I've never seen the pot type, but the propylene glycol type are all over Boston. What they release is definitely vapor, not smoke. (The vapor clouds act very di

I've never seen the pot type, but the propylene glycol type are all over Boston. What they release is definitely vapor, not smoke. (The vapor clouds act very differently than smoke clouds. They look and act like the steam clouds which emanate from manhole covers in cities, or from dry ice.)