Fact check: Wearing masks does not cause cancer 

Social media users have been sharing content online that claims wearing a face mask causes cancer due to oxygen deficiency. This claim is false.

Reuters Fact Check. REUTERS

Examples can be seen  here  and  here .  

One post reads: “The root cause of cancer is oxygen deficiency, which creates an acidic state in the human body. Dr Warburg also discovered that cancer cells are anaerobic (do not breathe oxygen) and cannot survive in the presence of high levels of oxygen, as found in an alkaline state.”

The post continues: “’All forms of cancer have two basic conditions: acidosis and HYPOXIA (LACK OF OXYGEN: MASKS). ‘Cancerous tissues are acidic, whereas healthy tissues are alkaline.’ ‘Deprive a cell of 35% of its oxygen for 48 hours and it may become cancerous.’”

A question about users being at a higher risk of cancer due to masks was addressed by a team of global health scientists and infection preventionists at the Meedan Digital Health Lab, a public health information hub,  here  . 

The experts found that due to the small size of oxygen and carbon dioxide molecules, masks do not decrease the amount of oxygen entering the mask or increase the amount of carbon dioxide inside the mask.

The lab explains: “There is no evidence that surgical masks or cloth masks cause significant deficiency of oxygen, a build-up of carbon dioxide, and other related negative health consequences. This information has been primarily circulating on social media among individuals or communities resistant to mask-wearing in general.” ( here  ) 

The risk of hypercapnia from wearing a face mask is very unlikely. Reuters Fact Check previously debunked this claim,  here  . 

American Lung Association, University of Maryland Medical System, the Ohio State University Wexner Medical Center and Mayo Clinic Health System all debunk the notion that wearing a mask lowers oxygen intake on their websites ,  herehere  and  here  . 

The posts say that masks cause cancer due to the lack of oxygen received. Healthcare professionals have been wearing face masks for years. If this claim were somewhat true, cancer rates would be noticeably high among this population.

The World Health Organization (WHO) says on its website that cancer stems from the transformation of normal cells into tumor cells. This happens in an interaction between genetic factors and three types of external carcinogens which are physical, chemical and biological. The WHO explains that “between 30–50% of cancers can currently be prevented by avoiding risk factors and implementing existing evidence-based prevention strategies.”

More information can be found  here  and  here  . 


False. Wearing a face mask does not cause cancer.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work  here  .