My evidence is entirely anecdotal, but it seems that the left is behind the push for smoking bans and the calls for legalizing marijuana.
At first glance, this incongruity makes no sense.
But these issues are not primarily about smoking, health or personal freedom for the far left. The far left is all about taxes and regulations. By legalizing marijuana, the left gets tax revenue and regulation. By pushing for smoking bans, they get more regulation.
It makes perfect sense while removing the haze from the leftists agenda. The left prefers big government over personal freedom.