One argument against wearing face masks to prevent COVID-19 transmission is that the coverings will lead to wearers suffering carbon dioxide poisoning.
This remains prevalent on social media and has become a political issue embraced by many Americans. A study reports that the claims are false.
This study published in the Annals of the American Thoracic Society fills a void in medical literature as to the effects of surgical or face masks on breathing and gas exchange.
Impetus for the study were reports of a public hearing in Florida earlier this year where "anti-maskers" made false claims about face mask use. The chief argument is that wearing a face mask is life-threatening.
"The public should not believe that masks kill," said Dr. Michael Campos, a study author. Dr. Campos works for the Miami Veterans Administration Medical Center and the Division of Pulmonary, Allergy, Critical Care and Sleep Medicine at the University of Miami.
He said his team's study shows the effects of wearing face masks are minimal even in people with very severe lung impairments such as chronic obstructive pulmonary disease.
In the study, Dr. Campos and his colleagues assessed problems with gas exchange - or CO2 levels - in healthy individuals as well as people with COPD before and while using surgical masks.
People with COPD "must work harder to breathe, which can lead to shortness of breath and/or feeling tired," said the ATS Patient Education Fact Sheet.
The study warned people wearing masks should also exercise caution, especially when exerting effort that causes them to breathe harder.
Dr. Campos said dyspnea, or the feeling of shortness of breath, felt by some face mask wearers isn't synonymous with alterations in gas exchange. It likely occurs from restriction of air flow with the mask, in particular when higher ventilation is needed on exertion.
Walking briskly up an incline will cause a mask wearer to experience feelings of breathlessness. Dr. Campos said an overly tight mask could also increase the feeling of breathlessness.