The Rockland County Homeland Security Task Force released the results of a terrorism preparedness study Thursday, and revealed where the county needs improved security.The study took a year to complete. The task force, composed of 25 people from law enforcement, schools, private businesses and local government, is calling for local police notification whenever large amounts of ammonium nitrate is sold or stolen. Ammonium nitrate is a chemical normally used as fertilizer, but it can also be used in bomb making. Amongst other suggestions, the task force is calling for the roofs of school and public buses to be numbered so vehicles are easily identifiable from the air. The group is also pushing for more signs alerting the public to numbers they can call if they see or suspect suspicious activity. The study suggests issuing official identification to all first responders. Task force members say they are hoping to set a precedent for other counties across the nation.Rockland County Executive Scott Vanderhoef added his own wish list to the study. Vanderhoef says he?s concerned about security in the county?s malls. He says private security currently available at malls is woefully inadequate. Vanderhoef is proposing a law that will require malls to register detailed emergency response plans with the county.