Washington, D.C., is an obvious target for any potential terrorist attack, but the reality behind possible non-conventional threats might surprise many. Deterrents in place range from building codes and restricted air space to thorough policing and controlling fear and panic.

Types of Attacks
A non-conventional emergency may be comprised of several different attacks: biological, chemical, and radiological.

Biological - A biological attack is the deliberate release of germs or other biological substances that can cause sickness.

• Anthrax, Botulinum Toxin, Plague

Chemical - A chemical attack is the deliberate release of a toxic gas, liquid or solid that can poison people and the environment.

• Sarin Gas, VX Nerve Gas, Mustard Gas

Radiological - A radiological dispersed attack is the use of common explosives to spread radioactive materials over a targeted area.

• "Dirty Bomb"

Biological & Chemical
One of the best ways for a terrorist to affect the largest number of people is to release a large amount of chemical or biological agents from relatively high above the ground, over a heavily populated area.

This is very difficult to do in the nation's capitol. The restricted air space above the city is meant to prevent a light aircraft -- such as a crop duster -- from reaching highly populated areas. Helicopters patrolling the skies, tactically placed surface to air missiles (SAM) sites, and military jets patrolling nearby all help to ensure the air space above DC is watched carefully and any potential threat is intercepted or eliminated.

Washington has another innate benefit. The city's building code restricts the height of most structures. Someone with ill will towards American citizens would not be able to release an agent from a 30-story building and have it spread over a concentrated population.

Both of these factors mean that any type of outdoor air-released attack will be fairly contained and not pose the threat it could in other jurisdictions.

Another threat would be releasing an agent in a highly populated, closed space, such as the Washington, D.C.'s subway system. This occurred in the Tokyo subway system in 1995 when Sarin gas was released. Tens of thousands were exposed to the deadly gas, 5,500 passengers received medical attention, and of those 12 died. While these attacks can indeed cause fear and chaos, in reality, only a very small percentage of those affected die from the exposure.

A conventional ground based explosion is another method for releasing a biological agent. Other than the fact that the dispersement takes place at ground level and, again, is relatively contained, an explosion is one of the worst ways to spread a biological agent. An agent such as anthrax, for example, is degraded by both heat and light. In any type of explosion there is usually enormous amounts of heat and light, killing or degrading much of the agent.

Dirty Bomb

The purpose of a radiologically dispersed device, otherwise known as a "Dirty Bomb," is not to cause mass casualties due to radiation, but instead it is at its most dangerous through the fear and panic that it causes. A dirty bomb would likely cause a ground-level explosion of varying intensity, depending on the amount and type of explosives used. Any type of radioactive material used would be fairly low grade, such as cesium or americium. Plutonian and Uranium are much more difficult to obtain and would be more valuable in building a conventional nuclear device. 

Once the explosion occurs, the highest amounts of radiation would be around the initial blast area. Most likely, the damage caused by the explosion would harm more people than the radiation. Radioactive debris and dust would travel relatively short distances - a few blocks - before the radiation threat diminished significantly. 

What Has Been Done
Washington, D.C., has taken steps to help prevent such attacks by stepping up security, removing certain newspaper and trash bins, and using canine units to patrol for explosive devices. Besides the constant video surveillance, new sensor units have been installed in metro stations to detect the first signs of a chemical agent release.

Unfortunately, it is very difficult for government at all levels to protect Americans from a person willing to die for a cause. However, officials have combined their efforts to increase the awareness of the average citizen with thorough policing and monitoring, limiting airspace access, and improved technology. Now, if an incident does occur, the outcome will be far less tragic.

Dexter Ingram is a member of the Washington Metropolitan Council of Governments' Bio-terrorism Task Force and a Threat Assessment Specialist at the Heritage Foundation.