The Legionnaires' disease outbreak in Central Harlem has been traced to 12 cooling towers, including several at city-run buildings like Harlem Hospital, officials said Thursday.

The health department offered five ZIP codes in central Harlem -- 10027, 10030, 10035, 10037, 10039 – that were at the center of the cluster, as officials stressed the disease was airborne and could reach people even outside of the directly affected buildings.