- Experts say most face masks provide at least some protection against the spread of COVID-19.
- They note that how a mask is worn is many times more important than the material used to make the mask.
- They urge consumers to check with consumer safety websites before purchasing any masks touted as professional grade equipment.
Experts say wearing almost any type of mask can help prevent the spread of COVID-19 if everyone is wearing masks.
However, less is known about how much protection mask wearers themselves get from their facial coverings.
The gold standard for face-worn protection is the N95 respirator, which has been certified to filter 95 percent of airborne particles.
3M, a leading manufacturer of N95 masks, states on its website: “Homemade masks do not serve as respiratory protection devices and may not provide any measurable exposure reduction. Unlike government-approved respirators, homemade masks are not designed and tested to reduce wearers’ exposure to airborne particulates.”
Some research, however, suggests that even cloth masks may provide limited protection against COVID-19.
“The use of cloth masks can potentially provide significant protection against the transmission of particles in the aerosol-size range,” concluded an April 2020 study published in the journal ACS Nano.
In the study, researchers from the Argonne National Laboratory in Illinois studied the ability of a wide variety of common materials to filter particles similar in size to the novel coronavirus.
They concluded that masks made from cotton, natural silk, and chiffon all provided significant filtration.
Higher thread counts and tighter weaves would make cotton masks more efficient, the study concluded, while the electrostatic properties of silk also enhanced protection.
The small size of the novel coronavirus — 0.12 microns — is often cited when doubt is cast on the filtration ability of various mask materials.
However, Keane Veran, co-founder and chief executive officer of mask manufacturer OURA, noted: “The virus is not transported alone and does not travel naked in the air. It travels in aerosols and droplets. These virus-containing aerosols can range from 0.3 to 3 micron in size. Therefore, the effectiveness of any mask should be gauged with this size in mind, not the size of the actual virus.”
The Argonne study noted that leakage around the edges of the mask decreased the already limited protection provided by these facial coverings by half or more.
“If you can get the mask to fit right, it’s more important than what it is made out of,” Sara L. Zimmer, PhD, an associate professor of biomedical sciences at the University of Minnesota Medical School, told Healthline.
“If most air is bypassing the filter, it’s not really functioning,” Zimmer said. “A condensed weave is better, but if there are too many layers… the air will go to the path of least resistance, which is the sides of the mask.”
Makers of homemade masks are capable of stitching together multiple layers of material, even a mix of cotton and silk cloth, as suggested by the Argonne study.
Some companies, such as Filti, are also selling nanofiber materials to at-home mask makers, saying these materials can provide N95-level protection.
Getting a homemade mask to fit like an N95, however, is a bigger challenge.
Alex Chan, managing partner of the mask and respirator retailer AEA Group, told Healthline that using lightweight cloth to prevent drooping, and a pattern that includes the ability to tuck the mask under the chin, are critical to having a well-fitting mask.
Having a nose clip can also help, but Chan noted “it’s very difficult to put nose clips in a DYI mask.”
“A common trick that some doctors use is to place a piece of double-sided tape across the bridge of the nose before putting the mask on,” Veran told Healthline. “If you place the double-sided tape between the inside of the mask and the bridge of your nose, it will create a better seal. You can also place an additional piece of cellophane or masking tape over the mask as well.”
N95 masks are in short supply and thus recommended for use only in healthcare facilities treating COVID-19 and other infectious diseases.
However, Chan notes, N95-equivalent masks, such as KN95 masks made in China and FFP-2 masks from Europe, are more available and affordable.
“Currently in the U.S. we definitely need to be wearing proven masks or respirators to protect the users as well as others,” he said. “While medical N95s and medical surgical masks are not available for the public, there are still ways to get similar products.”
Chan recommends that Americans maintain a supply of KN95 respirators for use in situations where physical distancing is impossible.
In addition, ASTM level 2 certified surgical masks — which are tested for filtration of both inhaled and exhaled sub micron particles — can be for everyday use.
Ideally, he said, cotton or homemade masks should be used only when community spread of COVID-19 has subsided.
“In countries like Hong Kong, South Korea, Japan, and Singapore, you won’t find cloth masks at the height of their infection count,” said Chan. “It is only now when they have truly reversed the curve where cloth masks are issued, and even then, these are not homemade or ordinary cloth masks. Instead, they are engineered to be almost equivalent to ASTM Level 1 mask performance.”
“Furthermore,” he added, “citizens there are even required to switch to their surgical masks when they visit certain areas like hospitals.”
The Food and Drug Administration (FDA) maintains a
of KN95 masks
The list can be used as a buying guide to avoid knockoff products that do not meet FDA standards for respirators.
Buyers also need to be wary about buying “surgical masks” that may not meet ASTM level 2 standards. Only masks approved by the FDA and coded as “FXX” medical devices should be used.
“There’s a big difference between healthcare certified masks and those not targeted to the healthcare industry,” said Zimmer.
“If they are on the FDA list there’s a very good chance they are legitimate,” added Chan. “If there’s no name I’d be very wary of that.”
If all you have is a cloth mask, wear it. Any mask is better than no mask, particularly for protecting others — but for your own benefit as well.
“If everyone is wearing a mask, there will be less viral particles potentially aerosolized in the first place,” Dr. Erum Ilyas, a dermatologist and functional textiles expert, told Healthline. “It will reduce the viral load in the environment to also impact the effectiveness of masks.”
“To understand this, think about swim goggles,” Ilyas said. “They are not 100 percent effective at blocking water from entering when underwater because there is a huge water load to block. I’d bet they are pretty darn close to 100 percent effective at blocking water from entering while above water, where there is little to block.”