In 2004, Mikel Aristregi documented street children in Cambodia, fascinated by the bonds they forged among themselves, a coping mechanism against an onslaught of threats along the harsh landscape of Phnom Penh’s boulevards. So when he learned of children living in the sewers of Ulan Bator, Mongolia, he went there in pursuit of a similar project.

Instead, amid a maze of hot water pipes, he found a grim underground world of homeless alcoholic adults.

“Seems like the problem of the street children had been more or less eradicated because of the work of many international and local groups,” said Mr. Aristregi, 37, of Spain. “But nobody was taking care of those people.”

Pressure and attention from nongovernmental organizations and children’s rights advocates had forced the Mongolian government to alleviate the suffering of street children. The homeless alcoholics, however, were left to fend for themselves — subterranean untouchables of the capital of the most sparsely populated country in the world.

Mr. Aristregi changed plans and began to photograph this bleak world, hoping that international attention — if not outrage — might similarly force authorities to take action.

He quickly learned that access and communication were barriers. He enlisted a young English student to help him enter their world. But — predictably — their behavior was erratic: they were often drunk and saw him as somebody from whom they could cadge money, food or cigarettes. They had fits of anger and aggression, threatening Mr. Aristregi and his interpreter, so that they would have to leave until things were calm enough to approach again.

And then there was the cold.

Ulan Bator is often described as the coldest capital city in the world. Temperatures can drop below minus-40 degrees. “Sometimes, the only thing I could think about was just how cold I was,” Mr. Aristregi said in an e-mail exchange. “I used to start working early in the morning,” when the homeless were calmer, but the temperatures were lower.

Climbing in and out of these enclaves, with their varying temperatures, warmer with the pipes, posed tricky technical problems, too. “To change a medium-format film roll I had to take off my gloves and it was painful, and took me a long time,” he said. “When I went into a hole, the temperature difference between outside and inside could be over 50 degrees, which produced water condensation on the lenses, so I could not take photos for over 30 minutes.”

Mikel Aristregi

But the plight of these homeless people is dire, and the strength of their alcohol — nearly 200 proof, Mr. Aristregi said — underscores the magnitude of their despair. He said some people used this alcohol to clean engines. Some buy the alcohol, cheap and strong, in bulk, then resell to the homeless for about 35 cents, a sum they raise by scrounging the streets for discarded plastic to sell.

Mr. Aristregi was disappointed by the lack of help this population received, either from the government or religious shelters. Alcoholism, according to a 2006 study by the World Health Organization, affects 22 percent of men and 5 percent of women in Mongolia. There is no infrastructure for help, and limited resources and limited understanding hinder well-intentioned efforts. Recidivism is high.

Evangelical groups, he said, lure the homeless with offers of food, clothing and showers. But their promises of salvation are ignored, with the men resting inside for a few days before returning to the streets and their stupors. The government, he said, has one hospital where alcoholics are taken for up to two years. But there are few opportunities for work once they get out, so the path often leads back to the streets and drink.

For Mr. Aristregi, who plans to return to Ulan Bator to better document the hospitals and detention centers where some of the homeless end up, getting people beyond Mongolia’s borders to know and understand the problem is essential to addressing it. As he emphasized in his e-mails, documenting these suffering individuals also compels one to action.

Mr. Aristregi couldn’t help but empathize.

“When they were calm, usually in the morning, and started talking about their things, their old stories, what happened to some guy or whatever, you could feel something like pure friendship,” Mr. Aristregi said. “It was the kind of friendship that you had with your best friend when you were 7 or 8, that you could argue so easily, but make peace even faster. The dependency on each other for survival used to make their relations true, even childish, a little bit romantic.”

Mikel Aristregi

Mr. Aristregi’s project, titled “—40/96º,” first came to our attention by way of Fotovisura.

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