FALSE: Prolonged face mask use causes hypoxia, hypercapnia

(Editor's note: An earlier version of the story rated the claim as PARTLY FALSE, since one source said that people with certain underlying conditions are at risk of suffering from hypoxia or hypercapnia if they use a mask for prolonged hours. Upon further review, it was found that more substantial evidence was needed to support this claim. The earlier version of this story also failed to clarify that the Centers for Disease Control and Prevention's advice on who should not wear face masks is not necessarily related to risks of hypoxia and hypercapnia. These have been corrected.)

Claim: Wearing a face mask for a prolonged period of time causes hypoxia and/or hypercapnia.

Hypoxia is a condition in which the body's tissues are starved of oxygen. Hypercapnia means having excessive carbon dioxide in the bloodstream.

Several Facebook users made similar text posts enumerating alleged "dangers" of wearing face masks for a long time, following with advice on how to use them. Others posted a graphic containing the same text.

The claim said that wearing a mask for a long time may cause oxygen in the blood and the brain to be reduced, may cause the wearer to start feeling weak, and may even lead to death.

Another viral post claimed that the prolonged use of a face mask poses a health risk due to the repeated inhalation of excess carbon dioxide.

"Bagamat kailangan at mahalaga ang pagsuot ng face mask dapat niyo din pong malaman na may posibleng panganib sa kalusugan ang matagal na paggamit nito dahil sa paulit ulit na paglanghap ng sobrang carbon dioxide na inilalabas natin kada buga o exhalation. Ang paulit ulit na paghinga natin ng carbon dioxide ay pwedeng magdulot ng pagkahilo. At ang mataas na carbon dioxide sa ating dugo ay tinatawag na hypercapnia," the text read.

(Even though the use of face masks is necessary and important, you should also know that there is a possible health risk in its prolonged use because of repeated intake of excess carbon dioxide that we exhale with every breath or exhalation. The repeated inhalation of carbon dioxide may cause dizziness. And the high amount of carbon dioxide in our blood is called hypercapnia.)

Multiple posts containing this text were flagged by Claim Check, Facebook's platform for monitoring posts with potentially dubious information.

Rating: FALSE

The facts: Using face masks does not cause hypoxia nor excessive carbon dioxide intake.

The World Health Organization (WHO) Philippines said there is no evidence that using face masks for a prolonged period of time causes any adverse effect on the brain or heart function.

"The use of face masks does not cause hypoxia nor excessive intake of carbon dioxide. Masks are designed to allow proper breathing and oxygenation, and there is no evidence to show that prolonged use of face masks [causes] adverse effect on the brain or heart function," WHO Philippines told Rappler.

The Centers for Disease Control and Prevention (CDC) also identified contact transmission caused by touching a contaminated respirator as the primary hazard of extended use of respirators, and added that while extended use can cause additional discomfort, the practice should be tolerable and would not pose a health risk to medically cleared respirator users. The CDC recommends cloth face coverings, not surgical masks or respirators, for non-healthcare workers.

Moreover, a study with 10 participant nurses found that while carbon dioxide levels were significantly elevated while wearing N95 respirators for a 12-hour shift, these levels did not reach the clinical definition of hypercapnia. The subjects of the study, however, reported perceived shortness of breath, headache, lightheadedness, and other subjective symptoms while wearing respiratory protection.

Meanwhile, the CDC said that cloth face coverings should not be placed on children younger than two years of age, anyone with breathing difficulties or is unconscious, incapacitated, or unable to remove the covering without help. However, the CDC did not say that the use of masks could cause hypoxia or hypercapnia.

Other organizations also fact-checked these claims. Agence France-Presse (AFP) said the claims that prolonged face mask use can cause hypoxia and hypercapnia are false and unlikely, respectively. According to AFP, Kenyan infectious disease epidemiologist Mark Nanyingi said that people with chronic respiratory illnesses may exert unnecessary pressure on their lungs if they use masks, and those with chronic obstructive pulmonary disease (COPD) can suffer from hypoxia or hypercapnia if they wear face masks for prolonged hours.

One study entitled, "Risks of N95 Face Mask Use in Subjects With COPD," found that among the 7 of 97 subjects who removed the N95 respirator during a 10-minute rest period and 6-minute walk test, many manifested symptoms of hypoxemia or hypercapnia. The paper said that other patients, like those with asthma or severe heart failure, should be included in future studies on the safety of N95 use.

The CDC also told Reuters it is unlikely that the use of a mask will cause hypercapnia.

"The CO2 will slowly build up in the mask over time. However, the level of CO2 likely to build up in the mask is mostly tolerable to people exposed to it. You might get a headache but you most likely [would] not suffer the symptoms observed at much higher levels of CO2," the CDC said.

The claim also included advice to take the mask off when they are alone, particularly in cars. "Pull it off when you are alone. I see a lot of people in their car with AC on still wearing face mask. Ignorance or illiteracy?" the text read.

WHO Philippines said that decision-makers should consider a risk-based approach to decide the settings and circumstances when non-medical masks may be used in the community. "It is often difficult to keep adequate physical distance in the car or vehicle, and the use of a mask in that setting might prevent one from spreading COVID-19 or other respiratory infections to others. Masks should only be used as part of a comprehensive package of interventions," WHO said.

In the past, Rappler debunked a false claim regarding the release of an "official" coronavirus face mask– Loreben Tuquero/Rappler.com

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