Some women sex workers in Calcutta, India are reported to earn as little as $1.85 a day (100 Indian Rupees). There are around 10,000 prostitutes in the region.
In 2013, customers were beginning to pay for services using fake rupee notes. Many male customers were reportedly paying with counterfeit 500 rupee and 1,000 rupee notes. A non-governmental organization began training the sex workers on how to spot fake money, as well as installing ultraviolet light machines that could determine whether a note was fake. After the campaign, the number of reported fake notes used in the area declined by 20 percent.
Source: “Teaching Indian sex workers to spot fake currency,” BBC News, April 2, 2013.