https://www.city-journal.org/article/the-harm-caused-by-masks
Evidence continues to mount that mask mandates were perhaps the worst public-health intervention in modern American history. While concluding that wearing masks “probably makes little or no difference” in preventing the spread of viruses, a recent Cochrane review also emphasized that “more attention should be paid to describing and quantifying the harms” that may come from wearing masks. A new study from Germany does just that, and it suggests that the excess carbon dioxide breathed in by mask-wearers may have substantial ill-effects on their health—and, in the case of pregnant women, their unborn children’s.
Mask-wearers breathe in greater amounts of air that should have been expelled from their bodies and released out into the open. “[A] significant rise in carbon dioxide occurring while wearing a mask is scientifically proven in many studies,” write the German authors. “Fresh air has around 0.04% CO2,” they observe, while chronic exposure at CO2 levels of 0.3 percent is “toxic.” How much CO2 do mask-wearers breathe in? The authors write that “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.”
In other words, while eight times the normal level of carbon dioxide is toxic, research suggests that mask-wearers (specifically those who wear masks for more than 5 minutes at a time) are breathing in 35 to 80 times normal levels.
The German study, a scoping review of existing research, aimed “to investigate the toxicological effects of face masks in terms of CO2 rebreathing on developing life, specifically for pregnant women, children, and adolescents.” The latter two groups, of course, have been among those most frequently subjected to mask mandates in schools, despite Covid’s low levels of risk for them and the evidence that masks don’t work.