A proposed supervised site for people to inject illegal drugs is causing controversy in New York City.

Mayor Bill de Blasio backs the plan to combat fatal overdoses. The city’s Health Department released a study on the program that says it could prevent 130 overdoses a year.

Speaking on WNYC radio, the mayor said he understands the concerns surrounding the plan but that he believes it will help.

“What’s clear to me is this will save lives,” said de Blasio. “We will see a number of people who would otherwise have died of an overdose be in a setting where they can be saved.”

If approved, the sites would open at current needle exchange sites in Brooklyn’s Gowanus neighborhood, the Longwood section of the Bronx and Manhattan’s midtown west and Washington Heights.