People who inject drugs in a facility where staff members provide clean needles and guard against overdoses say they have reduced their use of public spaces for drug use, a new study finds.

Using supervised injection facilities also has given them a greater ability to use hygienic injecting practices and provides better protection from fatal overdoses, they told authors of the study.

More than 100 supervised injection facilities operate legally in 166 cities throughout the world, Reuters reports. There are no such facilities that are legally sanctioned in the United States. The study involved one staff member and 22 participants from one community-based organization that has successfully operated an underground facility since September 2014.

Lead author Peter Davidson of the University of California, San Diego told Reuters no one has ever overdosed in a supervised injection facility, where staff members are equipped with the opioid overdose antidote naloxone. The findings were published in the International Journal of Drug Policy.