Making Sense of Smells A Guide for Understanding Farmstead Odors Part 5: Odor Intensity and...

Making Sense of SmellsA Guide for Understanding Farmstead Odors

Part 5: Odor Intensity and Offensiveness

Douglas W. HamiltonWaste Management SpecialistBiosystems and Agricultural Engineering

Odor Measurement

How does it smell?

How Strong?

Charcter

Intensity

Two Methods for Intensity

1. Referencing Suprathreshold

2. Descriptive Category Scale

Referencing Suprathreshold Odor Intensity

Odors are compared to standards of known intensity


using dilutions of 1-Butanol



using dilutions of 1-Butanol

CH3CH2CH2OH


Port

1 2 3 45 6 7 8

www.rka-inc.com

Purdue Agricultural Air Quality Laboratory


Port vol/vol 1-butanol ppm

1 122 243 484 965 1946 3887 7758 1,550

www.rka-inc.com

Purdue Agricultural Air Quality Laboratory



1 122 243 484 965 1946 3887 7758 1,550

www.rka-inc.com


Results reported in ppm 1-butanol



1 122 243 484 965 1946 3887 7758 1,550

www.rka-inc.com



Intensity = 105 ppm 1-butanol



Log10Intensity = 2.02 ± 0.267N = 12


Descriptive Scale Odor Intensity

Panel rates Intensity on a scale independent of

an external standard

1. Dilutions of odor are presented to panel.


www2.dpi.qld.gov.au/environment


2. Panelists rate odor intensity on a descriptive scale.


Intensity Scale

0 = no odor

1 = very faint

2 = faint

3 = distinct

4 = strong

5 = very strong

6 = extremely strong


2. Panelists rate odor intensity on a descriptive scale.

3. Statistics are performed to determine consensus of the panel.


www.library.thinkquest.org

Intensity vs Concentration

0

1

2

3

4

5

6

1 10 100 1000

Odor Concentration (OU)

Od

or

Inte

nsi

ty

Measured Swine Odor Relationship

6 = Extremely strong5 = Very Strong4 = Strong3 = Distinct2 = Faint1 = Very Faint0 = No Odor

Misselbrook, et al. 1993

www.library.thinkquest.org

Intensity vs Offensiveness

Odor Measurement

How does it smell?

How Strong?

Charcter

Intensity

Odor Measurement

How Good or Bad?

How Strong?

Hedonic Tone

Intensity

Odor Measurement

How Bad?

How Strong?

Offensiveness

Intensity

Offensiveness is an Intrinsic Property of an Odor

A odor will be equally offensive, no matter how strong.

Offensiveness by Olfactometry

1. Equal Intensity samples are presented to panel.

www2.dpi.qld.gov.au/environment


1. Equal Intensity samples are presented to panel

2. Panel rates offensiveness on a descriptive scale.

Offensiveness Scale

0 = Inoffensive

1 = Very faintly Offensive

2 = Faintly Offensive

3 = Definitely Offensive

4 = Strongly Offensive

5 = Very Strongly Offensive

6 = Extremely Offensive


1. Equal Intensity samples are presented to panel

2. Panel rates offensiveness on a descriptive scale.

3. Statistics are performed to determine consensus of the panel.

Notes Odors

Character Verbal Description Offensiveness

PersistenceTop Note

Middle Note

Base Note

Concentration Detection Level

Recognition LevelOU

Intensity Intensity Intensity

Measuring Farmstead Odors

Notes Odors

Character Verbal Description Offensiveness

PersistenceTop Note

Middle Note

Base Note

Persistency

Concentration Detection Level

Recognition LevelOU

Intensity Intensity Intensity

Measuring Farmstead Odors

Making Sense of Smells A Guide for Understanding Farmstead Odors Part 5: Odor Intensity and...

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