This chart offers information about how far to stand away from a Improvised Explosive Device (IED) threat. Threats include pipe bombs, suicide bombers, briefcase, car, semi-trailer, etc. "It is important to note that the given distances do not guarantee safety, they are estimates based on test data and the area near and around the evacuation distances are still potentially dangerous. Minimum evacuation distance is the range at which a life-threatening injury from blast or fragmentation hazards is unlikely. However, non-life-threatening injury or temporary hearing loss may occur."
Financial and Banking Information Infrastructure Committee: http://www.fbiic.gov/