In 1994, Canadian photographer Gerry Yaum saw a documentary about the sex tourism industry in Thailand. Two years later, he visited the country for the first time and has since returned many times with the intent of raising awareness about conditions by documenting the sex workers there and sharing their stories with the world. Yaum’s recent exhibition, “Body Sellers: The Sex Workers of Thailand,” incorporates photographs he made over three trips between 2007 and 2012 to the city of Pattaya, a world-famous destination for sex tourism. He spent between two and three weeks shooting every day with an 8-by-10 camera in sessions lasting around two hours.

Unlike some of his earliest environmental portraits, Yaum photographed his subjects—a mix of male, female, and “ladyboy” workers from go-go dance bars, beer bars, and the streets—against a white backdrop. “The white background large format was part of an evolution, a simplification and in a way, a magnification,” Yaum said via email. “I felt the technique was a bit like putting a spotlight on something. It focuses your point of view. There is nowhere for viewers to hide. They must confront the subject.”

Poverty-stricken young men and women in Thailand are often drawn to sex work, Yaum said, because it is dramatically more lucrative than other types of work available to them. And while Yaum said the workers often told him how the money from their work was helping their families back home, extended conversations revealed their deeper feelings about their work. “When you get to know them more and talk on a more intimate level, you understand that in almost all the workers there is sadness, a pain in their lives because of what they do.”

Returning again and again to such sadness, Yaum said, has been draining. “I am finding it harder and harder to return to the bars to make pictures. I keep wanting to leave the scene, but just when you say to yourself, ‘I’ve had enough. Let me out of here!’ you meet an incredible person, a person who has worked the bar for years and yet is kind, considerate, and has a compelling message. When you meet a person like that, you just have to tell their story, you just have to make their photograph, you forget your depression and your sadness and you dive back in.”

The challenges of Yaum’s work weren’t just emotional. Yaum learned to speak Thai to better communicate with his subjects, and he also had to learn the ins and outs of the bar world, which often meant steering clear of the workers’ sometimes hostile employers. Yaum also found it difficult to track down some of his subjects in order to rephotograph them over the years. “The problem with the bar world is that things are constantly changing. People move from bar to bar, go from one area of Thailand to another, some get sick, some go to jail and others get married to foreigners and leave the country. Whenever I have found it possible, I have tried to contact the people I have photographed before and continue to make new pictures with them,” Yaum said.

Over the years, Yaum said he has struggled with how to photograph his exploited subjects without exploiting them himself. “The conclusion I came to after talking to others and thinking about this for some time was that I needed to understand why I was making the pictures, what my goals were, what was the reason behind it all, what was I trying to express,” Yaum said. “In your inner heart you know why you’re doing something, you know if it’s right or wrong, you know your true motivations. If you’re doing something for the right reasons, for a greater good, then that’s the path you want to be on.”

While Yaum hopes that his photographs can serve as an agent of change, he said he fears that the sex industry in places like Pattaya has only grown since he started shooting there. “As long as there is poverty in places like Thailand, Cambodia, and the Philippines, there will be workers for the sex tourist bars of Southeast Asia. The only hope for the bar worker, as I see it, lies in education,” Yaum said. “Education can lead to other opportunities that might keep the worker from coming to the bars in the first place. No Thai girl or boy dreams of becoming a prostitute. No one dreams of selling their body for a living. Most work the job purely out of economic necessity. Give them other ways to make decent money and maybe things will change.”