The U.S. Environmental Protection Agency'sNational Homeland Security Research Center recently completed performance verifications of 10 indoor air filters designed to protect building residents from a biological attack from terrorists. The filters are designed to be installed in the ventilation air ducting within the mechanical system of a large building. In the event of an incident, the filters would remove biological agents from outside air drawn into the building and from air circulating within the building. The verification results will be posted for review on the agency's website