A needle and syringe programme (NSP), also known as needle exchange program (NEP), is a social service that allows injecting drug users (IDUs) to obtain clean and unused hypodermic needles and associated paraphernalia at little or no cost. It is based on the philosophy of harm reduction that attempts to reduce the risk factors for blood-borne diseases such as HIV/AIDS and hepatitis. History Needle-exchange programmes can be traced back to informal activities undertaken during the 1970s. The idea is likely to have been rediscovered in multiple locations. The first government-approved initiative (Netherlands) was undertaken in the early to mid-1980s, followed closely by initiatives in the United Kingdom and Australia by 1986. While the initial programme was motivated by an outbreak of hepatitis B, the AIDS pandemic motivated the rapid adoption of these programmes around the world. Operation Needle and syringe programs operate differently in different parts of the world; the first NSPs in Europe and Australia gave out sterile equipment to drug users, having begun in the context of the early AIDS epidemic. The United States took a far more reluctant approach, typically requiring IDUs to already have used needles to exchange for sterile ones - this "One-for-one" system is where the same number of syringes must be returned. According to Santa Cruz County, California, exchange staff interviewed by Santa Cruz Local in 2019, it is a common practice for exchanges to not count, but approximate the returned sharps by "eyeballing" the volume. Holyoke, Massachusetts, also uses the volume system. United Nations Office on Drugs and Crime for South Asia suggests visual estimation or asking the client how many they brought back. The volume-based method left potential for gaming the system and an exchange agency in Vancouver devoted significant effort to game the system. Some, such as the Columbus Public Health in Ohio weigh the returned sharps rather than counting. The practices and policies vary between needle and syringe program sites. In addition to exchange, there is a model called "needs-based" where the syringes are handed out without requiring any to be returned. According to a report published in 1994, Montreal's CACTUS exchange which has a policy of one-for-one, plus one needle with a limit of 15 had a return rate of 75-80% between 1991 and 1993. An exchange in Boulder, Colorado, implemented a one-for-one with four starter needles and reported an exchange rate of 89.1% in 1992. In the