Eighteen months ago, in a van parked on a city street corner, a heroin user dropped a syringe into a red plastic box marked with a hazardous waste warning.

Nashville had gathered its first dirty needle.

Since then, more than 250,000 used syringes were collected by Street Works, the city’s only syringe exchange program. The Street Works exchange operates five days a week from a roving van, handing out clean needles and collecting dirty ones.

“It makes the city safe,” said Thomas Gooch, who leads the exchange program. “Before we were picking these syringes up, people were using them and throwing them down wherever they were. For the most part, we have cleared that up.”

Syringe exchanges are research-backed programs that attempt to prevent the spread of diseases among intravenous drug users by providing free, clean syringes with no questions asked. As the opioid crisis increased heroin use across much of the nation, the importance of exchanges has grown.

Street Works gave out clean syringes in Nashville for more than a decade but for years operated in quiet defiance of state laws that made syringe exchanges illegal. Those laws were re-written in 2017, making Street Works the city’s official exchange program in February 2018.

Street Works could now do more than distribute clean syringes. Through coordination with the Nashville MEtro Public Health Department, Street Works began collecting used syringes in hazardous waste boxes, then turning them over to the government for safe disposal.

Since then, Street Works filled at least 714 two-gallon containers, each estimated to hold between 350 and 400 syringes, said Thomas Sharp, a Metro Health official. Altogether, the nonprofit gathered between 250,000 and 285,000 syringes.

It didn’t happen all at once, Gooch said.

In the first few months of 2018, few drug users brought their used syringes back to Street Works. Gooch thinks, although the exchange was legal, many people were unwilling to show evidence of their drug use.

Then, last summer, the Street Works syringe exchange program was featured by both The Tennessean and News Channel 5. The following month, Gooch filled more than 40 boxes with dirty needles for the first time ever.

If drug users doubted Street Works was legal, he said, now they were convinced.

“It was overwhelming,” Gooch said. “We weren’t ready for it.”

Brett Kelman is the health care reporter for The Tennessean. He can be reached at 615-259-8287 or at brett.kelman@tennessean.com. Follow him on Twitter at @brettkelman