The call to go back to work—to save the economy—is getting louder. We are selfish to worry about ourselves when the economy is sick, we hear. It is up to us to protect our economy, to rise above our fears, to get out there and fight as soldiers against a common enemy for the good of us all. Our jobs are at stake. A few of us will pay with our lives. But that’s war.
We may not be able to avoid the call to go back to the office, but we can still protect ourselves—and others. We’ve learned a lot about this new corona virus in the last few months, particularly how it spreads and how to stop it from spreading. A scientific and medical consensus has formed on what can be effective in combating COVID-19—and the common face mask is emerging as the most effective way to prevent its spread.
How strange is our world now? Someone coming to your office with a mask on would have made you run away just a short time ago. But COVID-19 changed everything. You will now run from those who don’t wear a mask.
Too Soon?
Forty million Americans are out of work, and by the time you read this, 120,000 will have died from the virus. COVID-19 infection is surging in several states, as more people come out from under lockdowns. Most visible are the hundreds of thousands protesting against police brutality—most of them not wearing masks.
One month was long enough to make many Americans feel they had been cooped up too long. Despite warnings from virtually every doctor and scientist that the virus is still out there, doors opened and people came out. Beaches in California and Florida were packed in the first hot days of the season. By Memorial Day, barbecues were in full swing. In churches, choirs sang.
An hour north of hard-hit Seattle, a conductor called on his choir to rehearse at the Mount Vernon Presbyterian Church. The April Tulip Festival was fast approaching and his Skagit Valley Chorale was a highlight, selling out the 650-seat venue for its Spring concert. The 60 singers who showed up to practice that evening were provided hand sanitizer, asked to refrain from hugs, and sang for two and a half hours, staying apart by what they thought was a safe distance. It wasn’t. Forty-five members of the choir were diagnosed with COVID-19 or developed symptoms, three were hospitalized, and two died, according to a report in the Los Angeles Times.
No mention was made of masks being worn. It is hard to imagine people singing with masks on.
In Wisconsin, the state Supreme Court overturned the governors “Safer at Home” ruling on May 13. Only days before, new confirmed cases in Wisconsin had dipped to below 200. In hundreds of pictures, we saw images of freedom loving Wisconsinites flooding into bars to celebrate. None of them appeared to have a mask on. Six days later, according to data kept by the Milwaukee Journal Sentinel, confirmed new cases shot up to over 500.
Meat processing plants kept workers on the job long after it was safe to do so, and the workers spread the virus to their families and communities. While the rate of transmission between people in general is low, it’s between 4.6 percent and 19.3 percent in households, according to several studies referenced by the Wall Street Journal.1 A spouse is at the highest risk, with a transmission rate of 27 percent, according to a study in China. (A late May study found that Chinese families who wore masks indoors as a precaution had a 79 percent lower risk of infection.)
I Protect You and I Protect Me
A surgical N95 face mask is the gold standard in masks—but even a cloth or paper variety of face mask can be very effective.
The N95, technically a respirator, gets its name from the fact that it is able to remove 95 percent of the particles in the air.
Do not confuse the surgical N95 with the kind of mask given to contractors (which provide protection against asbestos) or those worn by firefighters (which provide protection against ash). Contractors’ masks have valves that allow unrestrained and unfiltered exhalation. While a healthy person in a contractor’s N95 mask would be protected against those with the coronavirus, someone infected with the virus who is wearing the mask would be spewing virus particles through the valve.
In other words, “I protect me; I expose you,” said Dr. Atul Gawande2 of the contractor’s N95 writing in the New Yorker. The surgical 95 respirator, however, is a “I protect you and I protect me.”
The best-selling author, Rhodes scholar and surgeon at Boston’s Brigham and Women's Hospital, points to his own place of work as evidence of the effectiveness of wearing masks, which he considers one of the five pillars of safe reentry into the economy, along with hygiene, distancing, screening and culture. The Mass General Brigham Hospital System, of which his hospital is part, has 75,000 employees and despite handling an average of a thousand suspected cases a day during the Massachusetts peak infection stretch in May,has suffered only a few cases of COVID-19.
The N95 mask is as effective as 12-16 layers of cloth, which would be most uncomfortable to wear, says Gawande. Made of a melt-blown polypropylene fiber fabric, and super thin, you wouldn’t think it would be very effective Gawande explains. But an electrostatic charge is applied to the fibers.
“The static electricity captures viral particles the same way that a blanket in the dryer catches socks,” explained Gawande.
Of course, six layers of cloth would be impractical. You couldn’t breathe. A two-layer cloth mask is effective enough.
“You need at least 60 to 75 percent of us wearing a mask.” That’s enough to stop the spread in the general population, said Gawande, citing a recent study.3
Please leave the N95s for medical workers, implore well-meaning governments. They are in short supply and are not being made fast enough. They may be being produced in other countries, but they are keeping them for themselves.
Wearers of N95 are cautioned to wear them once and dispose of them. They are no good after they get wet, warns Dr. Gawande. Normal exhalation will wet the mask and weaken the electrostatic charge, rendering the thin N95s mostly ineffective.
Mass General takes other precautions in the workplace. U.S. hospitals, already known to be scrupulously clean, have added additional safeguards after COVID-19, like using video conferencing between doctors and patients and Plexiglas screens between people, and limiting up to four riders in an elevator (“a nightmare at shift changes”).
The cultural change required to adopt 100 percent mask use has been a special challenge. Gawande sees doctors drop their masks to talk to patients, and he admits that he does not tell them to pull them back up.
DIY Masks Can Be Pretty Good
While there is agreement that the N95 surgical mask is best, even home-made masks, washed in soapy water after each use, should reduce fomite (contaminated surfaces) spread and droplet-mediated airborne transmission, say researchers from the UK’s Cambridge and Greenwich Universities. Droplets over 1 µm will be almost completely stopped by home-made masks. With the viral load increasing in proportion to the size of the droplet, stopping the biggest droplets is critical. Even a thin facial tissue on the inside backed with two paper towels was able to achieve 90 percent of the function of surgical masks in stopping 20–200 nm droplets. Another study4 published the results of a modeling exercise that concluded that using facemasks, even home-made fabric ones, along with social distancing and some measure of lockdown, would be the way to manage COVID-19 pandemic and reopen the economy.
The Commute
As businesses contend with protecting workers from COVID-19, it may be up to individuals to protect themselves during their commutes. For many people, and especially those outside North America, where individual use of automobiles is the norm, the commute takes place in carpools, vans, buses and subways. Masks have been shown to be very effective in those situations as this one case vividly points out.
In Chongqing, a city of 30 million people in southwest China, an infected man began coughing on a bus he was taking, the first leg of his journey home to the country, a two-hour plus ride with 39 other passengers. He did not realize he had COVID-19 as he was not feeling sick and so didn’t think he needed to wear a mask. Five of his fellow passengers got sick. The man decided to buy and wear a mask when the bus stopped and continued on his way home in a minibus for 50 minutes with 14 other passengers. No passengers who rode with him on the minibus developed an infection.
Stop with the Heavy Breathing
The Coronavirus has made us hyperaware of people sneezing or coughing, but we find out that just talking or even breathing may also be responsible for spreading the disease. In a May 2020 “evidence study” published in Risk Analysis journal, researchers found that normal breathing and talking expels droplets, 80 to 90 percent of them less than 1 µm in diameter, which can stay in the air for a long time.
This would threaten to make our 6 feet distancing (2 meters in Europe and elsewhere) a joke. “There’s no stop sign at six feet that respiratory droplets obey,” said Dr. Gawande, who reminds us that there is dubious science behind the commonly accepted separation distance. It is a doubling of the 3 feet distance from the 1930s, which was verified in 1981 by measuring the distance between the chairs where girls were seated in a Texas elementary school class after a meningitis outbreak. But a 1948 study with Navy sailors may already have blown our 6 feet of social distancing out of the water. While most germs went only a foot and a half away, one “unusually good atomizer” could propel his germs more than 20 feet.
Heavy breathing, the sort you would do at the gym, singing like you would in a church choir (as in the aforementioned case north of Seattle) or a karaoke parties, yelling over a loud disco, loudly chanting at a protest (such as those occurring all over the U.S. at the moment) makes for worse viral loads.
“We identified 61 COVID-19 clusters in various communities. We observed clusters of COVID-19 cases from 18 (30%) healthcare facilities; 10 (16%) care facilities of other types, such as nursing homes and day care centers; 10 (16%) restaurants or bars; 8 (13%) workplaces; 7 (11%) music-related events, such as live music concerts, chorus group rehearsals, and karaoke parties; 5 (8%) gymnasiums; 2 (3%) ceremonial functions; and 1 (2%) transportation-related incident in an airplane. The largest non–healthcare-related cluster we observed was among >30 persons who attended a live music concert, including performers, audience members, and event staff,” say researchers in a study due to be published in an upcoming issue of the Emerging Infectious Diseases journal.
Another factor is prolonged exposure, generally defined as 15 minutes or more of unprotected contact with someone less than 6 feet away, said John Brooks, the CDC’s chief medical officer for the COVID-19 response.
From the developing consensus, those on the beach and at their barbecues were at relatively low risk. The biggest risks are borne by people who are close to each other–usually indoors—who are close to each other for more than 15 minutes, and who do not wear face masks.
It’s the Economy, Stupid
Reopening the economy while fending off a threat is hardly a new concept. In the 1975 Steven Spielberg adaptation of Peter Benchley’s book, Jaws, police chief Martin Brody and marine biologist Matt Hooper try in vain to get Amity Island’s mayor to close the beaches before another shark attack occurs. It’s still out there, they say, referring to a yet unseen mega great white shark. No way we’re closing down, says the mayor. Our economy depends on people visiting us for the summer. Of course, the result is carnage, over and over again.
Worried About the Wrong Things?
After all the handwashing, stripping the shelves bare of Clorox wipes, and forcing ourselves to not touch our faces—or anyone else’s—did that do any good?
A little, perhaps. Six percent of infections in a study in China were due to “environmental effects,” also known as fomite spread, or the virus spreading from contact with contaminated surfaces. Handwashing and wiping would have helped there. All the remaining infections were due to virus spread from droplets directly passed from one human to the other, whether in large droplets or in aerosol or atomized form.
However, no evidence of small droplets traveling long distance seems to have materialized. “If this were transmitted mainly like measles or tuberculosis, where infectious virus lingered in the airspace for a long time, or spread across large airspaces or through air-handling systems, I think you would be seeing a lot more people infected,” said Dr. John Brooks of the CDC in an interview with the Wall Street Journal1.
Out of an abundance of caution, we still think washing our hands repeatedly is a good idea. And, what can it hurt? However, putting out hand sanitizers and moving desks farther apart will do little to blunt the peaks of COVID-19. For that, a strategy of mitigating the threat from the air is necessary.
Viral Loads
If you consider the human body as a city under siege from the virus and our skin as the outer wall of our defense, the viruses that manage to breach the walls can be overcome by the body’s defenses, that is, its immunological systems. The defending army, or white blood cells, can defend the city—up to a point. If enough invaders breach the walls, the defending army will be overwhelmed.
Virologists refer to the number of virus in a droplet, for example, as the viral load, and once the load is great enough, the virus’s replication is more certain.
The scramble to wash hands may have been caused by thinking that any number of viruses could cause infection, due to what we knew about other viruses, theory, early studies—or perhaps an overabundance of caution.
A more recent study in Nature suggests that it takes at least a million SARS-CoV-2 viruses to reach a tipping point and cause an infection. Researchers were unable to culture live coronavirus if a throat swab had less than one million copies of viral RNA from the SARS-CoV-2. It will take further research to determine if more than a million viruses are needed to cause infection in a human body with a healthy immunology system.
From observation and study of clusters of COVID-19 spread, however, it appears that 15 minutes of being in close proximity (less than six feet) will put you at risk of infection. And that person can be asymptomatic and just breathing normally.
References
- How Exactly Do You Catch Covid-19? There Is a Growing Consensus, Daniela Hernandez, Sarah Toy and Betsy McKay, Wall Street Journal, June 16, 2020
- Amid the Coronavirus Crisis, a Regimen for Reentry, Atul Gawande, The New Yorker, May 13, 2020
- A Modeling Framework to Assess the Likely Effectiveness of Facemasks in Combination with ‘Lock-down’ in Managing the COVID-19 Pandemic, Stutt, R. O. J. H., Retkute, R., Bradley, M., Gilligan, C. A. andColvin, J.Proc. R. Soc. A Math. Phys. Eng., June 10, 2020
- Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population, van der Sande, M., Teunis, P.,and Sabel, R., PLoS One, July 9, 2008