Protecting public spaces from chemical attack.

• Position: Bioterrorism

IN PROTECTING PUBLIC spaces such as buildings and aircraft from potential chemical or biological terror attacks, an ounce of prevention may be worth a pound of sensing. Since the deadly 2001 anthrax mailings, research has focused on developing improved sensors to detect potential chemical or biological terror agents. However, these devices alone cannot head oft terrorist attacks, and while they should be part of an overall protection strategy, reliance on such technology can create a false sense of security, warns a Georgia Institute of Technology, Atlanta, researcher.

Protection for closed public spaces such as airport terminals and shopping malls therefore needs a new paradigm: a "systems engineering" approach, argues professor of chemistry Jiri Janata, who specializes in sensing and analytical instrumentation. It would include central command centers, response strategies tailored to the facility, protection of water and air circulation systems, and neutralizing and sterilizing chambers built into air circulation systems to limit the spread of terror agents.

"Correctly applied technology can improve security, but incorrectly applied technology--such as reliance on sensors that may or may not detect the actual agent being used-could create a false sense of security," Janata contends. "We need to think about everything in terms of a systems engineering approach. Very little has been done to integrate comprehensive systems."

Using sensors to protect public buildings faces two major challenges: There are too many potential chemical and biological agents to detect reliably, and even with the fastest sensors, some people will become victims before the sensor can respond and an alert can be sounded. Sensor development so far has focused mostly on a "short list" of toxic agents originally developed for military battlefield use. Janata points out that there are hundreds of other nonmilitary gases that could be just as deadly in civilian spaces--and for which no sensors have been deployed or are available.

"The problem with the whole sensing strategy is the presumption that you would know what is going to be used as a toxic agent," he cautions. "Unless you were in correspondence with the terrorists, you would not know that, so the selectivity of the sensors--defined in terms of 'toxicity' rather than a specific toxic compound--becomes an issue that makes the whole chemical sensing effort largely useless."

Should a toxic gas be released in a public...