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Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?

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This study examined homemade masks as an alternative to commercial face masks. Several household materials were evaluated for the capacity to block bacterial and viral aerosols. Twenty-one healthy volunteers made their own face masks from cotton t-shirts; the masks were then tested for fit. The number of microorganisms isolated from coughs of healthy volunteers wearing their homemade mask, a surgical mask, or no mask was compared using several air-sampling techniques. The median-fit factor of the homemade masks was one-half that of the surgical masks. Both masks significantly reduced the number of microorganisms expelled by volunteers, although the surgical mask was 3 times more effective in blocking transmission than the homemade mask. Our findings suggest that a homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection. (Disaster Med Public Health Preparedness. 2013;0:1-6).
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TestingtheEfficacyofHomemadeMasks:WouldTheyProtectinan
InfluenzaPandemic?
AnnaDavies,KatyAnneThompson,KarthikaGiri,GeorgeKafatos,JimmyWalkerandAllanBennett
DisasterMedicineandPublicHealthPreparedness/FirstViewArticle/July2013,pp16
DOI:10.1017/dmp.2013.43,Publishedonline:22May2013
Linktothisarticle:http://journals.cambridge.org/abstract_S1935789313000438
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AnnaDavies,KatyAnneThompson,KarthikaGiri,GeorgeKafatos,JimmyWalkerandAllanBennettTestingtheEfficacy
ofHomemadeMasks:WouldTheyProtectinanInfluenzaPandemic?.DisasterMedicineandPublicHealth
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ORIGINAL RESEARCH
Testing the Efficacy of Homemade Masks: Would
They Protect in an Influenza Pandemic?
Anna Davies, BSc, Katy-Anne Thompson, BSc, Karthika Giri, BSc, George Kafatos, MSc,
Jimmy Walker, PhD, and Allan Bennett, MSc
ABSTRACT
Objective: This study examined homemade masks as an alternative to commercial face masks.
Methods: Several household materials were evaluated for the capacity to block bacterial and viral aerosols.
Twenty-one healthy volunteers made their own face masks from cotton t-shirts; the masks were then tested
for fit. The number of microorganisms isolated from coughs of healthy volunteers wearing their homemade
mask, a surgical mask, or no mask was compared using several air-sampling techniques.
Results: The median-fit factor of the homemade masks was one-half that of the surgical masks. Both
masks significantly reduced the number of microorganisms expelled by volunteers, although the
surgical mask was 3 times more effective in blocking transmission than the homemade mask.
Conclusion: Our findings suggest that a homemade mask should only be considered as a last resort to
prevent droplet transmission from infected individuals, but it would be better than no protection.
(Disaster Med Public Health Preparedness. 2013;0:1–6)
Key Words: homemade facemasks, respirators, airborne transmission, microbial dispersion, pandemic
prevention
Wearing a face mask in public areas may
impede the spread of an infectious disease
by preventing both the inhalation of
infectious droplets and their subsequent exhalation
and dissemination. In the event of a pandemic
involving an airborne-transmissible agent, the general
public will have limited access to the type of high-
level respiratory protection worn by health care
workers, such as N95 respirators. Images of members
of the public wearing surgical masks were often used
to illustrate the 2009 H1N1 flu pandemic. However,
the evidence of proportionate benefit from widespread
use of face masks is unclear.
A recent prospective cluster-randomized trial compar-
ing surgical masks and non-fit-tested P2 masks (filters
at least 94% of airborne particles) with no mask use in
the prevention of influenza-like illness. The findings
of the study found that adherence to mask use
significantly reduced (95% CI, 0.09-0.77; P5.015)
the risk for infection associated with influenza-like
illness, but that less than 50% of participants wore
masks most of the time.
1
Facemasks may prevent
contamination of the work space during the outbreak
of influenza or other droplet-spread communicable
disease by reducing aerosol transmission. They may
also be used to reduce the risk of body fluids, including
blood, secretions, and excretions, from reaching the
wearer’s mouth and nose.
To date, studies on the efficacy and reliability of face
masks have concentrated on their use by health care
workers. Although health care workers are likely to
be one of the highest risk groups in terms of exposure,
they are also more likely to be trained in the use of
masks and fit tested than the general public. Should
the supply of standard commercial face masks not
meet demand, it would be useful to know whether
improvised masks could provide any protection to
others from those who are infected.
METHODS AND MATERIALS
In this study, common household materials(see
Table 1) were challenged with high concentrations
of bacterial and viral aerosols to assess their filtration
efficiencies. Surgical masks have been considered the
type of mask most likely to be used by the general
public, and these were used as a control. The pressure
drop across each of the materials was measured to
determine the comfort and fit between face and mask
that would be needed to make the material useable in
mask form. We devised a protocol for constructing a
‘‘homemade’’ mask, based on the design of a surgical
mask, and volunteers were invited to make their own
masks. These were then quantitatively fit tested. To
determine the effect of homemade and surgical masks
in preventing the dispersal of droplets and aerosol
particles produced by the wearer, the total bacterial
Disaster Medicine and Public Health Preparedness 1
Copyright &2013 Society for Disaster Medicine and Public Health, Inc. DOI: 10.1017/dmp.2013.43
count was measured when the volunteers coughed wearing
their homemade mask, a surgical mask, and no mask.
Testing the Filtration Efficiency
A range of common household materials were tested, together
with the material from a surgical mask (Mo
¨lnlycke Health Care
Barrier face mask 4239, EN14683 class I), for comparison.
Circular cutouts of the tested materials were placed without
tension in airtight casings, creating a ‘‘filter’’ in which the
material provided the only barrier to the transport of the aerosol.
A Henderson apparatus allows closed-circuit generation of
microbial aerosols from a Collison nebulizer at a controlled
relative humidity. This instrument was used to deliver the
challenge aerosol across each material at 30 L/min using
the method of Wilkes et al,
2
which is about 3 to 6 times per
minute the ventilation of a human at rest or doing light work,
but is less than 0.1 the flow of an average cough.
Downstream air was sampled simultaneously for 1 minute into
10 ml of phosphate buffer manucol antifoam using 2 all-glass
impingers. One impinger sampled the microorganisms that
had penetrated through the material filter, while the other
sampled the control (no filter). The collecting fluid was
removed from the impingers and assayed for microorganisms.
This test was performed 9 times for each material. The
filtration efficiency (FE) of the fabric was calculated using the
following formula (cfu indicate colony-forming units):
FE ¼Upstream cfu Downstream cfu 100
Upstream cfu
The pressure drop across the fabric was measured using a
manometer (P200UL, Digitron), with sensors placed on
either side of the filter casing, while it was challenged with a
clean aerosol at the same flow rate.
Microorganisms
Two microorganisms were used to simulate particle challenge:
Bacillus atrophaeus is a rod-shaped spore-forming bacterium
(0.95-1.25 mm) known to survive the stresses caused by
aerosolization.
3
The suspension was prepared from batches
previously prepared by the Health Protection Agency, Centre
for Emergency Preparedness and Response Production Division.
4
Each material was challenged with approximately 10
7
cfu
B atrophaeus.
Bacteriophage MS2 (MCIMB10108) is a nonenveloped
single-stranded RNA coliphage, 23 nm in diameter, known
to survive the stresses of aerosolization.
5
Each material was
challenged with approximately 10
9
plaque-forming units
(pfu) of bacteriophage MS2.
The two test organisms can be compared in size to influenza
virus, which is pleomorphic and ranges from 60 to 100 nm;
Yersinia pestis, which is 0.75 mm; Banthracis,which is 1 to
1.3 mm; Francisella tularensis, which is 0.2 mm; and Mycobacterium
tuberculosis, which is 0.2 to 0.5 mm.
6
Bacteriophage MS2 and
B atrophaeus were chosen as the test organisms to represent
influenza virus. This decision was made not only because of the
lower risks of associated infection but also because the work
would be technically easier to carry out using an Advisory
Committee on Dangerous Pathogens (ACDP) class 1 organism
versus an ACDP class 2 organism influenza.
Making the Face Mask
For this study, 21 healthy volunteers were recruited, 12 men
and 9 women. The participants were aged between 20 and
44 years; the majority was in the 20- to 30-year age range.
Each volunteer made a homemade face mask following a
protocol devised by the authors. All face masks were made
with 100% cotton t-shirt fabric using sewing machines to
speed construction. A surgical mask (Mo
¨lnlycke Health Care
TABLE 1
Filtration Efficiency and Pressure Drop Across Materials Tested with Aerosols of Bacillus atrophaeus and Bacteriophage
MS2 (30 L/min)
a
Material
B atrophaeus Bacteriophage MS2 Pressure Drop Across Fabric
Mean % Filtration Efficiency SD Mean % Filtration Efficiency SD Mean SD
100% cotton T-shirt 69.42 (70.66) 10.53 (6.83) 50.85 16.81 4.29 (5.13) 0.07 (0.57)
Scarf 62.30 4.44 48.87 19.77 4.36 0.19
Tea towel 83.24 (96.71) 7.81 (8.73) 72.46 22.60 7.23 (12.10) 0.96 (0.17)
Pillowcase 61.28 (62.38) 4.91 (8.73) 57.13 10.55 3.88 (5.50) 0.03 (0.26)
Antimicrobial Pillowcase 65.62 7.64 68.90 7.44 6.11 0.35
Surgical mask 96.35 0.68 89.52 2.65 5.23 0.15
Vacuum cleaner bag 94.35 0.74 85.95 1.55 10.18 0.32
Cotton mix 74.60 11.17 70.24 0.08 6.18 0.48
Linen 60.00 11.18 61.67 2.41 4.50 0.19
Silk 58.00 2.75 54.32 29.49 4.57 0.31
a
Numbers in parentheses refer to the results from 2 layers of fabric.
Are Homemade Masks Effective?
Disaster Medicine and Public Health Preparedness2
Barrier face mask 4239, EN14683 class I) was used as
a control. Also, all volunteers completed a questionnaire
indicating their opinions of mask wearing.
Determining the Fit Factor of the Mask
A commercial fit test system (TSI PortaCount Plus Respirator
Fit Tester and N95- Companion Module model 8095) was
used to measure respirator fit by comparing the concentration
of microscopic particles outside the respirator with the
concentration of particles that have leaked into the respirator.
The ratio of these 2 concentrations is known as the fit factor.
To conduct the fit test, the apparatus was set up and operated
according to the manufacturer’s instructions.
Volunteers were instructed to fit their surgical and homemade
face masks with no help or guidance from the operator; to
ensure that the mask was comfortable for 2 minutes; the
participants were given time to purge any particles trapped
inside the mask. The fit test was then conducted with
volunteers performing the following consecutive exercises,
each lasting 96 seconds: (1) normal breathing, (2) deep
breathing,
7
(3) head moving side to side, (4) head moving up
and down, (5) talking aloud (reading a prepared paragraph),
(6) bending at the waist as if touching their toes, and
(7) normal breathing.
Determining the Effect of Masks in Preventing the
Dispersal of Droplets and Aerosol
An enclosed 0.5-m
3
mobile sampling chamber, or cough box,
which was constructed for the purpose of sampling aerosols and
droplets from healthy volunteers (PFI Systems Ltd, Milton
Keynes), was placed in a 22.5-m
3
high-frequency particulate
air-filtered environmental room. Four settle plates were placed
in the cough box to sample for droplets, together with a 6-stage
Andersen sampler to sample and separate small particles.
8
A Casella slit-air sampler
9
was also attached to the cough box.
Tryptose soya agar was used as the culture medium. Volunteers
wearing protective clothing (Tyvek suits) coughed twice into
the box, and the air inside was sampled for 5 minutes. Each
volunteer was sampled 3 times: wearing the homemade mask,
the surgical mask, and no mask. The air within the cough box
was high-frequency particulate air filtered for 5 minutes
between each sample to prevent cross-contamination between
samples. The plates were incubated for a minimum of 48 hours
at 378C before counting.
Statistical Analysis
To evaluate the face mask fit, the median and interquartile
range were calculated for each exercise and face mask for
the 21 individuals. Wilcoxon sign rank tests were used to
compare the masks. The same approach was used to
determine differences between the different mask types
and their efficacy in preventing dissemination of droplets
and particles
RESULTS
Filtration Efficacy
All the materials tested showed some capability to block
the microbial aerosol challenges. In general, the filtration
efficiency for bacteriophage MS2 was 10% lower than for
B atrophaeus (Table 1). The surgical mask had the highest
filtration efficiency when challenged with bacteriophage
MS2, followed by the vacuum cleaner bag, but the bag’s
stiffness and thickness created a high pressure drop across
the material, rendering it unsuitable for a face mask. Simi-
larly, the tea towel, which is a strong fabric with a thick
weave, showed relatively high filtration efficiency with both
B atrophaeus and bacteriophage MS2, but a high pressure
drop was also measured.
The surgical mask (control) showed the highest filtration
efficiency with B atrophaeus. Also, as expected, its measured
low pressure drop showed it to be the most suitable material
among those tested for use as a face mask. The pillowcase and
the 100% cotton t-shirt were found to be the most suitable
household materials for an improvised face mask. The slightly
stretchy quality of the t-shirt made it the more preferable
choice for a face mask as it was considered likely to provide a
better fit.
Although doubling the layers of fabric did significantly
increase the pressure drop measured across all 3 materials
(P,.01 using Wilcoxon sign rank test), only the 2 layers of
tea towel material demonstrated a significant increase in
filtration efficiency that was marginally greater than that of
the face mask.
In the questionnaire on mask use during a pandemic,
6 participants said they would wear a mask some of the time,
6 said they would never wear a mask, and 9 either did not
know or were undecided. None of the participants said that
they would wear a mask all of the time. With 1 exception, all
participants reported that their face mask was comfortable.
However, the length of time each participant kept their mask
on during testing was minimal (15 min), and with long-term
wear, comfort might decrease.
Facemask Fit Testing
A Wilcoxon sign rank test showed a significant difference
between the homemade and surgical mask for each exercise
and in total (all tests showed P,.001). The median and
interquartile range for each mask and exercise are given in
Table 2.
Prevention of Droplet and Particle Dissemination
When Coughing
Results from the cough box experiments showed that both
the surgical mask and the homemade mask reduced the total
number of microorganisms expelled when coughing (P,.001
and P5.004, respectively; see Table 3).
Are Homemade Masks Effective?
Disaster Medicine and Public Health Preparedness 3
On analyzing the effect of mask wearing in reducing the
number of microorganisms isolated from the Anderson air
sampler (Table 4), the surgical mask was found to be
generally more effective in reducing the number of micro-
organisms expelled than the homemade mask, particularly at
the lowest particle sizes. The number of microorganisms
isolated from the coughs of healthy volunteers was generally
low, although this varied according to the individual sampled
(Table 3). It is possible, therefore, that the sampling
limitations negatively affected the statistical analysis.
Pearson x
2
tests comparing the proportion of particles greater
than 4.7 mm in diameter and particles less than 4.7mmin
diameter found that the homemade mask did not significantly
reduce the number of particles emitted (P5.106). In contrast,
the surgical mask did have a significant effect (P,.001).
DISCUSSION
Facemasks reduce aerosol exposure by a combination of the
filtering action of the fabric and the seal between the mask
and the face. The filtration efficiency of the fabric depends
on a variety of factors: the structure and composition of the
fabric, and the size, velocity, shape, and physical properties of
the particles to which it is exposed.
10
Although any material
may provide a physical barrier to an infection, if as a mask it
does not fit well around the nose and mouth, or the material
freely allows infectious aerosols to pass through it, then it will
be of no benefit.
The test organisms in this study can be used to estimate
the efficacy of these masks against influenza virus because
essentially any aerosolized particle will behave predominately
in the air as a result of its physical characteristics rather than
its biological properties (ie, influenza virus particles will travel
in the air in the same manner as particles of an equivalent
size). Therefore, as we have tested a viral pathogen smaller
than influenza and a bacterial pathogen larger than influenza,
we have tested the face masks with a suitable challenge across
the size range of influenza virus particles. Furthermore, the
data from this study could also be applied to other organisms
within this size range that are potentially transmitted via the
aerosol route.
Quantitative fit testing can only estimate the combined
effects of filtration efficiency and goodness of fit. Although
sensitive to particles with diameters as small as 0.02 mm, it is
not sensitive to variations in particle size, shape, composition,
or refractive index. As a result, this method of fit testing
does not allow the distinction between true bioaerosols and
droplet contamination.
A study conducted in the Netherlands using a commercial
fit-test system (Portacount Plus Respirator Fit Tester) on
volunteers wearing both improvised masks made from tea
cloths and surgical masks over a 3-hour period found results
similar to those found in this study.
11
The authors
demonstrated a median protection factor of between 2.2
and 2.5 for various activities when wearing a mask with a tea
TABLE 2
Median and Interquartile Range Results from
Respirator Fit Testing of Homemade and Surgical
Masks
Median Interquartile Range
Condition Homemade Mask Surgical Mask
Normal breathing 2.0 (2.0, 2.5) 6.0 (2.5, 9.0)
Heavy breathing 2.0 (2.0, 3.0) 7.0 (2.5, 13.5)
Head moving side to side 2.0 (1.0, 2.0) 5.0 (3.0, 7.0)
Head moving up and down 2.0 (1.5, 2.0) 5.0 (3.0, 7.0)
Bending over 1.0 (1.0, 2.0) 3.0 (2.0, 9.0)
Talking 2.0 (1.0, 2.0) 6.0 (3.0, 12.0)
Normal 2.0 (1.0, 2.0) 5.0 (2.0, 8.5)
All data 2.0 (1.0, 2.0) 5.0 (3.0, 9.0)
TABLE 3
Median Colony-Forming Units by Sampling Method
Isolated From Volunteers Coughing When Wearing a
Surgical Mask, a Homemade Mask, and No Mask
Median Interquartile Range
Sampling Method No Mask Homemade Mask P
Air 6.0 (1.0, 26.5) 1.0 (0.5, 6.5) .007
Settle plates 1.0 (0.0, 3.0) 1.0 (0.0, 2.0) .224
Total 2.0 (0.0, 12.3) 1.0 (0.0, 3.0) .004
Median Interquartile Range
Sampling Method No Mask Surgical Mask P
Air 6.0 (1.0, 26.5) 1.0 (0.5, 3.0) .002
Settle plates 1.0 (0.0, 3.0) 0.0 (0.0, 0.0) .002
Total 2.0 (0.0, 12.3) 0.0 (0.0, 1.0) ,.001
TABLE 4
Total Colony-Forming Units Isolated by Particle Size
From 21 Volunteers Coughing When Wearing a
Surgical Mask, Homemade Mask, and No Mask
Particle Diameter, mm No Mask Homemade Mask Surgical Mask
.7935
4.7-7 18 7 7
3.3-4.7 5 4 4
2.1-3.3 47 7 5
1.1-2.1 100 16 6
0.65-1.1 21 6 3
Total 200 43 30
Are Homemade Masks Effective?
Disaster Medicine and Public Health Preparedness4
towel filter and protection factors of between 4.1 and 5.3
for the surgical mask. It was interesting that the study also
found that median protection factors increased over the
3-hour period for those wearing the homemade masks,
decreased for those wearing filtering face piece (FFP2) masks
that lower the wearer’s exposure to airborne particles by a
factor of 10, and showed no consistent pattern for those
wearing a surgical mask.
11
The materials used in this published study were fresh and
previously unworn. It is likely that materials conditioned
with water vapor, to create a fabric similar to that which has
been worn for a couple of hours, would show very different
filtration efficiencies and pressure drops. In contrast, a study
of breathing system filters found a greater breakthrough of
bacteriophage MS2 on filters that had been preconditioned.
Although the droplet sizes for both virus and bacteria were
the same and affected the filter media in a similar manner, it
was suggested that the viruses, after contact with the moisture
on the filter, were released from their droplet containment,
and driven onward by the flow of gas.
12
The average concentration of Streptococcus organisms in
saliva has been estimated to be 6.7 310
7
cfu/mL,
13
which
is higher than that of influenza viruses in inoculated
volunteers.
14
Therefore, the number of oral microorganisms
isolated may well provide an indication of the concentration
of influenza being shed. Results from the cough box
demonstrated that surgical masks have a significant effect in
preventing the dispersal of large droplets and some smaller
particles when healthy volunteers coughed. The homemade
mask also prevented the release of some particles, although
not at the same level as the surgical mask. The numbers
of microorganisms isolated from the coughs of healthy
volunteers was in general very low, and it is likely that had
we used volunteers with respiratory infections, the homemade
mask may have shown a more significant effect in preventing
the release of droplets.
It was observed during this study that there was greater
variation among volunteers in their method of fitting the
surgical mask. The need to tie the straps at the back of the
head meant that the surgical mask was fit in a variety of ways.
In contrast, the face mask had looped elastic straps that were
easier for the volunteer to fit.
Comfort should be an important factor in the material used to
make a homemade mask. The pressure drop across a mask is a
useful measure both of resistance to breathing and the
potential for bypass of air around the filter seal. If respiratory
protection is not capable of accommodating the breathing
demands of the wearer, then the device will impose an extra
breathing load on the wearer, which is especially impractic-
able for people with breathing difficulties. Furthermore,
the extra breathing load may induce leakage owing to the
increased negative pressure in the face mask.
15
In practice, people will not wear an uncomfortable mask for
a long period; even if they do, it is unlikely that they will
wear the mask properly. During the outbreak of severe acute
respiratory syndrome, an account of a flight from Bangkok,
Thailand, to Manchester, England. described mask wearers
removing their mask to cough, sneeze, and wipe their nose
(not necessarily into a handkerchief) and to sort through the
communal bread basket.
16
For those who wear a mask for
necessity, such as health care workers, regular training and fit
testing must be emphasized. Whereas, for those who choose
to wear a homemade mask, the requirements of cleaning and
changing the mask should be highlighted. Most importantly,
the lower protective capabilities of a homemade mask should
be emphasized so that unnecessary risks are not taken.
CONCLUSION
A protective mask may reduce the likelihood of infection, but
it will not eliminate the risk, particularly when a disease has
more than 1 route of transmission. Thus any mask, no matter
how efficient at filtration or how good the seal, will have
minimal effect if it is not used in conjunction with other
preventative measures, such as isolation of infected cases,
immunization, good respiratory etiquette, and regular hand
hygiene. An improvised face mask should be viewed as the
last possible alternative if a supply of commercial face masks is
not available, irrespective of the disease against which it may
be required for protection. Improvised homemade face masks
may be used to help protect those who could potentially, for
example, be at occupational risk from close or frequent
contact with symptomatic patients. However, these masks
would provide the wearers little protection from microorgan-
isms from others persons who are infected with respiratory
diseases. As a result, we would not recommend the use of
homemade face masks as a method of reducing transmission
of infection from aerosols.
About the Authors
Public Health England (HPA), Porton Down Salisbury (Dr Walker, Miss Thompson,
Davies and Giri, and Mr Bennett); PHE, Colindale, London (Mr Kafatos),
United Kingdom.
Address correspondence and reprint requests to Jimmy Walker, PhD, PHE, Porton
Down, Salisbury, SP4 0JG UK (e-mail: jimmy.walker@phe.gov.uk).
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Are Homemade Masks Effective?
Disaster Medicine and Public Health Preparedness6
... The relevant research is extremely limited. For example, in Sven Fikenzer's and Davies's studies, ventilation and cardiopulmonary exercise capacity were reduced by surgical masks in 9and 12 healthy males, respectively [5,6]. The studies published so far have each recruited only a small number of male subjects with a relatively large age span; however, age and gender differences are important factors affecting exercise and cardiopulmonary function [7,8]. ...
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Objective: To explore the impacts of surgical mask in normal subjects on cardiopulmonary function and muscle performance under different motor load and gender differences. Design: Randomized crossover trial. Setting: The Fifth Affiliated Hospital of Guangzhou Medical University, June 16th to December 30th, 2020. Participants: Thirty-one college students (age: male 21.27 ± 1.22 years; female 21.31 ± 0.79 years) were recruited and randomly allocated in two groups. Interventions: Group 1 first received CPET in the mask-on condition followed by 48 h of washout, and then received CPET in the mask-off condition. Group 2 first received CPET in the mask-off condition followed by 48 h of washout, then received CPET in the mask-on condition. The sEMG data were simultaneously collected. Main outcome measures: The primary outcome was maximum oxygen uptake (VO2 max) from CPET, which was performed on a cycle ergometer-this is the most important parameter associated with an individual's physical conditioning. The secondary parameters included parameters reflecting exercise tolerance and heart function (oxygen uptake, anaerobic valve, maximum oxygen pulse, heart rate reserve), parameters reflecting ventilation function (respiration reserve, ventilation volume, tidal volume, breathing frequency), parameters reflecting gas exchange (end-tidal oxygen and carbon dioxide partial pressure, oxygen equivalent, carbon dioxide equivalent, and the relationship between dead space and tidal volume) and parameters reflecting skeletal muscle function [oxygen uptake, anaerobic valve, work efficiency, and EMG parameters including root mean square (RMS)]. Results: Comparing the mask-on and mask-off condition, wearing surgical mask had some negative effects on VO2/kg (peak) and ventilation (peak) in both male and female health subjects [VO2/kg (peak): 28.65 ± 3.53 vs 33.22 ± 4.31 (P = 0.001) and 22.54 ± 3.87 vs 26.61 ± 4.03 (P < 0.001) ml/min/kg in male and female respectively; ventilation (peak): 71.59 ± 16.83 vs 82.02 ± 17.01 (P = 0.015) and 42.46 ± 10.09 vs 53.95 ± 10.33 (P < 0.001) liter in male and female respectively], although, based on self-rated scales, there was no difference in subjective feelings when comparing the mask-off and mask-on condition. Wearing surgical masks showed greater lower limb muscle activity just in male subjects [mean RMS of vastus medialis (load): 65.36 ± 15.15 vs 76.46 ± 19.04 μV, P = 0.031]. Moreover, wearing surgical masks produced a greater decrease in △tidal volume (VTpeak) during intensive exercises phase in male subjects than in female [male - 0.80 ± 0.15 vs female - 0.62 ± 0.11 l P = 0.001]. Conclusions: Wearing medical/surgical mask showed a negative impact on the ventilation function in young healthy subjects during CPET, especially in high-intensity phase. Moreover, some negative effects were found both in ventilation and lower limb muscle actives in male young subjects during mask-on condition. Future studies should focus on the subjects with cardiopulmonary diseases to explore the effect of wearing mask. Trial registration: Chinese Clinical Trial Registry ( ChiCTR2000033449 ).
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The unprecedented threat of COVID‐19 and the likelihood of other emerging infectious diseases have accentuated the need for sustainable and effective masks and respirators (MAR). MAR assists in minimizing the risk of infection and controlling the spread of pathogens. However, during the COVID‐19 pandemic, there was a worldwide scarcity of MAR due to unprecedented global demand. There are also notable limitations in commonly used MAR, such as low filtration efficiency, poor fit, non‐reusability, physiological impact, lack of biocompatibility and non‐biodegradability, and inability to kill pathogens. Therefore, there remains an unmet need for a comprehensive study focusing on potential materials and new technologies for MAR. Here we outline a comprehensive overview of the limitations of conventional MAR followed by required potential solutions (such as using nanofibers/graphene base filters/metal‐organic framework as filter media, laser scanning and 3D printing for fit and seal, applying antimicrobial nanomaterials coating on filter media, using reusable and biodegradable materials, developing high‐performing cloth masks, improving hydrophobicity, etc.). The information on potential materials and new technologies of MAR and research evidence outlined here can inform further research and development of high‐performing and sustainable respiratory protection technologies to improve the health and safety of the first responders and the community. The shortcomings of the commonly used conventional facemasks/respirators are pointed out, followed by the outline of potential materials and technologies that can inform the development of more effective technologies for respiratory protection.
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Background Non-pharmaceutical interventions (NPIs) used to limit SARS-CoV-2 transmission vary in their feasibility, appropriateness and effectiveness in different contexts. In Bangladesh a national lockdown implemented in March 2020 exacerbated poverty and was untenable long-term. A resurgence in 2021 warranted renewed NPIs. We sought to identify NPIs that were feasible in this context and explore potential synergies between interventions. Methods We developed an SEIR model for Dhaka District, parameterised from literature values and calibrated to data from Bangladesh. We discussed scenarios and parameterisations with policymakers with the aid of an interactive app. These discussions guided modelling of lockdown and two post-lockdown measures considered feasible to deliver; symptoms-based household quarantining and compulsory mask-wearing. We compared NPI scenarios on deaths, hospitalisations relative to capacity, working days lost, and cost-effectiveness. Results Lockdowns alone were predicted to delay the first epidemic peak but could not prevent overwhelming of the health service and were costly in lost working days. Impacts of post-lockdown interventions depended heavily on compliance. Assuming 80% compliance, symptoms-based household quarantining alone could not prevent hospitalisations exceeding capacity, whilst mask-wearing prevented overwhelming health services and was cost-effective given masks of high filtration efficiency. Combining masks with quarantine increased their impact. Recalibration to surging cases in 2021 suggested potential for a further wave in 2021, dependent on uncertainties in case reporting and immunity. Conclusions Masks and symptoms-based household quarantining synergistically prevent transmission, and are cost-effective in Bangladesh. Our interactive app was valuable in supporting decision-making, with mask-wearing being mandated early, and community teams being deployed to support quarantining across Dhaka. These measures likely contributed to averting the worst public health impacts, but delivering an effective response with consistent compliance across the population has been challenging. In the event of a further resurgence, concurrent messaging to increase compliance with both mask-wearing and quarantine is recommended.
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Covid-19 outbreak raised great awareness about ventilation system performance in indoor spaces. Specifically, the HVAC system design and operating parameters, such as air change per hours, air recirculation ratio, filtration device performance, and vents location, play a crucial role in reducing the spread of viruses, molds, bacteria, and general pollutants. Concerning the transportation sector, the SARS-COV-19 outbreak brought a reduction of payload for different carriers. Specifically, this has been particularly severe for the railway sector, where train coaches are typically featured by rather elevated occupancy and high air recirculating ratios. In this framework, to improve the Indoor Air Quality and to reduce the Covid-19 contagion risk into railway carriages, this paper investigates the energy, economic and environmental feasibility of diverse ventilation strategies. To do so, a novel simulation tool for the complete dynamic performance investigation of trains was developed in OpenStudio. Here, the Wells-Riley model was adopted to assess the Covid-19 contagion risk. To prove the capabilities of the proposed approach, a suitable case study related to an existing medium-distance train operating in South/Central Italy is presented. The conducted numerical simulations returns interesting results also providing useful design criteria.
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The worldwide pandemic of SARS‐CoV‐2 which causes coronavirus disease 2019 (COVID‐19) has resulted in first‐time responses in recent history as most of affected countries are confining residents to their homes. When sick people are detected, home quarantine is usually recommended because of the lack of available hospital rooms for first‐stage symptoms that do not require constant medical monitoring. In this situation, one can thus wonder about the transmission of the disease to other household members. In this paper, we numerically investigate the transport of the aerosol generated by an infected person quarantined to his bedroom to the other rooms in a typical French detached house by performing TRNSYS‐CONTAM simulations. The intent here is to assess the exposure concentration to the virus of the other household members when simple strategies are employed to reduce the risk of airborne transmission. Due to the uncertainty regarding the evaluation of different parameters such as the emission of contaminated droplets and the infectivity of the occupants, critical cases have been considered in this study. The main results show that, even if remediation actions lower the exposure of other occupants, the risk of contamination remains high even if the contagious person is quarantined to its bedroom.
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The current pandemic and the increasing global pollution level have been the recent driving force for scientists to develop more efficient and cost-effective masks to safeguard human life. Mask has become an essential carry out for each individual to shield them from becoming prey to various deadly respiratory diseases due to viruses, smoke, and allergens. In this review, we are elaborately explaining the categories of masks and their necessity of it in our daily life. Taking into consideration the latest pandemic situation we aim at developing a High-tech mask with enhanced filtrating properties and very economical so that it is affordable for every individual. The motive of the review study is to provide a general idea about the efficiency of different types of masks so that one can get knowledge and information about the different masks available and innovative ideas about them.
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Introducción. En diciembre de 2019 en Wuhan, China, se presentó un brote de neumonía atípica generado por el virus SARS-CoV-2, el cual es un tipo de coronavirus causante de la enfermedad COVID-19, que se convirtió con el tiempo en una pandemia. En este contexto, el uso de los elementos de protección personal tomó un especial interés, en especial para la atención del trabajo de parto vaginal, dada la confusión en los círculos obstétricos respecto a la mejor forma de proteger al personal sanitario en dichos casos. El objetivo de este artículo de revisión es identificar cuáles son los elementos de protección personal indicados en la atención del parto vaginal y su correcto uso en tiempos de COVID-19. División de temas tratados. Se realizó una revisión narrativa de la literatura accediendo a las bases de datos: PubMed, Medline, Elsevier, Google Académico y sitios web como la Organización Mundial de la salud (OMS), Centros para el Control y la Prevención de Enfermedades (CDC, por sus siglas en inglés) y el Colegio Americano de Obstetras y Ginecólogos (ACOG), entre otros. Se usaron palabras claves como “Infecciones por Coronavirus”, “Parto Normal”, “Protección Personal”, “Personal de Salud”, “Dispositivos de Protección Respiratoria” y “Dispositivos de Protección de los Ojos”. La literatura permitió identificar aspectos introductorios al tema, epidemiología, características generales de los elementos de protección personal, y los elementos específicos para el uso correcto en la atención del parto vaginal. Conclusiones. El trabajo de parto es considerado como un procedimiento generador de aerosoles, por lo que se recomienda principalmente el uso de tapabocas N95 o un respirador que ofrezca mayor protección para personal de salud en la atención del parto vaginal, con el fin de evitar la infección por SARS-CoV-2; sin embargo, se debe insistir en el uso adecuado y completo de los elementos de protección personal como lo son la bata quirúrgica, el gorro, el protector ocular y guantes, independientemente de la sintomatología de la paciente. Introduction. In December 2019, in Wuhan, China, there was an outbreak of atypical pneumonia caused by the SARS-CoV-2 virus, which is a type of coronavirus causative of COVID-19, which overtime became a pandemic. In this context, the use of personal protective equipment is of special interest, especially when providing care in vaginal delivery, due to the confusion in obstetric circles regarding the best way to protect healthcare personnel in these cases. The objective of this review article is to identify which are the personal protective elements indicated for providing care in vaginal birth and their correct use during COVID-19. Division of Covered Topics. A narrative review of the literature was carried out, accessing the following databases: PubMed, Medline, Elsevier, Google Scholar, and websites such as the World Health Organization (WHO), Center for the Control and Prevention of Diseases (CDC), and the American College of Obstetricians and Gynecologists, among others. Keywords such as “Coronavirus Infections”, “Normal Birth,” Personal Protective Elements,” “Healthcare Personnel”, “Respiratory Protective Devices”, and “Eye Protection Devices” were used. The literature allowed us to identify introductory aspects on the matter, epidemiology, general characteristics of personal protective elements, and the specific elements for correct use when providing care in vaginal birth. Conclusions. Labor is considered an aerosol-generating procedure. Therefore, the main recommendation is the use of an N95 mask or a respirator which allows for greater protection for healthcare personnel when assisting vaginal birth, in order to avoid infection due to SARS-CoV-2. However, there must be an adequate and complete use of personal protective equipment, such as surgical gowns, hats, eye protection and gloves, regardless of the patient’s symptomatology. Introdução. Em dezembro de 2019 em Wuhan, na China, houve um surto de pneumonia atípica gerada pelo vírus SARS-CoV-2, que é um tipo de coronavírus que causa a doença COVID-19, que, com o tempo, acabou se tornando uma pandemia. Nesse contexto, o uso de elementos de proteção individual tornou-se de particular interesse, especialmente para a assistência do parto vaginal, dada a confusão nos círculos obstétricos quanto à melhor forma de proteger os profissionais da saúde nesses casos. O objetivo deste artigo de revisão é identificar os elementos de proteção individual indicados na assistência do parto vaginal e seu uso correto em tempos de COVID-19. Divisão de tópicos abordados. Foi realizada uma revisão narrativa da literatura acessando as seguintes bases de dados: PubMed, Medline, Elsevier, Google Scholar e sites como a Organização Mundial da Saúde (OMS), Centros de Controle e Prevenção de Doenças (CDC, na sigla em inglês) e o Colégio Americano de Obstetras e Ginecologistas (ACOG), entre outros. Foram utilizadas palavras-chave como “Infecções por Coronavírus”, “Parto Normal”, “Proteção Pessoal”, “Pessoal de Saúde”, “Dispositivos de Proteção Respiratória” e “Dispositivos de Proteção Ocular”. A literatura permitiu identificar aspectos introdutórios ao tema, epidemiologia, características gerais dos elementos de proteção individual e elementos específicos para o uso correto na assistência do parto vaginal. Conclusões. O trabalho de parto é considerado um procedimento gerador de aerossóis, portanto, recomenda-se principalmente o uso de máscaras N95 ou um respirador que ofereça maior proteção para os profissionais de saúde na assistência do parto vaginal, a fim de evitar a infecção pelo SARS-CoV-2; no entanto, deve-se insistir no uso adequado e completo de elementos de proteção individual, como bata cirúrgica, touca, protetor ocular e luvas, independentemente dos sintomas do paciente.
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The effect of relative humidity (RH) on the airborne stability of two small bacterial viruses, S-13 and MS-2, was studied. Poorest recovery of S-13 was obtained at 50% RH. Humidification prior to aerosol sampling significantly increased the recovery of S-13 at RH deleterious to the airborne virus. A commercial preparation of MS-2 suspended in a buffered saline solution showed a rapid loss of viability at RH above 30%, whereas a laboratory preparation containing 1.3% tryptone showed high recoveries at all RH studied. Dilution of the commercial MS-2 into tryptone broth conferred stability on the airborne virus. Humidification prior to sampling significantly reduced the viable recovery from aerosols of commercial MS-2, whereas the laboratory preparation was unaffected.
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