for right now, it's ubiquitous - you can't escape it, which means you can't escape the negative health effects of it.
i don't think it's useful to send marijuana users to jail, but i do think we need stricter bylaws around it's use in residential spaces, to discourage people from polluting residential neighbourhoods with second-hand smoke. the intent should be to keep the smoke in the bar districts, so you can go into them to smoke if you want - but can, by default, avoid it, if you want.