By now, most Americans have heard of naloxone — also known by the brand name Narcan — the medication that reverses opioid overdoses if administered quickly enough, by injection or nasal spray. But few American cities have blanketed their neighborhoods with naloxone like Dayton has.

Montgomery County agencies distributed 3,300 naloxone kits last year, and are on course to more than double that number this year, holding trainings at treatment centers and 12-step meetings as well as at local businesses and schools.

Starting in 2014, Richard Biehl, the Dayton police chief, directed all his officers to carry naloxone — going against some of his peers in other Ohio cities, including a sheriff in a neighboring county who outright refused to equip his deputies with it. Some in Ohio and elsewhere continue to oppose so-called harm reduction tools like naloxone, saying they enable drug use, but the evidence is overwhelming that they save lives.

“We really jumped on it because we saw it as absolutely consistent with our public mission to save lives,” Chief Biehl said.

Research suggests he was right. A recent study from Stanford estimated that wider availability of naloxone could prevent 21,000 deaths over the next decade — more than expanding access to medications for addiction or reducing painkiller prescriptions could.

But as fentanyl analogs — whose chemical structure is slightly different and can be more lethal — started entering the drug supply in Dayton, it became harder to revive overdose victims with the standard dose of naloxone. So the city, with state support, has spent a lot more to provide higher doses — $350,000 last year.

The investment has paid off, said Helen Jones-Kelley, executive director of Alcohol, Drug Addiction and Mental Health Services for Montgomery County. “If nothing else, you get that second chance with them — and in some cases that third or fourth chance,” she said. “It gives people the opportunity to get connected to services, who would not otherwise have had that chance at life.”