Excess carbon dioxide breathed in by people wearing face masks may have substantial ill-effects on their health, especially among vulnerable population groups, including pregnant women, children and adolescents, a new study on potential risks associated with face masks has revealed.
The study conducted by German researchers and published on ScienceDirect represents a scoping review based on a systematic literature search regarding CO2 exposure, and mask effects on carbon dioxide breathing.
The authors indicated that many studies scientifically proved that mask-wearers breathe in greater amounts of air, noting that a significant increase in carbon dioxide occurs while wearing a mask. According to the study, fresh air has around 0.04% CO2, while chronic exposure at CO2 levels of 0.3% is considered to be "toxic." However, mask-wearers, specifically those who wear masks for more than 5 minutes at a time, breathe in much more - 35 to 80 times normal levels.
"Masks bear a possible chronic exposure to low level carbon dioxide of 1.41–3.2% CO2 of the inhaled air in reliable human experiments," the German authors stated.
Speaking about adverse impacts of such a toxic exposure to CO2 on people's health, the researchers mentioned high blood pressure, reduced thinking ability, respiratory problems, as well as reproductive concerns.
"While the effects of short-term exposure on cognitive performance begin at 0.1% CO2 levels, [...] exceeding the limit of 1% CO2 the harmful effects include respiratory acidosis, metabolic stress, increased blood flow and decreased exercise tolerance," read the study.
The study also analyzed the effects of wearing a mask on the health of pregnant women and children. It was emphasized that carbon dioxide rebreathing is far above "the 0.8% CO2 limit set by the US Navy to reduce the risk of stillbirths and birth defects on submarines with female personnel who may be pregnant."
It was pointed out that the data on the toxicity of carbon dioxide on reproduction has been known for 60 years. They cited recent data from Australia, which showed that lockdown restrictions, including required mask use, "in the absence of high rates of COVID-19 disease, were associated with a significant increase in stillborn births."
"There is circumstantial evidence that popular mask use may be related to current observations of a significant rise of 28% to 33% in stillbirths worldwide and a reduced verbal, motor, and overall cognitive performance of two full standard deviations in scores in children born during the pandemic," the scientists said.
As this phenomenon of re-breathing of CO2 and its possible implications on people's health, in particular early life, have not been evaluated in depth, the scientists suggested that more studies should be focused on this area.
In addition to the increased CO2 intake there are other health threats that can be posed by wearing masks. According to the authors, other noxious agents in masks contribute to such long-term effects including the "inhalation of synthetic microfibers, carcinogenic compounds and volatile organic compounds." Moreover, the increased carbon dioxide content of the breathing air behind the mask may result in a displacement of oxygen.