I work in a city centre and regularly see/smell people smoking weed which is one thing, but recently on my than one occasion, I've seen people with a pipe and smoking it or putting stuff into it (crack or heroin perhaps). This is on a back street off a very busy street. I've started reporting it to the police as once they were sorting their pipe and there was a family with little kids a few metres away, but I don't think there's much the police can do, is there?