ASTM F2101-23

Standard Test Method for Evaluating the Bacterial Filtration Efficiency (BFE) of Medical Face Mask Materials, Using a Biological Aerosol of <emph type="ital" >Staphylococcus aureus</emph>

SIGNIFICANCE AND USE
5.1 This test method offers a procedure for evaluation of medical face mask materials for bacterial filtration efficiency. This test method does not define acceptable levels of bacterial filtration efficiency. Therefore, when using this test method it is necessary to describe the specific condition under which testing is conducted.  
5.2 This test method has been specifically designed for measuring bacterial filtration efficiency of medical face masks, using Staphylococcus aureus as the challenge organism. The use of S. aureus is based on its clinical relevance as a leading cause of nosocomial infections.  
5.3 This test method has been designed to introduce a bacterial aerosol challenge to the test specimens at a flow rate of 28.3 L/mm (1 ft3/min). This flow rate is within the range of normal respiration and within the limitations of the cascade impactor.  
5.4 Unless otherwise specified, the testing shall be performed with the inside of the medical face mask in contact with the bacterial challenge. Testing may be performed with the aerosol challenge directed through either the face side or liner side of the test specimen, thereby allowing evaluation of filtration efficiencies which relate to both patient-generated aerosols and wearer-generated aerosols.  
5.5 Degradation by physical, chemical, and thermal stresses could negatively impact the performance of the medical face mask material. The integrity of the material can also be compromised during use by such effects as flexing and abrasion, or by wetting with contaminants such as alcohol and perspiration. Testing without these stresses could lead to a false sense of security. If these conditions are of concern, evaluate the performance of the medical face mask material for bacterial filtration efficiency following an appropriate pretreatment technique representative of the expected conditions of use. Consider preconditioning to assess the impact of storage conditions and shelf life for disposable products, an...
SCOPE
1.1 This test method is used to measure the bacterial filtration efficiency (BFE) of medical face mask materials, employing a ratio of the upstream bacterial challenge to downstream residual concentration to determine filtration efficiency of medical face mask materials.  
1.2 This test method is a quantitative method that allows filtration efficiency for medical face mask materials to be determined. The maximum filtration efficiency that can be determined by this method is 99.9 %.  
1.3 This test method does not apply to all forms or conditions of biological aerosol exposure. Users of the test method should review modes for worker exposure and assess the appropriateness of the method for their specific applications.  
1.4 This test method evaluates medical face mask materials as an item of protective clothing but does not evaluate materials for regulatory approval as respirators. If respiratory protection for the wearer is needed, a NIOSH-certified respirator should be used. Relatively high bacterial filtration efficiency measurements for a particular medical face mask material do not ensure that the wearer will be protected from biological aerosols, since this test method primarily evaluates the performance of the composite materials used in the construction of the medical face mask and not its design, fit, or facial-sealing properties.  
1.5 Units—The values stated in SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance of the standard.  
1.6 This test method does not address breathability of the medical face mask materials or any other properties affecting the ease of breathing through the medical face mask material.  
1.7 This test method may also be used to measure the bacterial filtration efficienc...

General Information

• Status: Published
• Publication Date: 28-Feb-2023
• ICS: 11.140 - Hospital equipment
• Technical Committee: F23 - Personal Protective Clothing and Equipment
• Drafting Committee: F23.40 - Biological

Relations

• Refers: ASTM E171/E171M-11(2020) - Standard Practice for Conditioning and Testing Flexible Barrier Packaging
• Effective Date: 01-May-2020
• Refers: ASTM E171/E171M-11(2015) - Standard Practice for Conditioning and Testing Flexible Barrier Packaging
• Effective Date: 01-Oct-2015
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM F1494-13 - Standard Terminology Relating to Protective Clothing
• Effective Date: 01-Jul-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E171/E171M-11 - Standard Practice for Conditioning and Testing Flexible Barrier Packaging
• Effective Date: 15-Nov-2011
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM F1494-03(2011) - Standard Terminology Relating to Protective Clothing
• Effective Date: 01-Feb-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM E177-08 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2008
• Refers: ASTM E177-06b - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 15-Nov-2006
• Refers: ASTM E177-06a - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2006
• Refers: ASTM E691-05 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2005

Overview

ASTM F2101-23 is the standard test method developed by ASTM International for evaluating the bacterial filtration efficiency (BFE) of medical face mask materials. This method utilizes a biological aerosol containing Staphylococcus aureus to challenge mask materials. The BFE test quantifies the percentage of aerosolized bacteria filtered by a mask material-an essential indicator for manufacturers, regulatory agencies, and healthcare facilities to assess protective performance. However, this standard does not define acceptable BFE performance criteria; testing conditions and interpretation of results must be specified as appropriate for intended use.

Key Topics

• Bacterial Filtration Efficiency (BFE)

  • Measures the ability of medical face mask materials to prevent passage of aerosolized bacteria.
  • Expressed as the ratio of the upstream bacterial challenge to downstream residual bacteria.
  • The maximum measurable filtration efficiency by this method is 99.9%.

• Test Parameters

  • Utilizes Staphylococcus aureus as the challenge organism due to its clinical relevance.
  • Aerosol is introduced at a flow rate of 28.3 L/min, reflecting typical respiratory rates.
  • Test can be performed with exposure on either the face-side or liner-side to assess protection from patient- and wearer-generated aerosols.

• Limitations and Considerations

  • The test evaluates only material filtration-does not assess mask fit, design, or total respiratory protection.
  • It does not address breathability or other properties affecting user comfort.
  • Preconditioning and pretreatment testing are advised if real-world stresses (flexing, wetting, storage conditions) are concerns.

Applications

ASTM F2101-23 is widely used to support:

• Manufacturers

  • Provides objective data for product development and quality control of medical face masks, surgical masks, and related protective materials.
  • Helps in certifying mask material performance for healthcare markets.

• Healthcare Facilities

  • Assists in procurement by ensuring incoming face mask and protective clothing meet specified BFE criteria.

• Regulatory and Testing Laboratories

  • Standardizes BFE evaluation for comparative assessment of mask materials and products.

• Broader Use

  • The method may also be applicable to other porous medical products, such as:
    • Surgical drapes and gowns
    • Sterile barrier systems

Important Note: This standard is not intended to certify respiratory protective devices (respirators). For protection against airborne pathogens, appropriate NIOSH-certified respirators should be selected.

Related Standards

For comprehensive assessment of medical face mask and protective material performance, ASTM F2101-23 should be used in conjunction with related standards, including:

• ASTM F1494 - Terminology Relating to Protective Clothing
• ASTM E171/E171M - Practice for Conditioning and Testing Flexible Barrier Packaging
• ANSI/ASQ Z1.4 - Sampling Procedures and Tables for Inspection by Attributes
• ISO 2859-1 - Sampling Plans for Inspection by Attributes

These standards provide additional guidance for terminology, sample conditioning, statistical quality control, and testing protocols, ensuring a robust and standardized approach to evaluating protective medical materials.

---

By following ASTM F2101-23, manufacturers and testing laboratories can reliably assess bacterial filtration efficiency, supporting the delivery of safe and effective medical face masks and related products essential for infection control in healthcare settings.

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: F2101 − 23
Standard Test Method for
Evaluating the Bacterial Filtration Efficiency (BFE) of
Medical Face Mask Materials, Using a Biological Aerosol of
Staphylococcus aureus
This standard is issued under the fixed designation F2101; 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.
INTRODUCTION
Workers, primarily those in the healthcare profession involved in treating and caring for individuals
injured or sick, as well as the patient, can be exposed to biological aerosols capable of transmitting
disease. These diseases, which may be caused by a variety of microorganisms, can pose significant
risks to life and health. Since engineering controls cannot eliminate all possible exposures, attention
is placed on reducing the potential of airborne exposure through the use of medical face masks.
1. Scope 1.5 Units—The values stated in SI units or inch-pound units
are to be regarded separately as standard. The values stated in
1.1 This test method is used to measure the bacterial
each system may not be exact equivalents; therefore, each
filtration efficiency (BFE) of medical face mask materials,
system shall be used independently of the other. Combining
employing a ratio of the upstream bacterial challenge to
values from the two systems may result in nonconformance of
downstream residual concentration to determine filtration effi-
the standard.
ciency of medical face mask materials.
1.6 This test method does not address breathability of the
1.2 This test method is a quantitative method that allows
medical face mask materials or any other properties affecting
filtration efficiency for medical face mask materials to be
the ease of breathing through the medical face mask material.
determined. The maximum filtration efficiency that can be
determined by this method is 99.9 %. 1.7 This test method may also be used to measure the
bacterial filtration efficiency (BFE) of other porous medical
1.3 This test method does not apply to all forms or condi-
products such as surgical gowns, surgical drapes, and sterile
tions of biological aerosol exposure. Users of the test method
barrier systems.
should review modes for worker exposure and assess the
1.8 This standard does not purport to address all of the
appropriateness of the method for their specific applications.
safety concerns, if any, associated with its use. It is the
1.4 This test method evaluates medical face mask materials
responsibility of the user of this standard to establish appro-
as an item of protective clothing but does not evaluate
priate safety, health, and environmental practices and deter-
materials for regulatory approval as respirators. If respiratory
mine the applicability of regulatory limitations prior to use.
protection for the wearer is needed, a NIOSH-certified respi-
1.9 This international standard was developed in accor-
rator should be used. Relatively high bacterial filtration effi-
dance with internationally recognized principles on standard-
ciency measurements for a particular medical face mask
ization established in the Decision on Principles for the
material do not ensure that the wearer will be protected from
Development of International Standards, Guides and Recom-
biological aerosols, since this test method primarily evaluates
mendations issued by the World Trade Organization Technical
the performance of the composite materials used in the
Barriers to Trade (TBT) Committee.
construction of the medical face mask and not its design, fit, or
facial-sealing properties.
2. Referenced Documents
2.1 ASTM Standards:
This test method is under the jurisdiction of ASTM Committee F23 on Personal
Protective Clothing and Equipment and is the direct responsibility of Subcommittee
F23.40 on Biological. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 1, 2023. Published March 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2001. Last previous edition approved in 2022 as F2101 – 22. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F2101-23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2101 − 23
E171/E171M Practice for Conditioning and Testing Flexible 3.2 For definitions of other protective clothing-related terms
Barrier Packaging used in this test method, refer to Terminology F1494.
E177 Practice for Use of the Terms Precision and Bias in
4. Summary of Test Method
ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to
4.1 The medical face mask material is clamped between a
Determine the Precision of a Test Method six-stage cascade impactor and an aerosol chamber. The
F1494 Terminology Relating to Protective Clothing
bacterial aerosol is introduced into the aerosol chamber using
a nebulizer and a culture suspension of Staphylococcus aureus.
2.2 ANSI/ASQ Standard:
The aerosol is drawn through the medical face mask material
ANSI/ASQ Z1.4 Sampling Procedures and Tables for In-
using a vacuum attached to the cascade impactor. The six-stage
spection by Attributes
4 cascade impactor uses six agar plates to collect aerosol droplets
2.3 ISO Standard:
which penetrate the medical face mask material. Control
ISO 2859-1 Sampling Plans for Inspection by Attributes
samples are collected with no test specimen clamped in the test
2.4 Military Standard:
apparatus to determine the upstream aerosol counts.
MIL-STD 36954C (1973) Military Specification: Mask,
4.2 The agar plates from the cascade impactor are incubated
Surgical, Disposable
for 48 h and counted to determine the number of viable
particles collected. The ratio of the upstream counts to the
3. Terminology
downstream counts collected for the test specimen are calcu-
3.1 Definitions:
lated and reported as a percent bacterial filtration efficiency.
3.1.1 aerosol, n—a suspension of solid or liquid particles in
a gas.
5. Significance and Use
3.1.2 agar, n—a semi-solid culture medium used to support
5.1 This test method offers a procedure for evaluation of
the growth of bacteria and other microorganisms.
medical face mask materials for bacterial filtration efficiency.
3.1.3 airborne exposure pathways, n—inhalation routes of This test method does not define acceptable levels of bacterial
exposure to the medical face mask wearer.
filtration efficiency. Therefore, when using this test method it is
necessary to describe the specific condition under which testing
3.1.4 bacterial filtration effıciency (BFE), n—the effective-
is conducted.
ness of a medical face mask material in preventing the passage
of aerosolized bacteria, expressed in the percentage of a known
5.2 This test method has been specifically designed for
quantity that does not pass the medical face mask material at a
measuring bacterial filtration efficiency of medical face masks,
given aerosol flow rate.
using Staphylococcus aureus as the challenge organism. The
use of S. aureus is based on its clinical relevance as a leading
3.1.5 biological aerosol, n—a suspension of particles con-
cause of nosocomial infections.
taining biological agents which have been dispersed in a gas.
3.1.6 blood-borne pathogen, n—an infectious bacterium or 5.3 This test method has been designed to introduce a
bacterial aerosol challenge to the test specimens at a flow rate
virus, or other disease-inducing microbe carried in blood or
other potentially infectious body fluids. of 28.3 L/mm (1 ft /min). This flow rate is within the range of
normal respiration and within the limitations of the cascade
3.1.7 body fluid, n—any liquid produced, secreted, or ex-
impactor.
creted by the human body.
5.4 Unless otherwise specified, the testing shall be per-
3.1.8 medical face mask, n—an item of protective clothing
formed with the inside of the medical face mask in contact with
designed to protect portions of the wearer’s face, including the
the bacterial challenge. Testing may be performed with the
mucous membrane areas of the wearer’s nose and mouth, from
aerosol challenge directed through either the face side or liner
contact with blood and other body fluids during medical
side of the test specimen, thereby allowing evaluation of
procedures.
filtration efficiencies which relate to both patient-generated
3.1.8.1 Discussion—Medical face masks also function to
aerosols and wearer-generated aerosols.
partly limit the spread of biological contamination from the
mask wearer (health care provider) to the patient.
5.5 Degradation by physical, chemical, and thermal stresses
could negatively impact the performance of the medical face
3.1.9 protective clothing, n—an item of clothing that is
mask material. The integrity of the material can also be
specifically designed and constructed for the intended purpose
compromised during use by such effects as flexing and
of isolating all or part of the body from a potential hazard; or,
abrasion, or by wetting with contaminants such as alcohol and
isolating the external environment from contamination by the
perspiration. Testing without these stresses could lead to a false
wearer of the clothing.
sense of security. If these conditions are of concern, evaluate
the performance of the medical face mask material for bacterial
filtration efficiency following an appropriate pretreatment tech-
Available from American Society for Quality (ASQ), 600 N. Plankinton Ave.,
Milwaukee, WI 53203, http://www.asq.org.
nique representative of the expected conditions of use. Con-
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
sider preconditioning to assess the impact of storage conditions
4th Floor, New York, NY 10036, http://www.ansi.org.
and shelf life for disposable products, and the effects of
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. laundering and sterilization for reusable products.
F2101 − 23
5.6 If this procedure is used for quality control, perform 7. Reagents
proper statistical design and analysis of larger data sets. This 6
7.1 Tryptic Soy Agar (TSA).
type of analysis includes, but is not limited to, the number of
7.2 Tryptic Soy Broth (TSB).
individual specimens tested, the average percent bacterial
filtration efficiency, and standard deviation. Data reported in
7.3 Peptone Water.
this way help to establish confidence limits concerning product
7.4 Staphylococcus aureus, ATCC #6538.
performance. Examples of acceptable sampling plans are found
in references such as ANSI/ASQ Z1.4 and ISO 2859-1.
8. Hazards
8.1 Sterilize all apparatus and supplies which come into
6. Apparatus and Materials
contact with the bacterial challenge suspension by autoclaving
6.1 Apparatus:
at 121 to 123 °C for a minimum of 15 min. Extreme care must
6.1.1 Autoclave, capable of maintaining 121 to 123 °C.
be taken to avoid contamination of the laboratory spaces by
6.1.2 Incubator, capable of maintaining 37 6 2 °C. complete sterilization or high-level disinfection of all apparatus
6.1.3 Analytical Balance, capable of weighing 0.001 g. and supplies. This will reduce the possibility of laboratory
6.1.4 Vortex Mixer, capable of mixing the contents of 16 mm contamination.
by 150 mm test tubes.
8.2 Staphylococcus aureus is common to the normal flora of
6.1.5 Orbital Shaker, capable of achieving 100 to 250 rpm.
the body, however, it is a leading cause of nosocomial
6.1.6 Refrigerator, capable of maintaining 2 to 8 °C.
infections and is a human pathogen. Technicians conducting
6.1.7 Six-Stage Viable Particle Cascade Impactor.
the testing must have proper microbiological training. Gloves
6.1.7.1 The use of plastic petri dishes is permitted but their
and other protective clothing equipment should be worn during
dimensions should be as close as possible to the dimensions of
testing to prevent contamination.
the glass dishes for which the impactor is designed. The
8.3 All aerosols must be contained to prevent exposure and
agar-to-grid distance for each stage of the impactor is also very
reduce laboratory contamination.
important. The volume of agar should be determined according
to the type of petri dishes selected. A volume of 27 mL is
9. Media Preparation
generally recommended for the glass dishes offered with the
9.1
...

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: F2101 − 22 F2101 − 23
Standard Test Method for
Evaluating the Bacterial Filtration Efficiency (BFE) of
Medical Face Mask Materials, Using a Biological Aerosol of
Staphylococcus aureus
This standard is issued under the fixed designation F2101; 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.
INTRODUCTION
Workers, primarily those in the healthcare profession involved in treating and caring for individuals
injured or sick, as well as the patient, can be exposed to biological aerosols capable of transmitting
disease. These diseases, which may be caused by a variety of microorganisms, can pose significant
risks to life and health. Since engineering controls cannot eliminate all possible exposures, attention
is placed on reducing the potential of airborne exposure through the use of medical face masks.
1. Scope
1.1 This test method is used to measure the bacterial filtration efficiency (BFE) of medical face mask materials, employing a ratio
of the upstream bacterial challenge to downstream residual concentration to determine filtration efficiency of medical face mask
materials.
1.2 This test method is a quantitative method that allows filtration efficiency for medical face mask materials to be determined.
The maximum filtration efficiency that can be determined by this method is 99.9 %.
1.3 This test method does not apply to all forms or conditions of biological aerosol exposure. Users of the test method should
review modes for worker exposure and assess the appropriateness of the method for their specific applications.
1.4 This test method evaluates medical face mask materials as an item of protective clothing but does not evaluate materials for
regulatory approval as respirators. If respiratory protection for the wearer is needed, a NIOSH-certified respirator should be used.
Relatively high bacterial filtration efficiency measurements for a particular medical face mask material do not ensure that the
wearer will be protected from biological aerosols, since this test method primarily evaluates the performance of the composite
materials used in the construction of the medical face mask and not its design, fit, or facial-sealing properties.
1.5 Units—The values stated in SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in nonconformance of the standard.
1.6 This test method does not address breathability of the medical face mask materials or any other properties affecting the ease
of breathing through the medical face mask material.
This test method is under the jurisdiction of ASTM Committee F23 on Personal Protective Clothing and Equipment and is the direct responsibility of Subcommittee
F23.40 on Biological.
Current edition approved Aug. 1, 2022March 1, 2023. Published September 2022March 2023. Originally approved in 2001. Last previous edition approved in 20192022
as F2101 – 19.F2101 – 22. DOI: 10.1520/F2101-22.10.1520/F2101-23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2101 − 23
1.7 This test method may also be used to measure the bacterial filtration efficiency (BFE) of other porous medical products such
as surgical gowns, surgical drapes, and sterile barrier systems.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
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:
E171/E171M Practice for Conditioning and Testing Flexible Barrier Packaging
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
F1494 Terminology Relating to Protective Clothing
2.2 ANSI/ASQ Standard:
ANSI/ASQ Z1.4 Sampling Procedures and Tables for Inspection by Attributes
2.3 ISO Standard:
ISO 2859-1 Sampling Plans for Inspection by Attributes
2.4 Military Standard:
MIL-STD 36954C (1973) Military Specification: Mask, Surgical, Disposable
3. Terminology
3.1 Definitions:
3.1.1 aerosol, n—a suspension of solid or liquid particles in a gas.
3.1.2 agar, n—a semi-solid culture medium used to support the growth of bacteria and other microorganisms.
3.1.3 airborne exposure pathways, n—inhalation routes of exposure to the medical face mask wearer.
3.1.4 bacterial filtration effıciency (BFE), n—the effectiveness of a medical face mask material in preventing the passage of
aerosolized bacteria, expressed in the percentage of a known quantity that does not pass the medical face mask material at a given
aerosol flow rate.
3.1.5 biological aerosol, n—a suspension of particles containing biological agents which have been dispersed in a gas.
3.1.6 blood-borne pathogen, n—an infectious bacterium or virus, or other disease-inducing microbe carried in blood or other
potentially infectious body fluids.
3.1.7 body fluid, n—any liquid produced, secreted, or excreted by the human body.
3.1.8 medical face mask, n—an item of protective clothing designed to protect portions of the wearer’s face, including the mucous
membrane areas of the wearer’s nose and mouth, from contact with blood and other body fluids during medical procedures.
3.1.8.1 Discussion—
Medical face masks also function to partly limit the spread of biological contamination from the mask wearer (health care provider)
to the patient.
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.
Available from American Society for Quality (ASQ), 600 N. Plankinton Ave., Milwaukee, WI 53203, http://www.asq.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
F2101 − 23
3.1.9 protective clothing, n—an item of clothing that is specifically designed and constructed for the intended purpose of isolating
all or part of the body from a potential hazard; or, isolating the external environment from contamination by the wearer of the
clothing.
3.2 For definitions of other protective clothing-related terms used in this test method, refer to Terminology F1494.
4. Summary of Test Method
4.1 The medical face mask material is clamped between a six-stage cascade impactor and an aerosol chamber. The bacterial
aerosol is introduced into the aerosol chamber using a nebulizer and a culture suspension of Staphylococcus aureus. The aerosol
is drawn through the medical face mask material using a vacuum attached to the cascade impactor. The six-stage cascade impactor
uses six agar plates to collect aerosol droplets which penetrate the medical face mask material. Control samples are collected with
no test specimen clamped in the test apparatus to determine the upstream aerosol counts.
4.2 The agar plates from the cascade impactor are incubated for 48 h and counted to determine the number of viable particles
collected. The ratio of the upstream counts to the downstream counts collected for the test specimen are calculated and reported
as a percent bacterial filtration efficiency.
5. Significance and Use
5.1 This test method offers a procedure for evaluation of medical face mask materials for bacterial filtration efficiency. This test
method does not define acceptable levels of bacterial filtration efficiency. Therefore, when using this test method it is necessary
to describe the specific condition under which testing is conducted.
5.2 This test method has been specifically designed for measuring bacterial filtration efficiency of medical face masks, using
Staphylococcus aureus as the challenge organism. The use of S. aureus is based on its clinical relevance as a leading cause of
nosocomial infections.
5.3 This test method has been designed to introduce a bacterial aerosol challenge to the test specimens at a flow rate of 28.3 L/mm
(1 ft /min). This flow rate is within the range of normal respiration and within the limitations of the cascade impactor.
5.4 Unless otherwise specified, the testing shall be performed with the inside of the medical face mask in contact with the bacterial
challenge. Testing may be performed with the aerosol challenge directed through either the face side or liner side of the test
specimen, thereby allowing evaluation of filtration efficiencies which relate to both patient-generated aerosols and wearer-
generated aerosols.
5.5 Degradation by physical, chemical, and thermal stresses could negatively impact the performance of the medical face mask
material. The integrity of the material can also be compromised during use by such effects as flexing and abrasion, or by wetting
with contaminants such as alcohol and perspiration. Testing without these stresses could lead to a false sense of security. If these
conditions are of concern, evaluate the performance of the medical face mask material for bacterial filtration efficiency following
an appropriate pretreatment technique representative of the expected conditions of use. Consider preconditioning to assess the
impact of storage conditions and shelf life for disposable products, and the effects of laundering and sterilization for reusable
products.
5.6 If this procedure is used for quality control, perform proper statistical design and analysis of larger data sets. This type of
analysis includes, but is not limited to, the number of individual specimens tested, the average percent bacterial filtration efficiency,
and standard deviation. Data reported in this way help to establish confidence limits concerning product performance. Examples
of acceptable sampling plans are found in references such as ANSI/ASQ Z1.4 and ISO 2859-1.
6. Apparatus and Materials
6.1 Apparatus:
6.1.1 Autoclave, capable of maintaining 121 to 123 °C.
F2101 − 23
6.1.2 Incubator, capable of maintaining 37 6 2 °C.
6.1.3 Analytical Balance, capable of weighing 0.001 g.
6.1.4 Vortex Mixer, capable of mixing the contents of 16 mm by 150 mm test tubes.
6.1.5 Orbital Shaker, capable of achieving 100 to 250 rpm.
6.1.6 Refrigerator, capable of maintaining 2 to 8 °C.
6.1.7 Six-Stage Viable Particle Cascade Impactor.
6.1.7.1 The use of plastic petri dishes is permitted but their dimensions should be as close as possible to the dimensions of the
glass dishes for which the impactor is designed. The agar-to-grid distance for each stage of the impactor is also very important.
The volume of agar should be determined according to the type of petri dishes selected. A volume of 27 mL is generally
recommended for the glass dishes offered with the Andersen impactor. The volume used with the selected petri dishes should give
an agar-to-grid distance comparable to that obtained with a reference glass dish filled with 27 mL of agar or the volume mentioned
by the supplier.
6.1.8 Vacuum Pump, capable of 57 L/m (2 ft /mm).
6.1.9 Air Pump/Compressor, capable of 15 psig minimum.
6.1.10 Peristaltic Pump, capable of delivering 0.01 mL/min.
6.1.11 Nebulizer, capable of delivering a mean particle size of 3.0 μm 6 0.3 μm and a challenge level of 1700 to 3000 viable
particles per test, as determined according to 12.3.
6.1.12 Glass Aerosol Chamber, 60 cm by 8 cm diameter tube.
6.1.13 Colony Counter, manual or automatic, capable of counting up to 400 colonies/plate.
6.1.14 Timers, capable of 0.1 s accuracy.
6.1.15 Automatic Pipetor, capable of delivering 1.0 mL 6 0.05 mL.
6.1.16 Flow Meters, capable of 28.3 L/min.
6.1.17 Aerosol Condenser.
6.1.18 Pressure Gauge, capable of 35 kPa 6 1 kPa accuracy.
6.1.19 Air Regulator.
6.2 Materials:
6.2.1 Flasks, 250 to 500 mL Erlenmeyer.
6.2.2 Petri Dishes, sterile, 15 by 100 mm.
6.2.3 Pipettes, 1 mL, 5 mL, and 10 mL.
6.2.4 Test Tube Rack, stainless.
6.2.5 Bottles, sterile, glass, 100 to 500 mL capacity.
6.2.6 Inoculating Loop.
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