ISO 24269:2026

International
Standard
ISO 24269
First edition
Nonwovens — Performance
2026-08
requirements and test methods for
filtration and safety — Materials for
general use face coverings
Nontissés — Exigences de performances et méthodes d'essai
de filtration et de sécurité — Matériaux pour masques faciaux
d'usage général
Reference number
© ISO 2026
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Published in Switzerland
ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Performance requirement. 3
4.1 Filtration .3
4.2 Safety.4
4.3 Preparation of test specimens .4
5 Filtration performance test . 4
5.1 Test for sub-micron particulate filtration efficiency (PFE).4
5.1.1 General .4
5.1.2 PFE Test for polystyrene latex particulate filtration efficiency .4
5.1.3 PFE Test for NaCl particulate filtration efficiency .9
5.2 Test for water aerosol filtration efficiency with bacteria (BFE) .14
5.2.1 General .14
5.2.2 Principle .14
5.2.3 Reagents and materials .14
5.2.4 Apparatus .16
5.2.5 Safety warning .17
5.2.6 Preparation of test specimen .17
5.2.7 Test procedures .18
5.3 Test for water aerosol filtration efficiency with viruses (VFE) .19
5.3.1 General .19
5.3.2 Principle .19
5.3.3 Reagents and materials .19
5.3.4 Apparatus . 20
5.3.5 Safety warning .21
5.3.6 Preparation of test specimen .21
5.3.7 Test procedures .21
5.3.8 Test results . 22
5.4 Test for pollen particle filtration efficiency . 22
5.4.1 General . 22
5.4.2 Principle . 23
5.4.3 Materials . 23
5.4.4 Apparatus . 23
5.4.5 Preparation of test specimen . 25
5.4.6 Test procedure. 25
5.4.7 Test results . 26
5.5 Test for differential pressure . 26
5.5.1 General . 26
5.5.2 Principle . 26
5.5.3 Apparatus . 26
5.5.4 Preparation test specimen .27
5.5.5 Measurement of test specimen . 28
5.5.6 Test results . 28
6 Safety test .28
6.1 Test for free formaldehyde. 28
6.2 Test for specific azo dyes . 28
6.3 Test for heavy metal . 28
6.3.1 Reagents . 28
6.3.2 Test procedure. 29
6.4 Test for pH . 30

iii
7 Marking . .30
7.1 Labelling instruction . . . 30
7.2 Label requirements . 30
Bibliography .31

iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
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This document was prepared by Technical Committee ISO/TC 38, Textiles.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
Introduction
There are many different types of masks that cover the mouth, nose and chin, including those for medical,
dust-proof and general use. While the performance evaluation standards for these masks vary by countries
and regions, the test methods for evaluating the performance of medical masks and dust-proof masks are
similar.
However, general use face coverings which are masks used by the general public in their daily lives are, in
reality, subject to different performance, safety parameters and test methods. Therefore, it is believed that
masks for general use should also have universal standards.
Unlike medical and dust-proof masks, general use face coverings used by the general public are focused
on ensuring a certain level of performance and safety for the wearer; they are not required to have the
performance of respiratory protective devices as discussed in ISO TC94, Personal safety -- Personal protective
equipment, SC15, Respiratory protective devices and are considered sufficient if their performance meets
the requirements of the general public’s daily living environments.
Thus, by standardizing test methods, performance and safety parameters for general use face coverings,
people around the world can wear general use face coverings with peace of mind and maintain their health
in their daily lives. In addition, the standardization of performance of general use face coverings is expected
to lead to the development of new materials and products, thereby invigorating the market. In this way, a
smooth and stable supply of general use face coverings can be made available to greater numbers of the
general public.
vi
International Standard ISO 24269:2026(en)
Nonwovens — Performance requirements and test methods
for filtration and safety — Materials for general use face
coverings
1 Scope
This document specifies the performance requirements and test methods for filtration property and safety
of materials for nonwoven general use face coverings for single use.
This document specifies the following filtration properties:
— sub-micron filtration efficiency (PFE),
— water aerosol filtration efficiency with bacteria (BFE),
— water aerosol filtration efficiency with viruses (VFE),
— pollen particle filtration efficiency, and
— differential pressure.
This document specifies the following safety items:
— free formaldehyde,
— specific azo dye,
— heavy metals, and
— pH.
This document applies to nonwoven general use face coverings. It does not apply to medical face masks (see
[1]
EN 14683 ), medical devices, or personal protective equipment (PPE) in the scope of ISO/TC94/SC15,
Respiratory protective devices (RPD).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 3071, Textiles — Determination of pH of aqueous extract
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 14184-1, Textiles — Determination of formaldehyde — Part 1: Free and hydrolysed formaldehyde (water
extraction method)
ISO 14362-1, Textiles — Methods for determination of certain aromatic amines derived from azo colorants —
Part 1: Detection of the use of certain azo colorants accessible with and without extracting the fibres
ISO 14362-3, Textiles — Methods for determination of certain aromatic amines derived from azo colorants —
Part 3: Detection of the use of certain azo colorants, which may release 4-aminoazobenzene

ISO 16604, Clothing for protection against contact with blood and body fluids — Determination of resistance
of protective clothing materials to penetration by blood-borne pathogens — Test method using Phi-X 174
bacteriophage
ISO 29463-1, High efficiency filters and filter media for removing particles in air — Part 1: Classification,
performance, testing and marking
ISO 80000-1, Quantities and units — Part 1: General
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
general use face covering
product worn on the face, specifically covering at least the wearer’s nose and mouth, with the primary
purpose of providing source control which reduces the spread of potentially infectious aerosols by the
wearer and to provide a degree of particulate filtration to reduce the amount of inhaled particulate matter
in the normal life environment, instead of in the hazardous environment where the PPE or RPD is required
Note 1 to entry: For many users, the term "mask" is synonymous with any product worn on the wearer's face that
provides a certain level of filtration efficiency. In other words, the general use face coverings in this document are also
masks, but to clarify the difference between medical face masks and other face masks, this document refers to general
use face masks as face coverings.
3.2
sub-micron particulate filtration efficiency
sub-micron PFE
efficiency of the filter material in capturing aerosolized particles smaller than one micron, expressed as
the percentage of a known number of particles that do not pass through the general use face covering (3.1)
material at a given flow rate or face velocity
[2]
[SOURCE: ASTM F2100-25 ]
3.3
water aerosol filtration efficiency with bacteria
water aerosol BFE
effectiveness of the general use face coverings in preventing the passage of aerosolized bacteria, expressed
in the percentage of a known quantity that does not pass the general use face covering material at a given
aerosol flow rate
[3]
[SOURCE: ASTM F2101-25 ]
3.4
water aerosol filtration efficiency with viruses
water aerosol VFE
efficiency to collect aerosol containing virus among the droplets produced when coughing, sneezing, and
talking
[4]
[SOURCE: JIS T9001 ]
3.5
pollen particle filtration efficiency
efficiency to collect pollen particles in the air
[4]
[SOURCE: JIS T9001 ]
3.6
differential pressure
air permeability of the general use face covering, measured by determining the difference of pressure across
the general use face covering under specific conditions of air flow, temperature and humidity
Note 1 to entry: The differential pressure is an indicator of the “breathability” of the general use face covering.
[5]
[SOURCE: EN 14683:2025 ]
3.7
personal protective equipment
PPE
any device or appliance designed to be worn or held by an individual for protection against one or more
health and safety hazards
[6]
[SOURCE: ISO/TS 20141:2022 , 3.8]
3.8
respiratory protective device
RPD
personal protective equipment (3.7) designed to protect the wearer’s respiratory tract against inhalation of
hazardous atmospheres
[7]
[SOURCE: ISO/TS 16975-1:2016 , 3.8]
3.9
medical face mask
item of protective garment designed to protect portions of the wearer's face, including at least the mucous
membrane areas of the wearer's nose and mouth, to minimise the direct transmission of infective agents
between staff and patient
[8]
[SOURCE: ISO 11610:2023 , 10.2.3]
4 Performance requirement
4.1 Filtration
General use face covering shall be subjected to at least one filtration performance test item shown in Table 1,
to conform to this document. The differential pressure test shall be performed.
Table 1 — Performance requirement of general use face covering
Performance Test methods
Functional test item Unit
requirement (Clause No.)
using polystyrene
Sub-micron
% ≥95 5.1.2
latex particles
particulate filtration
efficiency (PFE)
using NaCl ≥50 5.1.3
Water aerosol filtration efficiency with
% ≥95 5.2
bacteria (BFE)
Water aerosol filtration efficiency with
% ≥95 5.3
viruses (VFE)
Pollen particle filtration efficiency % ≥95 5.4
Differential pressure Pa <300 5.5
The tests are applied to the main product part related to breathing only (excluding accessories such as
elastic head harness).
4.2 Safety
General use face coverings shall be subjected to the safety tests in Table 2.
Safety tests other than those listed here should also be conducted as necessary. National regulations can
apply.
Table 2 — Safety requirements for general use face covering
Test items Unit Requirement Test method
Free formaldehyde μg/g ≤75 ISO 14184-1
ISO 14362-1
a b
Specific azo dye μg/g ≤30
ISO 14362-3
Heavy metals (as Lead) ppm <20 Clause 6.3
pH 4,0 to 7,5 ISO 3071
a
Test is performed for the coloured or stained products only.
b
Generated 24 specific aromatic amines each should not be more than 30 μg/g.
4.3 Preparation of test specimens
All tests specified in 4.1 and 4.2 shall be carried out on finished products or samples cut from finished
products. In case the products do not have enough size for the tests, the tests shall be carried out on the
same materials and the same layers of the products.
NOTE 1 The examples of not enough size of the sample are general use face coverings for children, three-
dimensional type, etc.
NOTE 2 The required performance of filtration is expected when no air leakage occurs from the general use face
covering wearer in practical use.
5 Filtration performance test
5.1 Test for sub-micron particulate filtration efficiency (PFE)
5.1.1 General
Perform the test for sub-micron particulate filtration (PFE) by selecting one test method from the two types
of PFE tests which are a test using polystyrene latex particles or a test using NaCl, as described below.
5.1.2 PFE Test for polystyrene latex particulate filtration efficiency
5.1.2.1 Principle
Filtered and dry air is passed through an aerosol generator to create an aerosol from a suspension containing
latex particles. For testing, the aerosol is diluted by mixing with clean air and allowed to dry. Under
constant flow, the aerosol is introduced into the chamber with a face velocity of 9,6 cm/s. The sub-micron
particulate filtration efficiency (PFE) is calculated by counting the number of aerosol particles upstream
and downstream of the test specimen.
5.1.2.2 Reagents
a) Water, grade 3 water as specified in ISO 3696.
b) Ultrapure water, grade 1 water as specified in ISO 3696.
c) Polystyrene latex particle reagent, consists of spherical polystyrene-based standard particles with
a nominal diameter of 0,1 μm dispersed in water. It is also allowed to use spherical polystyrene-based

standard particles with a nominal diameter of 0,3 μm dispersed in pure water based on the agreement
between the delivering and receiving parties. The diameter of the polystyrene latex particles used in
this test shall be shown in the test report.
5.1.2.3 Apparatus
The test apparatus for this test is shown in Figure 1.

Key
1 compressed air supply unit
2 HEPA filter
3 aerosol generator path flow meter
4 dilution path flow meter
5 humidifier
6 aerosol generator
7 heating drier
8 upper test duct
9 particle counter
10 test specimen
11 differential pressure gauge
12 particle counter
13 lower test duct
14 HEPA filter
15 constant flow suction pump
16 mixing apparatus
17 test specimen holder
18 temperature/relative humidity measuring device
Figure 1 — Example of test apparatus for sub-micron particulate filtration efficiency (PFE)
5.1.2.3.1 Compressed air supply unit (see Figure 1, key 1), supply dry air without the use of vaporized oil
with an oil-free mechanism and a built-in air dryer. The discharge pressure is not less than 0,2 MPa and the
flow rate of air is not more than 108 l/min.

5.1.2.3.2 HEPA filter (see Figure 1, keys 2 and 14), specified in ISO 29463-1 and installed back of the
compressed air supply unit to obtain clean air and in front of the unit discharging the air to the environment
in order to filter the test particles from the air that has passed through the test path.
5.1.2.3.3 Aerosol generator (see Figure 1, key 6), generates aerosol of a specified concentration through
7 8 3
a heating device and mixing and diluting with dry air with the capacity of (10 to 10 ) particles/m .
5.1.2.3.4 Humidifier (see Figure 1, key 5), humidifies the air introduced into the test path.
5.1.2.3.5 Test duct, composed by upper test duct (see Figure 1, key 8) and lower test duct (see Figure 1,
key 13), made of stainless-steel cylinder with an inner diameter of 79 mm ±1 mm and a length of about
1 030 mm and supported vertically. Particles are introduced from the upper end and sucked from the lower
end by the suction pump with a constant flow rate. The duct is divided into upper and lower parts at a
position of about 790 mm from the upper end, and a test specimen (see Figure 1, key 10) is placed between
the upper and lower ducts. The test duct shall have the switching mechanism for introducing clean air and
air containing the generated aerosol.
5.1.2.3.6 Specimen holder (see Figure 1, key 17), with an inner diameter of 79 mm ± 1 mm, having the
structure that allows the specimen to be supported in a flat state without sagging.
5.1.2.3.7 Differential pressure gauge (see Figure 1, key 11), measures the differential pressure between
the upstream and downstream of the test specimen in the test path.
5.1.2.3.8 Constant flow suction pump (see Figure 1, key 15), equipped with a flow meter and capable of
sucking the test air at a constant flow rate of 28,3 l/min.
5.1.2.3.9 Temperature/relative humidity measuring device (see Figure 1, key 18), measures the
temperature and relative humidity in the test path.
5.1.2.3.10 Particle counters (see Figure 1, keys 9 and 12), a light-scattering airborne particle counter
to count the aerosol particles, with the particle size categories of close to 0,3 μm and 0,1 μm in geometric
particle size, or those with the particle size categories of boundary 0,3 μm and 0,1 μm, which is installed
at upper duct and lower duct, respectively via a connecting tube of which the inner diameter shall be
determined so that the air speed becomes 9,6 cm/s by calculation from the suction flow rate of the particle
counter.
NOTE In case the suction flow rate of the particle counter is 0,3 l/min, the inner diameter of the connecting tube
is calculated as 8,1 mm.
5.1.2.4 Preparation of test specimen and test environment
Condition the general use face covering product sample at a temperature of (20 ± 3) °C and relative humidity
of (50 ± 5) % for more than 4 h, then cut 5 test specimens from the general use face covering product samples
with 11 cm in diameter.
For a pleated product, cut off the left and right glued parts, open the pleats of the product, and make a flat
plate-shaped test specimen. If the product has a three-dimensional shape or the product is too small to take
a flat test specimen, it is allowed to prepare a test specimen composed with all layers of the product.
Place the test apparatus in a room at a temperature of (20 ± 3) °C, and run the humidifier to adjust the test
duct to be a temperature of (20 ± 3) °C and relative humidity of (50 ± 5) %.

5.1.2.5 Test procedures
5.1.2.5.1 Preparation of polystyrene latex suspension
a) Carefully submerge the reagent bottle with the polystyrene latex particle reagent in the ultrasonic bath
filled with water for 5 min to 10 min to disperse the particles.
b) Pour a few drops of polystyrene latex particle reagent from the reagent bottle into a graduated cylinder
containing ultrapure water and place the cylinder in an ultrasonic bath for dispersion to prepare
polystyrene latex suspension. The dilution ratio of the polystyrene latex particle reagent to ultrapure
water is preferably 1 in 1 000 or more for example, one drop of reagent into 300 ml of ultrapure water.
5.1.2.5.2 Preparation of test apparatus
a) Add a predetermined amount of polystyrene latex suspension to the aerosol generator (see Figure 1, key
6) and attach the aerosol generator to the test apparatus. Adjust two needle valves, one (see Figure 1,
key 4) is for the flow rate of diluted dry air and the other (see Figure 1, key 3) is for the flow rate sent to
the aerosol generator, and set the dilution ratio in about 1 in 1 000 to 1 in 10 000.
b) Start the test apparatus. Measure the number of particles in the test duct using the particle counter, and
confirm that the number of particles falling into the particle size classification corresponding to the
polystyrene latex particle size used (hereinafter referred to as the "single count number") is not more
than one per min (confirm the cleanness).
c) Start generation of the aerosol consisting of polystyrene latex particles and introduce it into the test
duct.
d) Count the particle number in the aerosol in the test duct using the particle counter, and adjust the flow
rate of diluted dry air and flow rate sent to aerosol generator, so that the single count number will be
7 8 3
(10 to 10 ) /m (for example, if the suction flow rate of the particle counter is 300 ml/min, then the
particle count number becomes 3 000 /min to 30 000 /min). If the particle number does not fall within
the specified range even if the dilution rate of the flow is adjusted, use polystyrene latex suspension
prepared with a new concentration and repeat the adjustment until it falls within the specified range.
5.1.2.5.3 Background of measurement
After confirming the stability of the particle number in aerosol in the test duct, perform one-minute count
again using the particle counter 10 times in a row. Average 10 counts on the upstream and downstream sides
each, calculate the conversion coefficient by Formula (1), and round to the third decimal place according to
ISO 80000-1.
(1)
where
R is the conversion coefficient;
U is the average number of particles of 10 measurements of upstream;
b
D is the average number of particles of 10 measurements of downstream.
b
5.1.2.5.4 Measurement of test specimen
a) Switch the air introduction path to the test duct to the clean air side and let clean air flow for at least 1
min. Confirm that the inside of the test duct is clean.
b) Stop the constant flow suction pump and open the test duct.
c) Set a test specimen on the specimen support unit in a way that the outside of the general use face
covering faces up.
d) Close the test duct, start the constant flow suction pump, and introduce clean air at 28,3 l/min at least
for 1 min.
e) Switch the air introduction path to the test duct to the generated aerosol side.
f) Measure each single count number on the upstream and downstream sides each with the particle
counter every minute, three times in a row.
g) Switch the air guide path to the test duct to the clean air side and let the clean air flow for at least 1 min
to confirm the cleanness in the test duct.
h) Stop the constant flow suction pump and open the test duct.
i) Change the test specimen.
j) Run five cycles from a) to i) repeatedly for the five test specimens.
5.1.2.6 Test results
Calculate sub-micron particulate filtration efficiency (PFE: P ) by Formula (2), and round the values of five
FE
specimens each and the average value to the first decimal place according to ISO 80000-1.
If the calculation result shows 100 %, the value shall be “99,9 % or more” in the report.
(2)
where
P is the sub-micron particulate filtration efficiency (%);
FE
D is the average number of particles of 5 measurements of downstream;
s
U is the average numbers of particles for 5 measurements of upstream side;
s
R is the conversion coefficient.
5.1.3 PFE Test for NaCl particulate filtration efficiency
5.1.3.1 Principle
Filtered dry air is sent into an aerosol generator where the NaCl suspension solution is prepared and the
generated aerosol is mixed with air to dilute. The diluted generated aerosol passes through the test filter,
and the particle concentration is measured simultaneously by detectors located upstream and downstream
of the test filter. The collection efficiency of the test filter is determined from the ratio of the particle
concentrations measured by detectors at upstream and downstream of the test filter.
NOTE The NaCl particle size is controlled by compressing the NaCl suspension solution.
5.1.3.2 Reagents and materials
The following analytical grade reagents shall be used.
5.1.3.2.1 NaCl, analytical grade.
5.1.3.2.2 Water, ion-exchanged and/or freshly distilled and/or ultra-filtered and/or filtered with reverse
osmosis (RO) or equivalent water to Grade 3 according to ISO 3696.
5.1.3.2.3 NaCl particle suspension solution, prepared with the concentration of 2 % (mass/volume) by
using NaCl (5.1.3.2.1) and Water (5.1.3.2.2).

5.1.3.3 Apparatus
The test equipment mainly consists of an aerosol generator device and a filter testing device. A schematic
diagram of an apparatus is shown in Figure 2.

Key
1 clean air supply
2 flow control valve
3 heater
4 aerosol ionizer
5 aerosol generator
6 pneumatic cylinder
7 test specimen filter holder
8 test specimen filter
9 pressure transducer
10 switching valve
11 upstream photometer
12 downstream photometer
13 pressure transducer
14 flowmeter
15 filter
16 flow control valve
17 vacuum pump
A to vacuum
B exhaust
Figure 2 — Example of test apparatus for NaCl particulate filtration efficiency (PFE)
5.1.3.3.1 Clean air supply (see Figure 2, key 1), supply clean compressed air to the aerosol generator.

5.1.3.3.2 Flow control valve (see Figure 2, keys 2 and 16), control the supplying air flow to heater.
5.1.3.3.3 Heater (see Figure 2, key 3), used for remove the moisture from supplying air by heating the air.
5.1.3.3.4 Aerosol ionizer (see Figure 2, key 4), applies high voltage to the air passing through the nozzle
and the ionized air is mixed with the aerosol in the chamber. The aerosol ionizers may be selected by
availability with checking the quality.
5.1.3.3.5 Aerosol generator (see Figure 2, key 5), consists of solution reservoir and multiple atomizers.
The atomizers generate NaCl aerosols of any particle size. The particle size is controlled by compressing and
the size-controlled NaCl aerosols are then ejected by a high-velocity jet.
5.1.3.3.6 Pneumatic cylinder (see Figure 2, key 6), this cylinder presses down on the upper test specimen
filter holder, compressing the test specimen filter into the upper and lower holders before the test begins.
5.1.3.3.7 Filter holder (see Figure 2, key 7), upper filter folder to fix the test specimen filter between this
upper holder and lower holder.
5.1.3.3.8 Test filter (see Figure 2, key 8), placed between upper filter holder and lower holder.
5.1.3.3.9 Pressure transducer (see Figure 2, keys 9 and 13), measures the differential pressure and air
flow rate of the test filter when the air passes through the test specimen filter.
5.1.3.3.10 Switching valve (see Figure 2, key 10), adjusts the air flow amount through the filter.
5.1.3.3.11 Upstream photometer (see Figure 2, key 11), measures the NaCl particle concentration at
upstream of the test specimen filter by using this photometer by light scattering method.
5.1.3.3.12 Downstream photometer (see Figure 2, key 12), measures the NaCl particle concentration at
downstream of the test specimen filter by using this photometer as same method of upstream.
5.1.3.3.13 Flowmeter (see Figure 2, key 14), measures the air flow amount passing through test specimen
filter.
5.1.3.3.14 Filter (see Figure 2, key 15), recovers the remaining NaCl particles by this filter.
5.1.3.3.15 Vacuum pump (see Figure 2, key 17), exhaust the air passed through the test specimen filter.
5.1.3.4 Preparation of test specimen
Test specimens are taken from the product. In the case of pleated products, the adhesive parts on the left
and right sides are cut off, and the pleats on the face part of the product are opened to create a flat test
specimen for testing. Prepare at least 5 test specimens for one test.
If the product has a three-dimensional shape, a flat test piece is taken. In addition, if the product size is small
or the structure does not allow for a sufficient measurement area, the same material as the material used in
the product may be prepared and used as a substitute. In this case, all layers shall be arranged in the same
order as the product.
The test specimens shall be prepared with the size enough to cover the filter holder testing portion.
NaCl particles are neutralized to the Boltzmann equilibrium state. The neutralization method is not
specified. An example of the neutralization method is described in 5.1.3.3.4.
The NaCl particle concentrations in this test shall not exceed 50 mg/m .

5.1.3.5 Test procedures
5.1.3.5.1 Preparation of NaCl suspension and NaCl aerosol
NaCl suspension solution shall be prepared with 2 % (mass/volume) by using NaCl (5.1.3.2.1) and water
(5.1.3.2.2). The prepared solution shall be put into the aerosol generator. The NaCl aerosol shall have a
particle size distribution at the specified test conditions, measured with a scanning mobility particle sizer
or equivalent, with a median particle size distribution of 0,075 µm ± 0,020 µm and a standard geometric
deviation not exceeding 1,86.
5.1.3.5.2 Preparation of test apparatus
Check the amount of NaCl suspension solution in the aerosol generator, and if it is insufficient, replace the
NaCl solution completely and do not refill it to maintain the correct solution concentration.
Supply clean compressed air from outside and turn on the apparatus and heater. Set the pressure of each
section and the flow rate of air supply to the filter. At this time, make sure that the neutralizer is also turned
on.
The testing condition of a face velocity shall be set at (10 ± 0,5) cm/s and amount of air flow shall not exceed
85 l/min.
EXAMPLE 1 In case of the size of filter holder of 100 cm , the air flow amount will be approximately 60 l/min for the
face velocity of 10 cm/s.
EXAMPLE 2 In case of the size of filter holder of 49 cm , the air flow amount will be approximately 30 l/min for the
face velocity of 10 cm/s.
5.1.3.5.3 Test condition and test procedure
a) The product shall be preconditioned at a relative humidity of (50 ± 5) % and (20 ± 3) °C for 4 h.
b) The test is carried out at (25 ± 5) °C and a relative humidity of (30 ± 10) %.
c) Place the test specimen filter in a specimen filter holder. Confirm to be stable state of the upstream and
downstream concentrations. Once the downstream test particle concentration becomes stable, start
the measurement and collect the data.
d) The test result is adopted as the collection efficiency value at starting points at least 4 s and not exceed
15 s after the test starting.
e) Measure the NaCl particle concentrations of upstream and downstream of test specimen filter by the
particle concentration measuring device using a light scattering method and recorded.
5.1.3.6 Test results
The collection efficiency value is calculated by using the Formula (3).
(3)
where
E is the particle collection efficiency of the test specimen filter (%);
C is the test particle concentration at the upstream of the test specimen filter (mg/m );
C is the test particle concentration at the downstream of the test specimen filter (mg/m ).
i
The detection methods other than light scattering may be used if it is verified that the measurement
sensitivity is the same.
5.2 Test for water aerosol filtration efficiency with bacteria (BFE)
5.2.1 General
This test method determines the degree of the water aerosol filtration efficiency with bacteria by using
the aerosol containing airborne bacteria which is filtered through the test specimen of the general use face
covering.
5.2.2 Principle
A test specimen is set between a 6-stage Andersen cascade impactor for bacteria (hereinafter referred to
as “cascade impactor”) and an aerosol cham
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