BioWatch is a United States Federal Government program to detect the release of pathogens into the air as part of a terrorist attack on major American cities. Reportedly operating in Philadelphia, New York City, Washington, DC, San Diego, Boston, Chicago, San Francisco, St. Louis, Houston, Los Angeles and 21 other cities, the BioWatch program was created in 2001 in response to the increased threat of bioterrorism sparked by the 2001 anthrax attacks, and was announcing in President George W. Bush's State of the Union Address of 2003. The program, described as "the nation's first early warning network of sensors to detect biological attack" operates via a system of filters located within existing Environmental Protection Agency air filters which monitor the quality of the air. Results from t