False health claims circulate about wearing masks during pandemic

CLAIM: Wearing a mask can cause hypercapnia, and lead viruses to travel into the brain.

AP’S ASSESSMENT: False. There’s no evidence that wearing a mask causes hypercapnia, or that masks can trap the virus and lead to an infection in the brain. Hypercapnia occurs when there is too much carbon dioxide in the bloodstream. Mild cases can lead to issues such as headache and anxiety; severe cases can interfere with breathing.

THE FACTS: Dozens of posts circulated on social media this week claiming that wearing a mask would cause more harm than going without one.

“By wearing a mask, the exhaled viruses will not be able to escape and will concentrate in the nasal passages, enter the olfactory nerves and travel into the brain,” several false posts on Facebook and Twitter stated.

One Facebook post featured the quote and falsely noted that wearing masks over a period can cause hypercapnia.

“Wearing masks causes hypercapnia which causes severe respiratory problems which will be BLAMED on 2nd wave of C O Vid not the masks,” the post stated. The post featured an illustration from Wikimedia Commons, which was labeled as showing “carbon dioxide toxicity.”

Social media posts displaying the illustration also had a statement edited onto the graphic: “This is hypercapnia. It can be caused by rebreathing your own exhaled CO2 by wearing a mask continually.”

There’s no evidence that wearing a mask will trap the virus in the nose and lead to an infection in the brain, said Sarah Stanley, associate professor of infectious diseases and vaccinology at the University of California, Berkeley School of Public Health.

“Keep in mind that many people —for example surgeons or certain kinds of scientists—have routinely worn masks for long periods of time without clear adverse effects,” Stanley said. “With how common mask wearing has always been, even before COVID-19, we would know if hypercapnia was a problem with wearing masks.”

Stanley also noted that when infected with COVID-19, the tissues in the nose already harbor the virus. “Breathing out the virus is not going to appreciably change the amount that is there,” she said in an email. “Therefore, there should be no reason why wearing a mask would increase your chance of infection in the brain.”

The Centers for Disease Control and Prevention revised their guidance on wearing face masks in April. The organization now says that wearing face coverings helps to prevent transmitting the virus.

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This is part of The Associated Press’ ongoing effort to fact-check misinformation that is shared widely online, including work with Facebook to identify and reduce the circulation of false stories on the platform.

Here’s more information on Facebook’s fact-checking program: https://www.facebook.com/help/1952307158131536