Since the onset of the coronavirus pandemic, people around the world are advised to wear masks or facial coverings to reduce the risk of infection and help contain the spread of the virus, particularly when social distancing is difficult to maintain.

However, rumor has it that wearing face masks for an extended time will cause insufficient oxygen intake and even poison users with excess carbon dioxide (CO2).

On this matter, experts pointed out that there is no reason to worry as wearing masks, either cloth face coverings, surgical masks, or even N95 respirators for healthcare workers, poses no risk to healthy people.

"There is no risk of hypercapnia (CO2 retention) in healthy adults who use face coverings, including medical and cloth face masks, as well as N95s," Dr. Robert Glatter, an emergency physician at Lenox Hill Hospital, New York, has told Healthline, an American website and provider of health information headquartered in San Francisco, California.

"Carbon dioxide molecules freely diffuse through the masks, allowing normal gas exchanges while breathing," Glatter explained.

According to Darrell Spurlock, director of the Leadership Center for Nursing Education Research at Widener University, there is no concern that wearing surgical or cloth masks may retain CO2.

"The dose of CO2 we might rebreathe while masking is quickly and easily eliminated by both the respiratory and metabolic systems in the body," Spurlock told Healthline.

"CO2 is present in the atmosphere at a level of about 0.04 percent. It is dangerous in an atmosphere when it is greater than about 10 percent," Bill Carroll, an adjunct professor of chemistry at Indiana University, Bloomington, was quoted as saying by the U.S. magazine Health.

Meanwhile, experts emphasized that people who have severe lung disease or sleep apnea need to consider the use of masks and better to consult with doctors.

Someone with severe lung disease and are struggling to maintain oxygenation and balanced CO2 due to lung damage "may be more sensitive to CO2 levels," Spurlock said.