It's not "smoke" that is the problem,
Jane. And your smoke is vented, anyway. It's the abundance of 'tar' from the tobacco that is
in the smoke. It's the stuff that turns the filters brown, it's the stuff hat turned everything in my rental house brown, it's the stuff that turns your lungs brown...of course, the extra chemicals don't help much either. Anyway, 'tar' is normally a liquid at room temps, but in the smoke it is a vapor because of the heat of the burning tobacco. Anything that the smoke can come in contact with, walls, drapery, aluminum window frames, computer out and insides, etc. is usually much cooler, closer to room temp. That means the vapor will easily condense on those surfaces. Since the inside of a computer is usually warmer than the room, that tar may not solidify but remain as a sticky liquid. That makes it extremely good at collecting dust particles which are always in house/office air.
I'm not sure the goo is electrically conductive and even the dust may not be unless the humidity is very high. But all that junque makes for a greatly intensified collection of the tar and any harmful chemicals that may also be in the smoke. We threw away much of the stuff in that rental house (cabinets, electrical outlets, air vents, etc.) because it was just too messy and time consuming to clean them. We did put most of the ceiling fans blades and trim pieces in our dishwasher. That's when we discovered they were white!
This all may be 'anecdotal' but the whole crew of workmen were happy to see all that stuff in up in the dumpster!
Oh yeah, the smoke in the 'valley' is probably not good to breath continuously, but I'm pretty sure most of it gets blow away fairly often. And they are much less concentrated than a closed house with two smokers! Of course. it's not just the
visible particulates that are harmful, it can be just as unhealthful in some areas that don't look 'smokey'!