How Masks Work: What You Should Know About Them

You don’t have to be in the thick of a global pandemic to benefit from wearing a mask. Worn properly, they’re a great way to reduce your risk of getting sick — or getting someone else sick.

Wondering what type of masks are best, when to wear them or how they work?

Pediatric infectious disease specialist Frank Esper, MD, answers these questions and more in a crash course on masking.

How masks prevent spread of respiratory illness

Masks prevent the spread of infections by acting as barriers for the respiratory droplets and small particles that we expel when breathing out, talking, singing and more. Coughing and sneezing can propel these germ clouds even farther, up to 26 feet.

“Masking protects both you and the people around you,” Dr. Esper states. “The particles you put out get caught inside your mask, while the particles other people put out hit the outside.”

They aren’t effective 100% of the time, but research shows that, when used properly, high-quality masks are an extremely helpful tool for preventing the spread of respiratory infections like the flu, respiratory syncytial virus (RSV), COVID-19 and even the common cold.

Types of masks and respirators

There are many different types of masks on the market that prevent infectious disease transmission. Which option is best for you depends on the situation you’re in and your health history.

In high-risk situations, you may choose to use a respirator instead of a mask. Respirators are protective masks (like N95s) that are more securely fitted to the face. They also offer better quality filtration, protecting against both small and large droplets. Regular masks only filter large droplets.

The options include:

• Cloth masks: Reusable and washable, cloth masks are less effective than most medical masks, but according to research, they still provide some protection. Steer clear of fashion masks that use loose-weave fabrics, include a vent or have designs, like sequins or embroidery, that create holes in the material.
• Medical masks: Lightweight, disposable and easy to use, medical masks provide better filtration and fluid resistance than cloth masks and are ideal for use in lower-risk settings. In the U.S., check for an American Society for Testing and Materials (ASTM) marking to be sure the brand you buy is certified safe.
• Clear masks: These masks are made to help people with hearing loss communicate with you. The clear panels allow them to see your face and read your lips.
• N95 respirators: These devices provide a higher level of filtration (95%, as the name suggests) and fit tightly to your face. They’re used in high-risk healthcare and industrial settings. In the U.S., N95 respirators that are safe are marked with a logo from the National Institute for Occupational Safety and Health (NIOSH) and a testing and certification (TC) approval number.
• KN95 respirators: Produced in China, KN95s also offer 95% filtration. The main differences are in design and certification: N95s use straps that wrap around your head for a tight fit, while KN95s often use ear loops. KN95s are certified safe by the China Certification & Inspection Group.
• KF94 respirators: Manufactured in South Korea, KF94 masks have a “boat-like” shape that some wearers find more comfortable than N95s and KN95s. They offer 94% filtration and are considered as good as N95 and KN95 masks. Certified KF94s will have Korean approval markings.

Even the best mask is only as good as its fit. The mask should be snug, yet comfortable against the sides of your face, without gapping. The material should allow you to breathe easily.

How to mask properly

You’ll get the greatest benefit from your mask if you practice the following simple but effective storage, handling and hygiene procedures.

• Putting on your mask: Always wash your hands first. When you put your mask on, it should cover your nose and mouth and be secure under your chin. Adjust the straps or ear loops as needed to ensure that your mask fits well.
• Using your mask correctly: “Remember: To be effective, your face mask needs to cover both your mouth and your nose,” Dr. Esper stresses. “Don’t wear your mask around your neck or chin or over your head — that doesn’t protect anyone.”
• Removing a disposable mask: If you need to take your mask off, wash your hands. Then, remove it by its ties or loops and throw it away. “If you’re going back into a high-risk space, obtain a new mask, wash your hands and put it on before re-entering,” Dr. Esper instructs.
• Cleaning a reusable mask: Fold your cloth mask by its outside corners and place it in a laundry basket or washing machine. Then, wash your hands thoroughly to prevent spreading germs. Wash reusable masks in warm or hot water and detergent after every use. Either air-dry it (preferably in the sun) or put it in the dryer to eliminate any remaining moisture.

When it’s most important to wear a mask

Although some jobs and circumstances require masking, most of the time, the choice to wear personal protective equipment is yours. Dr. Esper recommends wearing a mask if you are:

• Sick with a respiratory infection or caring for someone who is
• Vulnerable to severe complications or spending time with someone who is (examples include infants, people over age 60, pregnant women and people who are immunocompromised)
• In an area where community transmission levels are high
• Attending a large, indoor event

While masking is no longer required in most settings, some people choose to keep them on hand.

“It’s like keeping an umbrella handy for a rainy day or, in this case, respiratory season,” Dr. Esper illustrates.

Is masking safe?

There are some people who can’t wear masks for medical reasons, but generally speaking, wearing a mask is safe for most people. While inhaling high levels of carbon dioxide is dangerous, masks are designed to prevent CO2 gas from building up.

“It’s a good idea to step outside and drink some water every hour or two if you have to wear a mask all day,” Dr. Esper advises. “Dehydration is the biggest risk that comes with wearing a mask.”

People who can’t safely wear masks include:

• Children under 2
• People with severe heart or lung problems
• People who can’t take their mask off by themself

While rare, people with certain disabilities or chronic conditions may not be able to mask either.

If you or a family member isn’t able to wear a mask, a face shield may be a good alternative. They don’t offer the same level of protection that masks do, but studies suggest they can still make a difference.

“If you wear a mask around someone who can’t, you’re helping protect them, too,” Dr. Esper reminds us.

Additional protective measures

Masking is a great way to protect yourself against certain kinds of infectious diseases — but it’s not the only way, and it’s not a substitute for other precautions, like:

• Washing your hands regularly
• Carrying an alcohol-based hand sanitizer to use when a sink and running water aren’t available
• Practicing good cough and sneeze etiquette
• Staying home when you’re sick
• Avoiding touching your face
• Regularly cleaning and disinfecting surfaces
• Ventilating indoor spaces
• Staying up to date on vaccines

“If you do all of these things consistently, your odds of staying sniffle-free go down substantially,” Dr. Esper notes. “They’ll go down even further if you choose to wear a mask, too.”