Odour Mass (EROM), evaporated in one cubic metre of neutral gas at standard conditions.
European Reference Odour Mass (EROM)
Accepted reference value for the European odor unit, equal to a defined mass of a certified reference material. One EROM is equivalent to 123 mg n-butanol (CAS-nr. 71-36-3). Evaporated in 1 cubic meter of neutral gas this produces a concentration of 0,040 µmole/mol.
Micro gas chromatograph
Analyzer based on the technique of gas chromatography. It separates different molecules of a gas mixture for identification and quantification purpose. The miniaturization of the analyzer compared with conventional chromatographs makes it compact, integrable in an industrial rack cabinet and enables the analysis time to be divided by 10. With this type of instrument, a sample can be analyzed on site under a minute.
Odor concentration
The concentration of an odorant mixture is conventionally defined as the dilution factor to be applied to an effluent so that it is no longer perceived as an odor by 50% of people in a sample population.
Odor concentration is expressed in odor units per cubic meter (ou.m-3 or ouE.m-3, if it is determined according to standard EN13725).
Odor flow rate
The odor flow rate corresponds to the product of the odor concentration (ou.m-3 or ouE.m-3) by the air flow rate of the source (m3.h-1) : it is expressed in ou.h-1 or en ouE.h-1
Odor intensity
Odor intensity is the intensity of olfactory sensation. It is related to the concentration of odorant mixture. The following equation, called «Stevens' Law» or «Odor power law» defines the relationship between odor intensity and the concentration of the odorous mixture :
- I = k.(C-Co)n or log I = log k + n log(C-Co)
- I : perceived intensity
- C : concentration of odorant mixture in the inhaled air (ppm)
- Co : concentration at the perception threshold of the odorant mixture (ppm)
- n : coefficient of odor increase, usually between 0.2 and 0.8
- k : constant for each mixture
Odor unit (ou.m-3)
One odour unit is the amount of (a mixture of) odorants present in one cubic meter of odorous gas (under standard conditions) at the panel threshold
Panelist
Person involved in sensory analysis
Surface source
Source of diffuse emissions over a defined area.
Example: settling tanks, lagoons, aeration ponds
TCD detector (Thermal Conductivity Detector)
Thermal conductivity detector also known as katharometer. This universal detector measures changes in thermal conductivity of gaseous mixtures according to their composition. A large number of compounds can be detected: hydrocarbons, aromatics, solvents, permanent gases (CO, H2S, N2, etc.) for example.
VDI3940 Standard
“Determination of Odorants in Ambient Air by Field Inspections”
German standard defining in particular the percentage of «odor time» in the environment.
Volatile Organic Compunds (VOC)
Naturally occurring or man-made substances, present in the air, always composed of carbon and other elements such as hydrogen, halogens, oxygen, sulfur. Butane, propane, ethanol and paint solvents are among the most common VOCs in air. They have known health effects, short-term (irritation of eyes, throat, chest tightness) and long term (carcinogens such as benzene and formaldehyde).
Volume source
Source of diffuse emission in a defined volume.
Example: building containing process odors
