It has been nearly 30 years since the first needle exchange program opened in the United States, in Tacoma, Wash., in 1988. It was a health measure to prevent injecting drug users from sharing needles, and therefore spreading H.I.V. and hepatitis. The idea was controversial, to say the least. Many people felt — and still feel — that it enables drug use and sends a message that drug use is O.K. and can be done safely.