Hello,
Would 3mL of an Ammonium Sulfide solution be considered unsafe and/or annoying if it were used outside on private property?

I live in a city and want to keep my stoop clear of those wanting to use it as a smoking, foul language and vomit stop (yep, cleaned it up last sat). I have an adjoining neighbor that I don't want to offend, would the odor linger or blow away fairly quickly if used outdoors?

Thank you, Ann Taylor

I don't think it is a good idea, please read this safety card
Safety (MSDS) data for ammonium sulfide solution

Do you want a chemical deterrent? There are lots of really smelly compounds that aren't poisonous. If these people are younger than yourself there is also a method that is used outside shops where I live. They play a really high pitched sound, people under a certain age can hear it and it's really unpleasant but people over a certain age can't. Et voilà yob deterrent!