On Friday, January 9, the nation's threat level was lowered to elevated risk ("yellow") from high risk ("orange").

HHS and the Centers for Disease Control and Prevention (CDC) are providing information to assist the public health community in increasing their level of preparedness for different threat agents. Information on threat agents is available at the CDC website at http://www.cdc.gov. General information about the health effects of terrorism threat agents is available at http://www.bt.cdc.gov and http://www.atsdr.cdc.gov

For questions, technical assistance, or to report an event, please call the CDC Emergency Operations Center at 770-488-7100.

The FBI defines the concept of terrorism as "The unlawful use of force or violence committed by a group or individual against person or property to intimidate or coerce a government, the civilian population or any segment thereof, in furtherance of political or social objectives."

Weapons of Mass Destruction

• Any destructive device having a propellant charge of more than 4 ounces,…Explosive or incendiary charge of more than ¼ ounce
   
• Poisonous gas
   
• Any weapon involving a disease organism
   
• Any weapon that is designed to release radiation or radioactivity at a level dangerous to human life.

Biological Agents

• Bacteria such as anthrax, E. coli, salmonella, pneumonic plague, q-fever, tularemia
   
• Viruses such as smallpox, influenza, hantavirus, and hemorrhagic fevers
   
• Toxins such as botulinum, ricin, staphylococcus and mycotoxins

Nuclear Agents

• Nuclear materials that could emit gamma rays
   
• Not necessarily nuclear power plants or bombs

Incendiary Devices

• Any device that causes fire ( Pan American airlines over Lockerbie, Scotland)

Chemical Agents

• Nerve gases such as Sarin, Tabun, Soman and VX
   
• Blister agents and irritants such as lewisite, sulfur mustard, phosgene oxime
   
• Blood agents such as hydrogen cyanide and cyanogen chloride

Explosive Devices

• Any type of explosive (Oklahoma City bombing used fertilizer as one component)