Terrorism: Q & A | Responding to Chemical Attacks

Responding to Chemical Attacks

How serious a threat are chemical weapons?
Chemical weapons are very dangerous, but they’re not easy to

Subway riders injured in Aum Shinrikyo
sarin gas attack, Tokyo, March 20, 1995.
(AP Photo/Chikumo Chiaki )

acquire or use. Synthesizing chemical warfare agents is often difficult, particularly in home laboratories, and these supertoxic chemicals are extremely dangerous to handle and deliver in the large quantities needed to inflict mass casualties. Aum Shinrikyo, a Japanese doomsday cult, spent an estimated $30 million on chemical weapons research and had many scientists in its ranks, but it managed to kill only 19 people with the nerve agent sarin—both because it encountered problems making sarin, experts say, and because it had difficulty using it as a mass-casualty weapon.

How do chemical weapons work?
To harm people, most chemical warfare agents must be inhaled, although some act through the skin or eyes. Various agents come in gas, liquid, aerosol-spray, or dry-powder form. An agent’s effect depends on the purity of the chemical, its concentration in the air, the wind and weather conditions at the time of its release, and the length of a victim’s exposure. Enclosed spaces are more dangerous than outdoors.

Do terrorists have chemical weapons?
Aum Shinrikyo is the only terrorist group known to have possessed and used sophisticated chemical agents, but U.S. intelligence agencies have long warned that terrorist groups such as Hamas are seeking such weapons. Evidence recovered in Afghanistan suggests that Osama bin Laden’s al-Qaeda terrorist network was conducting crude chemical warfare experiments. Information on how to make such weapons has been available in scientific literature for decades and is now posted on the Internet, and experts say many of the raw materials are not hard to obtain. Also, Iran, Iraq, North Korea, Libya, Sudan, and Syria—all labeled state sponsors of terrorism by the U.S. government—are thought to have significant chemical warfare capabilities that they might pass along to terrorists.

What are the different sorts of chemical agents?
The deadliest types are:

Nerve agents such as sarin and VX, which disrupt the body’s nervous system;
Choking agents such as chlorine and phosgene, which attack the lungs; and
Blood agents such as cyanide, which carry tissue-killing poisons throughout the body.

Depending on the level of exposure (1 milligram or less is often enough), nerve agents such as sarin and VX can kill a victim in as little as 10 to 15 minutes. Blood agents also act rapidly, but choking agents can take several hours to kill.

Blister-causing agents such as mustard gas attack the skin and eyes and also can be fatal if inhaled, although much greater quantities are required to cause death. The effects of mustard gas—pain and skin blistering—take one to six hours to appear. Other agents such as the potent hallucinogen BZ aim to incapacitate rather than kill.

Beyond these military-grade substances, thousands of toxic industrial chemicals (such as chlorine, phosgene, and cyanide) and agricultural pesticides could cause mass casualties, depending how they are prepared and dispersed. The Chemical Weapons Convention, a 1993 disarmament and nonproliferation treaty, names 29 specific substances and 14 broad families of chemicals—some widely used in commercial industry—that could be used as weapons.

How might terrorists stage a major chemical attack?
Several ways. Experts say terrorists could try to set off a homemade chemical device in a public area, release a gas such as chlorine into the air by bombing a chemical plant, or blow up a vehicle transporting hazardous materials, among other scenarios.

Could a chemical spill kill large numbers of people?
It could, depending on the amount of toxic chemical released, the atmospheric and weather conditions, and the spill’s proximity to a densely populated area. One notorious precedent is the 1984 release of methyl isocyanate gas from a Union Carbide pesticide plant in Bhopal, India, that killed almost 4,000 people—the worst industrial accident ever. A recently disclosed U.S. Army study warned that as many as 2.4 million deaths and injuries could result from a terrorist attack on a chemical plant that resulted in a release of deadly vapors over a city.