Since FOD contains any loose material that can make its way into a system, the hazard level for having such occurrences is extremely high. An example would be FOD making its way into an aircraft engine. This could lead to anything from minor repair to catastrophic failure. 
NASA has identified the potential hazards of FOD and has put control and prevention mechanisms into place for preventing them. These topics will be discussed shortly.
One such program employed by Kennedy Space Center is AWARENESS + PREVENTION = COMPLIANCE