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Visualizing the effectiveness of face masks in obstructing respiratory jets



The use of face masks in public settings has been widely recommended by public health officials during the current COVID-19 pandemic. The masks help mitigate the risk of cross-infection via respiratory droplets, however, there are no specific guidelines on mask materials and designs that are most effective in minimizing droplet dispersal. While there have been prior studies on the performance of medical-grade masks, there is insufficient data on cloth-based coverings which are being used by a vast majority of the general public. We use qualitative visualizations of emulated coughs and sneezes to examine how material- and design-choices impact the extent to which droplet-laden respiratory jets are blocked. Loosely folded face masks and bandana-style coverings provide minimal stopping-capability for the smallest aerosolized respiratory droplets. Well-fitted homemade masks with multiple layers of quilting fabric, and off-the-shelf cone style masks, proved to be the most effective in reducing droplet dispersal. These masks were able to curtail the speed and range of the respiratory jets significantly, albeit with some leakage through the mask material and from small gaps along the edges. Importantly, uncovered emulated coughs were able to travel noticeably farther than the currently recommended 6-foot distancing guideline. We outline the procedure for setting up simple visualization experiments using easily available materials, which may help healthcare professionals, medical researchers, and manufacturers in assessing the effectiveness of face masks and other personal protective equipment qualitatively.
Visualizing the eectiveness of face masks in obstructing respiratory jets
Siddhartha Verma,1,a) Manhar Dhanak,1, b) and John Frankenfield1, c)
Department of Ocean and Mechanical Engineering, Florida Atlantic University, Boca Raton,
FL 33431, USA
(Dated: 4 June 2020)
The use of face masks in public settings has been widely recommended by public health officials during the current
COVID-19 pandemic. The masks help mitigate the risk of cross-infection via respiratory droplets, however, there are no
specific guidelines on mask materials and designs that are most effective in minimizing droplet dispersal. While there
have been prior studies on the performance of medical-grade masks, there is insufficient data on cloth-based coverings
which are being used by a vast majority of the general public. We use qualitative visualizations of emulated coughs
and sneezes to examine how material- and design-choices impact the extent to which droplet-laden respiratory jets are
blocked. Loosely folded face masks and bandana-style coverings provide minimal stopping-capability for the smallest
aerosolized respiratory droplets. Well-fitted homemade masks with multiple layers of quilting fabric, and off-the-shelf
cone style masks, proved to be the most effective in reducing droplet dispersal. These masks were able to curtail the
speed and range of the respiratory jets significantly, albeit with some leakage through the mask material and from small
gaps along the edges. Importantly, uncovered emulated coughs were able to travel noticeably farther than the currently
recommended 6-foot distancing guideline. We outline the procedure for setting up simple visualization experiments
using easily available materials, which may help healthcare professionals, medical researchers, and manufacturers in
assessing the effectiveness of face masks and other personal protective equipment qualitatively.
Infectious respiratory illnesses can exact a heavy socio-
economic toll on the most vulnerable members of our soci-
ety, as has become evident from the current COVID-19 pan-
demic1,2. The disease has overwhelmed healthcare infrastruc-
ture worldwide3, and its high contagion rate and relatively
long incubation period4,5 have made it difficult to trace and
isolate infected individuals. Current estimates indicate that
about 35% of infected individuals do not display overt symp-
toms6, and may contribute to significant spread of the dis-
ease without their knowledge. In an effort to contain the un-
abated community spread of the disease, public health offi-
cials have recommended the implementation of various pre-
ventative measures, including social-distancing and the use of
face masks in public settings7.
The rationale behind the recommendation for using masks
or other face coverings is to reduce the risk of cross-infection
via the transmission of respiratory droplets from infected to
healthy individuals8,9. The pathogen responsible for COVID-
19 is found primarily in respiratory droplets that are expelled
by infected individuals during coughing, sneezing, or even
talking and breathing10–15. Apart from COVID-19, respira-
tory droplets are also the primary means of transmission for
various other viral and bacterial illnesses, such as the common
cold, influenza, tuberculosis, SARS (Severe Acute Respira-
tory Syndrome), and MERS (Middle East Respiratory Syn-
drome), to name a few16–19. These pathogens are enveloped
within respiratory droplets, which may land on healthy in-
dividuals and result in direct transmission, or on inanimate
objects which can lead to infection when a healthy individ-
ual comes in contact with them10,18,20,21. In another mode of
a)Electronic mail:;; Also
at Harbor Branch Oceanographic Institute, Florida Atlantic University, Fort
Pierce, FL 34946, USA
b)Electronic mail:
c)Electronic mail:
transmission, the droplets or their evaporated contents may re-
main suspended in the air for long periods of time if they are
sufficiently small. This can lead to airborne transmission19,22
when they are breathed in by another person, long after the
infected individual may have left the area.
Several studies have investigated respiratory droplets pro-
duced by both healthy and infected individuals when per-
forming various activities. The transport characteristics of
these droplets can vary significantly depending on their diam-
eter23–28. The reported droplet diameters vary widely among
studies available in the literature, and usually lie within the
range 1µm500µm29 , with a mean diameter of approxi-
mately 10µm30. The larger droplets (diameter > 100µm)
are observed to follow ballistic trajectories under the ef-
fects of gravity and aerodynamic drag20,31. Intermediate-
sized droplets20,31,32 may get carried over considerable dis-
tances within a multiphase turbulent cloud33–35. The smallest
droplets and particles (diameter < 5µmto 10µm) may remain
suspended in the air indefinitely, until they are carried away
by a light breeze or ventilation airflow20,32.
After being expelled into the ambient environment, the res-
piratory droplets experience varying degrees of evaporation
depending on their size, the ambient humidity, and tempera-
ture. The smallest droplets may undergo complete evapora-
tion, leaving behind a dried-out spherical mass consisting of
the particulate contents (e.g., pathogens), which are referred to
as ‘droplet nuclei’36. These desiccated nuclei, in combination
with the smallest droplets, are potent transmission sources on
account of two factors: 1) they can remain suspended in the air
for hours after the infected individual has left the area, poten-
tially infecting unsuspecting individuals who come into con-
tact with them; and 2) they can penetrate deep into the airways
of individuals who breathe them in, which increases the likeli-
hood of infection even for low pathogen loads. At present, the
role of droplet nuclei in the transmission of COVID-19 is not
known with certainty, and the matter is the subject of ongoing
studies37–39. In addition to generating microscopic droplets,
This is the author’s peer reviewed, accepted manuscript. However, the online version of record will be different from this version once it has been copyedited and typeset.
the action of sneezing can expel sheet-like layers of respi-
ratory fluids40, which may break apart into smaller droplets
through a series of instabilities. The majority of the fluid con-
tained within the sheet falls to the ground quickly within a
short distance.
Regardless of their size, all droplets and nuclei expelled by
infected individuals are potential carriers of pathogens. Var-
ious studies have investigated the effectiveness of medical-
grade face masks and other personal protective equipment
(PPE) in reducing the possibility of cross-infection via these
droplets13,33,41–47. Notably, such respiratory barriers do
not prove to be completely effective against extremely fine
aerosolized particles, droplets, and nuclei. The main is-
sue tends to be air leakage, which can result in aerosolized
pathogens being dispersed and suspended in the ambient en-
vironment for long periods of time after a coughing/sneezing
event has occurred. A few studies have considered the filtra-
tion efficiency of homemade masks made with different types
of fabric48–51, however there is no broad consensus regarding
their effectiveness in minimizing disease transmission52,53.
Nonetheless, the evidence suggests that masks and other face
coverings are effective in stopping larger droplets, which al-
though fewer in number compared to the smaller droplets and
nuclei, constitute a large fraction of the total volume of the
ejected respiratory fluid.
While detailed quantitative measurements are necessary for
comprehensive characterization of PPE, qualitative visualiza-
tions can be invaluable for rapid iteration in early design
stages, as well as for demonstrating the proper use of such
equipment. Thus, one of the aims of this letter is to describe a
simple setup for visualization experiments, which can be as-
sembled using easily available materials. Such setups may be
helpful to healthcare professionals, medical researchers, and
to industrial manufacturers, for assessing the effectiveness of
face masks and other protective equipment qualitatively. Test-
ing designs quickly and early on can prove to be crucial, es-
pecially in the current pandemic scenario where one of the
central objectives is to reduce the severity of the anticipated
resurgence of infections in the upcoming months.
The visualization setup used in the current study is shown
in Figure 1, and consists of a hollow manikin head which was
padded on the inside to approximate the internal shape and
volume of the nasal- and buccal-cavities in an adult. In case
a more realistic representation is required, such a setup could
include 3D-printed or silicone models of the internal airways.
The manikin was mounted at a height of approximately 5 feet
and 8 inches to emulate respiratory jets expelled by an average
human male. The circular opening representing the mouth is
0.75 inches in diameter. The pressure impulse that emulates
a cough or a sneeze may be delivered via a manual pump as
shown in Figure 1, or via other sources such as an air com-
pressor or a pressurized air canister. The air capacity of the
pump is 500ml, which is comparable to the lower end of the
total volume expelled during a cough54. We note that the setup
here emulates a simplified representation of an actual cough,
which is an extremely complex and dynamic problem55.We
use a recreational fog/smoke machine to generate tracer par-
ticles for visualizing the expelled respiratory jets, using a liq-
Face Mask
FIG. 1: Left - Experimental setup for qualitative
visualization of emulated coughs and sneezes. Right - A laser
sheet illuminates a puff emerging from the mouth.
uid mixture of distilled water (4 parts) and glycerin (1 part).
Both the pressure- and smoke-sources were connected to the
manikin using clear vinyl tubing and NPT fittings wherever
The resulting ‘fog’ or ‘smoke’ is visible in the right panel
of Figure 1, and is composed of microscopic droplets of the
vaporized liquid mixture. These are comparable in size to
the smallest droplets expelled in a cough jet (approximately
1µmto 10µm). We estimate that the fog droplets are less than
10µmin diameter, based on Stokes’ law and our observation
that they could remain suspended for up to 3 minutes in com-
pletely still air with no perceptible settling. The laser source
used to generate the visualization sheet is an off-the-shelf
5mW green laser pointer with a 532nm wavelength. A plane
vertical sheet is created by passing the laser beam through
a thin cylindrical rod (diameter 5mm) made of borosilicate
We first present visualization results from an emulation of
an uncovered heavy cough. The spatial and temporal evolu-
tion of the resulting jet is shown in Figure 2. The aerosolized
microscopic droplets visible in the laser sheet act as tracer
particles, revealing a 2-dimensional cross section of the con-
ical turbulent jet. These tracers depict the fate of the small-
est ejected droplets, and any resulting nuclei that may form.
We observed high variability in droplet dispersal patterns from
one experimental run to another, which was caused by other-
wise imperceptible changes in the ambient airflow. This high-
lights the importance of designing ventilation systems that
specifically aim to minimize the possibility of cross-infection
in a confined setting23,56–58.
Despite high variability, we consistently observed jets that
travelled farther than the 6-foot minimum distance proposed
by the U.S. Centers for Disease Control and Prevention7. In
the images shown in Figure 2, the ejected tracers were ob-
served to travel up to 12 feet within approximately 50 seconds.
Moreover, the tracer droplets remained suspended midair for
up to 3 minutes in the quiescent environment. These obser-
vations, in combination with other recent studies35,59, suggest
that current social-distancing guidelines may need to be up-
dated to account for aerosol-based transmission of pathogens.
This is the author’s peer reviewed, accepted manuscript. However, the online version of record will be different from this version once it has been copyedited and typeset.
3 feet
6 feet
3 feet
6 feet
9 feet
12 feet
3 feet
FIG. 2: An emulated heavy cough jet travels up to 12 feet in approximately 50 seconds, which is twice the CDC’s recommended
distancing guideline of 6 feet7. (a) 2.3 seconds after initiation of the emulated cough (b) 11 seconds (c) 53 seconds.
We note that although the unobstructed turbulent jets were ob-
served to travel up to 12 feet, a large majority of the ejected
droplets will fall to the ground by this point. Importantly, both
the number and concentration of the droplets will decrease
with increasing distance59, which is the fundamental rationale
behind social-distancing.
We now discuss dispersal patterns observed when the
mouth opening was blocked using three different types of face
masks. For these results, we focus on masks that are read-
ily accessible to the general public, and which do not draw
This is the author’s peer reviewed, accepted manuscript. However, the online version of record will be different from this version once it has been copyedited and typeset.
away from the supply of medical-grade masks and respirators
for healthcare workers. Figure 3 shows the impact of using a
folded cotton handkerchief mask on the expelled respiratory
jet. The folded mask was constructed by following instruc-
tions recommended by the U.S. Surgeon General60. It is evi-
dent that while the forward motion of the jet is impeded sig-
nificantly, there is notable leakage of tracer droplets through
the mask material. We also observe a small amount of trac-
ers escaping from the top edge of the mask, where gaps ex-
ist between the nose and the cloth material. These droplets
remained suspended in the air until they were dispersed by
ambient disturbances. In addition to the folded handkerchief
mask discussed here, we tested a single-layer bandana-style
covering (not shown) which proved to be substantially less ef-
fective in stopping the jet and the tracer droplets.
We now examine a homemade mask that was stitched using
two-layers of cotton quilting fabric consisting of 70 threads
per inch. The mask’s impact on droplet dispersal is shown in
Figure 4. We observe that the mask is able to arrest the for-
ward motion of the tracer droplets almost completely. There
is minimal forward leakage through the material, and most of
the tracer-escape happens from the gap between the nose and
the mask along the top edge. The forward distance covered by
the leaked jet is less than 3 inches in this case. The final mask
design that we tested was a non sterile cone-style mask that
is available in most pharmacies. The corresponding droplet-
dispersal visualizations are shown in Figure 5, which indicate
that the flow is impeded significantly compared to Figure 2
and Figure 3. However, there is noticeable leakage from gaps
along the top edge. The forward distance coverd by the leaked
jet is approximately 6 inches from the mouth opening, which
is farther than the distance for the stitched mask in Figure 4.
A summary of the various scenarios examined in this study
is provided in Table I, along with details about the mask ma-
terial and the average distances travelled by the respiratory
jets. We observe that a single-layer bandana-style covering
can reduce the range of the expelled jet to some extent, com-
pared to an uncovered cough. Importantly, both the mate-
rial and construction technique have a notable impact on the
masks’ stopping-capability. The stitched mask made of quilt-
ing cotton was observed to be the most effective, followed by
the commercial mask, the folded handkerchief, and finally,
the bandana. Importantly, our observations suggest that a
higher thread count by itself is not sufficient to guarantee bet-
ter stopping-capability; the bandana covering, which has the
highest thread count among all the cloth masks tested, turned
out to be the least effective.
We note that it is likely that healthcare professionals trained
properly in the use of high-quality fitted masks will not ex-
perience leakage to the extent that we have observed in this
study. However, leakage remains a likely issue for members
of the general public who often rely on loose-fitting home-
made masks. Additionally, the masks may get saturated after
prolonged use, which might also influence their filtration ca-
pability. We reiterate that although the non-medical masks
tested in this study experienced varying degrees of flow leak-
age, they are likely to be effective in stopping larger respira-
tory droplets.
In addition to providing an initial indication of the effec-
tiveness of protective equipment, the visuals used in this study
can help convey to the general public the rationale behind
social-distancing guidelines and recommendations for using
face masks. Promoting widespread awareness of effective pre-
ventative measures is crucial, given the high likelihood of a
resurgence of COVID-19 infections in the fall and winter.
The data that supports the findings of this study is available
within the article.
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2 in
Leakage from
the top
Leakage through
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(c) (d)
FIG. 3: (a) A face mask constructed using a folded handkerchief. (b) 0.5 seconds after initiation of the emulated cough (c) 2.27
seconds (d) 5.55 seconds.
2 in
Leakage from
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TABLE I: A summary of the different types of masks tested, the materials they are made of, and their effectiveness in impeding
droplet-dispersal. The last column indicates the distance travelled by the jet beyond which its forward progression stops. The
average distances have been computed over multiple runs, and the symbol ‘’ is used to indicate the presence of high
variability in the first two scenarios listed.
Mask type Material Threads per inch Average jet distance
Uncovered — 8 feet
Bandana Elastic T-shirt material 85 3 feet 7 inches
Folded handkerchief Cotton 55 1 foot 3 inches
Stitched mask Quilting cotton 70 2.5 inches
Commercial maskaUnknown Randomly assorted fibers 8 inches
aCVS Cone Face Mask
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This is the author’s peer reviewed, accepted manuscript. However, the online version of record will be different from this version once it has been copyedited and typeset.
... ASTM has recently provided a framework for the specifications of barrier face covering performance [18]. However, the document recognizes that no accepted methodologies were defined to measure total filtration efficiency from loose-fitting face masks and face coverings despite recent studies have demonstrated the relation of mask design features and fitting with air leakage and overall filtration performance [19], [20], [21], [22]. ...
... Indeed, the median [fist quartile; third quartile] values of TFE measured without nosepiece at the three flow rates were 12 [9,15] %, 21 [17,29] % and 32 [25,39] % respectively. With the nosepiece in place, the same group of masks tested in identical testing conditions presented TFE values of 15 [13,19] %, 28 [22,33] % and 40 [31,45] %. The comparison of TFE values obtained with and without nosepiece over the 26 tested masks indicated that a significant increase in TFE was achieved when the nosepiece was present (p<0.05, ...
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Surgical and community face masks are used worldwide to reduce the transmission of respiratory infections in indoor environments. Performance parameters for these loose-fitting devices are mainly focused on material filtering efficiency, while, differently from face respirators, there are no standards methods for measuring the fraction of air leaking at the face seal. This study quantifies the total filtration efficiency (TFE), a parameter based both on filter efficiency and air leakage, of 50 face mask models with the aim of understanding the role of several mask design features on TFE performance. An instrumented head form equipped with sensors for measuring volumetric airflow and differential pressure was used to simulate the air exhalation from the mouth of a person wearing a face mask. A Response Surface Method (RSM) was used to model the TFE experimental data. Results showed that TFE values ranged over a wide interval (from 5 % to 73 %), with better values at higher flowrates. A significant positive correlation was found between TFE and filter breathability. The presence of a nosepiece showed to increase the TFE on average from 4 % to 6 %, according to the flowrate. Significant improvements were associated only to nosepieces incorporating a metallic wire. The RSM model evidenced that the increase in the number of the filter layers, and the use of a meltblown layer, result in higher TFE only when a nosepiece is in place. Differently, the benefit of the nosepiece is less marked for masks made of highly breathable filters. To improve overall mask performance, the design of loose-fitting face masks should carefully compromise between breathability and filtration efficiency of the filter materials. The addition of a metallic nosepiece help improving the TFE by limiting the air leaking at the face seal.
... Fabrics that are commercially available to the public and even to most non-vertically integrated manufacturers will have additional variables. Research at Florida Atlantic University more strongly emphasizes that thread count alone is not sufficient to guarantee better filtration [59]; however, this conclusion is based not just on fabric construction but on face covering design. The authors of the study cited the example of a bandana with a high thread count performing more poorly than fitted face coverings of lower thread count fabric. ...
... However, they also conclude that face coverings are quite effective at preventing the spread of the wearer's exhaled air [38]. This aligns with other reports [15,24,59] and the common messages regarding the social contract of wearing a face covering to protect others. The fluid dynamics analysis should inform future testing and evaluation of materials for the general use of face coverings. ...
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Textile supply chain challenges due to the COVID-19 pandemic and the Russia-Ukraine war give unique insights into how health crises and geopolitical instability could dry up supplies of vital materials for the smooth functioning of human societies in calamitous times. Coinciding adverse global events or future pandemics could create shortages of traditional face coverings among other vital materials. Reusable face coverings could be a viable relief option in such situations. This review identifies the lack of studies in the existing literature on reusable fabric face coverings available in the market. It focuses on the development, filtration mechanisms, and factors associated with the filtration efficiency of reusable knitted and woven fabric face coverings. The authors identified relevant papers through the Summon database. Keeping the focus on readily available fabrics, this paper encompasses the key aspects of reusable face coverings made of knitted and woven fabrics outlining filtration mechanisms and requirements, development, factors affecting filtration performance, challenges, and outcomes of clinical trials. Filtration mechanisms for reusable face coverings include interception and impaction, diffusion, and electrostatic attraction. Face covering development includes the identification of appropriate constituent fibers, yarn characteristics, and base fabric construction. Factors significantly affecting the filtration performance were electrostatic charge, particle size, porosity, layers, and finishes. Reusable face coverings offer several challenges including moisture management, breathing resistance factors, and balancing filtration with breathability. Efficacy of reusable face coverings in comparison to specialized non reusable masks in clinical trials has also been reviewed and discussed. Finally, the authors identified the use of certain finishes on fabrics as a major challenge to making reusable face coverings more effective and accessible to the public. This paper is expected to provide communities and research stakeholders with access to critical knowledge on the reusability of face coverings and their management during periods of global crisis.
... At the same time, it is evidenced that the multi-scalar approach to spatial management is effective in better control and containment of community transmission. The possible air travel distance of droplets from a person coughing varies between 20 cm using commercial masks to 1.12 m using a bandana [50]. Therefore, wearing masks is a very useful way to prevent the disease spread, but it is not so effective if only a few use them in crowded places or if minimum distances are not considered. ...
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The spread of COVID-19 at a large scale and at a rapid pace indicates the lack of social distancing measures at multiple levels. The individuals are not to be blamed, nor should we assume the early measures were ineffective or not implemented. It is all down to the multiplicity of transmission factors that made the situation more complicated than initially anticipated. Therefore, in facing the COVID-19 pandemic, this overview paper discusses the importance of space in social distancing measures. The methods used to investigate this study are literature review and case study. Many scholarly works have already provided us with evidence-based models that suggest the influential role of social distancing measures in preventing COVID-19 community spread. To further elaborate on this important topic, the aim here is to look at the role of space not only at the individual level but at larger scales of communities, cities, regions, etc. The analysis helps better management of cities during the pandemics such as COVID-19. By reflecting on some of the ongoing research on social distancing, the study concludes with the role of space at multiple scales and how it is central to the practice of social distancing. We need to be more reflective and responsive to achieve earlier control and containment of the disease and the outbreak at the macro level.
... However, our schlieren visualizations clearly showed a significant reduction of the spreading distance of the exhaled air when wearing a surgical mask or FFP2 mask (Videos S2, S3, S5, and S6 in the Supplementary Materials). The sealing effect of face masks for respiratory jets has recently been demonstrated, proving that any kind of face covering alters the trajectory and influences the travel distance of the exhaled air [54,55]. Using schlieren visualizations, Kerl et al. [31] proved that wearing a surgical mask as well as an FFP2 mask results in a diversion of the exhaled air and an uplifting effect by the thermal plume of the human body under resting conditions and while coughing. ...
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Physical exercise demonstrates a special case of aerosol emission due to its associated elevated breathing rate. This can lead to a faster spread of airborne viruses and respiratory diseases. Therefore, this study investigates cross-infection risk during training. Twelve human subjects exercised on a cycle ergometer under three mask scenarios: no mask, surgical mask, and FFP2 mask. The emitted aerosols were measured in a grey room with a measurement setup equipped with an optical particle sensor. The spread of expired air was qualitatively and quantitatively assessed using schlieren imaging. Moreover, user satisfaction surveys were conducted to evaluate the comfort of wearing face masks during training. The results indicated that both surgical and FFP2 masks significantly reduced particles emission with a reduction efficiency of 87.1% and 91.3% of all particle sizes, respectively. However, compared to surgical masks, FFP2 masks provided a nearly tenfold greater reduction of the particle size range with long residence time in the air (0.3–0.5 μm). Furthermore, the investigated masks reduced exhalation spreading distances to less than 0.15 m and 0.1 m in the case of the surgical mask and FFP2 mask, respectively. User satisfaction solely differed with respect to perceived dyspnea between no mask and FFP2 mask conditions.
... Jak już wspomniano, choroby te mogą powodować cięższy przebieg infekcji, gorsze rokowanie, a zakażenie SARS-CoV-2 -zaostrzać chorobę podstawową. Ponadto początkowo sądzono, iż stosowanie inhalacji przyczynia się do znacznej transmisji wirusa [42,43]. Kolejne badania pokazały jednak, iż zagrożenie zwiększonego przenoszenia się koronawirusa poprzez nebulizację, przy zachowaniu wszelkich środków bezpieczeństwa, jest niewielkie [44,45]. ...
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Infekcje wirusowe, w tym koronawirusowe, powodują zaostrzenia astmy i POChP. Ostatnie badania dowodzą jednak, że astma nie jest czynnikiem ryzyka ciężkiego przebiegu COVID-19, a SARS-CoV-2 jej nie zaostrza. Nie stwierdzono zwiększonego nasilenia objawów, zwiększonego ryzyka zgonu, częstości wentylacji mechanicznej i intubacji, długość pobytu, ponownego przyjęcia lub śmiertelności z powodu COVID-19 u chorych na astmę. Pacjenci z POChP są bardziej podatni na zakażenie koronawirusem i cięższy przebieg infekcji, co może być spowodowane zwiększoną ekspresją ACE2 (receptor dla SARS-CoV-2) w nabłonku oskrzeli i tkance płuc w tej grupie chorych oraz powiązaniem wyższego poziomu ekspresji ACE2 z niższą czynnością płuc. Wśród pacjentów hospitalizowanych występowanie POChP jest istotnie skorelowane z większym nasileniem objawów COVID-19, co prowadzi do gorszego rokowania. Współwystępowanie COVID-19 z innymi przewlekłymi chorobami dróg oddechowych, takimi jak astma i POChP, stanowi nie lada wyzwanie terapeutyczne. Jednak, pomimo początkowych obaw, schematy oraz metody terapii astmy i POChP w dobie pandemii nie uległy zmianie. W astmie postępujemy zgodnie z wytycznymi GINA, a w POChP – rekomendacjami GOLD. Zaleca się, aby nie zmieniać planów leczenia ustalonych przez lekarzy i aby pacjenci kontynuowali terapię wziewną. Podstawą leczenia pozostają glikokortykosteroidy w postaci inhalacji. Obecnie w codziennej praktyce telewizyty są dobrym rozwiązaniem w kontrolowaniu przebiegu astmy i POChP, podtrzymywaniu terapii i modyfikacji postępowania. Niestety w trakcie telewizyty nie jesteśmy w stanie skontrolować techniki przyjmowania leków wziewnych. Odpowiedzią na ten problem może być inhalator Forspiro®, który ma unikalny mechanizm poprawnej techniki inhalacji. Jego cechy, takie jak: prosta, kompaktowa budowa umożliwiająca intuicyjne używanie, minimalna liczba wymaganych czynności przy stosowaniu, informacja zwrotna dla chorego o prawidłowym procesie inhalacji, mogą w znacznym stopniu ułatwić terapię stosowaną samodzielnie, w domu przez pacjenta.
... 32 Verma et al. have investigated the efficacy of different commercially available face masks by determining the distance traveled by the respiratory jets. 33 Many investigations have been conducted by researchers to test the efficacy of masks, all of which primarily focused on smaller-sized droplets (0-100 lm). 14, [34][35][36][37] Flow-field generated by coughing with and without surgical masks has been investigated by Kahler and Hain to study the flow blockage caused by the masks using PIV measurements. ...
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The advent of the COVID-19 pandemic has necessitated the use of face masks, making them an integral part of the daily routine. Face masks occlude the infectious droplets during any respiratory event contributing to source control. In the current study, spray impingement experiments were conducted on porous surfaces like masks having a different porosity, pore size, and thickness. The spray mimics actual cough or a mild sneeze with respect to the droplet size distribution (20–500 [Formula: see text]) and velocity scale (0–14 [Formula: see text]), which makes the experimental findings physiologically realistic. The penetration dynamics through the mask showed that droplets of all sizes beyond a critical velocity penetrate through the mask fabric and atomize into daughter droplets in the aerosolization range, leading to harmful effects due to the extended airborne lifetime of aerosols. By incorporating spray characteristics along with surface tension and viscous dissipation of the fluid passing through the mask, multi-step penetration criteria have been formulated. The daughter droplet size and velocity distribution after atomizing through multi-layered masks and its effects have been discussed. Moreover, the virus-emulating particle-laden surrogate respiratory droplets are used in impingement experiments to study the filtration and entrapment of virus-like nanoparticles in the mask. Furthermore, the efficacy of the mask from the perspective of a susceptible person has been investigated.
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This study investigates the aerosol transmission in queuing and dining scenarios in canteens and explores the effectiveness of control measures. An improved Wells-Riley equation is adopted to calculate the infection risk. The dilution of exhaled aerosols is difficult in the crowded queuing scenario, where the replacement of queuing positions increases the cross-infection risk. The highest infection risk is 1.16% and 1.08% for the linear-queue and cross-queue condition, respectively. Shortening the queuing duration, increasing the separation distance, and wearing masks can considerably reduce the infection risk. In the dining scenario, the effect of increasing ACH is limited on reducing the local concentration. An exhaust vent installed close to the top of the partition can effectively remove the local high-concentration aerosols. Intermittent occupation of a seat can considerably reduce the transmission risk between the consecutive dinners taking that seat. These findings should contribute to improved control of infectious transmission in canteens. ARTICLE HISTORY
Recent advancements in the growth of classification tasks and deep learning have culminated in the worldwide success of numerous practical applications. With the onset of COVID-19 pandemic, it becomes very important to use technology to help us control the infectious nature of the virus. Deep learning and image classification can help us detect face mask from a crowd of people. However, choosing the correct deep learning architecture can be crucial in the success of such an idea. This study presents a model for extracting features from face masks utilizing pre-trained models ConvNet, InceptionV3, MobileNet, DenseNet, ResNet50, and VGG19, as well as stacking a fully connected layer to solve the issue. On the face mask 12 k dataset, the study assesses the effectiveness of the suggested deep learning approaches for the task of facemask detection. The performance metrics used for analysis are loss, accuracy, validation loss, and validation accuracy. The maximum accuracy is achieved by DenseNet and MobileNet. Both the models gave a comparable and good accuracies in terms of training and validation (99.89% and 99.79%), respectively. Further, the paper also demonstrates the deployment of deep learning architecture in the real-world using Raspberry Pi 2B (1 GB RAM).KeywordsFace mask detectionDeep learningVGG19DenseNetMobileNetInceptionV3ConvNetResNet50
Coronavirus disease 2019 (COVID-19) plays a vital role in the pollution of micro-plastic. Currently, the increase in the use of polypropylene-based face masks has been an issue in waste management. This scenario will someday cause big environmental problems if the wastes are improperly managed. Thus, this review is aimed at analyzing the waste contributed by face masks and studying the factors that help fasten the degradation of face masks. These findings were analyzed according to the degradation of the polypropylene-based face mask under a few headings. The results have been presented and fallen into respective categories, and it shows that polypropylene does undergo deterioration in the landfill burial under the dumping site soil. It has been confirmed that there was heavy colonization of microbial communities from the used face masks. Thus, it is recommended that more research need to be done further to test the microbial effects of polypropylene-based face masks.
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Speech droplets generated by asymptomatic carriers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are increasingly considered to be a likely mode of disease transmission. Highly sensitive laser light scattering observations have revealed that loud speech can emit thousands of oral fluid droplets per second. In a closed, stagnant air environment, they disappear from the window of view with time constants in the range of 8 to 14 min, which corresponds to droplet nuclei of ca. 4 μm diameter, or 12- to 21-μm droplets prior to dehydration. These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments.
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There were 3 influenza pandemics in the 20th century, and there has been 1 so far in the 21st century. Local, national, and international health authorities regularly update their plans for mitigating the next influenza pandemic in light of the latest available evidence on the effectiveness of various control measures in reducing transmission. Here, we review the evidence base on the effectiveness of nonpharmaceutical personal protective measures and environmental hygiene measures in nonhealthcare settings and discuss their potential inclusion in pandemic plans. Although mechanistic studies support the potential effect of hand hygiene or face masks, evidence from 14 randomized controlled trials of these measures did not support a substantial effect on transmission of laboratory-confirmed influenza. We similarly found limited evidence on the effectiveness of improved hygiene and environmental cleaning. We identified several major knowledge gaps requiring further research, most fundamentally an improved characterization of the modes of person-to-person transmission.
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Background The pandemic of COVID-19 is growing, and a shortage of masks and respirators has been reported globally. Policies of health organizations for healthcare workers are inconsistent, with a change in policy in the US for universal face mask use. The aim of this study was to review the evidence around the efficacy of masks and respirators for healthcare workers, sick patients and the general public. Methods A systematic review of randomized controlled clinical trials on use of respiratory protection by healthcare workers, sick patients and community members was conducted. Articles were searched on Medline and Embase using key search terms. Results A total of 19 randomised controlled trials were included in this study – 8 in community settings, 6 in healthcare settings and 5 as source control. Most of these randomised controlled trials used different interventions and outcome measures. In the community, masks appeared to be more effective than hand hygiene alone, and both together are more protective. Randomised controlled trials in health care workers showed that respirators, if worn continually during a shift, were effective but not if worn intermittently. Medical masks were not effective, and cloth masks even less effective. When used by sick patients randomised controlled trials suggested protection of well contacts. Conclusion The study suggests that community mask use by well people could be beneficial, particularly for COVID-19, where transmission may be pre-symptomatic. The studies of masks as source control also suggest a benefit, and may be important during the COVID-19 pandemic in universal community face mask use as well as in health care settings. Trials in healthcare workers support the use of respirators continuously during a shift. This may prevent health worker infections and deaths from COVID-19, as aerosolisation in the hospital setting has been documented.
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The ongoing COVID-19 outbreak has spread rapidly on a global scale. While the transmission of SARS-CoV-2 via human respiratory droplets and direct contact is clear, the potential for aerosol transmission is poorly understood1–3. This study investigated the aerodynamic nature of SARS-CoV-2 by measuring viral RNA in aerosols in different areas of two Wuhan hospitals during the COVID-19 outbreak in February and March 2020. The concentration of SARS-CoV-2 RNA in aerosols detected in isolation wards and ventilated patient rooms was very low, but it was elevated in the patients’ toilet areas. Levels of airborne SARS-CoV-2 RNA in the majority of public areas was undetectable except in two areas prone to crowding, possibly due to infected carriers in the crowd. We found that some medical staff areas initially had high concentrations of viral RNA with aerosol size distributions showing peaks in submicrometre and/or supermicrometre regions, but these levels were reduced to undetectable levels after implementation of rigorous sanitization procedures. Although we have not established the infectivity of the virus detected in these hospital areas, we propose that SARS-CoV-2 may have the potential to be transmitted via aerosols. Our results indicate that room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can effectively limit the concentration of SARS-CoV-2 RNA in aerosols. Future work should explore the infectivity of aerosolized virus.
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Cases of COVID-19 have been reported in over 200 countries. Thousands of health workers have been infected and outbreaks have occurred in hospitals, aged care facilities and prisons. World Health Organization (WHO) has issued guidelines for contact and droplet precautions for Healthcare Workers (HCWs) caring for suspected COVID-19 patients, whilst the US Centre for Disease Control (CDC) has recommended airborne precautions. The 1 - 2 m (≈3 - 6 ft) rule of spatial separation is central to droplet precautions and assumes large droplets do not travel further than 2 m (≈6 ft). We aimed to review the evidence for horizontal distance travelled by droplets and the guidelines issued by the World Health Organization (WHO), US Center for Diseases Control (CDC) and European Centre for Disease Prevention and Control (ECDC) on respiratory protection for COVID-19. We found that the evidence base for current guidelines is sparse, and the available data do not support the 1 - 2 m (≈3 - 6 ft) rule of spatial separation. Of ten studies on horizontal droplet distance, eight showed droplets travel more than 2 m (≈6 ft), in some cases more than 8 meters (≈26 ft). Several studies of SARS-CoV-2 support aerosol transmission and one study documented virus at a distance of 4 meters (≈13 ft) from the patient. Moreover, evidence suggests infections cannot neatly be separated into the dichotomy of droplet versus airborne transmission routes. Available studies also show that SARS-CoV-2 can be detected in the air, 3 hours after aeroslisation. The weight of combined evidence supports airborne precautions for the occupational health and safety of health workers treating patients with COVID-19.
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We report temporal patterns of viral shedding in 94 patients with laboratory-confirmed COVID-19 and modeled COVID-19 infectiousness profiles from a separate sample of 77 infector–infectee transmission pairs. We observed the highest viral load in throat swabs at the time of symptom onset, and inferred that infectiousness peaked on or before symptom onset. We estimated that 44% (95% confidence interval, 25–69%) of secondary cases were infected during the index cases’ presymptomatic stage, in settings with substantial household clustering, active case finding and quarantine outside the home. Disease control measures should be adjusted to account for probable substantial presymptomatic transmission. Presymptomatic transmission of SARS-CoV-2 is estimated to account for a substantial proportion of COVID-19 cases.
Our understanding of the mechanisms of airborne transmission of viruses is incomplete. This paper employs computational multiphase fluid dynamics and heat transfer to investigate transport, dispersion, and evaporation of saliva particles arising from a human cough. An ejection process of saliva droplets in air was applied to mimic the real event of a human cough. We employ an advanced three-dimensional model based on fully coupled Eulerian–Lagrangian techniques that take into account the relative humidity, turbulent dispersion forces, droplet phase-change, evaporation, and breakup in addition to the droplet–droplet and droplet–air interactions. We computationally investigate the effect of wind speed on social distancing. For a mild human cough in air at 20 °C and 50% relative humidity, we found that human saliva-disease-carrier droplets may travel up to unexpected considerable distances depending on the wind speed. When the wind speed was approximately zero, the saliva droplets did not travel 2 m, which is within the social distancing recommendations. However, at wind speeds varying from 4 km/h to 15 km/h, we found that the saliva droplets can travel up to 6 m with a decrease in the concentration and liquid droplet size in the wind direction. Our findings imply that considering the environmental conditions, the 2 m social distance may not be sufficient. Further research is required to quantify the influence of parameters such as the environment’s relative humidity and temperature among others.
The emergence of a pandemic affecting the respiratory system can result in a significant demand for face masks. This includes the use of cloth masks by large sections of the public, as can be seen during the current global spread of COVID-19. However, there is limited knowledge available on the performance of various commonly available fabrics used in cloth masks. Importantly, there is a need to evaluate filtration efficiencies as a function of aerosol particulate sizes in the 10 nm to 10 μm range, which is particularly relevant for respiratory virus transmission. We have carried out these studies for several common fabrics including cotton, silk, chiffon, flannel, various synthetics, and their combinations. Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, respectively, the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids (such as cotton–silk, cotton–chiffon, cotton–flannel) was >80% (for particles <300 nm) and >90% (for particles >300 nm). We speculate that the enhanced performance of the hybrids is likely due to the combined effect of mechanical and electrostatic-based filtration. Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency, implying the need for future cloth mask design studies to take into account issues of “fit” and leakage, while allowing the exhaled air to vent efficiently. Overall, we find that combinations of various commonly available fabrics used in cloth masks can potentially provide significant protection against the transmission of aerosol particles.
The COVID-19 pandemic has resulted in over 1.4 million confirmed cases and over 83,000 deaths globally. It has also sparked fears of an impending economic crisis and recession. Social distancing, self-isolation and travel restrictions forced a decrease in the workforce across all economic sectors and caused many jobs to be lost. Schools have closed down, and the need of commodities and manufactured products has decreased. In contrast, the need for medical supplies has significantly increased. The food sector has also seen a great demand due to panic-buying and stockpiling of food products. In response to this global outbreak, we summarise the socio-economic effects of COVID-19 on individual aspects of the world economy.