For two hours every saturday, a 1960s-era bus parks on a dead-end street in a dusty part of Fresno, California. Volunteers set up tarps and chairs on the sidewalk and people roll up in cars or on foot, pushing shopping carts or strollers. They’re here to dump their dirty syringes, sometimes hundreds at a time, and exchange them for clean ones. Providing this particular service in this particular location is crucial. Fresno is the poorest large city (with more than 250,000 residents) in California and in Fresno County, drug use is about twice the state average, according to the Fresno County Public Health Department.

Everyone at the needle exchange has a story about the life-altering moment they first injected drugs. A 30-something woman with wavy brown hair says that six months ago, before she started injecting meth, she was a “soccer mom” with a husband and kids, living in a nice home. Now she’s squatting in an abandoned building, waiting until the police discover her and kick her out. Another woman says she’d never tried drugs before a doctor prescribed her opioid painkillers. After her prescription ran out, buying pills cost her $200 to 300 a day. She started using heroin because it was cheaper, only $100 a day.