With the new coronavirus, known as SARS-CoV-2, the largest amount of viral shedding, or transmission, happens early in the course of the disease. Therefore, people may be contagious before they even start to show symptoms.

Moreover, scientific models suggest that up to 80 percent of transmission stems from asymptomatic carriers of the virus.

Emerging research suggests that widespread mask use may help limit the transmission of the virus by people who don’t realize that they may have it.

Respirators

Fit- and seal-tested respirators are made of tangled fibers that are highly effective at filtering pathogens in the air. These respirators must meet the rigorous filtration standards set by the National Institute for Occupational Safety and Health (NIOSH).

The diameter of the coronavirus is estimated to be 125 nanometers (nm). Keeping this in mind, it’s helpful to know that:

• Certified N95 respirators can filter 95 percent of particles that are 100 to 300 nm in size.
• N99 respirators have the ability to filter 99 percent of these particles.
• N100 respirators can filter 99.7 percent of these particles.

Some of these respirators have valves that allow exhaled air to get out, making it easier for the user to breathe. However, the downside of this is that other people are susceptible to the particles and pathogens that are exhaled through these valves.

Frontline healthcare and other workers who need to use these masks as part of their job are tested at least once a year to verify proper respirator size and fit. This also includes checking for air leakage using specific test particles. These routine tests help ensure that harmful particles and pathogens can’t leak through.

Surgical masks

There are various types of surgical masks. Typically, these disposable, single-use masks are cut into a rectangle shape with pleats that expand to cover your nose, mouth, and jawline. They are composed of breathable synthetic fabric.

Unlike respirators, surgical face masks don’t have to meet NIOSH filtration standards. They aren’t required to form an airtight seal against the area of your face that they cover.

How well surgical masks filter pathogens varies widely, with reports ranging from 10 to 90 percent.

Despite differences in fit and filtration capacity, a randomized trial found that surgical face masks and N95 respirators reduced participant risk of various respiratory illnesses in similar ways.

Adherence — or proper and consistent use — played a more pivotal role than the type of medical-grade mask or respirator worn by study participants. Other studies have since supported these findings.

Cloth masks

Do-it-yourself (DIY) cloth masks are less effective at protecting the wearer because most have gaps near the nose, cheeks, and jaw where tiny droplets can be inhaled. Also, the fabric is often porous and can’t keep out tiny droplets.

Although cloth masks tend to be less effective than their medical-grade counterparts, experimental results suggest they are far better than no mask at all when worn and constructed properly.

The CDC recommends wearing cloth face masks in public settings where compliance with physical distancing measures may be difficult to achieve and maintain. This is key in areas where community-based transmission is high.

This includes, but is not limited to, settings such as:

• grocery stores
• pharmacies
• hospitals and other healthcare settings
• job sites, especially if physical distancing measures aren’t feasible

However, the CDC recommends that just about everyone wear a cloth face mask.

People who can’t remove the mask on their own or have breathing issues shouldn’t wear masks. Neither should children under the age of 2 due to the risk of suffocation.

If you aren’t sure if a face mask is safe for you to wear, be sure to talk to your doctor. They can advise you on what type of face covering may be best for you if you need to be out in public.

• Use proper hand hygiene each time you put on, remove, or touch the surface of your face mask.
• Put on and take off the mask by holding it by the ear loops or ties, not by touching the front of the mask.
• Make sure the face mask fits snugly and the straps fit securely over your ears or behind your head.
• Avoid touching the mask while it’s on your face.
• Sanitize your mask properly.
• Run your cloth mask through the washer and dryer after each use. Wash it with laundry detergent. You can also place the face mask in a paper bag and store it in a warm, dry place for 2 or more days before wearing it again.
• If you must reuse your respirator or surgical mask, isolate it in a breathable container such as a paper bag for at least 7 days. This helps ensure the virus is inactive and no longer infectious.

In addition to physical distancing and using proper hand hygiene, many health experts consider the use of face masks to be a key measure in helping to prevent the spread of COVID-19.

Although homemade cloth masks aren’t as effective at filtering out small particles as respirators or surgical masks, they offer more protection than not wearing any face mask at all.

The effectiveness of homemade face masks can be enhanced with proper construction, wear, and maintenance.

As people return to work, continued use of appropriate face masks might help mitigate an increase in virus transmission.