N95s were used as a dust mask at the smelter I used to work at, they do not cause oxygen deprivation etc.

N95 masks are designed to protect the WEARER, not others. They are for use in a CONTAMINATED environment. You blow unfiltered air from your lungs out throught the unfiltered vent into the contaminated air. They therefore don't "protect your fellow humans" from anything. They weren't designed to. They were designed to protect the WEARER from dust and other large (relative to a virus) particles in the air.

But not only that....

Russell Blaylock, MD writes at https://www.technocracy.news/blaylock-face-masks-pose-serious-risks-to-the-healthy/ :

There is a difference between the N95 respirator mask and the surgical mask (cloth or paper mask) in terms of side effects. The N95 mask, which filters out 95% of particles with a median diameter >0.3 µm2 , because it impairs respiratory exchange (breathing) to a greater degree than a soft mask, [is] more often associated with headaches. In one such study, researchers surveyed 212 healthcare workers (47 males and 165 females) asking about presence of headaches with N95 mask use, duration of the headaches, type of headaches and if the person had preexisting headaches.2

They found that about a third of the workers developed headaches with use of the mask, most had preexisting headaches that were worsened by the mask wearing, and 60% required pain medications for relief. As to the cause of the headaches, while straps and pressure from the mask could be causative, the bulk of the evidence points toward hypoxia and/or hypercapnia as the cause. That is, a reduction in blood oxygenation (hypoxia) or an elevation in blood C02 (hypercapnia). It is known that the N95 mask, if worn for hours, can reduce blood oxygenation as much as 20%, which can lead to a loss of consciousness, as happened to the hapless fellow driving around alone in his car wearing an N95 mask, causing him to pass out, and to crash his car and sustain injuries.

Someone works as a smelter and says N95 masks don't cause oxygen deprivation, etc. That's called "anecdotal evidence." This published medical doctor says they absolutely do—and backs it up with facts based on actual scientific research conducted by medical scientists.

We'll just call it even.