Fact check: No evidence mask wearing will cause bacterial pneumonia

A graphic shared on social media falsely suggests that wearing a mask will cause bacterial infections and hypoxia, a condition in which the body’s cells do not receive enough oxygen.

Reuters Fact Check. REUTERS

The post (here) shows an illustration of lungs with a caption that reads: “Bacterial pneumonia. When you exhale your body is eliminating toxins and unhealthy bacteria. By wearing a mask the toxic matter is trapped on the fabric and you’re inhaling it all in, causing infections like bacterial pneumonia and hypoxia.”

Reuters has previously debunked claims that masks can cause bacterial infections (here and here)

A team of global health scientists and infection preventionists at the Meedan Digital Health Lab ( told Reuters there was “no evidence” to suggest face masks can increase the chance of developing pneumonia, “or any other bacterial, fungal or viral infection in the lungs”.

They added that masks are safe and effective for most people, though said there were some exceptions, such as “very young children (under two years of age in the United States) and people with health conditions that make it difficult to wear a mask (ex. certain pre-existing pulmonary or cardiac issues, mental health conditions, developmental disabilities).

“For the vast majority, wearing masks is an effective way to help reduce COVID-19 transmission without causing any major side effects, as long as masks are kept clean and used correctly,” they said.

While people do not develop pneumonia from simply breathing into their own masks, experts have advised people to ensure they regularly clean their non-medial face coverings in order to avoid contamination (p.10  here here) . The World Health Organisation also advises that masks are not worn during exercise, as sweat can make a mask wet and promote the growth of microorganisms (here).

The Facebook post also claimed that wearing a mask can cause hypoxia, a condition where a part of the body does not receive enough oxygen (here).

The American Lung Association and The Ohio State University Wexner Medical Center both say it is not true that wearing a mask lowers oxygen intake ( and here).

The Mayo Clinic non-profit academic medical centre has said that that wearing cloth masks presents no risk of hypoxia in healthy adult. “Carbon dioxide will freely diffuse through your mask as you breathe,” it says (here).

As these sources note, healthcare workers have worn face coverings for extended periods of time without injury (here and  here).


False. Correct use of masks will not cause bacterial pneumonia or hypoxia.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here .