TDC 9(6784 ) P3 
 
  
 
 
DRAFT TANZANIA STANDARD  
 
 
 
 
 
Textiles – Surgical face masks – Specification   
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU OF STANDARDS  
 
TDC 9(6784 ) P3 
 
  
DRAFT TANZANIA STANDARD
Textiles – Surgical face masks – Specification   
Foreword  
This Draft Tanzania Standard is being prepared by the Hospital Textile  Technical Committee, under the 
supervision of Textiles and Leather  Divisional Standards Committee and it is in accordance with the 
procedures of the Bureau.  
In the preparation of this Draft Tanzania Standard assistance was derived from:  
        IS 16289:2019  Medical Textiles — Surgical Face Masks — Specification  
        BS EN 14683:2019  Medical face mask  - Specifications  
In reporting the results of a test made in accordance with this  Draft  Tanzania Standard, if the final value, 
observed or calculated, is to be rounded off, it shall be done in accordance with TZS 4: 1979 Rounding 
off nume rical values .  
 
 
 
 
 
 
 
 
 
 
 
 
 
  
TDC 9(6784 ) P3 
 
 1. SCOPE  
This Draft Tanzania Standard specifies the performance requirements , sampling  and test methods of 
surgical face masks intended to  limit the transmission of infective agents from staff to  patients and (in 
certain situations) vice -versa during  surgical procedures in operating theatres and othe r health  care 
services such as patient care, with similar requirements.  
This Draft Tanzania Standard   is not applicable to masks intended exclusively for the personal 
protection of staff.   
2. NORMATIVE REFERENCES   
The following referenced documents are indispensable for the application 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:  
TZS 4 Rounding off numerical values   
TDC 9 ( 6787) P1 Textiles — Method for evaluation of the bacterial filtration efficiency  
surgical face masks .                                                                                                                                   
3. TERMS AND DEFINITIONS  
For the purpose of this Draft Tanzania Standard, the following definitions shall apply:  
3.1 surgical fac e mask 
medical device covering  the mouth, nose and chin providing a barrier to  minimize the direct 
transmission of infective agents  between staff and patient.  
 
3.2 bacterial  filtration efficiency (BFE)  
effectiveness of a surgical face mask to filter (prevent passage of) aerosol d roplets containing 
bacteria of specified particle size of 3.0 μm (micron) ± 0.3 μm. This is expressed as a percentage 
of a quantity that does not pass through the material . 
 
3.3 differential pressure/ delta P  
pressure drop across a surgical mask under specific conditions of air flow, temperature and 
humidity. This is an indicator of the breathability of the mask.  
 
3.4 sub-micron particle filtration efficiency (PFE)  
effectiveness of a material to filter  aerosol droplets containing bacteria of a specified  particle size 
range 0.1 μm. This is expressed as a  percentage of a quantity that does not pass through the  
material.  
 
3.5 fluid/splash resistance  
ability of a facemask’s material construction to minimize fluids from traveling through th e material 
and potentially coming into contact with the user of the facemask. Fluid resistance helps reduce 
potential exposure to blood and body fluids caused from splashes, spray or splatter. Resistance 
to penetration by synthetic blood is indicated as pa ss/fail at one of three distinct velocities of 80, 
120 and 160 mm of Hg. Penetration (visual evidence ) of synthetic blood on the side opposite 
impact results in fail at that pressure. Non -penetration results in a pass.  
 
  
TDC 9(6784 ) P3 
 
 3.6 colony forming unit (CFU)  
particle  containing one or more bacterial cells which gives rise  to a single bacterial colony on a 
culture plate.  
 
3.7 infective agent  
micro -organism that has shown to cause surgical wound infection or that  might cause infection in 
the patient or in members of  the surgical team . 
 
3.8 surgical procedure  
surgical intervention penetration skin or mucosa, performed by a surgical team under controlled 
environmental conditions.  
 
3.9 aerosol  
suspension of solid, liquid, or  solid and liquid particles in gaseous medium, the  particles having a 
negligible falling velocity, generally  considered to be less than 0.25 m/s.  
 
4. REQUIREMENTS   
 
4.1 General  
4.1.1  Materials  
The surgical face mask (Non -woven fabric) shall be manufactured from polypropylene, 
polyethylene or cellulos ic materials . 
  
4.1.2  Design  and construction  
The surgical face mask shall have a minimum of three layers; the innermost layer, outermost 
layer and middle layer.  The surgical face mask shall have a means by which it can be fitted 
closely over the nose, mouth and chin of the wea rer and which ensures that the mask fits 
closely at the sides.  
 
4.1.3  Manufacturing  
The production of surgical  face mask shall be full automated to avoid human intervention 
and possible contamination.  
 
4.1.4  Dyes and pigments  
For dyed or printed fabrics, dyes and pigments used shall not be carcinogenic.  
 
4.2 Performance requirements  
The surgical face mask shall not disintegrate  or split tear during intended use.  The surgical face 
masks shall conform to the requirements specified in Table 1. The surgical masks have been 
categorized into three classes based on performance, Class 1, Class 2 and Class 3.  
     
NOTE: Class 3 is splash/fluid resistant.  
 
 
 
 
 
 
 
 
 
  
TDC 9(6784 ) P3 
 
 Table 1: Performance Requirements for Surgical Face Mask  
S/N Characteristics  Requirements  Test methods  
Class 1 Class 2  Class 3  
1.  Bacteria filtration efficiency, %, min.  95 98 98 TDC 9( 6787 ) P1 
2.  Differential pressure, Pa, max.  29.4 29.4 49.0 Annex A  
3.  Splash resistance, mm Hg, min.  - - 120 Annex B  
4.  Sub-micron particulate filtration efficiency at 
0.1 μ, %, min.  - - 98 Annex C  
 
5. PACKING AND MARKING  
 
5.1. Packing  
The packing of surgical masks shall be done within an air -conditioned and dust free environment 
directly from the machine into dispenser boxes then outer cartons. The mask s should not be packed 
in poly s acks which do not offer suitable protection against the environment  at conditions .            
5.2. Marking  
Each package  of the surgical face  mask shall be legibly marked with the following information:  
a) Name of the product (i.e. surgical face  mask ) and class.  
b) Manufacturer ’s name, initials or trade -mark.  
c) Month and year of manufacturing  and expiry date  or batch /lot  number; and  
d) Number of pieces in a single package.  
 
6. Sampling and criteria for conformity  
6.1. Lot  
All the surgical face masks of the same grade and material, produced under similar conditions of 
manufacture shall constitute a lot.  
6.1.1.  Each lot shall be tested separately for ascertaining the conformity of the lot.  
6.1.2.  The number of masks to be selected from the lot shall depend on the size of the lot and shall  
be in accordance with col umn 2, col umn3 and col umn 5 of Table 2.  
6.1.3.  These face masks shall be selected at random  from the lot.  
 
 
 
  
TDC 9(6784 ) P3 
 
 6.2. Number of tests and criteria for conformity  
6.2.1.  All the face masks selected as per col 3 of Table 2 shall be examined for workmanship and 
finish ( see 4.1 ). 
 
6.2.1.1  Any mask failing in one or more of the above requirements shall be termed as defective. 
The lot shall be considered as conforming to the above requirements, if the total number 
of defectives found in the sample is less than or equal to the acceptance number given 
in col umn 4 of Table 2. Otherwise, the lot shall be rejected.  
 
6.2.2.  Out of the sample already found satisfactory  according to 6.2.1.1 , a sub -sample as per 
column 5 of Table 2 shall be taken. This sub -sample shall be further  tested for the remaining 
requirements.  
 
Table 2 : Number of Face Masks to be Selected  
S/N Lot size  Non-destructive testing  Destructive testing  
No. of masks to 
be selected  Acceptance 
number  No. of masks to 
be selected  Acceptance 
number  
1.  Up to  280 131) 1 8 0 
2.  281-500 20 2 8 0 
3.  501 to 1200  32 3 13 0 
4.  1201 to 3200  50 5 13 0 
5.  3201 to 10000  80 7 20 1 
1) Or lot size when less than 13.      
   
6.2.3.  The lot shall be considered as conforming to the requirements of the specification, if the total 
number of defective masks found in the sample (as per 6.2.2) is less than or equal to the 
acceptance number as given in col 6 of Table 2.  
 
 
 
 
  
TDC 9(6784 ) P3 
 
 ANNEX A  
(normative)  
 
METHOD FOR DETERMINATION OF BREATHABILITY (DIFFERENTIAL PRESSURE)  
A-1 PRINCIPLE   
A device which measures the pressure differential required to draw air through a measured surface 
area at a constant air flow rate is used to measure the air exchange pressure of the surgical mask 
material, as shown in Fig.1. Water -filled manometers (M1 and M2) are used to measure the pressure 
differential. A flow meter is used for measurement of the air flow.  
 
 
KEY 
1 – Air inlet                                                   4 – Filter material                                   7 – Vacuum pump  
2 – Flow meter                                             5 – Manometer M2  
3 – Manometer M1                                       6 – Valve  
Figure 1 – Apparatus for measuring air resistance  
 
An electric vacuum pump draws air through the  apparatus and a needle valve is used to adjust the air  
flow rate.  
 
 
 
TDC 9(6784 ) P3 
 
 A-2 APPARATUS  
A-2.1 Flow Meter , capable of measuring an air flow of 8 litre/min.  
A-2.2 Manometers , M1 and M2.  
A-2.3 Electric Vacuum Pump  
A-2.4 Valve  
A-3 TEST SPECIMENS  
Test specimens shal l be complete masks or shall be cut from masks. Each sp ecimen shall be able to 
provide five different circular te st areas of 2.5 cm in diameter. The nu mber of specimens that shall be 
tested shall be five. 
 
A-4 PROCEDURE  
A-4.1 The test specimen is placed across the 2.5 cm  diameter orifice  (total area 4.9 cm2) and clamped 
into place so that the tested area of the specimen will be in  line and across the flow of air.  
A-4.2 The pump is started and the flow of air adjusted  to 8 litres/minute.  
A-4.3 The manometers M1 and M2 are read and  recorded.  
A-4.4 The procedure described in steps B-4.1 through B-4.3 is carried out on five different areas of  the 
mask and the readings averaged . 
A-5 CALCULATION OF DIFFERENTIAL PRESSURE  
For each test speci men, calculate the differential pressure, ΔP as follows:  
ΔP = (X m1 - Xm2) / 4.9 
Where  
X m1 = water pre ssure, in mm, manometer 1, mean of five test areas, low pressure side of the material;  
X m2 = water pre ssure, in mm, manometer 2, mean of five test a reas, high pressure side of the material;  
4.9 = area of the test material, in cm2; and  
ΔP = pressure differential per cm2 of test material expressed as mm of water.  
 
A-6 TEST REPORT  
The test report shall include the following information:  
a) Flow rate during testing; and  
b) Differential pressure for each test specimen.  
 
 
  
TDC 9(6784 ) P3 
 
 ANNEX B  
(normative)  
METHOD FOR DETERMINATION OF SPLASH RESISTANCE  
B-1 PRINCIPLE  
A volume of synthetic b lood is disbursed at a specimen mask by a pneu matically controlled valve from 
a set distance at specified pressure to simulate the impact of blood or other body fluid  onto the 
specimen. The velocity and volume of fl uid are set to simulate a given health care scenario.   
B-2 APPARATUS AND REAGENTS  
B-2.1 A suitable test ap paratus to dispense a specified volume of synthetic blood through a small 
diameter cannula  (1.27 cm lon g with an internal diameter of 0.084 cm) over a  controlled amount of time 
at a specimen mask a set di stance away. The test apparatus consists of a specim en holding fixture, a 
targeting plate, a pressurized f luid reservoir, a pneumatically actuated valve wi th interchangeable 
cannula  and a valve controller. The  test apparatus includes a base for more convenient  mounting of the 
components and a hood or other compo nents to contain or control  the splash.  
B-2.2 Synthetic Blood  
B-2.3 Isopropanol , laboratory grade, for cleaning the apparatus.  
B-3 TEST SPECIMEN  
B-3.1 Use complete surgical face masks as the test specimen. I f in the design of a face mask, different 
materials or thickne ss of material are specified at different locations,  test each area of the specimen 
separately. If in the design of a surgical face mask, seams are claimed to offer the same protection as 
the base material, te st these areas of the face mask separately.  
B-3.2 Prior to test, the specimens shall be conditioned  to moist ure equilibrium in the standard 
atmosphere of  temperature 27 + 2 °C and relative humidity of 65 + 2  percent. When the test specimens 
have been exposed  to standard atmosphere for at least 6 h in s uch a way to  expose as far as possible, 
all portions of the specimens  to the atmosphere, they shall be deemed to have reached  moisture 
equilibrium.  
B-4 PROCEDURE  
B-4.1 Place a small droplet (approximately 0.1 ml)  of the synthetic blood on the normal inside  surface 
of an extra surgical face mask. The droplet must remain  easily visible to ensure that a droplet 
penetrating the  material shall be seen. If not, use talcum powder on  the normal inside surface of the 
surgical face mask to  enhance droplet visibility.  
B-4.2 Mount a specimen on the specimen holding  fixture and position the specimen so that the impact 
of the synthetic blood occurs in the desired area of the  mask. If the m ask contains pleats, spread the 
pleats  out when mounting the face mask onto the test  fixture  to present a single layer of material as the 
target area.  Use the centre of the specimen as the target area. The  inside of the mask shall contact the 
entire perimeter of  the viewing hole. The specimen mask shall be  supported by the specimen holding 
form. Remount the  specimen mask, if necessary.  
B-4.3 Locate the exit of the cannula 30.5 cm from the  target area of the specimen mask. Dispense the  
synthetic blood (approximately 2 ml) at a pressure of  120 mm of Hg onto the specimen surgical face 
mask.  Ensure that the synthetic blood hits the target area of  the surgical face mask.  
B-4.4 Inspect the viewing side of the specimen for  synthetic blood within 10 s of dispensing the synthetic  
blood against the target area. Using suitable lighting  note whether any synthetic blood, or other 
evidence  of wetness, or both appears on the viewing side of the  specimen. Use a cotton absorbent  
TDC 9(6784 ) P3 
 
 swab or similar item  to lightly daub the target area, if doubt exists for visible  penetration of the synthetic 
blood.  
B-5 TEST REPORT  
Any evidence of synthetic blood penetration on the  inner facing of the surgical face mask constitutes a  
failure at the specified pressure.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
TDC 9(6784 ) P3 
 
 ANNEX C  
(normative)  
METHOD FOR DETERMINATION OF SUB -MICRON PARTICULATE FILTERATION  
EFFICIENCY  
C-1 PRINCIPLE  
Filtered and dry air i s passed through an atomizer to produce an aerosol cont aining suspended latex 
spheres. This aerosol is then passe d through a charge neutralizer. The aerosol is then mixed and 
diluted with additional pre-conditioned air to pr oduce a stable, neutralized and dried aerosol of latex 
spheres to be used in the efficiency test.  
C-2 APPARATUS  
Aerosol test system consist ing of  clean, dry compressed air supply, HEPA fil ters, aerosol generator, 
charge neutralizer, humidifi er, test filter holder and duct assembly, pressure drop measuring device, air 
flow rate measuring device, tem perature and humidity detectors and optical particl e counters.  
C-3 TEST SPECIMEN  
C-3.1 Prior to test, the  specimens shall be conditioned to moisture equilibriu m in the standard 
atmosphere of temperature 27 + 2 °C and relative humidity of 65 + 2 percent. When the test specimens 
have been exposed to standard  atmosphere fo r at least 6 h in such a way to expose as far as possible , 
all portions of the specimens to the atmosphere, they shall be deemed to have reached moisture 
equilibrium.  
C-4 TEST PROCEDURE  
C-4.1 Set main airflow, dilution airflow and aerosol generator airflo w to test conditions. Establish airflow  
controls at required test face velocities as to have air  dilution (drying) for  aerosol generation of 2:1 or 
greater. Purge main ai rflow for 10 to 15 min. Warm up optical particle counter (OP C) for 15 to 30 
minutes. After OPC warm up, ch eck built in calibration signal or OPC output signal on an oscilloscope 
for stable gain on photomultiplier t ube or other optical detectors. Switch the OPC into main airflow and 
balance OPC  airflow against the main airflow. Observe OPC count data.  
C-4.2 Set-up the aerosol generator with a nominal  volume of the distilled water to be used in the latex  
dilutions. Without a material specimen in the test  system, establish the main system airflow and the 
OPC  sampling airflow for the upstream sampling probe.  Sample the upstream and downstream airflow 
for 1  min each. Verify complete drying of the aerosol  droplets by comparing these counts to count 
obtained  in D-4.1. Run this drying test for 1 h, sampling every  15 min for  upstream and downstream 
counting and  record aerosol stability and system relative humidity.  Measure the water consumption of 
the aerosol  generator. Record any dilution airflow and the required  air pressure for the aerosol 
generator.  
C-4.3 Fill the aerosol  generator with the desired  dilution of latex suspension. Without a filter media  
sample in the test specimen, close the system and  establish the required system airflows. Stabilize the  
system airflow with the aerosol suspension for  approximately 5 min, the n begin successive 1 min  
upstream and downstream counts for 15 min or until  reproducible counts are established. Verify that  
counting is within a 10 percent coincidence of the  OPC.  
C-4.4 Install the material specimen in the test system  and re -establish the  required airflows. Monitor the  
OPC airflow and adjust for the added material  specimen on the sample flow. Sample and record the  
upstream and downstream aerosol counts for a  minimum of 5 counts at each position using a 1 min  
sampling time. If the downstrea m count is less than  100, extend the test until 100 counts are obtained.  
However, do not count longer than 5 min to avoid the  loading the specimen.  
C-4.5 Monitor the upstream counts; if these counts  fall outside 100 + 1 percent penetration average 
with a  coefficient of variation of 3 percent, stop the test and  check the system for aerosol generation 
instability.   
TDC 9(6784 ) P3 
 
  
C-5 CALCULATION  
Average the upstream counts and the downstream  counts, then calculate the decimal efficiency by the  
following definition:  
 
Efficiency = 1− (average  downstream  counts )
(average  upstream  counts ) 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
TDC 9(6784 ) P3 
 
 ANNEX D  
(informative)  
 
INFORMATION FOR USERS  
D-1 When breathing, speaking, coughing, sneezing etc. one releases smaller or larger amounts of 
droplets of secretions from the mucous membranes in the mouth and nose. Those droplets quickly 
evaporate and leave nuclei suspended in the air. The majority of the nuclei are between 0.5 μm and 12 
μm in diameter and the larger ones can contain m icro-organisms from the source site. Nuclei can 
subsequently spread through the air to a susceptible site such as an open operating wound or sterile 
equipment.  
D-2 The surgical masks intended to be used in  operating theatres and health care settings with similar  
requirements are designed to protect the working  environment and not the wearer. When the primary  
intention is to protect the wearer from infection, the  use of other devices should be considered.  
D-3 A special case is that in which the wearer wishe s to protect himself/herself against splashes of 
potentially contaminated fluids. For  this application this standard specifies performanc e requirements 
and gives a test method for a special c lass of surgical masks offering protection against splashes.   
D-4 The degree of protection offered by a mask  depends on a number of  factors such as the filtration 
capacity of the material  and the fit of the mask on the wearer’s face. D ifferent designs are suited for 
different applications  and the careful choice of mask is therefore important in order to achieve the 
desired result.   
D-5 The filtration capa city of mask materials can vary depending on the filter  media. The fit of masks 
varies considerably from t hose which are held in place by ear loops fastened be hind the w earer’s ears 
to those with tie bands around the head and a nose clamp that can be shaped to the  wearer’s nose. 
The effect of a very good or less good fi t can be tested in vivo whereas the filtration capacit y may be 
reproducibly tested in vitro.  
D-6 The considerable variations in results when masks  are tested in vivo results in the need for large 
groups  of test subjects and observations. It is thus usual to  characterize mask performance using in 
vitro tests of  the material from which the mask is made. It is, however, important to consider the fit of 
the mask  carefully when a mask for a certain application is  chosen. Users should request such 
information from  their suppliers.  
D-7 A further factor t o be considered is the capacity of the mask to absor b moistu re from the exhaled 
air and thereby to maintai n its performance over a longer period of time. The more advanced designs 
easily  maintain their performance throughout even very long  operations whereas the less advanced 
ones are  intended only for short proced ures. There is no  scientific evidence th at demonstrates a 
limitation in wearing time for t he advanced surgical masks that are available today.  
D-8 The contamination risk resulting from hand contact  with a used mask means that it is essential that 
the mask is taken off and disposed of when n o longer worn over nose and mouth. W hen there is a 
further need for protection then a new mask should be put on. Touching a used mask or puttin g on a 
new one should always be followed by a full hand disinfection procedure . 
D-9 In summary, t o use an appropriate mask is an effective means to protect the working environment 
from droplet con tamination from nose and throat during health c are procedures. Masks with very 
different perfo rmance are, however, available. Therefore, s uch factors  as infection risk and mask fi 
should be carefully considered when choosing a mask.