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Face masks: How they work, the two types, who should wear them (hint: very few of you)

Before you run to the store to get a face mask, consider whether you really need one in the first place.

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People across the world are wearing face masks to protect against coronavirus

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For the most up-to-date news and information about the coronavirus pandemic, visit the WHO website.

Walk around any crowded area during flu season and you'll see people wearing medical face masks to protect themselves from germs and other contaminants. With the rapid spread of the coronavirus that causes COVID-19 and increased concerns about a US outbreak, face masks have flown off store shelves. But do they really work?

Disposable face masks block large particles from entering your mouth, while more tight-fitting N95 respirator masks are far more effective at shielding you from airborne illnesses. Both of these masks could potentially help protect you from getting a viral infection, but US government officials have emphasized that the American public should not purchase face masks to prevent themselves from getting infected. Instead, only people who are displaying symptoms of coronavirus should wear masks to prevent the spread of the disease to others. 

Read: Homemade face masks: 7 critical truths you need to know now

On Feb. 29, US Surgeon General Jerome Adams tweeted:

Adams' tweet echoes the Centers for Disease Control and Prevention's guidance that the general public should not use face masks to protect themselves from coronavirus -- only those who are exhibiting symptoms should wear masks to protect others. The CDC's page on COVID-19 treatment and prevention states: "CDC does not recommend that people who are well wear a face mask to protect themselves from respiratory diseases, including COVID-19."

Despite that, fears of coronavirus have made finding these masks online difficult. As of Feb. 29, both face masks and N95 respirator masks are either sold out online or marked up significantly, especially on Amazon and Walmart.com.

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A better way to protect yourself from coronavirus

Despite the small number of coronavirus cases in the US, many people are eager to protect themselves. The best way to protect yourself from the current coronavirus -- and any other virus such as the flu -- is to stick to basic hygiene habits. Wash your hands for at least 20 seconds, avoid touching your face (especially your mouth, nose and eyes), sneeze or cough into your elbow, stay home when you're sick and disinfect surfaces often. 

You can also use hand sanitizer to clean your hands if you don't have access to running water, but you shouldn't make your own if you can't buy it.

If, after heeding the above advice, you've determined you need a face mask, here's a primer on the different types and how they work.

Face mask vs. respirator

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This NIOSH-approved N95 respirator will prevent airborne particles from entering.

3M

If you've ever been to the dentist, surgical face masks will look familiar -- healthcare professionals use them to prevent the splashing of fluids into their mouths. They're loose-fitting and allow airborne particles in. People commonly wear face masks in East Asian countries to protect themselves from smog and respiratory diseases, but these masks aren't designed to block tiny particles from the air.

A face mask's main purpose is to keep out the liquid of an infected person's sneeze or cough from entering your mouth or nose (gross, I know). Wearing one can protect you from getting sick if you're in close contact with someone who is ill and also help prevent you from spreading your illness to someone else, as it's common practice for medical professions to wear them around sick patients. 

Face masks can also help prevent hand-to-mouth viral transmissions, because you can't directly touch your own mouth while wearing one. Viruses, however, can be transmitted through your nose or eyes and virologists say that surgical face masks cannot block airborne viruses from entering your body. 

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Surgical face masks don't block small particles, but they can prevent liquid from getting on your mouth or in your nose.

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For that you'll need a respirator, a tight-fitting protective device worn around the face. When people say "respirator," they're usually referring to the N95 respirator, which gets its name from the fact that it blocks at least 95% of tiny particles. Several brands manufacture N95 respirators, and they come in all different sizes. When shopping for this kind of mask, be sure the packaging says "N95" -- some masks will only say "respirator," but if they aren't marked as N95, you won't get the full level of protection. 

Dr. Michael Hall, a CDC vaccine provider, said in an email that N95 respirators are the most protective, but that surgical masks can be worn when taking public transport or entering crowded areas to help protect you from other people's coughs and sneezes.

N95 masks are tricky to put on, so make sure you watch a video or check out a guide on how to fit one to your face. Hall says that the key is to wear the mask firmly around your nose and mouth without any gaps. And once it's on, leave it on -- a respirator that's only worn sometimes isn't nearly as effective.

Do respirators actually prevent viral infections?

The answer to this is technically yes, but the exact effect is difficult to define -- especially at a large scale. Studies have shown that they're highly effective in preventing viral illnesses, but only in people who actually wore the masks correctly, which is rare. 

N95 masks are difficult to put on for people who aren't medical professionals. If you've put the mask on right, it gets hot and stuffy, so a lot of people take it off before it can do any good. In fact, some medical professionals believe that these masks actually create a more suitable environment for viruses to develop

Another study showed that respiratory masks are helpful in preventing viral infections, but only when combined with frequent hand washing. 

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The bottom line? A government-approved N95 mask can theoretically lower your chance of viral illness, but using basic preventative measures as encouraged by the medical and scientific community, is the most effective way to protect yourself. 

If you don't have access to an N95 mask and you need one to protect others from your illness, a surgical face mask will suffice. Though, as noted, you'll get less protection from airborne viruses if you wear a face mask. Hall says that wrapping a scarf or other cotton fiber around your nose and mouth can also work in a bind.

Do respirators protect against the new coronavirus?

The new coronavirus is officially called SARS-CoV-2, and it's part of a group of coronaviruses that includes both the common cold and the deadly SARS. The novel virus is spread through coughing, sneezing or contact with a sick person.

So, the same logic still holds -- a respirator, if worn correctly and combined with other virus prevention methods, can help lower the risk that you catch the disease. 

The CDC only recommends that people wear face masks or respirators if they're traveling in China or have already contracted the virus. It also states that face masks should be worn by health care workers or anyone who is taking care of a person who has the novel coronavirus. If you're in a place where coronavirus is present, however, or are especially concerned about the disease for another reason, a respirator can't hurt.

Read more: Coronavirus fact check: How to spot fake reports about the disease

Where to get a face mask if you need one

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Panic over the spread of the coronavirus has people clearly shelves of face masks at drugstores across the US.

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Hall said that N95 masks are difficult to find, because many brands have left the market. If you live near a store like CVS, Target or Walmart, however, you may be able to pick one up. The key is to make sure the mask is approved by the US National Institute for Occupational Safety and Health.

The CDC's website has a comprehensive list of all the NIOSH-approved N95 masks, which you can use to cross-check any mask before you buy it. These masks filter out at least 95% of airborne particles, so again, if you wear them correctly they're fairly effective.

If you'd prefer to go the face mask route, those are easy to find. Just Google "face masks near me" -- most drugstores should stock them. Make sure to look at the product details to make sure it's FDA-approved -- there are a lot of face masks on the market that haven't been cleared by the FDA.

Originally published Jan. 29.
Updates, Feb. 5: Adds new information from the CDC about the spread of the virus in the US; Feb. 28: Adds current availability of masks; Feb. 29: Adds new information from the US surgeon general.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.