I get a headache if I wear VR glasses for a few hours or if I watch TV for too long (and I don't get headaches normally). But I'm pretty sure neither is affecting my oxygen/CO2 levels.

In other words, headaches != oxygen starvation.

Again, you're acting like there is a debate about things, when there isn't, and you're attempting to deflect away from the points being made.

There is no question of whether or not covering one's mouth & nose with a piece of fabric (or whatever plastics in a disposable) reduces oxygen & increases CO2.

In case you're curious, you can buy a cheap piece of electronics, and test for yourself. Just like tens (hundreds?) of thousands of people have done since this farce began.

How long do doctors wear a mask for, at once, without a break or changing that mask? (pre-plandemic)

How often do doctors wear a mask, take it off for a few minutes, or even to eat, and then put it back on?

There is LOTS of evidence for the damage that those mask wearing moments cause to doctors, along with their lack of sleep, usually terrible diets, and dependence on the pharmaceutical industry. If there's anyone to not look at for how to treat your body, it's someone who works in the Rockefeller "medicine" system.

And it's not like forcing someone to wear a mask controls them in other ways. Robbers are "forced" to wear a mask when robbing a store to avoid getting caught. Was the robber controlled or made docile by the mask? Most stores would say no.

Hahaha! Right, forcing small children to not see facial expressions, to have hypoxia & hypercapnia, just to start with - totally isn't controlling them.

Once again, the whole "robbers" thing is completely unrelated - you're just trying to derail the conversation.

It has been studied quite extensively that having someone's face covered dehumanizes them, making it easier for others to harm/kill them. This is why head's have long been covered in various execution methods, and has plenty of clinical research (mostly by Nazis & Soviets - with the USSA as well)