We are not just talking about "clutching our pearls" at a "whiff of weed", though. We are also talking about the very real effects of secondhand smoke on the respiratory systems of people who are not choosing to inhale it. Hence my mention of "wide open spaces". If things are well-ventilated, I don't have a problem. But as Jim points out, even walking into a puff of smoke left by someone walking ahead of you can have an impact, esp. if your respiratory system is already compromised by acute or chronic illness. A smoker's right to puff anything (I think marijuana should be treated the same as tobacco, BTW) does not include the right to infringe my right to breathe relatively clean air. If I have to avoid a place due to the amount of smoking going on, it's the smoking that's the problem, not my lungs.