Will face masks cause fungal and bacterial pneumonia?

Rumours are doing rounds on social media that wearing face masks can cause fungal and bacterial pneumonia. On June 19, a Florida congressional candidate posted a tweet claiming that wearing face masks could lead to pneumonia.

“Excessive use of face masks causes fungal and bacterial pneumonia,” wrote Jessi Melton, a conservative business owner who is running to represent Florida’s 22nd Congressional District. The false post had thousands of retweets.

Davidson Hamer, an infectious disease specialist at Boston University, said he was unaware of any harm that comes from wearing masks besides discomfort.

“THERE’S NO EVIDENCE OF MASKS LEADING TO FUNGAL OR BACTERIAL INFECTIONS OF THE UPPER AIRWAY OR THE LOWER AIRWAY AS IN PNEUMONIA,” SAID HAMER, WHO IS ALSO A PROFESSOR OF GLOBAL HEALTH AND MEDICINE AT THE UNIVERSITY.

Hamer noted that bacterial growth could occur, in theory, if someone wore a mask that was already contaminated with moisture and became moldy. “Theoretically, it could happen, but it’s highly unlikely with just typical mask use,” he said.

However, he added, paper masks that become visibly wet should be discarded. Anne Monroe, an internal medicine physician and epidemiologist at George Washington University’s Milken Institute School of Public Health, agreed: “There’s no evidence to back up this claim. Digging into it a little bit more, in terms of mask use, it is important to follow general sanitation guidelines.”

She said it’s important that disposable masks be discarded and cloth masks be washed. “The idea that contamination could cause fungal pneumonia is not a valid conclusion,” she said. Monroe agreed with Hamer that it’s “potentially theoretical,” but that it has not been documented.

The real danger, Hamer said, is “spreading incorrect information like this, especially at a time when we really need to be encouraging more people to wear masks.” The number of confirmed new coronavirus cases per day in the U.S. hit an all-time high of 40,000 Friday — eclipsing the mark set during one of the deadliest stretches in late April.