North Carolina study on heart attacks after a smoking ban in 2010 is nicely picked apart by Alex Massie and Chris Snowden.
"Even if we assume that secondhand smoke does cause heart attacks, smoking bans have so little effect on so few non-smokers (and have no effect at all on the smokers, unless it compels them to quit), that the kind of reductions in the heart attack rate reported by these studies defy both science and common sense. If there is an effect, it is too small to measure and would never show up in population-level statistics. Once that is understood, it is obvious that any studies which claim a dramatic effect on the heart attack rate must be flawed, cherry-picked or distorted. Sure enough, when such studies are examined, they prove to be flawed, cherry-picked and distorted."
Well worth the read!