ASTM E1593-21

Standard Guide for Assessing the Efficacy of Consumer Products in Reducing the Perception of Malodor

SIGNIFICANCE AND USE
5.1 The purpose of this guide is to assess the ability of consumer products to reduce malodor intensity from a control state. Several experimental hypotheses are possible, depending on the objective of the test. Possible objectives with respective hypotheses are given in Appendix X1.  
5.2 Many consumer products are sold commercially with the intent of providing a means of improving the odor quality of a volume of air, or the odor quality of a substrate such as fabric or household surfaces, relative to some existing environmental condition. In the case of air care products, this typically involves the application of an odorous substance into the air space by means of some active or passive mechanism (for example, by spraying, or by evaporation). This procedure is also applicable to other mechanisms of odor reduction (for example, air filtration, chemical reactions, etc.).  
5.3 Selection of representative malodor sources is of critical importance. The malodor source must be readily available and of a consistent odor quality. A reasonable malodor source should be chemically and aesthetically correct. The experimenter and client must agree upon the appropriateness of a malodor source before further details of the test design are worked out. Experimental variation will be reduced by using uniform malodor sources. Information collected on malodor reduction will thus be more comparable from experiment to experiment and from laboratory to laboratory.  
5.4 The procedure recommended can be used for assessment of the malodor reduction and elimination efficacy of consumer products including: air fresheners, air filtration products, aerosol/spray and continuous/solid air freshener products, candles, fabric care products including detergents and fabric enhancing/conditioning products, surface care products including carpet care products, surface cleaning products such as sprays etc., pet care products, and other products intended to deliver a malodor reduction benefit. It s...
SCOPE
1.1 This guide covers standard procedures for the quantitative sensory assessment of perceived olfactory intensity of malodors for the purpose of assessing the malodor reduction efficacy of consumer products including, but not limited to, air care, fabric care, home care, pet care, and similar products.  
1.2 This guide is not intended to cover axillary deodorancy; refer instead to Guide E1207.  
1.3 Malodors may be from natural or synthetic sources.  
1.4 This guide is a compendium of information or series of options that does not recommend a specific course of action. The user of this guide is responsible for identifying the most appropriate test design and using the appropriate statistical tools to address the experimental design.  
1.5 This guide is designed to provide guidance in product formulation and new product development, and for quality control issues.  
1.6 The scope of this guide does not include all guidance necessary to support claims. For further guidance the researcher may refer to Guide E1958. The usage of methods described in this guide can be used as part of a comprehensive claims support strategy for technical types of claims (such as claims that the product will create a sensory change when used on malodor). However, this guide does not address other important elements of the claim support strategy, including determining the statistical confidence requirements, or determination of the consumer relevance of the data obtained, as discussed in 1.7.  
1.7 The testing of products designed to reduce malodors via sensory testing as outlined in the present Guide can yield technical support for products’ efficacy claims. The methods described in this guide—assesors with identified sensory acuity and trained, malodors that may be lab-created or synthetic, and controlled exposure to malodors in a controlled indoor environment—can deliver results with high internal validity. Internal validity refers to s...

General Information

• Status: Published
• Publication Date: 14-Jul-2021
• ICS: 71.100.70 - Cosmetics. Toiletries
• Technical Committee: E18 - Sensory Evaluation
• Drafting Committee: E18.07 - Personal Care and Household Evaluation

Relations

• Refers: ASTM E253-19 - Standard Terminology Relating to Sensory Evaluation of Materials and Products
• Effective Date: 15-Oct-2019
• Refers: ASTM E1958-19a - Standard Guide for Sensory Claim Substantiation
• Effective Date: 01-Aug-2019
• Refers: ASTM E1958-19 - Standard Guide for Sensory Claim Substantiation
• Effective Date: 01-Mar-2019
• Refers: ASTM E253-18a - Standard Terminology Relating to Sensory Evaluation of Materials and Products
• Effective Date: 01-Oct-2018
• Refers: ASTM E544-18 - Standard Practice for Referencing Suprathreshold Odor Intensity
• Effective Date: 01-Oct-2018
• Refers: ASTM E2263-12(2018) - Standard Test Method for Paired Preference Test
• Effective Date: 01-Aug-2018
• Refers: ASTM E253-18 - Standard Terminology Relating to Sensory Evaluation of Materials and Products
• Effective Date: 15-Jun-2018
• Refers: ASTM E1958-18 - Standard Guide for Sensory Claim Substantiation
• Effective Date: 01-Jun-2018
• Refers: ASTM E253-17 - Standard Terminology Relating to Sensory Evaluation of Materials and Products
• Effective Date: 01-May-2017
• Refers: ASTM E1958-16a - Standard Guide for Sensory Claim Substantiation
• Effective Date: 01-Oct-2016
• Refers: ASTM E1958-16 - Standard Guide for Sensory Claim Substantiation
• Effective Date: 01-Aug-2016
• Refers: ASTM E253-16 - Standard Terminology Relating to Sensory Evaluation of Materials and Products
• Effective Date: 01-Jun-2016
• Refers: ASTM E253-15b - Standard Terminology Relating to Sensory Evaluation of Materials and Products
• Effective Date: 01-Dec-2015
• Refers: ASTM E253-15a - Standard Terminology Relating to Sensory Evaluation of Materials and Products
• Effective Date: 01-Jun-2015
• Refers: ASTM E253-15 - Standard Terminology Relating to Sensory Evaluation of Materials and Products
• Effective Date: 15-Jan-2015

Overview

ASTM E1593-21 is the Standard Guide for Assessing the Efficacy of Consumer Products in Reducing the Perception of Malodor. Developed by ASTM Committee E18 on Sensory Evaluation, this guide establishes reliable procedures for quantitative sensory assessment of malodor reduction by consumer products. The aim is to enable product developers, quality control specialists, and researchers to objectively evaluate and compare how effectively products lessen the perceived intensity of undesirable odors from diverse sources, such as air, fabric, and household surfaces.

This standard applies to a wide range of consumer products, including air fresheners, air filtration devices, candles, fabric detergents and conditioners, surface cleaners, carpet care products, and pet care items. By providing a framework for controlled laboratory testing using trained sensory panels, ASTM E1593-21 helps ensure that malodor reduction claims are supported by credible, standardized data.

Key Topics

• Sensory Assessment Methods
  The guide details procedures for the quantitative sensory assessment of malodors, focusing on sensory panel selection, training, and consistent evaluation protocols to ensure data reliability.

• Selection of Malodor Sources
  Identification of representative and consistent malodor sources is critical. These can be natural, synthetic, or surrogate odors selected to mimic real-world scenarios and consumer environments.

• Testing Protocols
  The document outlines options for test design, sample preparation, treatment application, and the use of controls (e.g., malodor-only samples) under controlled indoor conditions to maximize test sensitivity and reproducibility.

• Panel Selection and Training
  Guidance is provided for recruiting and training assessors with suitable olfactory acuity, and for ongoing monitoring to ensure consistency and minimize experimental variability.

• Product Categories
  The guide is applicable to a wide array of consumer products, such as:

  • Air care (sprays, solids, candles, filters)
  • Fabric care (detergents, fabric conditioners, sprays)
  • Surface care (cleaners for carpets, hard surfaces)
  • Pet care (litter treatments, odor removers)

• Application Flexibility
  The procedures are designed as guidance rather than prescriptive methods. Users select the most appropriate options and statistical analyses based on their specific experimental objectives.

Applications

ASTM E1593-21 is fundamental for several practical uses in product development and quality assurance:

• Product Development:
  Enables R&D teams to screen and optimize formulas for deodorizing efficacy prior to market launch, supporting innovation in air care, home care, and fabric care solutions.
• Quality Control:
  Facilitates consistent internal testing and benchmarking of production lots to maintain odor reduction performance standards over time.
• Comparative Testing:
  Assists in evaluating the relative efficacy of competing products or formulations under standardized, repeatable conditions, ensuring unbiased results.
• Claim Support:
  Generates technical evidence for malodor reduction claims using validated sensory methodology, which may be included as part of a broader claims substantiation strategy.
• Consumer Relevance:
  Although the guide focuses on controlled sensory testing, data produced under ASTM E1593-21 can inform further studies with consumers to assess the real-world impact of odor reduction technologies.

Related Standards

• ASTM E253 – Terminology Relating to Sensory Evaluation of Materials and Products
• ASTM E544 – Practice for Referencing Suprathreshold Odor Intensity
• ASTM E1207 – Guide for Sensory Evaluation of Axillary Deodorancy (for products intended for underarm deodorancy)
• ASTM E1958 – Guide for Sensory Claim Substantiation
• ASTM E2263 – Test Method for Paired Preference Test

Refer to these documents for extended terminology, methodological guidance, and claims substantiation practices that complement ASTM E1593-21.

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Keywords: ASTM E1593-21, malodor reduction efficacy, sensory testing, air care products, odor elimination standards, consumer product assessment, deodorizing product evaluation, ASTM sensory evaluation, odor control standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1593 − 21
Standard Guide for
Assessing the Efficacy of Consumer Products in Reducing
the Perception of Malodor
This standard is issued under the fixed designation E1593; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope environment—can deliver results with high internal validity.
Internalvalidityreferstostudiesdesignedsothatvariablesthat
1.1 This guide covers standard procedures for the quantita-
mayobscurethefindingofaneffectarecontrolledormanaged.
tive sensory assessment of perceived olfactory intensity of
It is important to recognize that internal validity does not
malodors for the purpose of assessing the malodor reduction
assureexternalvalidity.Arobustsupportstrategyforamalodor
efficacy of consumer products including, but not limited to, air
efficacy claim is stronger with additional evidence that the
care, fabric care, home care, pet care, and similar products.
sensory effect is consumer perceivable. Such evidence of
1.2 This guide is not intended to cover axillary deodorancy;
product’s malodor reduction efficacy may be, for example,
refer instead to Guide E1207.
drawn from studies where consumers serve as evaluators, or
1.3 Malodors may be from natural or synthetic sources.
where the product is used to reduce malodors in a more
1.4 This guide is a compendium of information or series of representative environment (for example, at home).
options that does not recommend a specific course of action.
1.8 This standard does not purport to address all of the
The user of this guide is responsible for identifying the most
safety concerns, if any, associated with its use. It is the
appropriate test design and using the appropriate statistical
responsibility of the user of this standard to establish appro-
tools to address the experimental design.
priate safety, health, and environmental practices and deter-
1.5 This guide is designed to provide guidance in product
mine the applicability of regulatory limitations prior to use.
formulation and new product development, and for quality
Specific precautionary statements are given in Section 6 and
control issues.
X3.6.3.7.
1.6 The scope of this guide does not include all guidance
1.9 This international standard was developed in accor-
necessary to support claims. For further guidance the re-
dance with internationally recognized principles on standard-
searcher may refer to Guide E1958. The usage of methods
ization established in the Decision on Principles for the
described in this guide can be used as part of a comprehensive
Development of International Standards, Guides and Recom-
claims support strategy for technical types of claims (such as
mendations issued by the World Trade Organization Technical
claimsthattheproductwillcreateasensorychangewhenused
Barriers to Trade (TBT) Committee.
on malodor). However, this guide does not address other
important elements of the claim support strategy, including
2. Referenced Documents
determining the statistical confidence requirements, or deter-
2.1 ASTM Standards:
mination of the consumer relevance of the data obtained, as
E253Terminology Relating to Sensory Evaluation of Mate-
discussed in 1.7.
rials and Products
1.7 Thetestingofproductsdesignedtoreducemalodorsvia
E544Practice for Referencing Suprathreshold Odor Inten-
sensory testing as outlined in the present Guide can yield
sity
technical support for products’ efficacy claims. The methods
E1207Guide for Sensory Evaluation of Axillary Deodor-
describedinthisguide—assesorswithidentifiedsensoryacuity
ancy
andtrained,malodorsthatmaybelab-createdorsynthetic,and
E1958Guide for Sensory Claim Substantiation
controlled exposure to malodors in a controlled indoor
E2263Test Method for Paired Preference Test
This guide is under the jurisdiction of ASTM Committee E18 on Sensory
Evaluation and is the direct responsibility of Subcommittee E18.07 on Personal
Care and Household Evaluation. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 15, 2021. Published August 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1994. Last previous edition approved in 2013 as E1593–13. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1593-21. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1593 − 21
3. Terminology assessmentsareperformedundercontrolledconditionsinorder
to determine the effect of a given product in reducing the
3.1 The definitions in this section are specific to this
malodor intensity.
standard for the purpose of interpreting this standard; in some
4.3 Products should be tested in a manner that maximizes
cases they may be different than those found in Terminology
E253. For other definitions, see terms described in Terminol- testsensitivitywhileremainingconsistentwithnormalproduct
usage.
ogy E253
3.2 Definitions:
5. Significance and Use
3.2.1 activation time—the length of time between when a
5.1 The purpose of this guide is to assess the ability of
product is used (or activated) and its evaluation by assessors.
consumer products to reduce malodor intensity from a control
3.2.2 dose—a general term for the amount of product used
state.Severalexperimentalhypothesesarepossible,depending
on the objective of the test. Possible objectives with respective
3.2.3 malodor control—a test sample or experimental treat-
hypotheses are given in Appendix X1.
mentconsistingofachamberorsubstratecontainingamalodor
without any malodor reducing treatment (sometimes called a
5.2 Many consumer products are sold commercially with
negative control).
the intent of providing a means of improving the odor quality
of a volume of air, or the odor quality of a substrate such as
3.2.4 malodor counteraction—a reduction in malodor per-
ceptionachievedbyphysicalremovalorchemicalalterationof fabric or household surfaces, relative to some existing envi-
ronmental condition. In the case of air care products, this
the malodor molecule.
typically involves the application of an odorous substance into
3.2.5 malodor masking—the reduction or elimination of
the air space by means of some active or passive mechanism
olfactory perception of a defined odor stimulus by means of
(for example, by spraying, or by evaporation). This procedure
another volatile substance without the physical removal or
is also applicable to other mechanisms of odor reduction (for
chemical alteration of the defined stimulus from the environ-
example, air filtration, chemical reactions, etc.).
ment.
5.3 Selectionofrepresentativemalodorsourcesisofcritical
3.2.6 malodor reduction effıcacy—the degree to which a
importance.The malodor source must be readily available and
product treatment or process reduces perceived malodor inten-
of a consistent odor quality. A reasonable malodor source
sity.
should be chemically and aesthetically correct. The experi-
3.2.7 positive control—ablindedsampleknowntohavelow
menter and client must agree upon the appropriateness of a
ornomalodor.Thismaybe,forexample,aproductonlysample
malodor source before further details of the test design are
or a reference product known to be effective at removing
worked out. Experimental variation will be reduced by using
malodor.
uniform malodor sources. Information collected on malodor
3.2.8 product control—a treatment consisting of a chamber
reduction will thus be more comparable from experiment to
or treated substrate containing product only (no malodor).
experiment and from laboratory to laboratory.
3.2.9 synthetic or surrogate model—a mixture of chemical
5.4 The procedure recommended can be used for assess-
components formulated to represent an odor.
ment of the malodor reduction and elimination efficacy of
consumer products including: air fresheners, air filtration
3.2.10 treatment—within this guide, treatment refers to the
products, aerosol/spray and continuous/solid air freshener
act or manner in which the product or process being investi-
products, candles, fabric care products including detergents
gatedisdispensedintothevolumeofairortopicallyappliedto
andfabricenhancing/conditioningproducts,surfacecareprod-
the study substrate for testing.
ucts including carpet care products, surface cleaning products
such as sprays etc., pet care products, and other products
4. Summary of Guide
intended to deliver a malodor reduction benefit. It should be
4.1 This guide is limited to the assessment of a specific
noted that while product evaluations are fundamentally the
malodor intensity by trained assessors under controlled labo-
same, different treatment or measurement techniques may be
ratory conditions. Methods that reflect actual consumer envi-
necessary because of inherent differences in the product
ronmental conditions are valid for selected sensory tasks, but
delivery systems.
they may be less sensitive. Methods that include highly
5.5 Temporal Aspects—The procedures herein can be ap-
controlled environmental conditions will increase the chances
plied to evaluate temporal aspects of product performance,
ofdetectingsmalldifferencesamongtreatments.Thedegreeof
suchasdetermininghowlongittakesforaproducttowork,or
control of extraneous experimental factors in an experiment is
how long it takes malodor to develop (for example, after
variable and is governed by the purpose of the test, amount of
treatment, etc.).
resources available to provide that degree of control, and
desired level of statistical sensitivity (see Appendix X3).
5.6 These procedures can be used to assess efficacy against
any standard malodor, regardless of the mechanism of odor
4.2 The procedures described herein provide for the selec-
removal.
tion and training of individuals to perform the functions of
trained assessors, and for the presentation of treated or un- 5.7 This guide is designed to provide guidance in product
treated samples, or both, to these trained assessors, in order to formulation and new product development, and for quality
evoke an assessment of perceived malodor intensity. These control issues.
E1593 − 21
6. Precautions testing methods for assessing ability include discrimination,
ranking, or intensity scaling, or a combination thereof. It is
6.1 Extreme care should be taken when handling and
good practice to conduct such assessments in the manner in
preparing samples under conditions that will maintain the
which the assessors will ultimately make evaluations, for
odorless state of the laboratory area.
example on fabric or in chambers.
6.2 Appropriate safety precautions should be taken when
7.4.2 The malodorant(s) in question should be the focus of
handling all chemical compounds.
the screening. Several concentrations of each of the malodor-
ant(s) should be chosen for this testing. The concentrations
7. Selection of Assessors
should be representative of intensities experienced during
7.1 Purpose—The purpose of this series of tests is to screen
regularmalodorefficacytestingtoincludehighandlowlevels.
potential assessors for a malodor efficacy panel.The screening 7.4.3 Selected concentrations of each of the malodorants
determines olfactory acuity, specific anosmia to malodorants
should be presented to recruits in a manner consistent with the
and fragrance ingredients that are likely components in con- difference testing procedure described in ASTM MNL26 (2).
sumerproducts,interest,and,ifso,availabilityfortesting.Itis
7.4.4 The selection of assessors should first rest on the
very important to know if assessors have any anosmias and, if results of the acuity testing. Additional subjective tests for
so,towhatparticularodors.Thiswillallowthemtobeexcused
selected assessors may be necessary to accept or reject them
from evaluating odor control products used against that par- (that is, attitude, timeliness, and compliance). If the number of
ticular odor. This screening of potential assessors should be
recruits is greater than required, the additional subjective
divided into two phases (interview and testing). The two information gained from the interview process should be
phases should be conducted as separate sessions (see STP 758
applied.
(1) for assessor selection considerations).
8. Training of Panel
7.2 Assessor Recruitment—In order to ensure an adequate
number of assessors for testing, a larger number should be
8.1 Purpose—The purpose of the experimental procedures
recruited. This is to offset the attrition experienced in
discussed here is to recommend a program of training for a
interviewing,testing,andtrainingbasedontheassumptionthat
group of qualified individuals to perform malodor reduction
roughly half the number of recruits will fail.Afinal number of
efficacy assessment. Malodor reduction can be measured as
assessors should be selected in advance. A panel size of 20 is
changes in detection, discrimination, intensity,
typically recommended for a scaling experiment. However,
characterization, or combinations thereof.
through monitoring panel performance, the researcher may
8.2 Panel training is accomplished in three phases: (1)
determinethatfewerthan20assessorsareacceptable.Referto
orientation, (2) mock efficacy studies, and (3) regular monitor-
ASTM MNL26 (2) or Kraemer and Thieman (3), or both, for
ingofassessorperformance(see STP758 (1)forpaneltraining
other considerations affecting sample size.
considerations).
7.3 Interview (15 min)—During the interview, it is impor-
8.2.1 Orientation—One or more orientation sessions should
tantthatthetrainedassessorsfullyunderstandthenatureofthe
be held for the trainees. The objective of the orientation is to
testing for which he/she is volunteering, including the types of
familiarize the assessors with the task of evaluating malodor
malodorstobeusedinmalodortesting.Ifthepotentialassessor
reduction efficacy as objectively as possible in order to reduce
does not feel he/she can overcome any negative biases in
the experimental error. Orientation should include introducing
experiencing such malodors, they should not participate. In
the assessors to each other and to test personnel involved in
addition,he/sheshouldbemadeawareofandagreetothetime
conducting malodor efficacy, explaining the purpose of mal-
commitmentexpected,schedulingoftesting,and“goodtesting
odor reduction efficacy testing in the company, orienting and
practices” such as the following: refraining from smoking,
training assessors to the selected rating scale, discussing
refraining from wearing perfumed or fragranced personal care
typical testing procedures, describing assessor’s
products on the day of testing, and so forth.Ashort question-
responsibilities, and providing a tour of the facilities used to
naire regarding the person’s physical health should be admin-
conduct malodor efficacy testing.
istered to determine whether the candidate has nasal or upper
8.2.2 Mock Effıcacy Study—One or more mock studies for
respiratory allergies, asthma, or is prone to frequent colds.
training may be arranged to give the assessors the opportunity
These conditions may result in a decrease in an assessor’s
to practice making efficacy evaluations. Such practice tests
sensitivity and performance.
should include treatments with known efficacy against the
selected malodor and may include all types of products that
7.4 Testing—Thekeyconceptinthisphaseofscreeningisto
will be tested by the panel. The study may be similar to an
ensure that the panel is able to (1) discriminate, and (2) detect
actual efficacy test in order to smooth the transition from
the designated malodorant(s). A sequential analysis technique
training to regular testing. Assessors should be given the
is one way to accomplish this (4).
opportunitytopracticeanddemonstratetheabilitytomakethe
7.4.1 Recruits should be tested to determine their ability to
required odor measurements, which may include intensity
detect and discriminate the malodors of interest. Appropriate
judgments, discrimination tests, odor characterizations, or
combinations thereof. In addition, through discussion and
feedback, assessors should be trained to “smell through” any
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. extraneous odor(s), such as the fragrance of the product, to
E1593 − 21
evaluate malodor intensity. Individual assessor performance 9.3 Natural malodors must also be chosen with care and
can be monitored during the training phase by analyzing for mayrequirevalidationsimilartosyntheticodors.Forexample,
individual assessor variability. Individuals who exhibit errant the malodor source may require heating, or blending of
results should undergo additional training and monitoring. ingredients such as in the case of a cooking odor. Odors on
However, repeated underperformers should be dropped from fabricthatareproducedbymicrobialactionmaybeinfluenced
the panel. by storage temperature, time, and moisture conditions. Such
8.2.3 Replications (for Assessor Monitoring)—After initial preparationmethodsandingredientchoicesmustbedeveloped
training, performance of assessors should be monitored to to produce odors that are as similar as possible to those
ensure consistency over time. This may be done by using experienced by the end consumer.
replications. The number of replications obtained varies with
9.4 The following criteria may be used to validate the
the degree of experience of the panel. A group that is being
choice of malodorant(s). One or all of these criteria may be
used for the first time or is in the orientation stage may require
appropriate, depending on the specific mode of action of the
more replications. The task, the intensity of the malodor, the
products.
test facility capacity, and the olfactory fatigue all need to be
9.4.1 Chemical Composition—If the product is meant to
considered when determining the number of replications. A
function by some physical method (other than masking), the
minimumoftworeplicationsisrequiredinordertoensurethat
chemical composition of the malodor sample is critical. The
the data are reproducible and one can monitor the assessor’s
chemical compositions of the malodor sample and samples of
performance.
theactualmalodorsourceshouldbedeterminedbyappropriate
analytical methods. Similarities and differences should be
9. Selection and Qualification of Malodor Sources
noted and evaluated for relative importance.
9.4.2 Multiple Choice Data—The data generated from a
9.1 Synthetic malodors are used widely in odor testing
multiple choice descriptor panel can be used to support a
involving the determination of product efficacy. The synthetic
potential malodor sample. Malodor samples should be pre-
malodor is used to represent the actual odor. Synthetic mal-
sented at appropriate intensities. The number of assessors,
odors have several advantages, most of which center on
malodor samples, and possible descriptors should be consid-
avoiding logistical and safety difficulties associated with using
ered before beginning any such test. Other factors to consider
the actual malodor source (for instance, fecal odors). Another
include the sample presentation, descriptor terms, and accep-
advantage is better reproducibility. In general, laboratory
tancecriteria.Foranexampleballotandprofiles,seeAppendix
efficacy testing involves the screening of various materials for
their efficacy in reducing the perceived level of malodor X2.
9.4.3 Odor Profile Data—The data generated from an odor
intensity.
profile panel can also be used to support a potential malodor
9.1.1 When synthetic malodors are used, they must be
sample. Although this procedure is more time and resource
developed to be as similar as possible to the odor experienced
intensive, it will provide more detailed information on major
by the consumer, in both the chemical and perceptual sense.
and minor odor descriptors that are detected in a potential
Thus, any synthetic malodor sample model used should have
malodor sample. The considerations discussed relative to the
been tested previously for its validity as a sample of the actual
multiple-choicetestsshouldalsobeconsideredforodorprofile
odor.
tests.Forinformationconcerningodorprofiling,seeDravnieks
9.1.2 There are many potential techniques for accomplish-
(5) or Jeltema and Southwick (6), or both.
ing validation. The application of each technique, be it
descriptive, discrimination, or consumer testing, must be
9.5 Toxicological Review—The malodor sample should be
evaluated on its own merit. It is not within the scope of this
subjected to a safety review by the appropriate health and
guide to enumerate the details of all techniques; however, it is
safety professionals to ensure that human health is not
imperative that the results should indicate clearly that the
endangered, and that assessors are not being exposed to
synthetic malodor is reasonably similar to the actual malodor
regulated substances at levels exceeding those allowed by law.
as experienced by the consumer.
10. Sample Preparation Procedure
9.2 The use of surrogate malodors may also be appropriate.
Surrogates are created to represent natural odors when prepa- 10.1 Sample Preparation:
ration of the natural odor would be too complex or raise safety 10.1.1 Sample preparation is dependent on the use of the
concerns. Surrogate malodors may be created for example, by product and nature of the individual malodor standard.
using a standard set of microbes, nutrients, and incubation 10.1.2 Measurement of product performance requires a
conditionstorepresentamalodorthatmaybenaturallyformed minimumoftwotestsamples:(1)a(usuallyblinded)untreated
under more complex conditions. Wood smoke may be consid- malodor control, and (2) a combination of malodor and
ered as surrogate for tobacco smoke. product. If desired, the test can include a sample consisting of
9.2.1 The development of surrogate malodor should follow a product alone, that is, without malodor. Several different test
the same principles as outlined above for synthetic odors samples may be evaluated in the same panel session. The test
regarding consumer relevance and chemical behavior. Results samples are in addition to any identified control such as
of the tests with surrogate malodors will need validation to described in 11.2.1.
verify that the response of the surrogate is the same as the 10.1.3 The number of test samples that can be evaluated in
actual malodor. a single session will depend on the number of chambers or
E1593 − 21
substrates available, nature of the malodor, and skill of the 10.2.3 The selection of the malodor dosage and activation
panel.Theexperimenterwillneedtodetermineempiricallythe time will depend upon the objective of the test. A dose-
limitations imposed by the malodor and by the trained asses- responsestudyofthemalodormaybeusefultohelpdetermine
sors. The study protocol may need to include one or more the malodor dose relevant for the test objective. Depending
upon the conditions and length of the test, it may be necessary
approaches to address odor adaptation/fatigue. Approaches
may include time between samples, the number of samples to periodically re-dose. The re-dose amount for the malodor
may be different than the initial dose depending on the test
evaluated between breaks in testing, smelling a neutral
substance, and/or others. Verification of adequate recovery conditions and can also be evaluated with a dose-response
study.Activation time will depend on the chemical or biologi-
time, and appropriate number of total samples can be accom-
cal processes involved in the generation of the malodor. A
plished by, for example, looking for order effects in the results
time-intensity study may be useful for determining the activa-
of replicated test samples.
tion time for the malodor to reach a consumer, or technology,
10.1.4 The application of malodor and treatment to the
relevant intensity level.
chambers or substrates usually occurs sequentially chronologi-
cally. The application order will depend on the specific
10.3 Product Treatment Examples—The following guide-
treatmentuse.Typicaltreatmentsareasfollows:(1)malodoris
lines provide illustrations for some specific product forms; the
applied first, and product is applied second, and (2) product is
principles of this guide are not limited to only these examples.
applied first, and malodor is applied second. Depending on the
10.3.1 Aerosol Spray and Trigger Pump-type Delivery Sys-
objective of the testing, test chambers may be re-dosed one or
tems:
more times by the malodor or fragrance. In tests where either
10.3.1.1 Prior to applying product to the malodor in the
the malodor or treatment need to be re-applied to assess
chamber or on to a substrate, spray the products for 1 to 2 s
product performance, the treatment sequence can be repeated
(aerosol type sprayer) or 2 to 3 pumps (trigger type sprayer)
or modified. Modifications include re-dosing of the malodor
into a fume hood to clear the dip tubes.
only,re-applicationofthetreatmentonly,orsomecombination
10.3.1.2 There are two generally used methods of applica-
the two steps, which will depend on experiment design and
tion: equal spray time and equal weights. Note the weights
product being tested. Testing products where treatment effects
when using equal spray time.Adjust the spray time or weight
improve with additional applications is one example where
amount according to the volume of the chamber or area of
re-dosing may be important. An additional example where
substrate. Regardless of brand, valve type, actuator type, etc.,
re-dosing is applicable is when testing for the prevention of a
equal spray time will provide an estimate of product efficacy
malodorfromre-occurringafteraninitial,largerdosehasbeen
that will be representative of the total product being evaluated
mitigated.
(not including appearance attributes). Reminder: care should
betakenwhenselectingthespraytimetoensureconcentrations
10.1.5 For chamber studies: after the appropriate exposure
time for the malodorant or product, or both, has elapsed, both do not get too high, especially if using small chambers.
the malodorant and the product may or may not be removed 10.3.1.3 Apply the product to the chamber atmosphere
from the chamber(s). This decision must be made considering using a broad, sweeping motion and by directing the spray
the goal of the specific test.While removing the odorants, take toward the ceiling. This should be completed at least 5 min
care to preserve the odorless state of the surrounding labora- prior to evaluation by the assessors.
tory.
10.3.2 Continuous/Solid-type Delivery Systems—Prior to
conducting a test for effectiveness, determine a proper activa-
10.1.6 For chamber testing, the appropriateness of con-
tiontime.Thisintervalmayvaryfromafewminutestoseveral
trolled air flow or static air conditions must be determined
hours, depending on the mode of action and the volume of the
basedonthespecifictestobjectives.Amixermaybeneededif
test room.
staticconditionsareselected.Careshouldbetakeninselecting
materials of the mixer (refer to X3.5) and to understand any 10.3.3 Air Filtration Products Systems—Priortoconducting
a test for effectiveness, determine a proper operating time and
impacts of the mixer on performance of the product being
evaluated. For example, air flows may influence the emission device settings for the air filtration device.This time may vary
rate of evaporation-type air care devices. from several minutes to several hours, depending on the mode
of action and the volume of the test room.
10.1.7 Toxicological Review—The product exposure should
10.3.4 Fabric Care Products—Prior to conducting a test for
be subjected to a safety review by the appropriate health and
effectiveness, determine the proper fabric type, application
safety professionals to ensure that human health is not
method, fabric condition for evaluation (for example, pre-
endangered, and that assessors are not being exposed to
wash, post wash, post-dry, etc), and laundry cycle conditions
regulated substances at levels exceeding those allowed by law.
for the fabric care product. These conditions may include, but
10.2 Malodor Treatments:
are not limited to, the proper water hardness, time, wash
10.2.1 Theselectionofarepresentativemalodorsourceisof
temperature, any pretreatment, and type of drying method.
critical importance. No agreed-upon standards exist. Review
Pretreatment, such as soaking the fabric or applying product
5.3, Section 9, and Appendix X2.
directly to the fabric, will require determining the incubation
10.2.2 Testsaretypicallysetuptoevaluateasinglemalodor time and the amount of product to be used. Recommendations
at a time. Tests in which assessors are exposed to multiple fromthemanufacturerofthefabricshouldbeconsideredwhen
malodors can be confusing and may reduce test sensitivity. settingthetestprotocols.Theamountandtypeoffabricdrying
E1593 − 21
should be established in the test protocol. For non-laundering between each sample as described in 11.2.3. Chambers are
applications, use equal application time or amount depending evaluated in a manner that minimizes dilution of the chamber
on the product type.The type of product can be a fabric spray, contents. This is usually accomplished for chamber tests by
foam, solid, gel, liquid, or powder. having assessors smell the contents of the chamber through a
10.3.5 Pet Care Products—Prior to conducting a test for small port. For substrate tests, air flow in the room is
effectiveness, determine the proper operating time, application minimized during testing evaluations to minimize dilution.
amount, and method of application. Operating time may vary Verification of limited dilution may be accomplished by, for
from several hours to several weeks in the case of litter-type example, examining the evaluations for order effects.
products depending on the mode of action, soil amount,
11.2 Smelling Procedure:
amountofproductused,andthevolumeofthetestroom.Inthe
11.2.1 Amalodorcontrol(forexample,nil-product)sample,
case where the product is directly applied, such as a spray,
which all assessors smell first, can be used as a reference.This
foam, gel, liquid, or lotion, equal spray time or total amount
sample is identified as containing the malodor of interest
may be used as appropriate.
without treatment. Assessors then smell each test sample for
10.3.6 HouseholdCleaningProducts—Priortoconductinga
that particular odor.Tests may contain a blind malodor control
testforeffectiveness,determinetheproperapplicationamount,
in addition to the identified sample (see Section 10). The data
application method, activation time, and operating time. Equal
fromtheidentified,referencemalodorcontrolsampleisusually
dispensingtimeorapplicationamountmaybesuitabledepend-
not used in any analyses. In addition to acquainting the
ing on the product form and purpose, such as a powder
assessors with the malodor in question, this approach may
compared to a liquid carpet cleaner.Activation time can range
reducetheorderofpresentationeffectbetweensamplesaswell
from immediate to several hours and operating time can vary
as the effect of fatigue.
from several hours to several weeks depending on the mecha-
11.2.2 Smell the sample and evaluate the intensity of the
nism of action, cleaning surface area, cleaning surface
malodor using an appropriate sensory method (see ASTM
material, and product design. Product types include liquid,
MNL26 (2) or Practice E544). Other attributes such as overall
powders, sprays, gels, sticks, sponges, and foams.
intensity and qualitative change may also be assessed at this
10.3.7 Personal Care Products—(Not including axillary
time.
deodorants(TestMethodE1207.)Priortoconductingatestfor
11.2.3 The amount of time between samples depends on
effectiveness, determine the proper application amount, appli-
many factors (for example, adaptation and fatigue; see discus-
cation method, activation time, and operating time. Equal
sion at 10.1.3) and should be determined through experience
dispensing time or equal amounts of applied material may be
usinggoodexperimentaltechniques.Aminimumof1minuteis
appropriate depending on the form of the deodorizing product,
recommended and the time between samples is adjusted up
which may include, for example, gels, foams, liquids, solids,
depending on the adaptation of that particular malodor. Veri-
pastes, and creams.Application can be by way of a spray, bar,
fication of adequate recovery time, and appropriate number of
drop, sponge, or dispensed from a container (powder, for
totalsamplescanbeaccomplishedby,forexample,lookingfor
example).Dependingontheproduct,activationtimecanrange
order effects in the results of replicated test samples.
from an immediate response to several minutes depending on
11.2.4 Repeat 11.2.2 and 11.2.3 until all of the samples are
themechanismofaction,theregionofthebody,andindividual
evaluated. It is good practice for samples to include positive
physiology. Note that care must be taken to follow all appli-
controls (such as product-only controls) or reference products
cable ethical guidelines and regulations when conducting
(with known performance) and negative controls (such as
research with human subjects.
malodor without product), other controls (such as blank cham-
ber or clean substrate), and market targets, in addition to test
10.4 Cleaning—Re-used test facilities such as chambers
mustbethoroughlycleanedandfreefromanyodorsorresidual products.
contaminants before beginning a subsequent test. Cleaning
11.3 Whenever possible, the test should be scheduled in
procedures should be validated by for example, assessing the
such a way that only one assessor is in the chamber area at a
empty, cleaned chambers or other testing equipment for odor
time. If not possible, measures should be taken to ensure the
intensity.
independent nature of each evaluation, avoiding even uninten-
tional communication between assessors.
11. Sample Presentation to Assessors
11.1 For air evaluations, samples are presented to assessors 12. Data Collection and Analyses and Interpretation of
Results
in odor evaluation chambers. For substrate samples, substrates
may be presented directly to assessors. The samples should be
12.1 Sensory malodor intensity evaluations are obtained by
labeled with randomly generated, three-digit codes. Tempera-
using any industry recognized method (paired comparisons,
ture and relative humidity conditions should be controlled as
ranking, or scaling).
much as possible in the area where evaluations are taking
12.2 The statistical analyses to be conducted depend on the
place.Typicalconditionsare22°Cand50%relativehumidity.
objective of the test and the procedure used as well as test
Conditions should be recorded and be equivalent for all
design (see Appendix X1).
samples. Each assessor evaluates the samples following a
randomizationplan.Itshouldbenotedthatinordertomaintain 12.3 The interpretation of test results after statistical analy-
independence of judgments between samples, assessors rest in sis of the data are given in Appendix X1.
E1593 − 21
13. Keywords
13.1 aircareproducts;consumer;indoorair;malodorcoun-
teraction; sensory facilities; sensory test chamber construction
APPENDIXES
(Nonmandatory Information)
X1. EXPERIMENTAL DESIGNS AND ANALYSES FOR SELECTED EXPERIMENTAL OBJECTIVES
X1.1 Introduction X1.2.2.4 Statistical Approach—Null hypothesis (malodor
level): A+MAL=B+MAL; and statistical test: Student’s
X1.1.1 Experimental designs and statistical analyses are
paired ttest (two-tailed).
given for several experimental objectives that are encountered
X1.2.2.5 Possible Outcomes:
commonlyinmalodorcounteractionefficacytesting.Allofthe
(1) Reject Null Hypothesis—Conclude that one product is
designsinthissectionrequiretheuseofintensityratingscales.
more effective than the other in reducing the perception of
However, designs using ranking or paired comparisons may
malodor.
also be appropriately used. For further information on these
(2) Do Not Reject Null Hypothesis—Conclude that a dif-
techniques, see ASTM MNL26 (2).
ferencehasnotbeendemonstratedbetweenthetwoproductsin
X1.1.2 Before designing any study, several factors should
effectiveness, within the sensitivity of this experiment.
be considered carefully. Factors such as the background of the
X1.2.3 Design No. 3:
test, specific use for the data, resources available, and stage of
X1.2.3.1 Objective—Determine whether assessors are iden-
development will influence the choice of experimental design
tifyingthemalodoraccurately(thisisapanelmaintenanceand
and risk levels.The sensory professional should consult with a
screening test).
statistician to consider alternate designs or supplementary
X1.2.3.2 Research Question—Dotheassessorsindicatecor-
objectivesiftheydonothaverelevantstatisticalexpertise.See
rectly that a malodor difference exists between the malodor
also Kraemer and Thiemann (3).
alone and the product alone?
X1.2.3.3 Experimental Design—Two samples are evalu-
X1.2 Basic Test Designs
ated:malodoralone(MAL);andProductAalone(nomalodor).
X1.2.1 Design No. 1:
X1.2.3.4 Statistical Approach—Null hypothesis (malodor
X1.2.1.1 Objective—DeterminetheefficacyofProductAon
level): MAL ≤ A; and statistical test: Student’s paired t test
a given malodor.
(one-tailed).
X1.2.1.2 Research Question—Does Product A reduce the
X1.2.3.5 Possible Outcomes:
perception of malodor?
(1) Reject Null Hypothesis—Conclude that the assessors
X1.2.1.3 Experimental Design——Two samples are evalu-
are identifying the malodor correctly.
ated: (1) malodor alone (MAL); and (2) malodor plus Product
(2) Do Not Reject Null Hypothesis—Conclude that asses-
A (A+MAL).
sors may not be identifying the malodor correctly. This may
X1.2.1.4 Statistical Approach—Null hypothesis (malodor
indicate the need for retraining of the assessors on that
level): MAL ≤A+MAL; and statistical test: Student’s paired
malodor.Themalodorlevelshouldalsobeevaluated,asavery
t test (one-tailed).
low malodor level can cause this type of effect.
X1.2.1.5 Possible Outcomes:
X1.2.3.6 This test is often combined with another product
(1) Reject Null Hypothesis—Conclude that Product A is
and malodor test.
effective in reducing the perception of malodor.
(2) Do Not Reject Null Hypothesis—ConcludethatProduct
X1.3 Complex Test Designs
A has not been demonstrated to be effective in reducing
malodor, within the sensitivity of the experiment. X1.3.1 Often, more than one of the objectives discussed in
X1.3 may be addressed in a given design. This is achieved by
X1.2.2 Design No. 2:
combining the basic test designs that were discussed in X1.3.
X1.2.2.1 Objective—Determine the relative efficacy of two
Some of these are illustrated as follows:
products (A and B) on a given malodor.
X1.3.2 Design No. 1:
X1.2.2.2 Research Question—Does one of the products
reduce the perception of malodor more than the other? X1.3.2.1 Objectives:
(1)Determine the efficacy of each of three products on a
X1.2.2.3 Experimental Design—Two samples are evalu-
given malodor.
ated: (1) malodor plus ProductA(A+MAL); and (2) malodor
(2)Determine the relative efficacy of each product against
plus Product B (B+MAL).
the other products on a given malodor.
(1)Malodor plus Product A (A+MAL), and
(2)Malodor plus Product B (B+MAL). X1.3.2.2 Research Questions:
E1593 − 21
(1)Do any of the products reduce the perception of (1)Do any of the products reduce the perception of
malodor? malodor?
(2)Do the products differ in their ability to reduce the
(2)Do the products differ in their ability to reduce the
perception of malodor? perception of malodor?
X1.3.2.3 Experimental Design—Four samples are evalu-
(3)Do the assessors indicate correctly that a malodor
ated:
difference exists between the malodor alone and the products
(1)Malodor alone (MAL),
alone?
(2)Malodor plus Product A (A+MAL),
X1.3.3.3 Experimental Design—Five samples are evalu-
(3)Malodor plus Product B (B+MAL), and
ated:
(4)Malodor plus Product C (C+MAL).
(1)Malodor alone (MAL),
X1.3.2.4 Statistical Approach:
(2)Malodor plus Product A (A+MAL),
(1) Statistical Design—Randomized blocks or balanced
(3)Malodor plus Product B (B+MAL),
incomplete block designs. When conducting an incomplete
(4)Product A alone (no malodor), and
block design, the researcher must weigh the benefit of provid-
(5)Product B alone (no malodor).
ing fewer samples to each assessor against the risk of missing
X1.3.3.4 Statistical Approach:
an effect. When using an incomplete block design, product
(1) Statistical Design—Randomized blocks or balanced
variability and subject variability are combined, resulting in a
incomplete block designs.
less sensitive method for detecting product differences.
(2) Null Hypotheses:
(2) Null Hypotheses:
(a) Objective A:
(a) Objective A:
MAL# A1MAL (X1.3)
MAL# A1MAL (X1.1)
MAL# B1MAL
MAL# B1MAL
(b) Objective B:
MAL# C1MAL
A1MAL 5 B1MAL (X1.4)
(b) Objective B:
(c) Objective C:
A1MAL 5 B1MAL 5 C1MAL (X1.2)
MAL# A (X1.5)
(3) Statistical Tests:
MAL# B
(a)Two-way analysis of variance.
(3) Statistical Tests:
(b) Appropriate multiple-comparison procedures for
(a)Two-way analysis of variance.
multiple-test products versus control.
(b) Appropriate multiple-comparison procedures for
X1.3.2.5 Possible Outcomes:
multiple-test products versus control.
(1) Objective A:
(a) Reject Null Hypothesis—Concludethatatleastoneof
X1.3.3.5 Possible Outcomes:
theproductsiseffectiveinreducingtheperceptionofmalodor.
(1) Objective A:
Use an appropriate multiple-range test to determine which
(a) Reject Null Hypothesis—Concludethatatleastoneof
differences exist.
theproductsiseffectiveinreducingtheperceptionofmalodor.
(b) Do Not Reject Null Hypothesis—Conclude that none
Use an appropriate multiple-range test to determine which
of the products have been demonstrated to be effective in
differences exist.
reducing malodor, within the sensitivity of this experiment.
(b) Do Not Reject Null Hypothesis—Conclude that none
(2) Objective B:
of the products have been demonstrated to be effective in
(a) Reject Null Hypothesis—Concludethatatleasttwoof
reducing malodor, within the sensitivity of this experiment.
the products differ in their ability to reduce the perception of
(2) Objective B:
malodor. Use an appropriate multiple-range test to determine
(a) Reject Null Hypothesis—Conclude that one of the
which specific differences exist.
products is more effective than the other in reducing the
(b) Do Not Reject Null Hypothesis—Conclude that a
perception of malodor.
difference has not been demonstrated between the three prod-
(b) Do Not Reject Null Hypothesis—Conclude that a
ucts in their ability to reduce malodor, within the sensitivity of
differencehasnotbeendemonstratedbetweenthetwoproducts
this experiment.
in their ability to reduce malodor, within the sensitivity of this
X1.3.3 Design No. 2: experiment.
(3) Objective C:
X1.3.3.1 Objectives:
(1)Determine the efficacy of each of two products on a (a) Reject Null Hypothesis—Conclude that the assessors
are identifying the malodor correctly.
given malodor.
(2)Determine the relative efficacy of each product against (b) Do Not Reject Null Hypothesis—Conclude that the
assessors may not be identifying the malodor correctly. This
the other products on a given malodor.
(3)Determine whether assessors are identifying the mal- may indicate the need for retraining of the assessors on that
odor accurately. malodor. The malodor should also be evaluated, as a very low
X1.3.3.2 Research Questions: malodor level can cause this type of effect.
E1593 − 21
X1.3.4 Statistical Considerations for Complex Designs— X1.3.4.1 Comparisons of Interest—Allofthepossibleques-
The use of complex designs requires the consideration of tions of interest should be determined before a test is run.This
different statistical approaches. The statistician and sensory
permits the consideration of test designs that will reduce the
professional should meet to consider alternate designs or
complexit
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1593 − 13 E1593 − 21
Standard Guide for
Assessing the Efficacy of Air Care Consumer Products in
Reducing the Perception of Indoor Malodor
This standard is issued under the fixed designation E1593; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide covers standard procedures for the quantitative sensory assessment of perceived olfactory intensity of indoor
malodors for the purpose of assessing the deodorant efficacy of air care products. This guide is limited to static conditions
only.malodor reduction efficacy of consumer products including, but not limited to, air care, fabric care, home care, pet care, and
similar products.
1.2 It is recognized that, though sometimes desirable, the use of actual “live” or formulated live malodors is often impractical due
to the inherent variability of the malodor sources.This guide is not intended to cover axillary deodorancy; refer instead to Guide
E1207A live malodor source may be used when practical. However, the use of a formulated odor source has several advantages,
including consistency and availability.
1.3 The reader should be aware of good sensory practices when preparing the test environment or substrate, developing and
training the panel.Malodors may be from natural or synthetic sources.
1.4 The researcher is responsible for identifying the most appropriate test design and using the appropriate statistical tool to
address the experimental design.
1.4 This guide is a compendium of information or series of options that does not recommend a specific course of action. This guide
is not intended to support claims. If the research objective is claim related, then the researcher needs to refer to GuideThe user of
this guide is responsible for identifying the most appropriate test design and using the appropriate statistical tools to address the
experimental E1958.design.
1.5 This guide is designed to provide guidance in product formulation and new product development, and for quality control
issues.
1.6 The scope of this guide does not include all guidance necessary to support claims. For further guidance the researcher may
refer to Guide E1958. The usage of methods described in this guide can be used as part of a comprehensive claims support strategy
for technical types of claims (such as claims that the product will create a sensory change when used on malodor). However, this
guide does not address other important elements of the claim support strategy, including determining the statistical confidence
requirements, or determination of the consumer relevance of the data obtained, as discussed in 1.7.
This guide is under the jurisdiction of ASTM Committee E18 on Sensory Evaluation and is the direct responsibility of Subcommittee E18.07 on Personal Care and
Household Evaluation.
Current edition approved May 1, 2013July 15, 2021. Published May 2013August 2021. Originally approved in 1994. Last previous edition approved in 20062013 as
E1593 – 06.E1593 – 13. DOI: 10.1520/E1593-13.10.1520/E1593-21.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1593 − 21
1.7 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.testing of products designed to
reduce malodors via sensory testing as outlined in the present Guide can yield technical support for products’ efficacy claims. The
methods described in this guide—assesors with identified sensory acuity and trained, malodors that may be lab-created or
synthetic, and controlled exposure to malodors in a controlled indoor environment—can deliver results with high internal validity.
Internal validity refers to studies designed so that variables that may obscure the finding of an effect are controlled or managed.
It is important to recognize that internal validity does not assure external validity. A robust support strategy for a malodor efficacy
claim is stronger with additional evidence that the sensory effect is consumer perceivable. Such evidence of product’s malodor
reduction efficacy may be, for example, drawn from studies where consumers serve as evaluators, or where the product is used
to reduce malodors in a more representative environment (for example, at home).
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 6 and X3.6.3.7.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E253 Terminology Relating to Sensory Evaluation of Materials and Products
E544 Practice for Referencing Suprathreshold Odor Intensity
E1207 Guide for Sensory Evaluation of Axillary Deodorancy
E1958 Guide for Sensory Claim Substantiation
E2263 Test Method for Paired Preference Test
3. Terminology
3.1 The definitions in this section are specific to this standard for the purpose of interpreting this standard; in some cases they may
be different than those found in Terminology E253. For other definitions, see terms described in Terminology E253.
3.2 Definitions:
3.2.1 activation time—the length of time that between when a product is permitted to be exposed in a chamber prior to used (or
activated) and its evaluation by assessors.
3.2.2 assessor—dose—a general term for any individual responding to a stimuli in a sensory test.the amount of product used
3.2.3 malodor—an olfactory stimulus that, when detected, is considered unpleasant or undesirable by the target population.
3.2.3 malodor control—a test sample or experimental treatment consisting of a chamber or substrate containing a malodor without
any additional malodor reducing treatment.treatment (sometimes called a negative control).
3.2.4 malodor reduction effıcacy—counteraction—the degree to which a product treatment or process reduces perceived malodor
intensity. a reduction in malodor perception achieved by physical removal or chemical alteration of the malodor molecule.
3.2.5 malodor masking—the reduction or elimination of olfactory perception of a defined odor stimulus by means of another
odorousvolatile substance without the physical removal or chemical alteration of the defined stimulus from the environment.
3.2.6 malodor reduction effıcacy—the degree to which a product treatment or process reduces perceived malodor intensity.
3.2.7 panel—positive control—a group of assessors chosen to participate in a sensory test.blinded sample known to have low or
no malodor. This may be, for example, a productonly sample or a reference product known to be effective at removing malodor.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
E1593 − 21
3.2.8 product control—a treatment consisting of a chamber or treated substrate containing product only.only (no malodor).
3.2.9 spray time—the length of time in seconds for which an air care product is sprayed with the actuator depressed fully.
3.2.9 synthetic or surrogate model—a mixture of chemical components usedformulated to represent an odor.
3.2.11 trained assessor—an assessor with a high degree of sensory acuity and has experience in the test procedure and an
established ability to make consistent and repeated sensory assessments. A trained assessor functions as a member of a sensory
panel.
3.2.10 treatment—within this guide, treatment refers to the act or manner in which one treats the area or applies to a product or
process being investigated is dispensed into the volume of air or topically applied to the study substrate for testing.
4. Summary of Guide
4.1 This practiceguide is limited to the assessment of a specific malodor intensity by trained assessors under controlled laboratory
conditions. Methods that reflect actual consumer environmental conditions are valid for selected sensory tasks, but they may be
less sensitive. Methods that include highly controlled environmental conditions will increase the chances of detecting small
differences among treatments. The degree of control of extraneous experimental factors in an experiment is variable and is
governed by the purpose of the test, amount of resources available to provide that degree of control, and desired level of statistical
sensitivity (see Appendix X3).
4.2 The procedures described herein provide for the selection and training of individuals to perform the functions of trained
assessors, and for the presentation of treated or untreated samples, or both, to these trained assessors, in order to evoke an
assessment of perceived malodor intensity. These assessments are performed under controlled conditions in order to determine the
effect of a given product in reducing the malodor intensity.
4.3 Air care products Products should be tested in a manner that maximizes test sensitivity while remaining consistent with normal
product usage.
5. Significance and Use
5.1 The purpose of this guide is to assess the ability of air care consumer products to reduce indoor air malodor intensity from
a control state. Several experimental hypotheses are possible, depending on the objective of the test. Possible objectives with
respective hypotheses are given in Appendix X1.
5.2 Air careMany consumer products are sold commercially with the intent of providing a means of improving the odor quality
of a volume of air, or the odor quality of a substrate such as fabric or household surfaces, relative to some existing environmental
condition. This In the case of air care products, this typically involves the application of an odorous substance into the air space
by means of some mechanicalactive or physical mechanisms (for example, air fresheners). When the existing environment includes
some undesirable odor source or malodor, reduction of the perception of the malodor is usually accomplished with other odorous
substances by masking.passive mechanism (for example, by spraying, or by evaporation). This procedure is also applicable to other
mechanisms of odor reduction (for example, air filtration).filtration, chemical reactions, etc.).
5.3 Selection of representative malodor sources is of critical importance. The malodor source must be readily available and of a
consistent odor quality. A reasonable malodor source should be chemically and aesthetically correct. The experimenter and client
must agree upon the appropriateness of a malodor source before further details of the test design are worked out. Experimental
variation will be reduced by using uniform malodor sources. Information collected on malodor reduction will thus be more
comparable from experiment to experiment and from laboratory to laboratory.
5.4 The procedure recommended can be used for assessment of the malodor efficacy of air care product (for example, air
fresheners and air filtration).
5.5 These procedures can be used to assess efficacy against any standard malodor.
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5.4 These procedures are applicable in the assessment of any products that reduce the perception of any malodor, regardless of
the mode of action.The procedure recommended can be used for assessment of the malodor reduction and elimination efficacy of
consumer products including: air fresheners, air filtration products, aerosol/spray and continuous/solid air freshener products,
candles, fabric care products including detergents and fabric enhancing/conditioning products, surface care products including
carpet care products, surface cleaning products such as sprays etc., pet care products, and other products intended to deliver a
malodor reduction benefit. It should be noted that while product evaluations are fundamentally the same, different treatment or
measurement techniques may be necessary because of inherent differences in the product delivery systems.
5.6.1 These procedures are applicable to aerosol/spray and continuous/solid air freshener products, including candles. It should
be noted that while aerosol/spray and continuous/solid and candle product evaluations are fundamentally the same, different
treatment or measurement techniques may be necessary because of inherent differences in the product delivery systems.
5.6.2 These procedures are applicable to other air care products, including absorption, chemical reaction, and particulate removal.
5.5 Temporal Aspects—The procedures herein can be applied to evaluate temporal aspects of product performance, such as
determining how long it takes for a product to work, or how long it takes malodor to develop (for example, after treatment, etc.).
5.6 These procedures can be used to assess efficacy against any standard malodor, regardless of the mechanism of odor removal.
5.7 This guide is designed for use for product research to provide guidance in product formulation and new product development,
and for quality control issues.
6. Precautions
6.1 Extreme care should be taken when handling and preparing samples under conditions that will maintain the odorless state of
the laboratory area.
6.2 Appropriate safety precautions should be taken when handling all chemical compounds.
7. Selection of Assessors
7.1 Purpose—The purpose of this series of tests is to screen potential assessors for a malodor efficacy panel. The screening
determines olfactory acuity, specific anosmia to malodorants and fragrance ingredients that are likely components in air care
consumer products, interest, and, if so, availability for testing. It is very important to know if your assessors have any anosmias
and, if so, to what particular odors. This will allow them to be excused from evaluating odor control products used against that
particular odor. This screening of potential assessors should be divided into two phases (interview and testing). The two phases
should be conducted as separate sessions (see STP 758 (1) for panelist assessors’ assessor selection considerations).
7.2 PanelistAssessor Recruitment—In order to ensure an adequate number of assessors for testing, a larger number should be
recruited. This is to offset the attrition experienced in interviewing, testing, and training based on the assumption that roughly half
the number of recruits will fail. A final number of assessors should be selected in advance. A panel size of 20 is typically
recommended for a scaling experiment. However, through monitoring panel performance, the researcher may determine that fewer
than 20 assessors are acceptable. Refer to ASTM MNL 26MNL26 (2) or Kraemer and Thieman (3), or both, for other considerations
affecting sample size.
7.3 Interview (15 min)—During the interview, it is important that the trained assessors fully understand the nature of the testing
for which he/she is volunteering, including the types of malodors to be used in malodor testing. If the potential assessor does not
feel he/she can overcome any negative biases in experiencing such malodors, they should not participate. In addition, he/she should
be made aware of and agree to the time commitment expected, scheduling of testing, and “good testing practices” such as the
following: refraining from smoking for at least 1 h before testing, smoking, refraining from wearing perfume or after-shave
perfumed or fragranced personal care products on the day of testing, and so forth. A short questionnaire regarding the person’s
physical health should be administered to determine whether the candidate has nasal or upper respiratory allergies, asthma, or is
prone to frequent colds. These conditions may result in a decrease in an assessor’s sensitivity and performance.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
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7.4 Testing—The key concept in this phase of screening is to ensure that the panel is able to (1) discriminate, and (2) detect the
designated malodorant(s). A sequential analysis technique is one way to accomplish this (4).
7.4.1 Recruits should be tested to determine their ability to detect and discriminate the malodors of interest. Appropriate testing
methods for assessing ability include discrimination, ranking, or intensity scaling, or a combination thereof. It is good practice to
conduct such assessments in the manner in which the assessors will ultimately make evaluations, for example on fabric or in
chambers.
7.4.2 The malodorant(s) in question should be the focus of the screening. Several concentrations of each of the malodorant(s)
should be chosen for this testing. The concentrations should be representative of intensities experienced during regular malodor
efficacy testing to include high and low levels.
7.4.3 Selected concentrations of each of the malodorants should be presented to recruits in a manner consistent with the difference
testing procedure described in ASTM MNL 26MNL26 (2).
7.4.4 The selection of assessors should first rest on the results of the acuity testing. Additional subjective tests for selected
assessors may be necessary to accept or reject them (that is, attitude, timeliness, and compliance). If the number of recruits is
greater than required, the additional subjective information gained from the interview process should be applied.
8. Training of Panel
8.1 Purpose—The purpose of the experimental procedures discussed here is to recommend a program of training for a group of
qualified individuals to perform malodor efficacy assessments. reduction efficacy assessment. Malodor reduction can be measured
as changes in detection, discrimination, intensity, characterization, or combinations thereof.
8.2 Panel training is accomplished in three phases: (1) orientation, (2) mock deodorancyefficacy studies, and (3) regular
monitoring of panelistassessor performance (see STP 758 (1) for panel training considerations).
8.2.1 Orientation—One or more orientation sessions should be held for the trainees. The objective of the orientation is to
familiarize the assessors with the task of evaluating malodor reduction efficacy as objectively as possible in order to reduce the
experimental error. Orientation should include introducing the assessors to each other and to test personnel involved in conducting
malodor efficacy, explaining the purpose of malodor reduction efficacy testing in the company, orienting and training assessors to
the selected rating scale, discussing typical testing procedures, describing assessor’s responsibilities, and providing a tour of the
facilities used to conduct malodor efficacy testing.
8.2.2 Mock Effıcacy Study—One or more mock studies for training may be arranged to give the assessors the opportunity to
practice making efficacy evaluations. Products for testing should have known differences Such practice tests should include
treatments with known efficacy against the selected malodor and may include all types of air care products. products that will be
tested by the panel. The study may be similar to an actual efficacy test in order to smooth the transition from training to regular
testing. Assessors should be given the opportunity to practice and demonstrate the ability to make odor intensity judgments. the
required odor measurements, which may include intensity judgments, discrimination tests, odor characterizations, or combinations
thereof. In addition, through discussion and feedback, assessors should be trained to “smell through” any extraneous odor(s), such
as the fragrance of the product, to evaluate malodor intensity. Individual assessor performance can be monitored during the training
phase by analyzing for individual assessor variability. Individuals who exhibit errant results should undergo additional training and
monitoring. However, repeated underperformers should be dropped from the panel.
8.2.3 Replications—Replications (for Assessor Monitoring)—After initial training, performance of assessors should be monitored
to ensure consistency over time. This may be done by using replications. The number of replications obtained varies with the
degree of experience of the panel. A group that is being used for the first time or is in the orientation stage may require more
replications. The task, the intensity of the malodor, the test facility capacity, and the olfactory fatigue all need to be considered
when determining the number of replications. A minimum of two replications is required in order to ensure that the data are
reproducible and one can monitor the assessor’s performance.
9. Selection and Qualification of Malodor ModelsSources
9.1 Synthetic samples of malodors are used widely in odor testing involving the determination of air care product efficacy.
Synthetics product efficacy. The synthetic malodor is used to represent the actual odor. Synthetic malodors have several
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advantages, most of which center on avoiding logistical and safety difficulties associated with using the actual malodor source (for
instance, fecal odors). Another advantage is better reproducibility. In general, laboratory efficacy testing involves the screening of
various materials for their efficacy in reducing the perceived level of malodor intensity. The synthetic malodor is used to represent
the actual odor. The validity of results from these types of tests is maximized when the actual malodor source is used under
conditions representative of the consumer environment.
9.1.1 When synthetic samplesmalodors are used, they must be developed to be as similar as possible to the odor experienced by
the consumer, in both the chemical and perceptual sense. Thus, any synthetic malodor sample model used should have been tested
previously for its validity as a sample of the actual odor.
9.1.2 There are many potential techniques for accomplishing validation. The application of each technique, be it descriptive,
discrimination, or consumer testing, must be evaluated on its own merit. It is not within the scope of this practiceguide to
enumerate the details of all techniques; however, it is imperative that the results should indicate clearly that the synthetic
mixturemalodor is reasonably similar to the actual malodor as experienced by the consumer.
9.2 The use of surrogate malodors may also be appropriate. Surrogates are created to represent natural odors when preparation of
the natural odor would be too complex or raise safety concerns. Surrogate malodors may be created for example, by using a
standard set of microbes, nutrients, and incubation conditions to represent a malodor that may be naturally formed under more
complex conditions. Wood smoke may be considered as surrogate for tobacco smoke.
9.2.1 The development of surrogate malodor should follow the same principles as outlined above for synthetic odors regarding
consumer relevance and chemical behavior. Results of the tests with surrogate malodors will need validation to verify that the
response of the surrogate is the same as the actual malodor.
9.3 Natural malodors must also be chosen with care and may require validation similar to synthetic odors. For example, the
malodor source may require heating, or blending of ingredients such as in the case of a cooking odor. Odors on fabric that are
produced by microbial action may be influenced by storage temperature, time, and moisture conditions. Such preparation methods
and ingredient choices must be developed to produce odors that are as similar as possible to those experienced by the end
consumer.
9.4 The following criteria may be used to validate the choice of malodorant(s). One or all of these criteria may be appropriate,
depending on the specific mode of action of the products.
9.4.1 Chemical Composition—If the product is meant to function by some physical method (other than masking), the chemical
composition of the malodor sample is critical. The chemical compositions of the malodor sample and samples of the actual malodor
source should be determined by appropriate analytical methods. Similarities and differences should be noted and evaluated for
relative importance.
9.4.2 Multiple Choice Data—The data generated from a multiple choice descriptor panel can be used to support a potential
malodor sample. Malodor samples should be presented at appropriate intensities. The number of assessors, malodor samples, and
possible descriptors should be considered before beginning any such test. Other factors to consider include the sample presentation,
descriptor terms, and acceptance criteria. For an example ballot and profiles, see Appendix X2.
9.4.3 Odor Profile Data—The data generated from an odor profile panel can also be used to support a potential malodor sample.
Although this procedure is more time and resource intensive, it will provide more detailed information on major and minor odor
descriptors that are detected in a potential malodor sample. The considerations discussed relative to the multiple choice
multiple-choice tests should also be considered for odor profile tests. For information concerning odor profiling, see Dravnieks (5)
or Jeltema and Southwick (6), or both.
9.5 Toxicological Review—The syntheticmalodor sample should be subjected to a safety review by the appropriate health and
safety professionals to ensure that human health is not endangered, and that panelistsassessors are not being exposed to regulated
substances at levels exceeding those allowed by law.
10. Sample Preparation Procedure
10.1 Sample Preparation:
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10.1.1 Sample preparation is dependent on the use of the product and nature of the individual malodor standard.
10.1.2 Measurement of product performance requires a minimum of two test samples: (1) an a (usually blinded) untreated malodor
control, and (2) a combination of malodor and product. If desired, the test can include a sample consisting of a product alone, that
is, without malodor. Several different test samples may be evaluated in the same panel session. The test samples are in addition
to any identified control such as described in 11.2.1.
10.1.3 The number of test samples that can be evaluated in a single session will depend on the number of chambers or substrates
available, nature of the malodor, and skill of the panel. The experimenter will need to determine empirically the limitations
imposed by the malodor and by the trained assessors. The trained assessors’ evaluations need to be independent from the other
assessors. The main factor influencing the number of test samples is sensory adaptation/fatigue in detecting the malodor. Therefore,
plan adequate time to prevent adaptation between evaluations of the study protocol may need to include one or more approaches
to address odor adaptation/fatigue. Approaches may include time between samples, the number of samples evaluated between
breaks in testing, smelling a neutral substance, and/or others. Verification of adequate recovery time, and appropriate number of
total samples can be accomplished by, for example, looking for order effects in the results of replicated test samples.
10.1.4 The application of malodor and treatment to the chambers or substrates usually occurs sequentially chronologically. The
application order will depend on the specific treatment use. Typical treatments are as follows: (1) malodor is applied first, and
product is applied second;second, and (2) product is applied first, and malodor is applied second. Depending on the objective of
the testing, test chambers may be re-dosed one or more times by the malodor or fragrance. In tests where either the malodor or
treatment need to be re-applied to assess product performance, the treatment sequence can be repeated or modified. Modifications
include re-dosing of the malodor only, re-application of the treatment only, or some combination the two steps, which will depend
on experiment design and product being tested. Testing products where treatment effects improve with additional applications is
one example where re-dosing may be important. An additional example where re-dosing is applicable is when testing for the
prevention of a malodor from re-occurring after an initial, larger dose has been mitigated.
10.1.5 After For chamber studies: after the appropriate exposure time for the malodorant or product, or both, has elapsed, both
the malodorant and the product may or may not be removed from the chamber(s). This decision must be made considering the goal
of the specific test. While removing the odorants, take care to preserve the odorless state of the surrounding laboratory.
10.1.6 For chamber testing, the appropriateness of controlled air flow or static air conditions must be determined based on the
specific test objectives. A mixer may be needed if static conditions are selected. Care should be taken in selecting materials of the
mixer (refer to X3.5) and to understand any impacts of the mixer on performance of the product being evaluated. For example,
air flows may influence the emission rate of evaporation-type air care devices.
10.1.7 Toxicological Review—The product exposure should be subjected to a safety review by the appropriate health and safety
professionals to ensure that human health is not endangered, and that assessors are not being exposed to regulated substances at
levels exceeding those allowed by law.
10.2 Malodor Treatments:
10.2.1 The selection of a representative malodor source is of critical importance. No agreed-upon standards exist. Review 1.2, 5.3,
Section 9, and Appendix X2.
10.2.2 Tests are typically set up to evaluate a single malodor at a time. Tests in which assessors are exposed to different malodors
in different chambers multiple malodors can be confusing and may reduce test sensitivity.
10.2.3 The selection of the malodor dosage and activation time will depend upon the objective of the test. A dose-response study
of the malodor may be useful to help determine the malodor dose relevant for the test objective. Depending upon the conditions
and length of the test, it may be necessary to periodically re-dose. The re-dose amount for the malodor may be different than the
initial dose depending on the test conditions and can also be evaluated with a dose-response study. Activation time will depend
on the chemical or biological processes involved in the generation of the malodor. A time-intensity study may be useful for
determining the activation time for the malodor to reach a consumer, or technology, relevant intensity level.
10.3 Product Treatments: Treatment Examples—
10.3.1 The appropriateness of controlled air flow or static air conditions must be determined based on the specific test objectives.
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A mixer must be used if static conditions are selected.The following guidelines provide illustrations for some specific product
forms; the principles of this guide are not limited to only these examples.
10.3.1 Aerosol Spray and Trigger Pump-TypePump-type Delivery Systems:
10.3.1.1 Prior to applying product to the malodor in the chamber, chamber or on to a substrate, spray the products for 1 to 2 s
(aerosol type sprayer) or 2 to 3 pumps (trigger type sprayer) into a fume hood to clear the dip tubes.
10.3.1.2 There are two generally used methods of application: equal spray time and equal weights. Note the weights when using
equal spray time. Adjust the spray time or weight amount according to the volume of the chamber. chamber or area of substrate.
Regardless of brand, valve type, actuator type, etc., equal spray time will provide an estimate of product efficacy that will be
representative of the total product being evaluated (not including appearance attributes). Reminder: care should be taken when
selecting the spray time to ensure concentrations do not get too high, especially if using small chambers.
10.3.1.3 Apply the product to the chamber atmosphere using a broad, sweeping motion and by directing the spray toward the
ceiling. This should be completed at least 5 min prior to evaluation by the assessors.
10.3.2 Continuous/Solid-Type Delivery Systems—Prior Continuous/Solid-type Delivery Systems—Prior to conducting a test for
effectiveness, determine a proper activation time. It is difficult to give a specific value for this time interval since it will This
interval may vary from a few minutes to several hours, depending on the mode of action and the volume of the test room.
10.3.3 Air Filtration Products—Products Systems—Prior to conducting a test for effectiveness, determine a proper operating time
and device settings for the air filtration device. This time may vary from several minutes to several hours, depending on the mode
of action and the volume of the test room.
10.3.4 Fabric Care Products—Prior to conducting a test for effectiveness, determine the proper fabric type, application method,
fabric condition for evaluation (for example, pre-wash, post wash, post-dry, etc), and laundry cycle conditions for the fabric care
product. These conditions may include, but are not limited to, the proper water hardness, time, wash temperature, any pretreatment,
and type of drying method. Pretreatment, such as soaking the fabric or applying product directly to the fabric, will require
determining the incubation time and the amount of product to be used. Recommendations from the manufacturer of the fabric
should be considered when setting the test protocols. The amount and type of fabric drying should be established in the test
protocol. For non-laundering applications, use equal application time or amount depending on the product type. The type of
product can be a fabric spray, foam, solid, gel, liquid, or powder.
10.3.5 Pet Care Products—Prior to conducting a test for effectiveness, determine the proper operating time, application amount,
and method of application. Operating time may vary from several hours to several weeks in the case of litter-type products
depending on the mode of action, soil amount, amount of product used, and the volume of the test room. In the case where the
product is directly applied, such as a spray, foam, gel, liquid, or lotion, equal spray time or total amount may be used as appropriate.
10.3.6 Household Cleaning Products—Prior to conducting a test for effectiveness, determine the proper application amount,
application method, activation time, and operating time. Equal dispensing time or application amount may be suitable depending
on the product form and purpose, such as a powder compared to a liquid carpet cleaner. Activation time can range from immediate
to several hours and operating time can vary from several hours to several weeks depending on the mechanism of action, cleaning
surface area, cleaning surface material, and product design. Product types include liquid, powders, sprays, gels, sticks, sponges,
and foams.
10.3.7 Personal Care Products—(Not including axillary deodorants (Test Method E1207.) Prior to conducting a test for
effectiveness, determine the proper application amount, application method, activation time, and operating time. Equal dispensing
time or equal amounts of applied material may be appropriate depending on the form of the deodorizing product, which may
include, for example, gels, foams, liquids, solids, pastes, and creams. Application can be by way of a spray, bar, drop, sponge, or
dispensed from a container (powder, for example). Depending on the product, activation time can range from an immediate
response to several minutes depending on the mechanism of action, the region of the body, and individual physiology. Note that
care must be taken to follow all applicable ethical guidelines and regulations when conducting research with human subjects.
10.4 Cleaning—Re-used test facilities such as chambers must be thoroughly cleaned and free from any odors or residual
contaminants before beginning a subsequent test. Cleaning procedures should be validated by for example, assessing the empty,
cleaned chambers or other testing equipment for odor intensity.
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11. Sample Presentation to Assessors
11.1 Samples For air evaluations, samples are presented to assessors in odor evaluation chambers. The chambersFor substrate
samples, substrates may be presented directly to assessors. The samples should be labeled with randomly generated, three digit
three-digit codes. Temperature and relative humidity conditions should be controlled as much as possible. possible in the area
where evaluations are taking place. Typical conditions are 22°C22 °C and 50 % relative humidity, respectively. humidity.
Conditions should be recorded and be equivalent for all chambers.samples. Each assessor evaluates the chamberssamples
following a randomization plan. It should be noted that in order to maintain independence of judgments between samples, assessors
should be required to rest in between each sample as described in 11.211.2.3. Chambers should be are evaluated in a manner that
minimizes dilution of the chamber contents. This is usually accomplished for chamber tests by having assessors smell the contents
of the chamber through a small port. For substrate tests, air flow in the room is minimized during testing evaluations to minimize
dilution. Verification of limited dilution may be accomplished by, for example, examining the evaluations for order effects.
11.2 The smelling procedure is as follows:Smelling Procedure:
11.2.1 An initial malodor-only booth, A malodor control (for example, nil-product) sample, which all assessors smell first, is
recommended. This boothcan be used as a reference. This sample is identified as containing the malodor of interest. interest
without treatment. Assessors then smell each test boothsample for that particular odor. Tests may contain a blind malodor control
in addition to the identified sample (see Section 10). The data from the initial, malodor-only booth are identified, reference
malodorcontrol sample is usually not used in any analyses. In addition to acquainting the assessors with the malodor in question,
this approach may reduce the order of presentation effect between samples as well as the effect of fatigue.
11.2.2 Smell the chamber contents sample and evaluate the intensity of the malodor using an appropriate sensory method (see
ASTM MNL 26MNL26 (2) or PracticesPractice E544). Other attributes such as overall intensity and qualitative change may also
be assessed at this time.
11.2.3 The amount of waiting time between each evaluation depends on the time it takes to overcome sensory adaptation/fatigue.
The amountsamples depends on many factors (for example, adaptation and fatigue; see discussion at 10.1.3of time depends on
many factors and ) and should be determined through experience using good experimental techniques. A minimum of 1 minminute
is recommended and the time between samples is adjusted up depending on the adaptation of that particular malodor. Verification
of adequate recovery time, and appropriate number of total samples can be accomplished by, for example, looking for order effects
in the results of replicated test samples.
11.2.4 Repeat 11.2.111.2.2 and 11.2.211.2.3 until all of the samples are evaluated. Samples may consist of positive It is good
practice for samples to include positive controls (such as product-only controls) or reference products (with known performance)
and negative controls (product without malodor and malodor (such as malodor without product), other controls (such as blank
chamber), chamber or clean substrate), and market targets, as well asin addition to test products.
11.3 Whenever possible, the test should be scheduled in such a way that only one panelistassessor is in the chamber area at a time.
If not possible, measures should be taken to ensure the independent nature of each evaluation, avoiding even unintentional
communication between assessors.
12. Data Collection and Analyses and Interpretation of Results
12.1 Sensory malodor intensity evaluations are obtained by using any industry recognized method (paired comparisons, ranking,
or scaling).
12.2 The statistical analyses to be conducted depend on the objective of the test and the procedure used as well as test design (see
Appendix X1).
12.3 The interpretation of test results after statistical analysis of the data are given in Appendix X1.
13. Keywords
13.1 air care products; consumer; indoor air; malodor counteraction; sensory facilities; sensory test chamber construction
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APPENDIXES
(Nonmandatory Information)
X1. EXPERIMENTAL DESIGNS AND ANALYSES FOR SELECTED EXPERIMENTAL OBJECTIVES
X1.1 Introduction
X1.1.1 Experimental designs and statistical analyses are given for several experimental objectives that are encountered commonly
in malodor counteraction efficacy testing. All of the designs in this section require the use of intensity rating scales. However,
designs using ranking or paired comparisons may also be appropriately used. For further information on these techniques, see
ASTM MNL 26MNL26 (2).
X1.1.2 Before designing any study, several factors should be considered carefully. Factors such as the background of the test,
specific use for the data, resources available, and stage of development will influence the choice of experimental design and risk
levels. Ideally, the The sensory professional should meetconsult with a statistician to consider alternate designs or supplementary
objectives.objectives if they do not have relevant statistical expertise. See also Kraemer and Thiemann (3).
X1.2 Definitions of Statistical Terms
X1.2.1 Alpha Level (α)—Represents the probability of rejecting the null hypothesis when it is true, thus concluding falsely that
there is a difference (typically set at α< 0.05).
X1.2.2 Beta Level (β)—Represents the probability of failing to reject the null hypothesis when it is false, thus concluding falsely
that there is no difference (typically set at β < 0.20).
X1.2.3 Power of the Test (1 − β)—Represents the probability of rejecting the null hypothesis when it is false, thus concluding
correctly that there is a difference. This can also be viewed as the likelihood of detecting the minimum level of interest (typically
set at 1 - β > 0.80).
X1.2.4 Minimum Level of Interest—Represents the smallest difference that is important to detect.
X1.2.5 Product Sample Size— Should be based on the alpha and beta levels selected, minimum level of interest, and inherent
variability of the evaluation (scaling) method. See ASTM MNL 26(2) or Kraemer and Thiemann (3).
X1.2 Basic Test Designs
X1.2.1 Design No. 1:
X1.2.1.1 Objective—Determine the efficacy of Product A on a given malodor.
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X1.2.1.2 Research Question—Does Product A reduce the perception of malodor?
X1.2.1.3 Experimental Design—Two—Two samples are evaluated: (1) malodor alone (MAL); and (2) malodor plus Product A
(A + MAL).
X1.2.1.4 Statistical Approach—Null hypothesis (malodor level): MAL ≤ A + MAL; and statistical test: Student’s paired t test
(one-tailed).
X1.2.1.5 Possible Outcomes:
(1) Reject Null Hypothesis—Conclude that Product A is effective in reducing the perception of malodor.
(1) Reject Null Hypothesis—Conclude that Product A is effective in reducing the perception of malodor.
(2) Do Not Reject Null Hypothesis—Conclude that Product A has not been demonstrated to be effe
...