According to official data, there are over 4000 sex workers in Zurich right now. But nobody knows about the high dark figures.
Often, women come "temporarly" to the Langstrasse and the Niederdorf for working. They come with people smuglers and a visitor visa. This tendency has been growing with the eastern enlargement, for example with women from Hungary. Many of these women work under difficult circumstances (sometimes human trafficking) almost around the clock and are shamelessly exploited.
Other women get into an expensive downward spiral through horrendous lease costs and drug addiction.