Thanks to shows like The Wire, Baltimore has earned a reputation as a city of boarded up houses, shell casings, police tape, and discarded needles. And several researchers think that an environment with visible evidence of violence or drug use might make things harder on addicts — so they’re giving drug users smartphones to gain a better understanding of how the city works.

Dr. Debra Furr-Holden heads up the Drug Investigations, Violence and Environmental Studies lab at Hopkins; she also leads a group of researchers who explore every block of East Baltimore, creating a map of all the abandoned houses, makeshift memorials, and visible evidence of drug use. The idea is that some places by their very look or feel might make addicts more likely to relapse.

In a similar project, Dr. Kensie Preston of the NIH gives addicts smartphones with a program that helps users track when they crave drugs, when they resist those cravings, and when they give in. The phones also have a GPS logger; as NPR notes, “That means Epstein and his colleagues can follow on a map as an addict is sober for weeks, but one day after visiting a particular house or block, that person breaks down and relapses.”