what does sniffing markers do to your brain? and what does Air duster do to it also 
Both of these products simply deny your brain oxygen. By sniffing them, you put less oxcygen in your blood.
Sniffing markers? :rolleyes:
Sniffing markers containing solvents is hazardous to your health!
Sniffing markers in the open air isn’t very good for you, given the solvent fumes, but they certainly won’t deny your brain oxygen. Now if you put a bunch in a bag and breathed from the bag then you’d both be getting the solvent and denying your brain oxygen.
From here:
Also here:
So while the inhalants aren’t displacing the oygen in the air, unless, as you said, they were being breather from a bag, they do dispalce it in the lungs.
Although I was putting things rather simply. Depending on what is inhaled, it can have a vaierty of other effects, such as stimulating dopamine, to supresing the CNS similar to the way alcohol does.
I don’t want to belabour the point too much since solvent fumes are toxic anyway and you can do yourself damage even with accompanying oxygen, but I have difficulty seeing how solvent fumes would displace the oxygen in your lungs if they don’t also displace it in the outside air. I thought the abused inhalants referred to in your cites were normally sniffed out of bags or by other means that basically excluded everything but the solvent fumes. That doesn’t apply if you’re just getting “high” from using markers too much.