The Montgomery County Public Schools (Maryland) have emergency plans that are woven together under the national Incident Command System, an organizational structure and management tool that develops a clear chain of command. The county's Code Blue and Code Red emergency status programs are the foundation of its crisis preparedness efforts. In the event of a biological or chemical attack, many school systems have plans to implement a "shelter-in-place" program that requires all students and staff to be locked inside the school until it is safe to open the building. The heating, ventilation, and air conditioning would be shut down and the school sealed off from the outside air. The Charlotte-Mecklenburg Schools (North Carolina) are located near two large power plants. The school district has partnered with the county health department to plan responses to radiation poisoning. School administrators are also discussing the merits of establishing a curriculum on school-based terrorism. Internal communication presents a significant problem for large school systems. The Fairfax County Public Schools (Virginia) Office of Safety and Security has established emergency e-mail messaging and a group pager system for key leadership staff. In Georgia a course has been established to train school bus drivers in how to deal with suspicious packages, searching buses, and protecting buses. Other Georgia initiatives include the passage of legislation that requires all school visitors to check in at the front office, as well as the enactment of a law that requires all schools to develop comprehensive emergency plans. School safety officials in New York have emphasized the importance of practicing emergency plans at all their public schools. Safety drills are a key part of New York City schools' emergency plans.