1. Definition of odor concentration and odor intensity

Odor concentration (OU)

Definition: Odor concentration is a numerical value determined by dilution method, representing the multiple of clean air required to dilute odorous gases to odorless levels.

Unit: Usually expressed in OU/m ³ (Odor Unit per cubic meter), 1 OU/m ³ represents the amount of air that can cause olfactory perception in 1 cubic meterSouthOdor concentration.

Measurement method: The commonly used three-point comparative odor bag method (GB/T 14675-93) is used to determine the dilution factor of the diluted sample by an odor detector. For example, if there is no odor after diluting 300 times, the odor concentration is 300 OU/m ³.

Odor intensity (OI)

Definition: Odor intensity is a subjective classification based on human olfactory perception, describing the strength of odors.

Grading criteria: Usually using the 0-5 grading method (internationally recognized standards such as Japan and China):

Level 0: Odorless

Level 1: barely able to smell (detection threshold)

Level 2: Able to distinguish odor properties (recognition threshold)

Level 3: Clearly detectable

Level 4: Strong odor

Level 5:jiqiangUnbearable odor

Judgment criteria: Based on the sensory testing of the odor detector, combined with the concentration and characteristics of the odor (such as irritation and pleasure), a comprehensive judgment is made.

2. Relationship between odor concentration and odor intensity

There is a non-linear relationship between the two, usually associated by the following formula:

P = K \\cdot \\log(S)

P: Odor intensity (0-5 levels)

S: Odor concentration (OU/m ³)

K: Constant (varies depending on region and pollutant type, typically ranging from 0.3-0.6)

3. Measurement method

Odor concentration measurement:

1. Three point comparative odor bag method (GB/T 14675-93):

-Dilute the sample with odorless air, and the sniffer determines the odorless point through multiple dilutions and calculates the dilution factor.

-Suitable for rapid laboratory and on-site testing.

2. Dynamic dilution method:

-Automatically dilute the gas through the device and evaluate the concentration using sensors or sniffers.

3. Electronic nose technology:

-Estimating odor concentration (such as OU value) using sensor arrays and algorithm models is suitable for real-time monitoring.

Odor intensity measurement * *:

Sensory olfactory recognition method: trained olfactory recognition personnel directly determine the odor intensity level (0-5 levels).

Instrument assisted method: estimating intensity through an electronic nose or sensor array combined with an algorithm model.

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Odor concentration is an objective quantitative indicator used for environmental monitoring and emission control;

Odor intensity is a subjective perception rating used to evaluate its impact on human health and psychology;

The combination of the two can comprehensively evaluate odor pollution and guide treatment measures (such as selecting physical, chemical, or biological methods for treatment).