Why You Should Be Wearing Better Face Masks
It isn’t just about wearing any old mask. It’s about wearingڴڱپmasks. That’s the message that the Centers for Disease Control and Prevention (CDC) has begun to send, as it continues toits guidance on how to reduce the transmission of the virus that causes COVID-19.
David P. Calfee, MD, MS,chief hospital epidemiologist forNewYork-Presbyterian/Weill Cornell Medical Center, answers questions about mask quality, and why it’s so important for the general public.
How does mask quality vary?
The ability of a mask to protect the wearer and to protect those around the wearer—also called “source control”—is related to two important factors: fit and filtration. Masks vary in both of these factors. Fit is important because we don’t 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.
Are there ways to increase protection with our masks?
۱—we can increase the level of protection provided by improving the fit of the mask and/or by using a mask with greater filtration. No matter what your mask is made from, achieving a good fit is important.The fit of a mask depends on the mask itself,as well as theshape and other characteristics of the wearer’s head and face.
The CDC has recently described severalthat can be used to improve the fit of a face mask.One option is toweara tight-fitting cloth mask over a surgical mask.Another option is to tieknots inthe ear loops of a surgical mask,where the ear loopsconnectto the mask,and tuckin the extra mask material.ACDCfound thatthese two strategies canreduce a wearer’s exposure by more than 90%.Other recommended strategies include using a mask fitterand wearing a nylon covering overyourmask.
Somemasks have agreater ability to filter or trap particles, such as those made from tightly woven fabric.Researchperformedon a variety of maskstellsus thatclothmasks made of at least two tightly woven layers of fabricare more effectivethan those made of single layers or of more loosely woven fabric.You can alsoadd a layer of filter material, like avacuum cleaner bag,between the layers ofa cloth mask. Some peopleuseahigh-quality surgical or proceduremaskapprovedfor general use by the publicorarespirator designed with a high filtration capacity.
It is important to note, though, that when weincrease the filtration ofa mask, it can make it more difficult to breathethrough the mask,which could increase the chance that the wearer will removeoradjust the mask during use, potentially reducing its effectiveness.
Whichmasks should we avoid?
Masks with exhalation valves should be avoided because the exhalation valve allows exhaled air to bypass the filteringeffect of the mask, reducing the mask’s ability to provide source control.
What makes the N95s such a strong option, and why are they only recommended for use by medical professionals?
N95 respirators are designed to provide a high level of respiratory protection by providing filtration of very small particles and good fit.Prior to using an N95, the wearer typicallyundergoesa medical assessment,training, and formal assessment of fit.Achieving a tight fitor seal is critical in order forthis maskto functionwell.
N95s are not recommended for routine use by the general publicbecausethere is only alimited supply of them, and they’re needed inhealthcare settings.
Please discuss the KF94 masks, and whether they’re a good alternative.
KF94s are similar to N95s and provide a high level of protection. They’re 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.
Is it safe to set aside other preventative measures if people wear masks?
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. I also encourage everyone who is eligible to receive the COVID-19 vaccine to get it when they have the opportunity.
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