Face masks or facial coverings remain a very contentious topic. We have received a lot of comments from people who are pretty adamant that face masks are a total waste of time. Others insist that they will not go out in public without one. As we pointed out in this article, people are literally dying because they are fighting about face masks. This post is not a debate about pros and cons of facial coverings. Rather, it is a report on which face masks work best, thanks to a Duke University study (Science Advances, Aug. 7, 2020).
Dr. Eric Westman to the Rescue:
We have known Dr. Westman for a very long time. He is an associate professor of medicine and director of the Duke Lifestyle Medicine Clinic. He also directs the Duke Center for Smoking Cessation. He is board certified in internal medicine and obesity medicine. He is president of the American Society of Bariatric Physicians.
Dr. Westman has been a guest on our nationally syndicated public radio show, The People’s Pharmacy, on numerous occasions. We think of him as an expert on weight management, metabolism and diet. Here is one interview:
Show 958: Flipping the Food Pyramid Upside-Down
The old-style food pyramid with lots of starches and sugars at the base and fats at the tip may not be the healthiest way to eat.
Why, for goodness sakes, would we turn to Dr. Westman for insights on face masks? Weight loss, you bet. Smoking cessation, sure! But face masks are hardly his specialty. Here’s how Eric Westman became our go-to guy for face mask protection.
How To Determine Which Face Masks Work Best:
According to Wired (August, 12, 2020), Dr. Westman was an early mask adopter.
In April he was trying to help vulnerable people get access to face masks:
“Westman had been hard at work for weeks, raising money to pay out-of-work costume designers and sewing hobbyists who’d organized online to make hundreds of cloth masks out of hard-to-find fabric and elastics donated by a local ballet company. A physician and obesity researcher at Duke University, Westman had teamed up with other doctors and community organizers to distribute the masks for free to nursing homes, jails, homeless encampments, and to other places with vulnerable populations in the Research Triangle. They focused on reaching people who couldn’t easily socially distance, like farm workers, bus drivers, and grocery store employees, especially in Black and Latinx neighborhoods, which were expected to be hit the hardest.”
Before spending money to acquire facial coverings, Dr. Westman wanted to know which face masks work best. To do that he reached out to colleagues at Duke. Dr. Martin Fischer, a chemist and physicist answered the call.
A Do-It-Yourself Laser Test:
He and his colleagues developed a surprisingly simple way to test a variety of facial coverings. By utilizing a laser light source and a cell phone video camera the investigators were able to analyze the effectiveness of 14 different masks or facial coverings. The research was published in Science Advances (August 7, 2020).
The investigators included common surgical masks, cloth masks, bandanas, N95 masks with exhalation valves and fitted N95 masks with no exhalation valve. The subjects were told to say “STAY HEALTHY, PEOPLE” repeatedly while the investigators measured the number of particles that were detectable with or without a face mask.
The best facial covering was the fitted N95 mask. No droplets were able to escape that mask.
Three-layer surgical masks and do-it-yourself cotton masks were also reasonably effective at stopping the spread of droplets.
The Duke researchers reported that so-called gaiter masks or neck fleeces were the least effective. In fact, they counted more particles when people wore gaiter masks than nothing at all.
N95 masks with exhalation valves also performed poorly in this test. Would you like to see how the tests were conducted at Duke University? Here is a link to a video that is quite fascinating.
What Is the Bottom Line?
The bottom line seems to be that face masks can cut down on particle transmission, but there is considerable variability in effectiveness. You do not want a mask, even an N95 mask, if it has an exhalation valve. That’s because it will not protect others from your aerosol particles. It might protect you from them, but the whole point of wearing a mask is to first, protect others and second, protect you.
Doctors have traditionally worn N95 masks with exhalation valves to protect themselves from people who have highly contagious diseases such as measles or tuberculosis. But now we want masks that protect both ourselves and others. The fitted N95 masks without exhalation valves are our number one choice.
Sadly, they are hard to come by, except for health professionals. One of the co-authors of the Duke study was Warren S. Warren. He is a professor of biomedical engineering, physics, chemistry and radiology at Duke.
In an interview published in the Washington Post (Aug. 11, 2020), he shared these thoughts:
“Warren encouraged people to assess their face coverings with another basic test. ‘If you can see through it when you put it up to a light and you can blow through it easily, it probably is not protecting anybody.’”
“‘We’re not as a society going to be having everybody wear disposable N95 face masks,’ he said. ‘It’s not affordable, and it’s not reasonable.’ The researchers specifically made note of the effectiveness of common cotton cloth masks, finding that several of the ones tested performed about as well as surgical masks, which come in second to the N95. Experts with the WHO have recommended that fabric masks should ideally have three layers.”
You can read the paper by Dr. Westman and his colleagues at this link.
What Do You Think?
Share your own thoughts about face masks in the comment section below. You may also want to read the latest information about aerosol particles and COVID-19 transmission at this link. It just might convince you to wear a face mask even if you are staying more than six feet away from people.
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