The principle of the spread of the virus
It is generally accepted that particles of infected saliva and mucus are scattered a couple of meters from a sick person. Allegedly, coronaviruses are so heavy that they are not able to fly a greater distance. In convincing us of this, WHO relies on the properties of previously studied coronaviruses.
A sick person poisons the air with microscopic droplets with volumes of 7-200 microns. Details:
- During a minute's conversation, about 210 virions with sizes up to 100 microns get into the air.
- With a cough - from 10 to 50 thousand viral particles, of which only 20% are 100 microns in size, the rest are smaller.
- With a sneeze - from 100 to 800 thousand, of which only half have a size of 100 microns, and 30% of "sneezing" microbes from 1 to 25 microns.
After coughing, large particles of infection fly no more than 1 meter. They are the ones that settle on garments, hair and surfaces.
Moreover, large particles first enter the nasopharynx, and a person has time to “keep out” the infection further. Small ones immediately enter the lungs and lead to the development of fatal pneumonia.
That is why WHO strongly recommends wearing masks and keeping a distance of at least 2 meters.
Ok, but not that
Of course,
it's great that all this is there, but today something different is needed.
Practice
the use of protective masks by the population during an epidemic shows that
some avoid wearing masks for reasons that can be cited
aesthetic and psychological:
- somebody
does not wear a mask, because he considers them ugly / disfiguring; - someone (due to the positioning of masks as medical / industrial) considers them
wearing excessive security measures, that is, does not want to look like an alarmist; - someone subconsciously fears everything that
related to medicine (because it links the topic of health too closely with
the theme of life and death). This category of citizens avoids visiting a doctor and taking medications.
Not
to say nothing of the fact that there are people (the author of this article and all its readers) who now know about the research results regarding insufficient protection against
viruses, which are given by conventional medical masks. And since there is no confidence in
use, there is no incentive to wear.
Everything
this generates a request for a new type of respirator. Russian manufacturers
it has not yet been mastered, and foreign ones are gradually starting to. True, even there such
masks are still more of a niche rather than a mass product.
Clinical researches
The first study compared the effectiveness of plain face masks and N95 respirators. Almost three thousand medical workers were divided into two groups: the first half wore ordinary masks, the second wore respirators. In the first group, 207 people were ill with the seasonal influenza virus, in the second - 193. The difference between 7.2% and 8.2% is less than the statistical error.
Similar results were obtained by Canadian researchers. In a group of 446 nurses, 50 who wore masks and 49 who used respirators had the flu. The incidence was 23.6% and 22.9%, respectively - that is, the difference was again outside the margin of error.
These studies showed that replacing masks with respirators does not give a pronounced effect - masks and respirators were compared with each other, and not with a lack of protection in principle. To judge the effectiveness of protection against viruses, it would be required to recruit a control group that would not use protection at all.
Of course, conducting such a study in a hospital setting is extremely dangerous - nurses without masks and respirators would be vulnerable to other diseases and infections. Therefore, scientists from Australia moved the experiment from clinics to home conditions.
The researchers observed 143 families in which children contracted respiratory viral diseases. A third of families received medical masks, a third received disposable surgical respirators, and the rest did not use protection at all. In a group of 94 adults with surgical masks, the incidence was 5%. Of 92%, only 4% fell ill with N95 respirators. In the control group, the infection rate reached 17%.
The fourfold difference is impressive, but the researchers say there could be even fewer cases. Adults often neglected the rules for using masks and respirators - they wore them longer than they should, touched their eyes and lips with dirty hands, and disposed of masks incorrectly.
In February 2020, the European Center for Disease Control and Prevention issued guidelines for healthcare professionals working with patients amid the coronavirus pandemic. Recommendations prescribe the use of FFP-2 and FFP-3 respirators. In addition to a respirator, you must use goggles or a transparent visor, gloves and a moisture-resistant long-sleeved gown.
How to properly wear respirators and masks
It is important to understand that a medical mask does not provide reliable protection against infection. Its task is to reduce the risk of infection of others.
In epidemics, the use of masks helps to weaken the pathways of direct transmission of infection from sick to healthy.
Disposable masks and respirators must not be used longer than indicated on the packaging. Usually masks can be worn no more than 2-3 hours. Over time, they become wet from the exhaled moisture and only increase the risk of infection. Disposable respirators can last longer, some last up to 8 hours, so read the manufacturer's recommendations carefully.
Never reuse disposable protective equipment: they cannot be washed, dried or disinfected with antiseptics. Disposable respirators are designated with the letters NR, reusable respirators with one letter R.
Disinfect your hands before wearing a mask or respirator. When removing, do the same first thing - dangerous moisture can accumulate on the outer surface.
Respirators are harder to wear than medical masks. Condensation from breathing accumulates in them and the temperature rises. If you are not working in a clean room and are not afraid of infecting other people, you can use a vented respirator.
A mustache or beard will significantly reduce the effectiveness of the defense. The hairs do not allow the respirator to snuggle tightly to the face - the air is sucked in through the cracks and is not filtered.
Reusable respirators - personal protective equipment. It is highly discouraged to use the same respirator with other people. Disinfect thoroughly and remember to change filters on time.
Passion for the masks
Originally
all masks are divided into sterile and non-sterile. The latter include
most of the masks used in everyday life, medical institutions, in production. Mask,
that you bought at the pharmacy is also highly likely to belong to
non-sterile. This is not scary, sterility is not always needed and not
everyone.
So,
non-sterile masks:
1. Cotton-gauze. Made of cotton wool and
gauze or gauze only. In the latter case, usually can be used
multiple times. Before reuse, they should be boiled or
treat with a disinfectant solution and dry. Provides degree
filtration at the level of 80-85% (we are talking about the filtration of particles of moisture and / or solid
substances present in the air).
2. Three-layer nonwoven masks.
The same "pharmacy" mask familiar to us. Provides 95.9% filtration
(European protection class FFР2, or American N95).
Both
these types can be classified as so-called. procedural.
3.
This is not enough for surgeons in operating rooms, for them they produce 4-layer masks, in which the filter layer is either doubled or supplemented with an anti-liquid layer. Level
filtration - 99.9%, which corresponds to the European class of protection FFP3 or
the American N99 analogous to it.
Now
a little explanation. The mask filters out particles of moisture and solids. Human
inhales and exhales them along with the air. And if they are infected with a virus, he
gets infected too (starts infecting others). Thus, the mask protects not from the virus itself, but from dust or moisture particles, on
of which the virus may be located.
Main
question: will a mask save you from coronavirus? Sergey Bessarab, who wrote an article about the virus and protection against it,
gives a link at once to 2 studies devoted to this issue. Further quote:
«Statistically significant protection against SARS virus somehow provided only
surgical four-layer masks and masks of the N95 type. Disposable paper and
regular three-layer ones are as effective as a scarf or
a scarf tied around the face. True, it was later refuted and
efficiency of the vaunted N95 "(research
1, study 2).
Yet
one reason for the weak effectiveness of masks is that the nose and mouth are not
the only gateway for the virus. The lacrimal glands remain unprotected.
Thirdly,
(and this is important to remember): a disposable mask is not PPE (means
personal protection). Golubkova
A
A. "Masks and respirators in medicine: selection and use": "Medical masks (surgical,
procedural, etc.) are widely used in medical institutions,
however, even in the "factory" version, they are not certified as
Personal respiratory protection. This is due
the absence of an obturation strip in the "medical masks", which provides an airtight
adherence of the mask to the face, as a result of which polluted air during inhalation
enters the respiratory system of the user through a loose fit, bypassing
filter housing "
Golubkova
A. A. "Masks and respirators in medicine: selection and use": "Medical masks (surgical,
procedural, etc.) are widely used in medical institutions,
but even in the "factory" version are not certified as
Personal respiratory protection... This is due
the absence of an obturation strip in the "medical masks", which provides an airtight
adherence of the mask to the face, as a result of which polluted air during inhalation
enters the respiratory system of the user through a loose fit, bypassing
filter housing ".
Further
the author of the book refers to
the results of a Russian study, according to which penetration
microbial aerosols through masks of various types ranges from 34% (medical
three-layer) up to 95% (ordinary gauze bandage). A layer of cotton wool reduces the percentage
penetration up to 58%.
Why
then the manufacturer claims that medical masks will provide 95% or even
99% filtration? Apparently, because the masks themselves are tested, and not the masks worn by
per person.
Means
is it the uselessness of masks, even surgical ones? No. First, scientific
studies were certainly not read by all. Those who are able to understand correctly
the conclusions outlined there, even less. But when everyone is wearing masks, there is less panic and
nerves. Second, probability is a curious thing. You never know which one
she will benefit.
What to choose - a mask or a respirator?
We often use the words mask and respirator as synonyms, meaning a device that will protect the wearer from harmful environments: construction dust, corrosive smoke or a dangerous virus. But these are fundamentally different things.
A medical or surgical mask protects against infection that a doctor can transmit. The mask protects others, not the wearer. It creates a barrier between the doctor and the patient, trapping the droplets of moisture that fly out with the air when breathing, coughing or sneezing.
The respirator protects the wearer from airborne threats.This problem is solved in two ways: either the surrounding air is purified by filters, or another is used for breathing - from a cylinder or a special line. We will consider only the first type of respirators - filter respirators. Devices of the second type - insulating - are too bulky and difficult to use in everyday life.
Different objectives also explain the differences in the design of masks and respirators.
Masks
- this is the development of the idea of gauze dressings. A simple mask consists of three layers - between the outer and inner there is a layer of filtering material. In surgical, non-woven synthetic material is most often used - spunbond. For additional protection from biological fluids, a fourth layer is added to the structure - moisture-repellent.
Retainers help reduce the amount of air that passes through the folds around the nose. They are made of metal or wire and covered with cloth or rubber. The retainer folds to the shape of the face and presses the top edge of the mask tightly.
Respirators
more rigid. Simple disposable models resemble medical masks, but elastic inserts are always made in them. They help to firmly press the respirator to the face around the entire perimeter. This prevents air from leaking past the filter.
In some respirators, exhalation valves are made - through them, air flows past the filter. It is much more comfortable to breathe with their help, but such respirators do not protect others, therefore they cannot be used in medicine and surgery.
Advanced models are like gas masks - they can be used many times, the main thing is not to forget to change the filters. Respirators can only cover the nose and mouth - they are called half masks - or protect the entire face.
Ways of transmission of COVID-19
Coronavirus infection is spread by aerosol droplets when a sick person coughs, sneezes, talks, or even breathes. Each such drop contains several tens of thousands of viral particles. Therefore, one such drop that gets into the nasopharynx is enough for the development of a dangerous disease.
Drops falling on objects remain vital for several days. To get sick, all you have to do is touch an infected doorknob and then touch your face. Interesting fact! Within an hour, a person reflexively touches his nose or lips, rubs his eyes more than 23 times. However, in this case, you can be saved from the virus by washing your hands with soap, blocking access to your face with a respirator, or not parting with a protective mask.
The effectiveness of preventive measures against viruses determines the further development of events: the rapid spread of the disease or the end of the pandemic. During numerous studies it was found:
- The most reliable means of protecting respiratory organs from viruses are reusable masks and respirators (68% efficiency).
- Prevention of infection by contact - washing hands up to 10 times a day with soap under running water for 30-40 seconds (efficiency 55%).
- A combination of all existing preventive measures - washing and disinfecting hands with antiseptics, gloves, masks and gowns (91% efficiency).
The viability of COVID-19 on surfaces and objects is intimidating:
- on paper - 3 hours;
- banknote - 4 days;
- on wardrobe items or wooden surfaces - 2 days;
- glass - 4 days;
- plastic or metal - a week.
Popular respirator models
The most popular dust mask is a disposable item called a petal. It is made from a specially developed filter material. "Petal" is designed to capture fine dust. It should be noted that this simple filtering device is ineffective against high concentrations of abrasive particles. This protective mask is only suitable for short-term work that is associated with low air pollution. You need to change it every couple of hours.
The U-2K respirator is more effective. It has two protective layers: upper (polyurethane foam) and lower (polyethylene).Between them there is a filter material that reliably protects the respiratory system from all types of industrial dust: mineral, metal, cement, lime. It is not suitable for working with substances that emit toxic fumes. The model is used for repairing a room, if work is to be done on chipping, cutting ceramic tiles, sanding surfaces.
If during the repair it is still necessary to work with paints and varnishes, it is better to use multifunctional combined products, for example RU-60M. The model is designed for protection against aerosols and dust mixtures. The mask has breathing valves and two replaceable filtering - absorbing cartridges. The respirator is designed for 60 hours of continuous use. A more modern analogue of RU-60M is the insulating half-mask "Breeze-3201", "Alina-110" and respirator NRZ-0111.
Modern respirator RU-60M
When choosing respirators for breathing protection, it is necessary to take into account the type of work and the condition of the room. If there is good ventilation, it is quite possible to get by with a lighter version of the mask. When you have to work in a confined space, you need to choose a more reliable model, as well as take care of eye protection so that the dust does not irritate the mucous membrane. For such cases, a respirator in combination with protective goggles is suitable.
Sales leaders
Last year, pharmacy masks were gathering dust in pharmacy warehouses. Now it is the most bought-up commodity in the world. This is not surprising, because the COVID-19 pandemic is spreading rapidly and without adequate protective measures it cannot be stopped. But not only masks are used by cautious citizens. Due to the fact that pharmaceutical "rags" protect against viruses for only 2 hours, many have turned their eyes towards reusable dressings and disposable respirators. And love for the latter is not unfounded. After all, durable and comfortable respirators protect much longer than multi-layer masks.
We suggest you familiarize yourself with the best options:
"SAFETY"
A high-quality six-layer respirator with a charcoal filter will protect not only dust, but also from viral particles. One of the layers is made of meltbown, a material used to make medical masks. This layer reliably protects the respiratory tract from dangerous microbes.
"M Aura 9332+"
Medical antiviral respirator with maximum protection level and FFP3 valve. As a glove "sits" on the face and filters out solid and liquid particles by 99%. The high-strength model is characterized by wear resistance, that is, it retains its protective properties for as long as possible. Thanks to the valve located on the front of the product, the air goes down, and the mask is not moisturized from breathing. The respirator will suit the taste of those who wear glasses (they will not fog up).
Respirator from dust and viruses "3M VFlex 9101"
Despite the absence of a valve and a carbon filter, the product retains high protective properties in all conditions. The respirator will not let you down in severe frost, at high temperatures or in conditions of high humidity. The thoughtful design ensures a snug fit of the mask to the face, protects the product from deformation during inhalation and exhalation.
"Petal" 200
Effectively protects the respiratory tract from airborne bacteria and viruses. It is actively used by medical workers for the prevention of diseases transmitted by airborne droplets (ARVI, influenza, coronavirus, etc.). Cannot be used in high humidity or high temperature environments.
"DIN Eurmask 7355 with filter P3"
Reusable respirator half mask with replaceable filter perfectly protects against viruses, bacteria, toxic fumes and dust particles. The product is made of thermoplastic rubber with high protection class FFP3, it is sealed to the face and does not make breathing difficult. It is easy and pleasant to use this respirator.
"3M 8210 N95"
The respirator reliably protects the respiratory system by filtering the smallest particles. When choosing a mask or respirator, remember that the size of the coronavirus particles does not matter. Viruses themselves do not live in the air.They are found in mucous membranes, with coughs, sneezes, or breath released into the air by an infected person.
Even an ordinary scarf wrapped around the face can handle large particles. A textile four-layer or disposable pharmacy mask will protect against virions larger than 3 microns. And only medical respirator No. 95 practically does not pass the smallest aerosols of 0.3 microns.
Popular models
The "Petal" respirator is available for purchase in 3 models, namely: "Petal-200", "Petal-40", "Petal-5". Each of these masks has its own distinctive features and individual characteristics that must be carefully studied before purchasing. The number that follows the name of the RPE (5, 40 or 200) indicates how much harmful dust the mask can protect you from (for example, harmful substances can exceed the permissible value by 5, 40 or 200 times).
It should also be borne in mind that such an exaggeration of the maximum permissible concentration applies to the presence in the atmosphere of harmful elements up to 2 microns in size, more than 2 microns, all models of the Lepetok RPE mask have a multiplicity of increasing the permissible concentrations of aerosols in the ambient air equal to 200. Tu or another model of personal protective equipment can be easily distinguished externally, since each of them has its own color: "Petal-200" - white, "Petal-40" - orange, "Petal-5" - blue.
HEPA filter for coronavirus
How
we already wrote in one of the materials, it is possible that the epidemic of coronaviruses in
in the near future, if they do not become as regular as flu epidemics, then
will be repeated periodically. As you know, the current epidemic is already the third
(after the SARS and MERS epidemics).
It,
in turn, poses a problem to the whole world that we have not encountered
before: the need for massive provision of the population with means of individual
protection. Means, the effectiveness of which would be higher than that of four-layer
surgical masks. Reusable products
(in order to avoid periodic panic of the population and the lack of the most accessible
protection products on sale).
Illustration
will help us answer this question.
On
we see it:
- The size of the particles present in the air.
- Their visibility to the armed and naked eye.
- Their impact on health.
- Technology,
with which they can be filtered (size scale - microns).
We will quote
again the material of Sergei Bessarab: “The diameter of coronavirus virions, for example
SARS ranges from 100 to 140 nanometers (that's 0.1..0.14 microns). Majority
coronavirus has protrusions-thorns that add about 20 more to the diameter
nm. That is, viruses are included in the so-called. a subset of PM2.5 that describes all particles
in the range from 10 nm to 2.5 μm».
To ensure the absence of the virus in the inhaled air, it is enough to provide a mask or respirator with a HEPA filter, that is, something like this is needed.
Truth,
not everyone will decide to use such a mask in everyday life - that's
some transcendental level of survivalism and looks too much like a cosplay
Fallout games. However, if you agree to put up with a lower level
security, that is, an option without eye protection - half mask.
