No, they don't.
Masks don't reduce oxygen at all. Nurses and health practitioners wear surgical masks all day, and this was never an issue.
They don't cause hypoxia, and they don't cause brain damage. Whoever told you this is lying to you.
Oxygen and carbon dioxide diffuse through the masks. You are spreading false info. You should really stop spreading nonsense.
It is a "spit guard" (large droplets) as well as an incomplete aerosol droplet guard. A plastic face shield is great, but it doesn't have the coverage around the face that you need indoors. So it wouldn't work nearly as well as a suitable facemask. The mask is fitted to the face whereas with a face shield there is lots of space on the sides and underneath where expired droplets and aerosols easily escape. It would still likely be better than no mask, but not nearly as effective.
Ok tough guy. Not all of us are willing to get into a cage fight when someone makes a violent threat.
The mental health professionals he threatened deal with these kind of threats from time to time, and they knew they needed to report it to the police and get him away from there for their own safety.
You just said no like you know things. They have letters. Even the premier of Quebec said store owners can't discriminate against people not wearing masks if they say they have a medical exemption. There are old people on my social media telling me they're happy they finally have their medical exemption. Learn then talk.
If you are sleeping in your bed and there is an opening from your sheet to your face, the carbon dioxide coming from inside will reduce your oxygen content to cause brain damage. Saying putting the sheet on your face, with everyone saying it's harder to breathe, won't reduce oxygen is a new level of absurd. I deal with the HVAC industry, my articles are on the covers of their industry magazines. I'll tell you when oxygen is reduced and you will say "yes, expert".
https://www.youtube.com/watch?v=QRmVLYrqQG0My sister is a nurse. She never wears the mask all day and neither do the other workers, they wear it in the covid wing and more recently in the hallways. The only people who will wear a mask for anything close to 24 hours are brain surgeons or those who are in surgery that long, and they get massive hazard pay. You're just repeating memes.
"Oxygen and carbon dioxide diffuse through the masks. "
Duh, not a hot air balloon. Not all, some comes back. Enough to cause brain damage, which is why any normal medical organization is vehemently opposed to the masking of children, as it severely stunts brain development, and catastrophically so for children under the age of 2.
"Ok tough guy. Not all of us are willing to get into a cage fight when someone makes a violent threat."
He didn't say "I am going to" he said that what he feels like. I felt like slaughtering thousands when I was in New York, people spoke disrespectfully, but I only beat up one guy with an extra fat rich boy mouth. He is simply indicating in his unstable way that he is experiencing high levels of instability, almost to the point where he can't stand it. The fact that he left scared makes me think he isn't a very old guy, in schools kids tell each other "ill kill you" in happy rich suburb areas, because they're soft and don't know 15 year old kids murdered plenty of people in the places I've been.
You can't blame the shrink, it's not like you're analyzing "well what did he really mean by he'll kill me" when an unstable person says it, you get really nervous, for all my mouth flapping who knows what I would do in that situation. Regardless, he certainly didn't seem like a threat to the forum, just like level 3 unstable sort of.