Hidden behind a heavy black curtain in one of the nation’s busiest airports is Chicago’s unsettling response to a growing population of asylum-seekers arriving by plane.

Hundreds of migrants, from babies to the elderly, live inside a shuttle bus center at O’Hare International Airport’s Terminal 1. They sleep on cardboard pads on the floor and share airport bathrooms. A private firm monitors their movements.

Like New York and other cities, Chicago has struggled to house asylum-seekers, slowly moving people out of temporary spaces and into shelters and, in the near future, tents. But Chicago‘s use of airports is unusual, having been rejected elsewhere, and highlights the city’s haphazard response to the crisis. The practice also has raised concerns about safety and the treatment of people fleeing violence and poverty.

“It was supposed to be a stop-and-go place,” said Vianney Marzullo, one of the few volunteers at O’Hare. “It’s very concerning. It is not just a safety matter, but a public health matter.”