Why You Should Be Wearing Better Face Masks
It isn鈥檛 just about wearing any old mask. It鈥檚 about wearing听别蹿蹿别肠迟颈惫别听masks. That鈥檚 the message that the Centers for Disease Control and Prevention (CDC) has begun to send, as it continues to听听its guidance on how to reduce the transmission of the virus that causes COVID-19.听
David P. Calfee, MD, MS,听chief hospital epidemiologist for听NewYork-Presbyterian/Weill Cornell Medical Center, answers questions about mask quality, and why it鈥檚 so important for the general public.听
How does mask quality vary?听听
The ability of a mask to protect the wearer and to protect those around the wearer鈥攁lso called 鈥渟ource control鈥濃攊s related to two important factors: fit and filtration. Masks vary in both of these factors. Fit is important because we don鈥檛 want a loose-fitting mask to allow potentially infectious particles to pass around the mask, rather than through it, while the wearer exhales and inhales. Filtration refers to the ability of the mask to trap, or filter, particles. The ability to filter droplets and other small particles differs among the different materials from which masks are made.听
Are there ways to increase protection with our masks?听听
驰别蝉鈥we can increase the level of protection provided by improving the fit of the mask and/or by using a mask with greater filtration.听 No matter what your mask is made from, achieving a good fit is important.听The fit of a mask depends on the mask itself,听as well as the听shape and other characteristics of the wearer鈥檚 head and face.听听
The CDC has recently described several听听that can be used to improve the fit of a face mask.听One option is to听wear听a tight-fitting cloth mask over a surgical mask.听Another option is to tie听knots in听the ear loops of a surgical mask,听where the ear loops听connect听to the mask,听and tuck听in the extra mask material.听听A听CDC听听found that听these two strategies can听reduce a wearer鈥檚 exposure by more than 90%.听Other recommended strategies include using a mask fitter听and wearing a nylon covering over听your听mask.听听听听
Some听masks have a听greater ability to filter or trap particles, such as those made from tightly woven fabric.听Research听performed听on a variety of masks听tells听us that听cloth听masks made of at least two tightly woven layers of fabric听are more effective听than those made of single layers or of more loosely woven fabric.听You can also听add a layer of filter material, like a听vacuum cleaner bag,听between the layers of听a cloth mask. Some people听use听a听high-quality surgical or procedure听mask听approved听for general use by the public听or听a听respirator designed with a high filtration capacity.听听
It is important to note, though, that when we听increase the filtration of听a mask, it can make it more difficult to breathe听through the mask,听which could increase the chance that the wearer will remove听or听adjust the mask during use, potentially reducing its effectiveness.
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Which听masks should we avoid?听听
Masks with exhalation valves should be avoided because the exhalation valve allows exhaled air to bypass the filtering听effect of the mask, reducing the mask鈥檚 ability to provide source control.听听听
What makes the N95s such a strong option, and why are they only recommended for use by medical professionals?听听
N95 respirators are designed to provide a high level of respiratory protection by providing filtration of very small particles and good fit.听Prior to using an N95, the wearer typically听undergoes听a medical assessment,听training, and formal assessment of fit.听听Achieving a tight fit听or seal is critical in order for听this mask听to function听well.听听听
N95s are not recommended for routine use by the general public听because听there is only a听limited supply of them, and they鈥檙e needed in听healthcare settings.听
Please discuss the KF94 masks, and whether they鈥檙e a good alternative.
KF94s are similar to N95s and provide a high level of protection. They鈥檙e made of material like that used to make N95s and also do a good job filtering aerosol particles.
These are not currently used in healthcare settings, so it may be easier to get them. But note that they have a high filtration capacity, which may prevent some people from being able to comfortably and consistently wear them.
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Is it safe to set aside other preventative measures if people wear masks?听
In addition to wearing masks, I continue to recommend social distancing and hand hygiene as strategies to reduce the risk of COVID-19. We know these measures help reduce the transmission of the virus.听 I also encourage everyone who is eligible to receive the COVID-19 vaccine to get it when they have the opportunity.听听
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