People are now spreading recently mutated, more contagious coronavirus strains around the U.S., and the most infectious strains will rapidly become dominant. With this reality, it’s high time to improve our masks, say many infectious disease experts.
An achievable way to maximize protection for both yourself and others is to wear a double mask. But there are a few important things to know about how, and how not to, double mask. These recommendations are detailed below.
“Like many things in life, the devil is in the details,” said Dr. Thomas Russo, the chief of infectious disease at the University of Buffalo’s Jacobs School of Medicine and Biomedical Sciences.
Enhancing our masks, and ensuring we have good masks, is all the more crucial because much of the population likely won’t be vaccinated for at least many months, if not later in 2021.
“We need to double down on public health measures more than ever,” emphasized Dr. Russo, who treats patients at the Buffalo VA Medical Center.
When to double mask
If you’re going to be around other people (from outside your home), it’s a good idea to maximize your masking protection, explained Dr. Monica Gandhi, an associate division chief of the Division of HIV, Infectious Diseases, and Global Medicine at UCSF San Francisco General Hospital. When outdoors, a quality single mask, like a well-woven cloth mask, is often sufficient (but the masking choice, and perception of risk in each unique environment, is up to you.)
But when indoors, you’re usually sacrificing a major public health intervention to avoid becoming infected: ventilation. Inside, the particles people breathe out can linger in the air for hours. Additionally, indoor places might be crowded, which limits your ability to keep away from potentially infected people.
With this devious virus, it’s likely we at times come near an infected person, because many people don’t realize they’re infected: Some 40 to 45 percent of infected people never experience symptoms, according to the CDC. What’s more, over half of infections are spread by people who either have no symptoms or don’t have them yet (presymptomatic). You might be unwittingly infected, too.
“That’s why everyone needs to wear a mask,” said David Leighton, a professor in the Department of Chemical and Biomolecular Engineering at the University of Notre Dame who has researched the effectiveness of masks.
What’s a good double mask?
There are two simple ways to make a more protective mask, explained Dr. Gandhi, who recently published an analysis of masks in the scientific journal Cell. (These two masking strategies are illustrated in the graphic below as “Maximal protection masks.”) The goal is to effectively filter air, so viral particles don’t enter or leave your mask.
Option 1: A widely available surgical mask (or the popular, often available kn95 masks) that’s covered with a cloth mask of tightly-woven material. Both surgical and kn95 masks are made with a synthetic plastic-derived material (polypropylene) that effectively filters tiny particles from the air.
Option 2: A similar option, though not technically a double mask, is a three-layer mask.
This is a tightly woven cloth mask with a quality filter (this filter could even be a surgical mask without the earloops, said Dr. Gandhi) used between the mask’s two cloth layers. Many quality cloth masks are now designed to hold a filter.
You might be wondering about N95 respirator masks — the type you see nurses and doctors wearing. Why not just use one of those?
Much of the public doesn’t have access to N95 masks, which are approved for healthcare workers in the U.S. What’s more, N95 masks are often professionally-fitted to the faces of professionals, a protective standard not feasible for the public. That’s why Dr. Gandhi recommends the simple-to-make double mask, or the enhanced cloth mask, described above. It’s achievable.
It’s all about fit
Double-masking is largely about fit. Wearing a cloth mask over a surgical mask (or a kn95 mask) helps to conform the underlying, filtering mask to your face, closing any gaps.
A surgical mask alone, for example, often has big gaps at the edges, allowing for particles to easily enter and leave. “It leaks like a sieve, it leaks like crazy,” said Jim Smith, a chemist and expert in aerosols (small particles) at the University of California, Irvine. “Surgical masks need a way to seal better around your face. That’s the whole point of double masking, in my view.”
Clarification on wearing multiple masks
* Two usually better than one, especially if the strength of one is filtering and of the other is fit
* A three-layer mask where one layer is a filtering material is good
* I wouldn’t recommend wearing three masks at once /1 https://t.co/tu5JJw0eLV
— Linsey Marr (@linseymarr) January 28, 2021
Double masking, of course, is not a rule. It’s possible for some people to have a great fit with a single quality mask, noted Smith. But that’s not easy for everyone to achieve. We all have different faces. And we might be unsure about the fit or quality of our masks. A double mask can solve these common problems, he said.
“When in doubt, double masking is not unreasonable,” said the University of Buffalo’s Dr. Russo.
A big no-no of double masking
While double masking can be of great benefit, just thoughtlessly layering on a bunch of masks and/or filters could do more harm than good. If you use too many layers, you’re creating a barrier so little air can pass through. Instead, the air you breathe in and out will be forced to leak through the edges of the mask, meaning this air isn’t filtered. Viral particles can escape.
“The air is going to bypass the mask and you’re not going to have any filtration at all,” explained Notre Dame’s Leighton.
The big picture
Masks are one of three main public health interventions, not involving vaccines or medicines, to avoid a coronavirus infection, emphasized Dr. Gandhi. The others are ventilated places and distancing from people outside your home. Striving for all three is ideal, but understandably not always possible.
Yet the power of masks cannot be understated. In Kansas, counties that implemented a mask mandate in July 2020 saw a six percent decrease in COVID-19 cases. In sharp contrast, counties with no mandate saw a 100 percent increase in cases, .
Universal masking outside our homes largely deprives the virus of new hosts. “If we could get everyone in the world to wear masks for four weeks, the virus would have nowhere to go,” said Dr. Russo.
In the coming years, in a world where infectious disease is a historical constant and another eventual pandemic or epidemic is inevitable, masks, and perhaps enhanced masking, could become a prudent norm in the U.S. during bad outbreaks.
“I think the mask is here to stay,” said Smith.