Two masks may provide greater protection from the spread of the novel coronavirus, but experts say it depends on the quality of the masks and the way they’re worn. Miquel Llonch/Stocksy United

• Dr. Anthony Fauci has said that double masking “just makes common sense.”
• In theory, it’ll help reduce the spread of COVID-19 by filtering more particles.
• Double masking is most helpful when there are concerns about source control.

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On a recent appearance on the “Today” show, Dr. Anthony Fauci, who is the chief medical adviser on COVID-19 for the president, said that double masking is a move that “just makes common sense” and is “likely” to provide more protection against the transmission of COVID-19.

In addition, high profile figures like transportation secretary Pete Buttigieg and his husband, Chasten, have been spotted wearing double masks in recent weeks.

Is double masking a good idea for you? When and how should you go about doing it?

Here’s what we currently know.

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In theory, double masking helps control the spread of COVID-19

According to Firas Zabaneh, MT (ASCP), CIC, CIE, director of system infection prevention and control for Houston Methodist Hospital in Houston, Texas, double masking might help.

Zabaneh said the rationalization for wearing two masks is that you’re adding more layers of filtration.

Filtration efficiency is increased, Zabaneh said, so fewer particles penetrate through the masks.

However, he cautions that wearing two masks may give people a false sense of security.

If a person is wearing two low quality masks on top of each other, it may not be very effective.

In addition, if not done properly, wearing two masks could actually increase a person’s risk by allowing leakage around the edges.

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Why the fit of the mask matters

Binghamton University mechanical engineering assistant professor Scott Schiffres, PhD, who’s been working on testing masks since the COVID-19 pandemic began, said that increasing protection isn’t just about adding more layers of filtration.

If the masks are worn in a way that compromises the fit of the masks on the face, this may allow unfiltered air to leak through gaps.

For example, wearing two surgical masks won’t be better than one, Schiffres said.

“It is not the ability of the filter that limits performance,” he said, “but the fit to the face (how much air leaks at the face seal).”

“The surgical mask material itself is very good (>95 percent at 0.1 um), but in practice about 20 percent of the air will slip between the mask and the seal of the mask, so the efficiency would effectively be about 80 percent,” Schiffres said.

“If you were to just put two surgical masks one on top of another, more of the air would actually leak around the seal as the resistance through the masks increases, and even less air would be filtered, making this double masking detrimental,” he said.

“The most important thing,” Schiffres said, “is not to have a false sense of confidence in the filtration of the mask, as it can only be as good as the fit to your face allows.”

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How to maximize fit

The Centers for Disease Control and Prevention (CDC) released a Trusted Source on Feb. 10 outlining two methods that have been studied as a way to improve the fit of medical procedure masks.

One way involves knotting the ear loops of a medical mask and then tucking in and flattening any extra material so the mask fits closer to the face.

The other involves double masking by wearing a cloth mask over a medical procedure mask.

In an experiment, the CDC simulated what would happen when a person coughs when they and another person in their proximity are wearing various mask combinations.

The combinations included: no mask, a 3-ply medical mask alone, a cloth mask alone, double masks, unknotted mask, and knotted and tucked medical mask.

Altogether, 10 different combinations were tested.

They found that the unknotted medical mask alone blocked 40.2 percent of particles from the simulated cough, while the cloth mask alone blocked 44.3 percent.

However, when the two were combined, with the cloth mask over the medical mask, the particles blocked jumped to 92.5 percent.

In a second experiment, researchers found that adding a cloth mask over a medical mask reduced the exposure of the receiver by 82.2 percent.

In addition, knotting and tucking a medical mask reduced this exposure by 62.9 percent.

When the source of the cough was unmasked, but the receiver was wearing a double mask or a tucked medical mask, the receiver’s exposure was reduced 83 percent and 64.5 percent respectively.

The best results, however, were obtained when both the source and receiver were double masked or wearing knotted and tucked medical masks.

The exposure of the receiver was reduced 96.4 percent with double masking and 95.9 percent with knotted and tucked masks.

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When is it a good idea to wear two masks?

Zabaneh said that one case in which it’s a good idea to wear double masks is when there are concerns about source control.

“For source control purposes, anyone who is wearing a mask with an exhalation valve (including N95 respirators with exhalation valves) should apply a secondary mask on top of the primary one,” he said.

“This is intended to provide protection for others if the wearer of the mask with the exhalation valve is infected with SARS-CoV-2.”

In addition, the CDC is now recommending double masking as a way to improve mask fit and reduce the spread of COVID-19.

According to the CDC report, wearing a cloth mask over a medical mask can provide “substantially improved source control” as well as reducing exposure of the wearer.

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If you do double mask

Zabaneh suggests that if you double mask, you should choose a good quality mask that maximizes filtration.

It should be constructed in such a way that it creates a good seal on your face so that unfiltered air doesn’t leak around the mask.

In addition, you should be aware that double masking can potentially make it more difficult to breathe.

More layers of filtering materials means more resistance to air flow, Zabaneh said.

He suggests looking for masks that filter well and provide a good seal without inhibiting your breathing too much.

“There are many such masks on the market at this time,” Zabaneh said.ADVERTISEMENTWhen Do COVID-19 Symptoms Appear?

Learn more about COVID-19 symptoms, how long they take to appear, and when to contact a doctor.

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The Simple Science Behind Why Masks Work

• The CDC continues to advise wearing face masks to prevent the spread of COVID-19.
• Masks work by creating a physical barrier to the spread of virus-containing respiratory droplets.
• Growing evidence supports their effectiveness.
• While many Americans have objected to wearing masks, experts say their concerns are unfounded.

The Centers for Disease Control and Prevention (CDC) continues to strongly advise the wearing of face masks to prevent the transmission of SARS-CoV-2, the virus that causes COVID-19.

On July 14, 2020 the CDC Director Dr. Robert Redfield said in a Trusted Source: “Cloth face coverings are one of the most powerful weapons we have to slow and stop the spread of the virus — particularly when used universally within a community setting.”

While these recommendations have been met with some skepticism among the public, scientific evidence continues to show that masks do work.

As to the reasons why, the experts say the science is quite simple.

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Why face masks work

Transmission of the coronavirus is thought to occur through respiratory droplets that are released when people speak, sneeze, or talk, according to Dr. MeiLan Han, a professor of medicine in the division of pulmonary and critical care at the University of Michigan.

If these droplets land in the mouth or nose of people nearby, or are inhaled into the lungs, a person can contract the virus.

Masks create a physical barrier that catches these droplets and prevents them from spreading as far into the surrounding air as they normally would.

Han said the masks become even more important because a significant proportion of people who get COVID-19 either don’t exhibit symptoms or there’s a delay before symptoms show up.

Studies show, however, that these people can still transmit the virus to people around them.

The data suggest that the use of face coverings can help limit the spread of the disease by these asymptomatic and presymptomatic individuals, said Han.

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Growing evidence supports mask effectiveness

In the July 14, 2020 issue of the Journal of the American Medical Association (JAMA), the authors of an Trusted Source said that “the time is now” for universal mask wearing.

In support of their opinion, they pointed to two case studies that were published that same day.

The Trusted Source showed that a universal mask wearing policy in a Boston hospital system reduced the transmission of SARS-CoV-2.

Prior to the institution of the mask policy, new cases among healthcare workers who had either direct or indirect patient contact were increasing exponentially.

After the policy was put into place, however, the proportion of symptomatic healthcare workers who tested positive for COVID-19 “steadily declined,” according to the report.

The editorial additionally spoke about a Trusted Source in the CDC’s Morbidity and Mortality Weekly Report (MMWR) which showed that wearing a mask appeared to prevent two Missouri hairstylists from spreading the disease to their customers.

Both stylists had continued to see customers for several days after developing symptoms, but wore face masks as per local government ordinance. Ninety-eight percent of their customers wore masks as well.

Of the 139 customers that the stylists saw before being diagnosed, none developed COVID-19 symptoms during the follow-up period. None of their secondary contacts developed symptoms either.

In addition, of the 67 clients who agreed to be tested, none were positive for the virus.HEALTHLINE RESOURCECOVID-19: How we’re finding hope in the heartache

We’re sharing five stories of how people like you coped with the challenges of the pandemic. Learn how they built resilience and found joy over the past year, and get tips for your own life, too.Enter your emailSUBSCRIBE

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Answering the skeptics

Despite the scientific evidence supporting the wearing of masks, many Americans have voiced objections to their use.

We asked Dr. Vinisha Amin, hospital medicine physician at University of Maryland Upper Chesapeake Health to counter some of the more frequently raised concerns and misinformed myths that are currently being spread.

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1. Masks don’t work

“Let’s disintegrate that myth!” said Amin. “Masks are helpful and effective in protecting you and your loved ones from the virus.”

“There is a plethora of scientific data and research to help solidify this recommendation,” she added.

“In the scientific world, evidence-based medicine takes precedence, and we must put trust in our physicians and scientific community when they make such recommendations given that they are for your own and your loved ones’ medical/health safety,” Amin said.

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2. They’re so uncomfortable to wear

“That means you have only tried one mask and gave up quickly on finding one that works well,” said Amin.

“Yes, they may create humidity, but in that situation, wear a cotton material mask which is a more breathable material than polyester,” she advised.

“Yes, they might hurt your ears. In that situation find a mask where the elastic band that wraps around the ear is cloth covered or a softer elastic band which won’t irritate your skin,” she said.

“Yes, they fog up glasses. I have the same issue,” she added. “In that situation, place your eyeglasses over the mask on the bridge of your nose to help hold the mask in place and also help mitigate the fog under your glasses.”

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3. I’m worried about carbon dioxide building up and making me sick

“There is absolutely no scientific reasoning that supports the claim that there is carbon dioxide buildup due to masks,” said Amin.

“Healthcare professionals such as our physicians and surgeons have been utilizing tighter and more impenetrable masks for decades, yet we are still able to breathe through them,” she said.

She continued, “Masks allow for oxygen to penetrate in just as readily as they allow for carbon dioxide to penetrate out.”

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4. I’m not at high risk

Amin acknowledged that the most vulnerable people are those with comorbid conditions or those who are immunocompromised.

She noted, however, that “although you may be healthy and fit, you might not even be aware that you have acquired the virus and could be shedding high viral loads to your vulnerable loved ones at home.”

“We are all co-dependent on each other for our well-being and health as a community,” she explained.

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The Take Away

There’s growing evidence that masks do work in preventing the spread of COVID-19.

Masks works in a very simple way by capturing the virus-containing droplets we emit when we speak, cough, or sneeze.

Although the principle behind masks is a simple one, they’re a very important part of containing the disease.

Experts say they work best when we all cooperate and wear them.

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