UNC Health Care
Woman riding public transit, wearing a fade mask as she looks out the window

The Truth About Masks

Public health experts say the use of cloth face masks and coverings in public settings is a critical tool in the fight against coronavirus disease 2019 (COVID-19). Masks help people keep their germs to themselves and minimize the volume of airborne droplets that can spread the virus. And there’s growing evidence that masks may protect the people wearing them, too.

However, there has been much debate about wearing masks, and a great deal of misinformation has spread online.

UNC Health family medicine physician Sarah Ruff, MD, dispels some common misconceptions about masks.

Masks do not reduce your oxygen levels.

Some have suggested that carbon dioxide from exhaling gets trapped under the cloth of their masks and reduces their oxygen levels—making it hard to breathe. This isn’t true, Dr. Ruff says.

If worn properly, you still have plenty of airflow while wearing a mask, and carbon dioxide does not build up.

“This has been studied using continuous pulse ox monitoring (a test used to measure oxygen levels of the blood) and proven not to be true,” Dr. Ruff says. “Surgeons wear masks for hours at a time when performing long surgeries, and they’re fine.”

Wearing a mask does not make you sick.

Wearing a mask is about protecting others from your germs. Any concerns about the mask “holding” germs near your face and making you sick are unfounded, Dr. Ruff says.

“Any germs you already have, you have them. You’re not going to make yourself sick with your own germs,” Dr. Ruff says.

The only way a mask can make you sick is if you don’t follow proper hygiene protocols: Don’t touch the outside of your mask; assume it could have virus particles on it. Take off and put on the mask touching only the ties or elastic that goes around your ears. As soon as you take it off, wash your hands.

Also, be sure to wash your mask regularly. Ideally, you should have enough masks that you can wash them after each use. But if you have only one, be sure to wash it at least once a week.

“If you don’t take off your mask using the ear loop or you’re not storing it properly and you’re exposing it to germs, then when you put it back on your face, you could get a cold or even COVID. But if you wear a mask properly, then it’s not going to make you sick,” Dr. Ruff says.

Wearing a mask does not harm your immune system.

Some people have worried that a mask will make their bodies too sterile, keeping all germs out and weakening the immune system because it doesn’t have anything to fight. That won’t happen either, Dr. Ruff explains.

“A mask isn’t going to protect against everything, so there are still going to be bacteria that are on your hands that you don’t wash off or that you breathe in when you take your mask off,” Dr. Ruff says. “There are enough germs to go around, so you don’t need to worry that you’re not going to get beneficial good bacteria from wearing a mask.”

Remember, surgeons have worn masks for more than 100 years, and it hasn’t compromised their immune systems.

It is not better for people to get COVID-19 to gain herd immunity.

“Herd immunity” means that enough people have recovered from a virus and developed immunity such that the virus doesn’t spread anymore. Infectious disease experts say an estimated 50 to 66 percent of Americans will need to have antibodies insulating them against COVID-19 to develop herd immunity against the virus. We are still far from that number, and the death toll is already staggering.

So no, it’s not a good idea to forgo wearing a mask in an attempt to infect yourself.

“I don’t think anyone would want themselves or their family members to get COVID, because you just can’t predict who’s going to be asymptomatic and who’s going to have serious illness or die,” Dr. Ruff says. “That’s kind of like playing Russian roulette.”

In addition, it’s still unclear how effective COVID-19 antibodies are against possible reinfection and how long they last.


For the latest information on COVID-19, visit the CDC website and the UNC Health COVID-19 Resources page, and follow UNC Health on Twitter, Facebook, Instagram and YouTube.