The Science Behind Masking
Why should I wear a face mask?
If you contracted coronavirus, you would be most contagious and most at risk of spreading it at least 24 hours before you start to show symptoms. This means you could spread it to family members, neighbors, colleagues and others before you even know that you have it yourself. This is why masks are so important. Masks dramatically reduce the spread from individuals to the people around them. Likewise, there is clear evidence that face masks — not just N95s but cloth-based masks — reduce the risk of contracting the virus as well. It does this by significantly reducing the number of particles that we breathe in, reducing the risk of COVID-19. It has also been shown that face masks do a better job at this than neck warmers, bandanas or other alternative face coverings.
Many patients have concerns about "mandates" for using masks. You can think of masks like a speed limit. Speed limits are in place to help keep us safe and to keep those around us safe. The same goes for the recommendation to wear a mask. While you might feel like you would be able to control your vehicle above the speed limit, following the guidelines ensures everyone around us — whether that be on the road or in our community — stays safe.
Is there a time when it is safe not to wear a face mask?
You certainly don’t need to wear a mask all the time. If you are in your own home without people from outside your household, there of course isn’t a need for a face mask in that situation. Going for a bike ride or a walk with the family? If you are outdoors in a crowded area, you should also wear a mask. However, if you are outdoors where you can maintain a social distance of more than six feet, there is low risk of spreading or contracting coronavirus so you should feel free to take off your mask and enjoy some deep breaths of cold, crisp air.
What should I look for in a mask? Is there a certain type of mask that is most effective?
There are a few features we should look for in our mask. These are:
- The filtering ability of the cloth
- How well the mask fits your face
- The overall durability of the mask
The type of mask that seems to blend those three elements best is a multilayer cloth mask. Look for masks with two or three layers of a tightly woven fabric that can’t be easily seen through when held up to light. When worn properly, these masks are able to filter a significant portion of particles, even those as small as one micron. Fit is also incredibly important. If a mask is not fitted snugly over the bridge of your nose or has big gaps around your cheeks, then there’s easy flow of air in and out meaning it isn’t going to provide as much protection. If your mask doesn’t fit well or feels uncomfortable, try a different one. By considering these factors, you can really protect yourself. And remember, a mask only protects you if you’re wearing it properly, covering your nose and mouth well.
How do I care for my mask?
Disposable masks are difficult to clean because part of the protective function of these masks is the electrostatic properties of the material itself. The effectiveness is not just the filtering but actually how the particles behave as they pass through the filter. Surgical masks are essentially one time or one day use. As soon as they get soiled, wet or crumpled, you want to dispose of them as they will not provide the same degree of protection. Cloth masks have the durability benefit. Because the mask creates a moist environment, ensure it dries out when not wearing by not crumpling it up into a tight space. Also, wash it on at least a weekly basis with soap and water to ensure you’re removing any large particles and helping the mask to stay clean and filter well. For cloth masks with filters, follow directions on how often to change the filter out.
Does wearing a mask cause problems with oxygen and carbon dioxide levels?
There is always a theoretical possibility that it could. However, this is really only a concern for people who are highly sensitive to the amount of carbon dioxide or oxygen in their body. For example, patients with very severe COPD live with very high levels of carbon dioxide levels in their body already. While it may be more uncomfortable for them to wear a mask, they are still able to keep it on and maintain safe oxygen levels without any danger. People who have some degree of shortness of breath all the time (like those with COPD) may consider a cloth mask over a medical-grade mask that would allow air to flow a little more freely. This still provides protection but may be much more comfortable when wearing it.
Is it possible that masks can cause other health issues?
Like any other piece of clothing, a mask has the potential to irritate the skin around it. If this is a problem you experience, switch to a different mask, as it could be the material, dye or something used in processing that is causing the irritation. Otherwise, if you are regularly cleaning a longer-use mask or regularly disposing of a disposable one, your mask should not cause any respiratory issues. The benefits of wearing a mask far outweigh any highly unlikely risks.
Again, a mask is only protective if you’re wearing it. Find a mask that works for you and you can feel comfortable and rest easy that you’re doing your part to keep both you and those around you safe. You can also find more information about COVID-19, including this research on masks, at BJC.org/coronavirus.
John Paul Shoup, MD, is a BJC Medical Group Internal Medicine and Pediatrics physician in Wentzville, Mo. You can schedule an appointment with Dr. Shoup at BJCOnlineScheduling.org or by calling 636.928.WELL.
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