evidence: In summary, it is extremely unlikely that wearing a mask could lead to an increase in carbon dioxide within the area between the mask and face to the extent of causing hypercapnia. While face masks can keep out infectious aerosols, they are porous enough to allow oxygen intake and allow the escape of carbon dioxide. The idea that wearing face masks weakens the immune system is not supported by scientific evidence. This article published on The Conversation illustrates how wearing even a cloth face covering can help to limit the spread of COVID-19 by blocking infectious droplets, which is the main mode of disease transmission. [...] In this unprecedented time, as SARS-CoV-2 has brought the world to a standstill and strained healthcare systems worldwide, Facebook posts claiming that wearing a face mask can cause carbon dioxide toxicity and weaken the immune system, are spreading, let’s say, as fast as the virus. Posts that make statements such as: "Masks inhibit oxygen intake and increase CO2 intake, lowering efficiency of the human immune system, and do not stop viruses" or "Hypercapnia can be caused by rebreathing your own exhaled CO2 by wearing a mask continuously" can be found more and more on the Web.