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How Do Face Masks Work?

Currently, face masks are recommended to wear for the general public by the CDC and WHO. However, early in the pandemic the opposite was recommended which has led to some confusion about if masks even really work. Likely the finding that both pre-symptomatic and asymptomatic transmission are possible and common led to the recommendation to wear masks, as well as that studies showed viral load peaks in the days before symptoms begin. There is a lot of evidence that masks do work in preventing the spread of Covid-19, so let's look at some of the findings.

Laboratory studies of respiratory droplets shows that masks effectively block them. Hundreds of droplets from 20 to 500 micrometers can be generated when saying a simple phrase, but when a covering was worn nearly all of these droplets were blocked. Additional studies of the flu and common cold showed that wearing a mask significantly reduces the emission of droplets and aerosols. Masks can also prevent larger droplets from evaporating into smaller droplets, which can then travel farther.

The strongest evidence comes from real-world findings. A comparison of Covid-19 growth before and after mask mandates found that mask mandates led to a decline in daily Covid-19 growth rate and this became more apparent over time. Another study compared coronavirus deaths across almost 200 countries and discovered that those with cultural norms or government policies favoring mask-wearing had lower death rates. Some case reports have also shown favorable results. In one, a man flew from China to Toronto while wearing a mask and subsequently tested positive for Covid-19, all 25 people who were closest to him on the flight tested negative for the virus. In another case, two hairstylists had contact with 140 clients while sick with Covid-19, but wore masks and none of their clients tested positive.

Even if you live where many people do not wear masks, you would still reduce your chances of catching the virus by wearing one yourself. However, you could still catch the virus through your eye membranes, a risk that masking does not eliminate.

The best mask you can wear is one that is comfortable so you can wear it consistently. With the exception of valved masks, because they do not protect those around you. Instead they let unfiltered air and droplets out of the valve, so they are not effective.

Masks also let carbon dioxide out just as effectively as they let oxygen out and there is no scientific reasoning that supports that carbon dioxide builds up due to masks.

Wearing a mask, washing your hands and social distancing are all important pieces to preventing the spread of the virus, just because you are doing one of those things does not mean you should stop doing another. These three things are the best way to stay healthy and keep those around you healthy as well.

The more people that wear masks, the better. They will greatly reduce transmission and keep more people healthy. To view information about our masks visit our mask page here.


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