The Marshall Islands were one of the United States’s go-to nuclear testing sites in the 1940s and 1950s: Sixty-seven of the almost 200 tests during that period took place in these remote Pacific islands. Now, almost 60 years after the last bomb dropped, some of the islands abandoned because of the testing may finally be ready for humans to move back. That could be a relief for the Marshallese who are squeezed onto several unaffected—but increasingly overcrowded—islands. To find out whether the test sites are once again safe for humans, researchers took measurements of damaging gamma radiation on six affected islands, one unaffected island, and New York City’s Central Park. Five of the six islands fell below the 100 millirem per year threshold for human habitation, each averaging less than 40 millirem per year, according to a study published today in the Proceedings of the National Academy of Sciences . The sixth, Bikini Island, had a much higher level of radiation, at 184 millirem per year. Meanwhile, Central Park itself clocked in at 100 millirem per year, probably because of background radiation from granite found in the park. These low gamma radiation levels are promising, but researchers still have to study other ways people on the islands could absorb radiation—like through their diet—before giving Marshall Islands inhabitants the green light to move back.