Swipe to advance
Images from Getty Images, Dreamstime, ClearMask LLC

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Whether inside the hospital or out on the streets, face masks are one of the most effective tools in the battle against SARS-CoV-2. Masks significantly reduce the rate of COVID-19 infection among healthcare workers (HCWs). Notable drops in COVID-19 cases have been observed after states mandated face coverings. Deaths due to COVID-19 are lower in those countries most supportive of public mask-wearing.

Masks have a dual function for HCWs: They protect HCWs from acquiring SARS-CoV-2 from infected patients, and they also prevent unknowingly transmitting the virus to uninfected patients. Masks worn by the general public serve mainly to prevent the wearer from infecting others.

Yet not all masks are created equal, varying greatly in efficacy and comfort. Here are the latest data on the most commonly used face coverings, along with their relative benefits and limitations.

Image from ArcEnCiel/Amazon

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Anti-mask Masks

Let's begin with what is undoubtedly the worst available option, the porous face coverings made of fishnet, loose knitting, or lace being adopted by self-identified anti-maskers. More of a provocation than a protective measure, these masks are meant to be a statement of defiance — the wearer is complying with mandates while simultaneously flouting them.

Simulations show that effective face coverings worn by at least 80% of the population would curb the pandemic more appreciably than a strict lockdown. Centers for Disease Control and Prevention (CDC) director Robert Redfield has said that COVID-19 cases would be brought under control in 4-8 weeks if everyone wore a mask.

Image from Gina Ferazzi/Los Angeles Times/Getty Images

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Neck Gaiters

Neck gaiters are made of highly breathable, stretchy fabric and are worn around the neck, nose, and mouth. In early August, Duke University researchers conducting an optical test of various mask types reported that neck gaiters may increase virus transmission by dispersing larger droplets into a greater number of smaller droplets, which can hang in the air longer. The study has been critiqued for being overly simplistic, including only a single subject wearing a polyester spandex neck gaiter. Although another simulation involving coughing showed that neck gaiters were effective at containing expelled droplets, and more recent research indicates that doubling the layers of a gaiter blocks > 90% of all measured particles, their newly dubious status as possibly being worse than wearing no mask at all may prove hard to shake.

Image from iStock

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Bandanas

The same Duke University study had similarly discouraging news for those who favor bandanas as substitutes for masks. Bandanas were effective at reducing droplets by only a factor of two, the second worst finding of the 14 masks tested. Bandanas are better than nothing, however, and their ability to block virus-laden droplets can be improved by ensuring that they fit properly.

Image from Dreamstime

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Masks With Exhalation Valves or Vents

Unlike the masks worn mainly to prevent the wearer from spreading disease, masks with exhalation valves or vents are designed to protect only the wearer. These masks are often used by industrial laborers, who breathe in filtered air through the outside fabric portion of the mask and exhale through the valve, minimizing their exposure to chemicals, particulates, and other adverse elements.

The design feature that allows wearers to exhale renders such masks effectively useless, given that the one-way valves or vents can expel viral droplets, promoting transmission to others. In August, the CDC issued a warning against their use, and since then, bans have been issued by commercial air carriers, hospitals (such as the Mayo Clinic), and major US cities.

Image from Dreamstime

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Cloth Masks

Cloth face masks, whether homemade or purchased, have become a defining image of the pandemic. SARS-CoV-2 is thought to live on cloth for up to 2 days but can be easily killed using standard disinfection methods. The ability to wash and reuse cloth masks is a key advantage, which may offset the adverse environmental effects of disposable masks. Unique cloth masks may also be a form of personal expression that fosters their acceptance.

The effectiveness of cloth masks is less clear. Although comfort is a key driver of adherence, increased breathability negatively correlates with the ability to block droplet transmission. Cloth masks offer moderate efficacy at preventing the dissemination of particles the same size or smaller than those of SARS-CoV-2.

Image from Dreamstime

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Enhancing Cloth Masks' Efficacy

Mask efficiency is increased with more layers of fabric. Although one layer may reduce droplets emitted during speaking, two layers are required to impede those produced by coughing and sneezing. The World Health Organization (WHO) recommends that cloth masks have three layers to effectively separate the mouth from the outside environment, a design that has been shown to block droplets at a rate similar to those of surgical masks. Improving the fit of a cloth mask by adding a nylon overlayer also can enhance its ability to filter out particles.

Researchers have calculated the filter quality of various cloth mask materials. Weighing filtration efficiency and overall breathability, they concluded that a mask made of the nonwoven polymer polypropylene offers the highest filter quality. WHO provides a useful overview of the efficacy and breathability of nonmedical mask materials. Additional data show that filtration efficiency can be increased by using hybrid fabrics and higher-weave cotton.

Image from Wikimedia Commons

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Surgical Masks

Disposable surgical masks are composed of nonwoven, multilayered fabric. They are flat or pleated in appearance, and are affixed with straps that go around the ear, head, or both. Surgical masks must undergo standardized tests to ensure that they offer adequate filtration, breathability, and protection against fluid penetration and flammability. Given the circulation of knock-offs, consider these tips for spotting fraudulent masks. Surgical masks are three times as effective as homemade masks at blocking microorganism transmission during coughing. Surgical masks effectively minimized aerosol transmission of coronaviruses, influenza viruses, and rhinoviruses, although SARS-CoV-2 was not tested. A standard surgical mask will reduce the risk for COVID-19 infection by an estimated 65%, and the more form-fitting, the better. Care must be exercised during removal and disposal of these masks, as detectable levels of infectious virus have been shown to remain on the outside of surgical masks for up to 7 days.

Images from Shutterstock

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Elastomeric Respirators

These tight-fitting, reusable respirators purify the air via removable cartridges, achieving filtration rates at least equivalent to those of N95s. Full elastomeric facepieces cover the eyes, offering additional protection. With N95 masks in short supply, the CDC issued guidance recommending their use as a replacement. Additionally, one elastomeric respirator used repeatedly could replace hundreds to thousands of disposable N95 masks.

These respirators have limitations, such as the time required for cleaning and disinfection as well as the physical and psychologic discomfort sometimes caused by their wear. They are also not cleared by the FDA for fluid resistance. Versions with exhalation values should not be used, given the risk for viral transmission.

Image from Dreamstime

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Filtering Facepiece Respirators

The most effective mask option for HCWs is the filtering facepiece respirator, more commonly known as N95, N97, N99, or N100 masks. The number designation refers to the percentage of particles the masks can filter (ie, N95 masks filter 95% or more). Unlike surgical masks, these masks also filter smaller 0.075 µm solid particles. N95 masks are tested and certified by the National Institute for Occupational Safety and Health. They come in different sizes, and in healthcare settings they must be fit-tested to ensure efficacy.

Although a 2019 study found no significant difference between surgical and N95 masks in reducing the rate of laboratory-confirmed influenza among HCWs, other studies have shown the N95 masks to be superior in terms of reducing aerosol exposure and viral transmission. Given recent supply shortages and price gouging, it's reassuring that N95 masks past their expiration dates still retain their filtration efficiency after sterilization with ethylene oxide and hydrogen peroxide.

But the efficacy comes at a cost. N95 masks were described as "suffocating, uncomfortable, and difficult to tolerate for long durations" in a recent JAMA commentary, and prolonged wearing can result in facial bruising and abrasions.

Image from Dreamstime

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

International Respirators

The US Food and Drug Administration (FDA) authorized the purchase of imported masks to help meet demand. These essentially function the same as N95 masks but have different product names due to being approved under comparable standards in their respective countries (for example, the commonly available KN95 masks from China). The FDA provides a full list of approved imported respirators, and the CDC offers advice surrounding their purchase, including how to identify the warning signs that the masks do not perform as advertised.

Image from Curtis Compton/Atlanta Journal-Constitution/AP

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Face Shields

Because it's possible to contract COVID-19 through the mucous membranes of the eye, face shields provide superior protection against splash and spray of respiratory secretions for HCWs in certain settings. A recent study found that the COVID-19 infection rate dropped from 19% to 0% when HCWs were given face shields made of polyethylene terephthalate (250-μm thickness) in addition to three-layer surgical masks and other personal protective equipment.

While the CDC does not recommend the use of face shields as a replacement for face masks, as it is currently unclear whether they reduce viral spread, their value is evident as a supplemental piece of equipment. The CDC recommends that, at a minimum, face shields should be hooded, wrap around the sides of the wearer's face, and extend below the chin. Reusable face shields should be cleaned and disinfected after each use.

Image from ClearMask LLC

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

A Clear Improvement?

Although covering the mouth and nose can have a dramatic public health impact, there is a notable downside. Blocking the mouth can create challenges for deaf or hearing-impaired persons who rely on lip reading, and can impede language development of infants and young children. Some hope is offered by the recent FDA clearance of a fully transparent, surgical-grade face mask (ClearMask). Although the mask has obvious utility during this pandemic, its development began 3 years ago after the company's deaf co-founder experienced considerable difficulty understanding masked surgeons during a procedure.

Image from Dreamstime

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Masks for Children

The CDC recommends that children younger than 2 years should not wear masks due to the risk for suffocation. Like the CDC, the American Academy of Pediatrics (AAP) endorses the use of cloth masks for all children older than 2 years, "including the vast majority of children with underlying health conditions, with rare exception." The AAP's parenting website HealthyChildren.org features a guide for addressing common misconceptions about children and cloth masks. Parents will be seeking guidance on the best-fitting, most comfortable masks for their children as many begin returning to in-person school.

Images from Dreamstime

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

Wear It Well

The value of a face mask depends on it being worn correctly. Useful guides on proper mask use are available from the CDC, WHO, and private institutions like Johns Hopkins Medicine. They stress avoiding common errors like wearing the mask in such a way that it doesn't fully cover the mouth and nose, leaving no gaps on the sides, handling only the ear loops or ties when removing it, and cleaning your hands before putting it on and after taking it off. Others have proposed tips and tricks for testing a mask's integrity, such as holding it up to the light (the less transparency, the better) and trying to blow out a candle when wearing it (this shouldn't be possible with a high-quality mask).

Image from LG

A Visual Guide to Face Masks: What Works, What Doesn't

John Watson | September 17, 2020 | Contributor Information

The Future Face Mask

The pandemic has sparked creativity, with designers envisioning innovative takes on the face masks of the future. LG recently announced a lightweight, rechargeable, air-purifying mask that should reach certain markets by year's end. The designer Oliver Perretta has put forward a version that uses an electrical current to sterilize the mask surface. And for those more concerned with communication than contamination, LED face masks allow the user to display customized messaging. While many have yet to be tested, such state-of-the-art solutions will probably come with hefty price tags.

Start
 

Unmasking Mask Misinformation and Myths

Dr Mark Lewis provides talking points to counter misinformation on mask wearing.Medscape Perspectives, August, 2020
All Slideshows
1 26 Next