By now, you've probably heard about the nightmare scenario that almost came true: Al-Qaeda's aborted plot to release hydrogen cyanide into the New York City subway system. What you haven't heard much about are the systems to sniff out chemical weapons that are placed throughout New York's underground trains. And you probably won't, any time soon. Chemical weapon (CW) detection is really, really hard to do.
The U.S. military, for example, has been working on CW sensors for years. The systems are still awfully finicky. Take the CAM ("Chemical Agent Monitor"), which is used throughout the American armed services. The CAM relies on a technique called ion mobility spectroscopy. The machine sucks vapor samples in through a nozzle. Then it zaps the air with a radioactive material, like americium-241, sends its through an electrical field, and, finally, to an ion detector. The substance is identified by the amount of time it takes to run this little gauntlet. The problem is, breath mints, burning grass, and ammonia all set the machine off. So does diesel exhaust, noted Andrew Wolf, a chemist with the U.S. Army Soldier and Biological Chemical Command.
These military systems only get more confused in the subways, where there are "5-10 times the amount of particulates in [the] air as compared to the air above ground," CW specialist Jason Sigger noted here last year.
But even if these sensors worked perfectly, they might not be all that helpful. CAMs are hand-held machines that have to be right in the area of a chemical agent, in order to pick up any traces of it. (Area air-scooper are practically useless as chemical warning systems.) Which means a cop would have to get luckily enough to wave his sensor right at a chemical bomber in order to catch him. Even a weapon at the opposite end of a subway platform would probably go unnoticed.
That hasn't stopped the New York Metropolitan Transportation Authority from recently ordering up ion mobility spectrometers for themselves. Despite a slew of new, exotic detectors coming out of the national labs and industry, the choices for sensing chemical weapons still aren't all that great.
UPDATE 06/19/06 9:11 AM: "Using hydrogen cyanide, a toxic inhalation hazard, would certainly scare a lot of people just because it's a chemical. But because it can be smelled and it dissipates quite rapidly, it's not a great threat in small amounts," Jason Sigger notes. "A pistol would be as effective. It's good in a sense to hear of these incidents - it shows a much more clear example of what terrorist chemical incidents really are. They're a hazard, a threat just like any high explosive device or gun-waving nut, but not a WMD incident."
To Christian Beckner, "this story also raises questions about what were doing to protect the nations mass transit systems."
Last year the Congress appropriated $150 million for rail and mass-transit grants for FY 2006, via the Transit Security Grant Program. Were now nine months into FY 2006, and DHS hasnt even begun to distribute a penny of this $150 million (or if they have, they havent advertised it). Thats unacceptable.
