Just don't inhale
Waaaay back in the day when smokers were confined to the shipping dock (no smoking anywhere on the grounds anymore, I'm sure) at a place where I contracted, that was the place to hang out to get the lowdown on anything happening in the company. People always seemed more willing to talk to a fellow pariah. If you could recreate that outlaw atmosphere (intended) where people begin to feel they have more in common than an employer, communication may improve. Hot tubs?