Well, here is a horrifying bit of local news filled with graphic detail -- "Man, woman seriously burned in fire -- Cigarette sparks oxygen tank blaze; clothes melt to his body"
Just like that proverbial wreck, you have to look.
It seems oxygen tanks and cigarette smoking are a very dangerous mix indeed. Which leads me to question the safety on a casino floor when the two are in close proximity. I usually see at least two or three people with oxygen tanks every time I enter a casino, and naturally I encounter hundreds of people smoking.
This link from the New Jersey Health Department entitled "Hazards of portable oxygen equipment in smoking-permitted areas" certainly supports the theory
What it doesn't do is list any circumstances where fires broke out in casinos injuring patrons. It does list incidents of home fires, but perhaps the risk to the public isn't so great.
Maybe cigarette smoking slot players are not as rude as I generally hold them to be, giving oxygen tanks a wide berth.
I personally have yet to see a non-smoking slot area in Las Vegas, though I believe they exist elsewhere in the country.