Hello everyone, I hope you are well.
In the literature it is mentioned that medical masks are made of non-woven materials, in general the main component is polypropylene. Masks for medical use can be broadly classified into two types. Surgical masks and HEPA (High Efficiency Particulate Air) filter masks. The first is the mask that is frequented in health centers, mainly comes from infectious diseases transmitted by drops (saliva, cough or sneezes) through close contact, how it is proposed that SARS-CoV-2 is transmitted. Furthermore, HEPA filters are recommended for the prevention of airborne respiratory infections. Some authors differentiate the contagion by drops (example, Flügge drops 10,000-100,000 nm) from diseases transmitted by air, referring to the latter as those caused by pathogens that can survive for some prolonged period in air-displaced drops that when evaporate, they lose a large part of their mass (Well droplets 5,000-10,000 nm). An example in this case would be Mycobacterium tuberculosis.
The use of n95 filters has become popular in the population, filtering 95 percent of particles up to 0.3 um (300 nm) for a certain time. The size of SARS-CoV-2 virion causing the COVID-19 pandemic is 50-200 nm, which is below the limit for N95 respirators, and CDS advises that this type of filter does not offer total protection.
The question also arises, although the virus is smaller, would it (masks like n95 filter) help to eliminate the chances of contagion so that the mask stops drops loaded with viruses? Very specifically, my question is, which mask is appropriate? I also rode about a non-woven polyester one that was supposed to be washable, but I haven't come up with any clear information about it.
I also wanted to know about the recommendation for the use of a mask, during the first days there was a recommendation at the general public level not to use masks. You know what happened to this, I have seen government authorities recommending its use.
Beforehand thank you very much.
(Although I left questions, I think it would be interesting to discuss the topic, so I left it in the discussion section. )
Typical surgical masks should suffice although N95 ones are the most ideal.
N95 is better to protect the health care provider while the surgical mask will protect others from you
Hi,
This is one of the studies, based on which, recommendations for proper face mask usage for medical personnel, are being made:
https://www.hse.gov.uk/research/rrpdf/rr619.pdf
Just a few reminders to any otherwise healthy individual outside the medical field who is still inclined to use face masks against viral infections:
Breathing inside the mask is difficult and usually disrupts the proper breathing pattern (inhale through the nose, exhale through the mouth).
As a result, most users start inhaling and exhaling through the mouth (+ taking ever deeper breaths), which facilitates ingestion of viral/ bacterial agents (while the nose has a sort of a "filtering" mechanism, composed of hairs and secretion, which traps most inhaled particles/ bacteria/ viruses and obstructs them from reaching the lungs).
If the mask is properly sealed, after about 10 minutes, users notice a definite rise in warmth and moisture in the air space between the inner side of the mask and the face (which also creates suitable grounds for infection - bacteria and viruses love warm and humid weather).
Breathing with your mouth however (even more so when speaking), causes you to release bacteria indigenous to your oral cavity.
After about an hour or two, the warmth/ humid environment you have created with a properly sealed mask, makes these indigenous bacteria multiply - both on the inner surface of the mask and inside your own oral cavity.
The very same evening, you throat will be scratchy. The chances of you getting ill (even without a virus present) rise exponentially.
Many users (sadly, even medical personnel) touch their mask with their hands (gloved or not) to "remove it temporarily" or to "adjust it".
This action defeats the purpose of wearing a protective mask, as you infect yourself with whatever you have touched - no other biological vector of infection necessary.
Lastly, prepare to be dehydrated and very hungry, as one cannot drink and eat with a mask on. Users will need a safe, enclosed, clean space to do that, after mask removal and change.
I hope this clarifies some of the issues of using a face mask.
:)
Thank you all very much for your responses. I wanted to share a conversation I had with a colleague from the Immunoncology lab. Here are more aspects regarding the use of masks. I adapted the text and translated it into English, but the credit goes to Vincenzo Benedetti, he is medic and now he works in his PhD with Dr. Álvaro Lladser. With Vincenzo's prior authorization, I share the text with you:
“
The first thing I must clarify is that the division between surgical masks and HEPA is not such. The elements of personal protection for medical use are aimed at preventing the transmission of infectious agents for both staff and patients. Depending on the type of pathogen, different levels of protection are adopted (or isolation, as is commonly known), involving multiple aspects (such as body coverage, distance, ventilation). Masks for medical use in real hospital settings are classified into two types:
a) Simple surgical masks.
b) Special protection masks.
Surgical masks, which are commonly used by people, are designed exclusively to protect the patient (or third parties), not the professional (or user of the mask). That is why they are called surgical, because we are used by ward surgeons to preserve the aseptic environment of the operative wound and prevent secretions from the mouth (or nose) from falling into the surgical field.
On the other hand, special protection masks (or “respirators”), among which we find the N95 (according to the US NIOSH standard), or the FFP2 and FFP3 according to the European standard; are oriented to protect the user. Masks with HEPA filters do not exist in real use in hospital environments.
The classification of special masks, both in the American and European standards, are based on the proportion of particles of 300 nm that can filter under artificial laboratory conditions. This number is not arbitrary but is since it is in the "aerosol" range and therefore remains in suspension, and on the other hand it is the most penetrating particle size.
Smaller particles do not necessarily pass through the mask filter better. As you mentioned at the beginning, all those approved for medical use are non-woven, from simple to special surgical ones. The virtue of this is that, unlike clothing fabric, which is a simple regular screen depending on the hole size, medical masks use structures with irregular wefts of fibers superimposed in multiple directions as a barrier
This makes the filtration (or retention) of the particles dependent on at least three mechanisms according to size, from largest to smallest:
I) The first is impaction, the particles over 1 um collide directly against the fibers because their inertia prevents them from dodging them following the air flow.
II) The second is the interception, which occurs with slightly smaller particles (from 100 nm, but especially over 300 nm), which by surrounding the fiber following the flow, adhere to them by attractive forces (turbulent flow, rough surface fiber).
III) The last one, which predominates in particles
Centers for Disease Control and Prevention recommends using respirators in low-risk and high-risk situations, the World Health Organization recommends using masks in low-risk situations and respirators in high-risk situations.
To control the Covid-19 pandemic effectively, healthcare professionals and the public must hear and accept difficult truths. Unfortunately, rather than being honest; authorities have repeatedly changed advice about face masks. The mistrust has been fuelled by conflicting messages for healthcare professionals and the general public. Now, healthcare professionals and the public can no longer trust what is being said.
So, the only safe thing for anyone to do is to try to wear face masks that provide the best protection. The real difficulty is that the best medical grade respirator masks are in extremely short supply. Healthcare professionals, putting their lives on the line, need these masks to protect themselves from their infected patients.
Up to 25% of healthcare professionals in the UK are either off work due to sickness or because of suspected exposure. Excess deaths occur when healthcare systems can not care for patients who need treatment. The more healthcare workers who go off sick, the less care sick patients can receive.
The public can be protected by social distancing. As an intensivist I do not have this option, I must get very near to patients to look after them. So, I will be honest; medical grade respirator face masks do protect people from transmission of Covid-19. Cloth face masks are unlikely to provide much protection to uninfected people but may reduce viral spread from an infected person. Not going near patients with Covid-19 is certainly more effective than wearing any face mask. I therefore ask the public to fully engage with social distancing and preserve the respirator face masks for healthcare professionals who do not have this option.
Preprint Investigating COVID-19: Quantifying recurring methodological...
Good ideas
In many countries, various types of protective masks are accepted, and even covering the mouth with a handkerchief, a scarf, etc. It is important that the protective mask is tight, that it does not let through microscopic impurities, that it is not damp, dirty. Reusable masks can be used in many countries if they are washed and / or pressed at a temperature of min. 60 degrees C.
Greetings,
Dariusz Prokopowicz
Surgical masks for general use and N95 masks for use in the healthcare settings where healthcare professionals are directly engaged in care of the COVID-19 patients.
Typical surgical masks should suffice although N95 ones are the most ideal.
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