BioWatch's false positives have been known since its inception
Five patent applications attempting to improve BioWatch's reliability were filed between 2003, when the program's air samplers were first deployed, and 2006, LATimes.com reports.
Existing methods for detecting a release of disease-causing organisms into the environment were "inadequate," a patent application filed on behalf of Lawrence Livermore National Laboratory scientists in December 2006 said, according to LATimes.com.
The application noted that the program had a higher than acceptable rate of false positive results that would create confusion as to the presence of pathogens.
The Department of Homeland Security, however, has maintained that BioWatch has performed flawlessly.
"There has never been a false positive result," Homeland Security's Chief Medical Officer Alexander Garza said last month, LATimes.com reports.
Recent reports, however, have contradicted Garza. At least 56 false alarms have been recorded since the programs inception.
Some officials say that the number of false alarms renders the program worthless, citing the potential for disruption.
New York City ordered the removal of automated detectors, which had been tested in subways in 2008, after learning of repeated false pathogen indications .
"We are not deploying these to do science projects. We are deploying these to respond when they go off," Richard Falkenrath, a couterterrorism official for the NYPD, said at a biodefense conference in Baltimore in 2010, according to LATimes.com.