Wearing face masks can cause harmful levels of reduced oxygen.
Another viral meme featuring three people wearing masks while walking on a beach says face mask wearing "reduces oxygen up to 60%" and "increases risk of CO2 poisoning." [...] One Facebook post claimed "wearing a mask for an 8 hour shift can reduce your oxygen intake level to a 93 if you have healthy lungs ... it is not healthy to have your oxygen level at that." The post did not specify which type of mask it was referencing. [...] There is no evidence to support that the general public — which doesn't typically wear masks for prolonged periods of time — will experience significant reductions in oxygen intake level, resulting in hypoxemia. While CO2 can build up in face masks, it is unlikely that wearing a mask will cause hypercapnia, according to the CDC