http://hosted.ap.org/dynamic/stories/U/US_NYC_TERROR_DRILL?SITE=FLTAM&SECTION=US

In a separate test, the NYPD planted safe amounts of radioactive material - simulating less-powerful dirty bombs - in five unmarked test cars. All were successfully intercepted on the Brooklyn Bridge and several other bridges.

pproaching midnight, police got a hit on a red SUV that was quickly stopped. Supervisors at the scene took note on whether officers took proper precautions approaching the vehicle.

In back was a fake device specially designed by the Department of Energy to emit safe levels of neutrons, along with two technicians charged with protecting it.

---

This means the targets were emitting into the public.