The United States Environmental Protection Agency (EPA) responded to the September 11, 2001 attack on the World Trade Center (WTC) in conjunction with the President's declaration of a national disaster. The Federal Emergency Management Agency (FEMA), the federal government office coordinating disaster response, issued mission assignments to EPA related to: cleaning dust and debris from the streets of lower Manhattan assessing the ambient environment through analysis of air and dust samples providing washing stations for decontamination of personnel and equipment involved in dust and debris removal operations, and disposing of hazardous materials found at the WTC response and recovery site. Residents of lower Manhattan expressed concerns about the safety and reliability of cleaning methods utilized to remove dust and debris from residential unit interiors and building exteriors. Traditional FEMA support programs were available; however, residents requested additional assurance. To address concerns about the extent of indoor impact of dust and debris, as well as concerns regarding fire-related particle deposition, EPA Administrator Christine Todd Whitman formed an Interagency Indoor Air Task Force. The task force included representatives from the following agencies: EPA, FEMA, the New York City Department of Health and Mental Hygiene (NYCDOHMH), the New York City Department of Environmental Protection (NYCDEP), the New York City Office of Emergency Management, the New York City Mayors Office of Environmental Coordination, the New York State Health Department, the New York State Department of Environmental Conservation, the Occupational Safety and Health Administration (OSHA), and the Agency for Toxic Substances and Disease Registry (ATSDR). The multidisciplinary, interagency group focused on issues of concern to residents and developed coordinated strategies to address the concerns.