Wearing effective face masks while in public, especially inside, reduces the transmission of COVID-19 from respiratory exhalation.
There are two key methods of protecting ourselves and each other from becoming infected with COVID-19: vaccination and wearing face masks. Each of the vaccines approved for use in the U.S. are significantly effective against COVID. The same isn’t true of all face masks.
Significant differences exist in the efficacy of the many available types of face masks, from N-95 to homemade cloth masks. N95 and KN95 masks are clearly the most effective in stopping respiratory droplets and aerosols containing COVID.
Which face mask you choose to wear can make a huge difference in how well you protect yourself and others from the COVID virus. Let’s talk face masks and figure out what we should wear when traveling and while at home, but first let’s take a brief look at what’s happening with the pandemic in the U.S., to give us some insight.
The COVID Delta variant is the dominant strain in the U.S. and is more than 200 percent more contagious than all prior strains.
In the U.S. last week, there were more than a million new COVID-19 cases, plus more than 8,500 COVID-related deaths. The vast majority of infections are from the COVID Delta variant, which is more than 200 percent more contagious than previous strains of the virus. Of those hospitalized with COVID, almost all are unvaccinated Americans, though a tiny percentage are from breakthrough infections of fully vaccinated people.
Right now many unvaccinated Americans are hospitalized for COVID where vaccination rates are low and/or face mask use is also low. Seven states, primarily in the South, have fewer than ten percent of their ICU beds available, according to the latest statistics from the U.S. Department of Health and Human Services. Of the ICU beds used in those states, as many as 57 percent are COVID patients.
There are a wide variety of face masks available for people to wear to prevent the transmission of COVID-19. They range from commercially manufactured N95 and KN95 masks to surgical masks, masks with valves or vents and layered and unlayered, plus commercial or homemade cloth masks.
Face masks don’t work well against COVID unless they fit well, no matter how well their material can filter.
The U.S. Environmental Protection Agency (EPA) published research on determining the effectiveness of face masks against COVID-19 in April. They did detailed filtration studies on N95 masks that were new, expired, and sterilized for reuse. The results showed that they all had filtration of 95 percent or more. Surgical masks with ties provided 71.5 percent filtration. Surgical masks with ear loops provided just 38.1 percent filtration.
They also tested a variety of cloth face masks. The tests included knitted and woven materials. They looked at multi-layer and, single-layer masks. Face masks with and without nose bridges and using different attachment methods were tested. Among the masks was a three-layer knitted cotton mask that filtered at just 26.5 percent. Two-layer nylon woven tied mask with a nose bridge worked better at 79 percent. Other masks scored filtration between those.
EPA’s effective face mask filtration tests showed that fit and how well face masks are held on the face are critical to protection.
We can deduce from EPA’s results that of the masks they tested, unsurprisingly the N95 was the winner. In addition, it’s clear from their research that face mask fit is critical to any face mask’s effectiveness.
Since that study was published, the Delta variant has become the dominant COVID-19 strain. Our knowledge of how COVID-19 spreads has become enhanced. We know it’s not just large respiratory droplets that come out of our mouths and noses that carry COVID to others. It’s also respiratory generated aerosols, tiny droplets that transmit the viruses to others. Researchers at the University of Waterloo in Ontario, Canada, published their results in the journal, Physics of Fluids in July.
Commercially manufactured N95 and KN95 face masks were the winners in filtering out exhaled aerosols. These masks filtered out more than 50 percent of the aerosols. In contrast, most of the face masks in common use by the public, including looped surgical masks, filtered less. They only filtered out about ten percent of the exhaled aerosols that can accumulate indoors and spread the virus.
The University of Waterloo’s research shows that N95 and KN95 masks are clearly superior in filtering respiratory aerosols compared to all other masks tested.
How well the masks fit was clearly a primary factor in how poorly most of the face masks other than the N95 and KN95 masks did in the University of Waterloo tests. It’s important to note that the main difference to be concerned about with N95 versus KN95 is the attachment method. Unlike the N95 masks, the KN95 masks use ear loops. The way many pull down their face mask around their neck when not in use stretches the ear loop elastic. When the ear loops’ elasticity diminishes, the mask will lose its fit and its filtration ability. At that time, users should discard it.
Personally, I’ve thrown out my cloth masks and now I’m only wearing N95 or KN95 face masks for travel and at home to protect me from COVID.
The research by EPA and Waterloo University makes a compelling case for people to wear face masks during the pandemic, particularly inside, even if vaccinated. The N95 and KN95 face masks are tremendously effective. While other face masks are to varying degrees effective in stopping large respiratory droplets, except for the N95 and KN95 masks, the others aren’t particularly effective in filtering respiratory aerosols containing the COVID-19 virus.
After many years working in corporate America as a chemical engineer, executive and eventually CFO of a multinational manufacturer, Ned founded a tech consulting company and later restarted NSL Photography, his photography business. Before entering the corporate world, Ned worked as a Public Health Engineer for the Philadelphia Department of Public Health. As a well known corporate, travel and wildlife photographer, Ned travels the world writing about travel and photography, as well as running photography workshops, seminars and photowalks. Visit Ned’s Photography Blog and Galleries.