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Mask myth debunked: Face coverings don't hurt lung function or cause CO2 buildup

Masks are particularly important for people with underlying breathing problems.
People wearing masks ride a Safari cycle at Zoo Miami on Sept. 15.Wilfredo Lee / AP file

Contrary to viral claims, wearing surgical masks or cloth face coverings does not restrict the amount of oxygen a person breathes in, nor does it cause a dangerous buildup of carbon dioxide, according to a study published Friday in the journal Annals of the American Thoracic Society.

The study, though small, should help to further ease fears that masks are somehow physically harmful when, indeed, experts say mask use is by far one of the most effective ways to curb the spread of the coronavirus.

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The study of masks' impact on lung function was inspired, researchers said, by a group of West Palm Beach, Florida, residents who expressed anger at a commissioners meeting in late June when local leaders ultimately voted to mandate masks.

Some residents argued against the order, suggesting that wearing masks could lead people to inhale too much carbon dioxide. At least one other resident said without evidence that masks were "literally killing people."

Dr. Michael Campos, a pulmonologist affiliated with the Miami VA Medical Center and the University of Miami Hospital and Clinics, was watching the meeting on television and decided to do a study to determine whether masks have an impact on breathing.

Campos and colleagues tested the effects of wearing a typical surgical mask on the body's ability to take in oxygen and exhale carbon dioxide.

Fifteen study participants were military veterans with severe chronic obstructive pulmonary disease, or COPD. Their lung function was below 50 percent. The volunteers were then compared with 15 other people who served as healthy controls.

All participants wore masks for about 30 minutes and then walked for 6 minutes, still wearing the face coverings. Using standard blood tests, researchers found no differences in levels of oxygen or carbon dioxide circulating in any of the participants' systems.

In fact, experts say, people with underlying breathing problems like COPD may be best served by wearing masks.

"If you have a respiratory disease, you're at a much higher risk of contracting an infection, whether it's Covid-19 or the flu or any other respiratory problems," said Dr. Farrah Kheradmand, a pulmonologist and professor of medicine at Baylor College of Medicine in Houston, who was not involved with the research.

The study included basic surgical masks that are now widely available. It did not study N95 masks, which are recommended for health care workers.

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Citing growing evidence that people can spread the coronavirus even if they do not have symptoms, the study authors wrote that "universal mask use needs to be vigorously enforced in community settings, particularly now that we are facing a pandemic with minimal proven therapeutic interventions."

"We believe our data will help mitigate fears about the health risks of surgical mask use and improve public confidence for more widespread acceptance and use."

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