How Do Masks Work?
As we all know, health agencies around the world are requesting that everyone wear a protective mask out in public that covers the nose and mouth . Many governments have gone as far as to make wearing masks in public mandatory. As we’ve discussed before, respiratory viruses such as SARS-CoV-2 can be spread via aerosol droplets, tiny droplets of fluid from the lungs which are small enough to remain suspended in the air for a little while. These infected aerosol droplets are expelled when you breath, talk, cough or sneeze. Masks are meant to block these droplets from spreading to or from the wearer’s lungs.
For the majority of people in a day-to-day setting, a simple cloth mask (covering mouth AND nose) is more than sufficient to block the spread of disease. The airborne aerosols that viruses ride are too large to pass through the weave of these basic masks. A cloth mask acts as a barrier for aerosols from your lungs to enter the air and infect other people, limiting the spread of the virus. Surgical masks work on the same principle, though they're more effective due to a tighter weave and are designed to be disposable. Both are effective at preventing droplets from your lungs entering the air where they can infect others. Considering that it can be up to 14 days between when a person becomes contagious with COVID-19 and when they start showing symptoms, wearing a mask is an important step to prevent the spread of the virus.
The common quote is that you don’t wear the mask to protect yourself, you wear it to protect everyone else. This is true to an extent; masks are most effective at blocking the large unevaporated droplets that are fresh from the wearer’s lungs. The smaller droplets and dry particles that make it into the air are sometimes able to pass through the weave of the mask or float around the mask if it is not properly fitted to the wearer’s face or the wearer leaves the nose and/or mouth uncovered. That said, research has shown that both cloth and surgical masks do offer the wearer some direct protection from others. While these masks can’t keep out every coronavirus particle, there is utility in keeping out as many viral particles as possible. Though viruses do reproduce inside the body, one’s viral load (the number of virus particles that infect the body) will grow much faster if one is infected with ten virus particles instead of one. The fewer viral particles one is initially infected with, the slower the virus will spread through the body. This gives the immune system more time to respond and can result in a milder case of COVID-19 instead of a more severe one. Therefore, wearing a mask is definitely intended to be an act of communal protection, but it can save your life under the right circumstances.
Cloth masks are perfectly sufficient for everyday use; however, they aren’t good enough for healthcare workers. Those working in hospitals require direct protection for themselves from the virus because they are far more likely to come across COVID-19 particles than someone would on the street. For hospital environments, specialized masks such as N95 masks are needed. N95 is a technical standard; for a mask to meet this standard, it must filter out 95% of all particulates in the air. This video explains how the mask works. What makes it so effective is its multiple layers of spider web-like strands to which the particles stick. As an added layer of protection, these strands are given an electric charge similar to static electricity, so particles are even more likely to get stuck to the mask. On top of this, these masks are designed to form fit to the face so there are no gaps in the side through which any aerosols can enter. Part of the procedure for putting on an N95 mask is confirming that it fits to the face without leaving openings exposing the nose and mouth. But as said before, these masks are overkill for the common person, and their current scarcity makes it very important to reserve them for healthcare workers.
Popular Question
A disturbingly common myth is that wearing a mask can block the amount of oxygen one receives and can result in hypoxia. This has been proven false. Multiple studies have shown that masks do not significantly block airflow. Cloth masks are made from the same material as clothing, which a person can breathe through. Surgeons wear masks for hours on end during surgeries and there are no recorded instances of them fainting or having hypoxia. If someone feels like they can’t breathe in their mask, it is more likely to do with unfamiliarity wearing it and the placebo effect. If you are having trouble breathing while wearing a mask, try breathing slowly through your nose and limit talking. This can reduce the humidity inside your mask, which can contribute to making a mask uncomfortable. While some state health agencies have exceptions to mask laws for those with breathing conditions, none of these agencies name specific medical conditions that these exemptions would apply to and most health professionals don’t believe there are any respiratory conditions which would prevent one from breathing through a cloth mask. (N95 masks could make it harder for someone to draw in breath, but again, only medical professionals should be wearing these.)
It’s important to remember that wearing a mask by itself isn’t enough to stop the spread of COVID-19. Wearing a mask, practicing social distancing, and quarantining when you feel sick are all layers of protection that individually reduce your chances of infection a little bit, but together reduce your chances a lot. And if everyone were to practice all of these, it would take away Covid’s ability to reliably spread. If 95% of people consistently wore a mask, it could reduce the transmission rate of this disease by over 30%. We’ve talked before about how if we can lower the transmission rate below 1, this pandemic would slowly start to die off. It can be easy to forget how important these practices are when they work on such large scales. Your individual life might not be significantly affected by whether or not you wear a mask, but even a small difference in probability, when made by each of us, can add up to a significant change on the scale of a whole population.
In case you still have questions about how to wear a mask, make sure your mouth AND nose are covered with no gaps on the sides.
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