I don’t know enough about the residual air in the sinuses, so I can’t speak to that. All I know of the system is about the flap separating the oral cavity from the esophagus that would block the direct smoke. I can share a little about the breathing problem you mention. When I have quit cigarettes in the past I have also felt a greater tightening. From what I was able to find in my research, it was suggested that it was actually the opposite. Addiction, for lack of a better known statement, changes the wiring of your brain. The brain wants it, so on a level we aren’t conscious of it tricks our sensations to tell us we need it.
smoke itself causes a restriction. When we eliminate that and are able to take in more air that sensation of more air is interpreted as not having enough. Much like many of the times we feel hungry, we are actually thirsty, our bodies only have a limited number of sensations available to tell us something is different.
I quit cigarettes back in 2012 and took up running. Four years later I was running 12 miles a week (and still coughing a bit) and every time I was at rest with a low heartbeat and took a big breath I had the sensation of lacking enough air. It reduced a bit from immediately after quoting with no exposure to cigarettes, so I would guess each cigarette could “reset” the level of desire. It sticks around at least that long.
Of course I started smoking cigarettes again in 2017 due to the stresses of losing a child. So I’m at somewhere around a pack and a half a day. That’s why I am moving back to pipes again (smoked pipes back in college). I like pipes and want to quit cigarettes, but don’t want to start running again. My body was never built for it, and I now have “exercise induced” asthma. Which stinks, and also feels like another restriction.
Sorry, I have been known at times to be long in the wind...