COPENHAGEN, May 18 (Thomson Reuters Foundation) - In a dark tunnel in Copenhagen's red light district on a freezing night, Annika gasped for air as the stranger who agreed to pay her for sex started suffocating her with his bare hands.
A friend nearby heard her muffled cries and helped the 25-year-old Dane break free from the man's grasp. Annika, who declined to reveal her full name, said it was the fourth time in a year that she nearly died at the hands of her clients.
"If you don't give them what they want, even though it is not what you agreed in the beginning, some just snap," said Annika, who sold sex for nearly a year to pay for her drug addiction but quit the industry eight months ago.
"People think less of girls who are prostitutes. But when you're a street prostitute, they think even less of you," she told the Thomson Reuters Foundation on a street corner in Vesterbro, Copenhagen's red light district.
Studies show that sex workers in Denmark are violated or threatened by customers about 31 percent of the time while working the streets compared to only three percent in brothels, according to the Danish National Centre for Social Research.
For while prostitution is legal in Denmark, it is illegal to profit from other people selling sex, such as pimping, or to rent rooms to sex workers, which means prostitutes can end up having sex in places like parks, alleyways, behind parked cars and telephone booths.
This can put sex workers in danger from some clients and passers-by, according to rights groups, who are concerned that migrant or trafficked women are especially vulnerable as they are often afraid to report violence or assaults to the police.
A 2009 study by TAMPEP, the European Network for HIV/STI Prevention and Health Promotion among Migrant Sex Workers, estimated migrant workers make up about 65 percent of sex workers in a list of European countries, including Denmark, where there are high numbers from Nigeria and Thailand.
Annika said she reported her attack to the police but they dropped the case because she had no visible marks on her body.
"It made me feel like I didn't matter to anyone," she said.
This level of violence compelled Danish social entrepreneur Michael Lodberg Olsen to convert an old ambulance into a mobile unit where prostitutes can work for no charge in a safe and clean environment, guarded by volunteers from a distance.
Olsen, who has worked on initiatives for vulnerable people since the early 1990s, previously started "Fixelance", an ambulance converted into Denmark's first safe drug injection facility, as well as a street magazine that drug addicts could sell for money instead of stealing or turning to prostitution.
After parking the "Sexelance" in the red light district one night, Olsen said he was in disbelief when he saw two young men hit a street sex worker for no reason before walking off.
"To be the witness of brutal violence to a sex worker is ... very shocking and we can't allow that as a society," said Olsen, who launched Sexelance last November and now runs the vehicle each Friday and Saturday night with plans to operate daily.
Olsen and his team worked with sex workers like Annika to design the vehicle and its functions, such as its leopard print interiors and a light to indicate when it was in use.
He said Sexelance has been used around 64 times so far, and he hopes to open a permanent space where street workers can bring their clients or take short breaks.
"I think the attitudes against sex workers would change if we actually see them as people working," Olsen, 46, said.
Maja Lovbjerg Hansen from Street Lawyers, an organisation that provides legal aid to street sex workers, the homeless and drug users, said Sexelance was highlighting workers' rights for street prostitutes in a "dignified way".
"If you have a group of workers in other fields who are (working) in potentially dangerous conditions, you will always say, 'What can we do to make this more safe?'. And I think it's admirable that somebody's actually trying to do that,'" she said.
"We need to give these people normal workers' rights and start a process of destigmatising this field."
But for some migrant sex workers, many of whom have been trafficked into the country, working inside a mobile unit like Sexelance could be too conspicuous, said Michelle Mildwater, director of HopeNow which supports trafficked women in Denmark.
"They were concerned about the fact that it may well draw more attention to them - and it means that the police would find it easier to pick them up and arrest them," she said, referring to conversations she had with trafficked women about Sexelance.
Mildwater said migrant sex workers were most at risk of violence since they feared deportation by the authorities or repercussions from their traffickers if they went to the police.
Over the past decade, until 2016, there were nearly 600 people trafficked into Denmark, with most coming from Nigeria and eastern Europe, and working in prostitution, according to Denmark's Center Against Human Trafficking.
The anti-slavery campaign group Walk Free estimates there are 4.5 million victims of sex trafficking globally.
"The women who are foreign here, who don't have their papers in order and aren't allowed to work, they are particularly vulnerable to these attacks," said Mildwater inside a drop-in centre she runs at night to support Nigerian sex workers.
"The man doing this to her knows that if she calls the police, it's probably her who's going to get arrested."
Mildwater said she welcomed Sexelance's "provocative" way in drawing attention to the violence that street sex workers face.
Although she no longer sells sex, Annika said initiatives like Sexelance were helping to remove the stigma against sex workers and improve working conditions.
"Many times you get the feeling people think you are a weed that needs to be removed from the perfect garden," she said.
"But knowing that some people care and (are doing) things about the conditions for sex workers is comforting. So it's the beginning for more safety."