Face masks are unlikely to cause over-exposure to carbon dioxide, even in patients with lung disease, according to a new study which contradicts statements linking mask-wearing to poisoning by the exhaled gas.
As several governments across the world have made it mandatory to wear face masks during the COVID-19 pandemic, the researchers, including those from the University of Miami in the US, noted that some people were discouraging its use, claiming it may be a health risk.
The study, published in the Annals of the American Thoracic Society, assessed problems associated with changes in oxygen and carbon dioxide levels in healthy individuals, as well as those with chronic obstructive pulmonary disease (COPD) before and while using surgical masks.
According to the scientists, people with COPD, "must work harder to breathe, which can lead to shortness of breath and/or feeling tired."
"We show that the effects are minimal at most even in people with very severe lung impairment," said study co-author Michael Campos from the University of Miami.
As for the feeling of breathlessness that some healthy people may experience, Campos said, dyspnea -- or the feeling of shortness of breath -- felt by some while wearing masks is not synonymous of alterations in gas exchange.
"It likely occurs from restriction of air flow with the mask in particular when higher ventilation is needed (on exertion)," he explained.
"If you're walking briskly up an incline, for example, you may experience feelings of breathlessness. An overly tight mask may also increase the feeling of breathlessness," the scientists noted in a statement.
They said the solution is to slow down or remove the mask if one is at a safe distance from other people.
Campos stressed the importance of wearing a face mask to prevent COVID-19 infection.
If a surgical mask is not available, the researchers said a cloth mask with at least two layers is recommended by the US Centers for Disease Control and Prevention (CDC).
They said patients with lung disease, in particular, should avoid getting infected and should wear a face mask, which, along with handwashing and social distancing can reduce the risk of COVID-19 infection.
"We acknowledge that our observations may be limited by sample size, however our population offers a clear signal on the nil effect of surgical masks on relevant physiological changes in gas exchange under routine circumstances (prolonged rest, brief walking)," the scientists wrote in the study.
They believe it is important to inform the public that the discomfort associated with mask use should not lead to unsubstantiated safety concerns as this may attenuate the application of a practice proven to improve public health.
"The public should not believe that masks kill," Campos added.
