I think it's actually very hard on them, because a lot of the guards smoke. They go a short distance away, have a cigarette, and come back. You're constantly smelling somebody else smoking. For a lot of people.... I'm a person who struggled with nicotine addiction for years, and I go on and off smoking. I know that it is one of my coping mechanisms. It's a stress reducer for me. There isn't even an outdoor smoking area.
People then turn to whatever else they can find as stress reducers. They brew homebrew. They make booze and whatever. There's also a lot of money to be made, and I think that is a factor for workers of one kind or another bringing drugs in. There's a lot of money to be made.