latimes:

The Department of Homeland Security’s BioWatch air samplers, meant to detect a terrorist biological attack, have been plagued by false alarms and other failures.

President George W. Bush announced the system’s deployment in his 2003 State of the Union address, saying it would “protect our people and our homeland.” Since then, BioWatch air samplers have been installed inconspicuously at street level and atop buildings in cities across the country — ready, in theory, to detect pathogens that cause anthrax, tularemia, smallpox, plague and other deadly diseases.

But the system has not lived up to its billing. It has repeatedly cried wolf, producing dozens of false alarms in Los Angeles, Detroit, St. Louis, Phoenix, San Diego, the San Francisco Bay Area and elsewhere, a Los Angeles Times investigation found.

Worse, BioWatch cannot be counted on to detect a real attack, according to confidential government test results and computer modeling.