Here I want to tell you
everything about the Novel Coronavirus and the wearing of masks. As the
article is a big long, you can look at the summary of each paragraph and choose
the one you are most interested in to read. However, we suggest you read the
complete article, and we are sure you won't regret doing it.
1. Foreword
- Necessary protective measures against COVID-19 suggested by WHO
- Why infected persons should wear a mask to prevent the virus spread in the droplets from their sneezes and coughs
- Western people don’t want to wear masks because of their culture
2. How
masks avoid the spread of the Novel Coronavirus
- How does the virus spread by attaching to the droplets or droplet nuclei from sneezes/coughs/talking
- What are the BFE and PFE of the masks
- How do masks filtrate particles
- Filtration efficiency of different types of masks against various sizes of particles
- Diameter range of droplet nuclei and the filtration efficiency of different masks on this range
3. Significant
misunderstandings about masks
- Healthy people do not need to wear masks; only sick people need to wear masks
- Disposable surgical masks can’t provide respiratory protection due to their loose-fitting
- A disposable mask and a surgical mask are equal to each other
4. The correct method of
wearing a disposable mask
5. Mask types and
recommendations for which ones people should use in different scenarios
6. Two masks which you
could consider to have
1. Foreword
COVID–19 Coronavirus has become
a dreaded infection, known to many people on the planet that has access to the
Internet or media. Apart from the fact that it is plunging the global economy
into disarray, it is also taking down the world’s population. According to the
COVID-19 Coronavirus outbreak data on worldometers.info on April 12th, 2020,
16:42GMT 1,817,968 persons have been reported to be infected by the virus, and
112,370 persons have lost their lives to the dreaded COVID-19 Coronavirus
disease.
Another factor that makes
Coronavirus more frightening, aside from the death tolls that can result from
infection is its creepy mode of transmission. The virus spreads like flu bugs
and colds via droplets when an infected person coughs or sneezes. The droplets
can land on the surface of objects and can be picked up by the hands of other
people, or the droplets can even land on another person who is in close contact
with the infected person at the time the person coughs on sneezes.
The Novel Coronavirus:
called SARS-CoV-2 displayed in an electron microscope
A person can become infected
when they touch their nose, eyes, or mouth with contaminated hands. The crafty
transmission of Coronavirus is not without proven preventive measures. The
World Health Organization (WHO) stated the following as the necessary
protective measures against COVID-19 Coronavirus:
- Maintaining Social Distancing: There is a high risk of breathing in droplets, which contains the COVID-19 virus if an infected person coughs or sneezes. WHO advised that a distance of at least 1 meter should be maintained from anyone that is sneezing or coughing.
- Washing hand frequently: Washing of hands with water and soap or an alcohol-based rub kills the viruses that may be on the hands.
- Avoid touching nose, eyes, and mouth: Contaminated hands are the vectors of this virus. The virus can enter the body and make a person sick if the person touches their nose, eyes, or mouth with contaminated hands.
The preventive measures against
COVID-19 prescribed by WHO emphasized guarding against contact with
infected droplets, which proceeds from coughing or sneezing.
A mask is a useful material for
capturing droplets. Some studies have revealed that masks provide estimated
fivefold protection versus no barrier against pathogens. In the event of close
contact or talking with an infected person, a mask cuts the chances of passing
on the disease.
Therefore, it is expedient for
an infected person or a person showing signs of infection to wear a mask to
protect others from the disease. It is recommended for the family members who
are caring for an ill person to wear a mask, and ideally, both the caregiver
and the patient should wear masks.
It is not uncommon to see
people in East Asian countries wearing surgical masks in public to protect
themselves against pollution and pathogens even before the outbreak of
Coronavirus. The Japanese even wear masks for non-medical reasons ranging from
keeping warm during the winter to hiding a swollen lip or a red nose during the
allergy season.
This is a crazy thing to do in
Western society. This perception difference in wearing a mask is partly due to
Western cultural norms about covering the face. Social interaction in Western
society demands that you show your identity and make eye contact. Facial
expression is essential in Western communications. Since, the wearing of masks
has never been a part of Western culture, wearing one as a preventive measure
against Coronavirus seems absurd.
2. How masks prevent the spread
of the Novel Coronavirus
Although Western societies
believe that wearing a mask in public is absurd, with the outbreak of COVID-19
and the preventive capability of wearing masks, the wearing of a mask is now
portraying an individual to be socially responsible; one that cares about the
well-being of everyone around. Each sneeze will produce over 10,000 droplets,
which can travel up to 8 meters. Each cough will produce 1,000 to 2,000
droplets, which can travel up to 6 meters. Even talking produces about 500
droplets each minute. Now, imagine what could happen if these droplets are
coming out from an infected person who has refused to wear a mask.
When an infected person sneezes
or coughs, some of the thousands of big droplets (dia. greater than 100 μm)
fall to the ground or surface of objects within 10 seconds and can be picked up
by hands. This is why it is necessary to maintain good personal and communal
hygiene by the washing of hands with soap and water or alcohol-based
disinfectants.
The rest of the thousands of
tiny droplets (dia. less than 100μm)form spray clouds, evaporate and gradually
become droplet nuclei. These droplet nuclei flutter in the air and may infect
people when they breathe them in and they come in contact with their mucosa.
This emphasizes the strong need for wearing masks both by infected persons and
non-infected persons; that is, everybody needs to get their masks on.
Why Masks?
Masks are very effective for
capturing droplets. Some studies have also revealed that masks can provide
estimated fivefold prevention against pathogens. Masks vary based on the
materials used in producing them and for what purpose they are produced for.
Examples include gauze masks, cotton masks, ordinary disposable medical masks,
disposal surgical masks, and N95 respirator.
The ordinary disposable medical
masks and the disposal surgical masks belong to the medical mask category. One
of the critical points of the medical masks is the BFE – Bacterium Filtration
Efficiency, which is usually required to be greater than 95%. This point is
crucial for medical purposes because there are all kinds of bacteria in
hospitals, and healthcare workers and patients can avoid germs invading them by
wearing a medical mask. However, we can ignore this data when guarding against
the Novel Coronavirus (called SARS-CoV2). Usually, bacteria have a diameter
range from 0.5 to 5 μm and are much bigger than viruses, so the masks that can
filtrate bacteria may not filtrate viruses.
There is another critical point
of masks: the PFE – Particle Filtration Efficiency. The well-known N95
respirator is a kind of a mask that can filtrate a minimum of 95% of non-oil
particulate aerosols. The N95 respirator is evaluated, tested and approved by
NIOSH as per the requirements in 42 CFR Part 84. It is tested with 0.075 μm
sodium chloride particles and ensures the concentration of particles in the
mask is 95% lower than found outside the respirator.
Some studies found that not
only the N95 respirator but also ordinary disposable masks have a good
filtration ability with airborne particles. Commonly disposable masks have
three layers. The outer layer is made up of non-woven fabric, which can block
the big droplets. The middle layer is made up of melt-blown material, which can
capture the tiny droplets by the electrostatic effect. And the inner layer is
also made up of non-woven fabric, which can absorb the vapor you breathe out
and ensures it won’t affect the middle filtration layer.
The following chart shows the
capture efficiencies of different types of masks against various sizes of
particles. These include the N95 respirator, surgical mask, ordinary medical
mask, cotton mask, and gauze mask:
From the chart you can see for
droplets larger than 10 microns, even the poorest one (Gauze Mask) has a
capture efficiency close to 80%.
As we said before, the droplet
nuclei from an infected person’s sneeze, cough or talk will flutter in the air
and come to be a significant infection source. So, the crucial point of masks
is how they prevent the droplet nuclei from contacting people’s mouths and
noses. What size is a droplet nucleus? A study found that the diameter of 82%
of the droplet nuclei of particles is between 0.74 and 2.12 microns.
What are the filtration
abilities of the different masks for particles in this range?
From the chart above, you can
see that the N95/KN95 Masks, Surgical Masks, and Ordinary Medical Masks have
excellent efficiencies in capturing the droplet nuclei.
3. Significant
misunderstandings about masks
- Healthy people do not need to wear masks; only sick people need to wear masks.
The US CDC website ever read:
People who aren’t sick don't need to wear masks; only sick people need to wear
masks.
Is this true?
Sick people do need masks
because the primary way that people infected with the novel coronavirus
pneumonia spread the virus is by droplets caused by sneezing, coughing and
talking. To avoid infecting others, patients must wear masks to protect others
around them or when they travel.
However, as we have analyzed
before, masks have a good filter effect on droplets and droplet nuclei produced
by patients, especially N95 masks, surgical masks, and ordinary medical masks.
So, even for people who are not sick, it is recommended to wear masks in closed
transportation (bus, subway, etc.) when participating in public activities or
working in an office, especially when the distance between people is less than
6 feet.
Studies have shown that as long
as patients do not sneeze or cough, the viruses inside the droplet nuclei do
not exist more than 6 feet away from the patient's body, so it is essential to
keep a safe distance of 6 feet away from strangers in public. At the same time,
the research shows that in well-ventilated conditions, the droplet nuclei will
quickly dissipate with the flowing air, so in well-ventilated indoor and
outdoor environments, and ensuring that people are 6 feet away from each other,
masks can be avoided.
Note that indoor ventilation
here refers to natural ventilation rather than air conditioning, especially not
central air conditioning. In the case of patients in a room equipped with
central air-conditioning, the virus will spread everywhere. At the same time,
when you are at home, you should frequently open the windows for ventilation.
Since a large number of novel
coronavirus carriers are asymptomatic, these people are not detected as being
infected. At the same time, the study points out that these asymptomatic
carriers are also infectious. For these people, if they wrongly perceive that
non-patients do not need to wear masks, they will become a source of
transmission when they travel. So, even if you are not a patient or think you
are not a patient, please put on a mask for your own safety and the safety of
others.
In February, when the epidemic
was at its most intense, China stipulated that all people who went out must
wear masks. Now, even though the number of new cases in China has been
dramatically reduced, China still hasn't relaxed the control of wearing masks.
It's undeniable that in addition to the forced lockdown of cities and isolation
of confirmed and suspected patients, the forced wearing of masks has
contributed to China's rapid reduction in the transmission of the SARS-CoV-2.
Meanwhile, Eastern Asian countries like Japan and Korea have done good jobs in
controlling the spread of the COVID-19. People in those countries are more
likely to accept wearing masks than people in Western countries, which shows a
potential link.
At the same time, during this
time of an epidemic, when people put on masks in public, it helps to maintain
the confidence of people in other people. The subtext is that I care not only
about my own health, but also the health of others. Don't ever create the idea
that whoever wears a mask is a patient. Undoubtedly, such misconceptions will
encourage the spread of the virus.
- Disposable surgical masks can’t provide respiratory protection due to their loose-fitting.
A surgical mask
might prevent one from spreading the disease to others, but they provide no
protection to the one wearing it.
Does a disposable surgical mask
have any protective effect compared with an N95 mask? Scientists tested this
question by randomly
assigning over 2,000 nurses to wear N95 or surgical masks. Then
they tracked how many of them caught the flu. The results are as follows:
Refer to the picture below:
Surgical masks have similar
particle capturing capabilities as N95 masks, which may explain the results of
the experiment. Some people think that the virus may enter the nose and mouth
of the person through the edge of the mask due to the poor facial fit. As we
said earlier, the SARS-CoV-2 can spread through droplets and droplet nuclei to
the human oral and nasal mucosa to cause infection.
The size of the droplets is
large, and the transmission distance is short. Even if some of the droplets
come close to our mouth and nose, they are blocked by the front of the mask we
wear. At the same time, due to the electrostatic effect, most of the droplet
nuclei are absorbed by the inner fiber of the mask. Only a few of the droplets
may reach the seams where the edge of the mask does not fit our face, and some
of them may even reach our mouth and nose.
Would this amount of the virus
infect us? I drew a demo picture below for an explanation.
The answer is it is possible,
but if you are only facing one patient, the number of virus particles that
reach the seam will be very few, as shown in the picture above. If you don’t
wear a mask, say the infection rate may be 70%, but when wearing a mask, the
infection rate may drop to 7% (this is not real data, but only an example).
Your infection rate will be
lower when wearing an N95 mask, but the cost of an N95 is high. At the same
time, because of its seals, wearing an N95 often feels suffocating, so you can
choose to wear a disposable mask when the risk is not too high. What if you
have ten infected patients in front of you? God willing, if you are not a
medical staff member, you will not face such a situation! So, we can see why
doctors in the front line of epidemic prevention are equipped with N95 or even
N100 respirators, eye masks, protective coverall suit, etc.
- A surgical mask and a disposable mask are equal to each other.
Many people think that a
disposable mask and a surgical mask are the same things because all disposable
masks are not only similar in appearance but also basically three-layer in
structure. Even the definition of surgical masks on Wikipedia:
A surgical mask,
also known as a procedure mask, medical mask, or simply
as a face mask, is intended to be worn by health
professionals during surgery and during nursing to catch the
bacteria shed in liquid droplets and aerosols from the wearer's mouth
and nose.
This definition basically
confuses surgical masks with disposable masks, which is really very lax.
The most significant difference
between surgical masks and other disposable masks is that they must have the
ability to prevent blood penetration (Fluid Resistance). That is to say, when
surgeons operate on patients, blood from patients may accidentally splash on
the doctor's mask, so the surgical mask must have an ability to prevent blood
penetration; otherwise, the doctor is likely to be infected by the patient's
blood.
The US Standard for surgical
masks (ASTM F2100-11) states:
Surgical respirators are tested
on a pass/fail basis at three velocities corresponding to the range of human
blood pressure (80, 120, and 160 mmHg). The inside of the mask is then
inspected to see if any synthetic blood has penetrated to the inside of the
face mask.
There are many types of
disposable masks, including medical surgical masks, ordinary medical masks, and
civilian disposable masks. The difference between a medical surgical mask and
an ordinary medical mask is that the ordinary medical mask cannot prevent blood
penetration. T. The difference between the medical mask and the civilian mask
is that the medical mask must have the bacterial filtration efficiency (BFE)
more than 95%. As we mentioned earlier because the size of bacteria is much
larger than that of viruses, masks that can filter bacteria may not be able to
filter viruses, so this indicator has no significance for us when it comes to
preventing the Novel Coronavirus.
Therefore, for virus
prevention, the essential reference index for respiratory masks is particle
filtration efficiency (PFE). The N95 respirators require the filtering ability
of the masks for non-oil particles to be over 95% under the NIOSH standards;
however, N95 masks do not need to have the ability to prevent blood penetration
and filter bacteria. That's why the N95 Mask Certification Authority is NIOSH,
not the FDA because it is a civilian mask.
In summary, if a disposable
mask has a certain level of particle filtering ability (for example, more than
95%), it is equivalent to having that ability to defend against viruses.
Although the airtightness of a disposable respirator is not as good as that of
the N95 respirator, which cannot completely block the virus, as we analyzed
earlier, the disposable respirator does have a strong ability to filter
droplets and droplet nuclei. At the same time, we do not need to consider BFE
if we are in a non-sterile environment. So, in a daily working and living
environment, wearing disposable masks with a particle filtration efficiency of
more than 80% of that of the civilian disposable respirators greatly reduces
the risk of infection
4. The correct method of
wearing a disposable mask:
- Clean both hands before putting on the mask.
- Pull the side of the mask with the metal strip upwards; hang the elastic strings on both sides onto the back of the ears; then fully unfold the outer folded surface to ensure that the mask completely covers the mouth, the nose, and the chin; finally, press the metal strip nose clip with both hands to make sure the mask entirely fits the face.
- Try not to touch the mask again after wearing the mask. If it must be touched, wash your hands before and after wearing the mask.
- When removing the mask, try not to touch the outer layer of the mask, and the mask should be removed by releasing the elastic string at the back of the ears.
- After using the mask, it should be discarded into a garbage can and covered, and then wash your hands immediately.
5. Mask types and
recommendations for which ones people should use in different scenarios：
6. Two masks you could consider
to have:
Features:
- Filtrate more than 95% of non-oil particles and aerosols in the air
- Four-Layer Protection:
- The outer waterproof layer blocks large droplets.
- The melt-blown layer captures tiny droplets due to Electrostatic Effect.
- The structure layer builds a 3D space for non-contacts between your mouth and the respirator, which increases space to make you breathe smoothly.
- The inner layer is made in soft materials to make contact with your face friendly.
- Premium grade elastic earband and adjustable hook & loop strap make the mask quite easy to wear, perfect to fit, and comfortable for long periods of wearing.
- Reliable quality with CE & FDA certified.
Features:
- Filtrate more than 80% of non-oil particles and aerosols in the air
- Three-Layer Protection:
- The outer waterproof layer blocks large droplets.
- The melt-blown layer captures tiny droplets due to Electrostatic Effect.
- The inner layer is made in soft materials to make contact with your face friendly.
- Premium grade elastic earband and adjustable hook & loop strap make the mask quite easy to wear, perfect to fit, and comfortable for wearing.
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