The Capitol Hill anthrax incident occurred a month after the terrorist attacks on the World Trade Center and the Pentagon, while EPA and other federal agencies were continuing to respond to these attacks. The Capitol Police Board, which governs the U.S. Capitol Police Force, led the anthrax cleanup at the Capitol Hill site. Consisting at the time of our review of the House and Senate Sergeants-at-Arms and the Architect of the Capitol, the Board oversees the security of members of the Congress and the Capitol buildings, such as the congressional office buildings. The federal entities involved in the cleanup—including EPA, the Federal Emergency Management Agency, the Centers for Disease Control and Prevention, the U.S. Coast Guard, and the Department of the Army—reported to an incident commander who was appointed by the Capitol Police Board to make decisions on the day-to-day activities of the cleanup. The period from October 20, 2001, to November 13, 2001, is characterized as the emergency phase, which focused on identifying the extent of anthrax contamination; this was followed by the remedial, or cleanup, phase. Reporting to the Capitol Police Board’s incident commander, EPA managed the decontamination aspects of the cleanup. EPA’s activities at the Capitol Hill site included working with other agencies and entities to evaluate the effectiveness of potential disinfectants and cleanup technologies, isolating areas to prevent the spread of contamination, sampling to determine and confirm the extent of contamination (see fig. 1), removing critical items for special decontamination procedures, and cleaning up the contaminated areas and disposing of decontaminated items. At the Capitol Hill site, EPA sampled both surfaces and air in the buildings for the presence of anthrax, using three types of surface samples (wet swabs and wipes for nonporous surfaces and high efficiency particulate arresting (HEPA) vacuuming for porous materials) and four types of air samples. Four methods were used to remove anthrax found in congressional buildings: fumigating with chlorine dioxide gas, an antimicrobial pesticide; disinfecting with a liquid form of chlorine dioxide; disinfecting with Sandia foam; and using HEPA vacuuming (see fig. 2). During the cleanup, chlorine dioxide gas was identified as the best available fumigant for decontaminating parts of the Hart Senate Office Building, as well as for fumigating mail and packages. EPA oversaw the use of chlorine dioxide gas during three fumigation events in the Hart building. In addition, contractors removed items from congressional offices that were critical to congressional operations or personal effects of significance. These items were bagged, tagged, and moved for off-site decontamination. Approximately 3,250 bags of critical items were transported to a company in Richmond, Virginia, for decontamination treatment using ethylene oxide. Approximately 4,000 packages and other mail were collected from the mail rooms in congressional office buildings and also transported off site for decontamination using chlorine dioxide gas. In addition, drums of mail were sent to a facility in Lima, Ohio, for irradiation treatment. The Capitol Hill anthrax cleanup site included 26 buildings, most of them located in or near the Capitol Hill area of Washington, D.C. The buildings that required testing for anthrax contamination included congressional and judicial buildings; mail facilities; and other nearby buildings, such as the Library of Congress. Initial sampling was conducted along the route traveled by the letter opened in the Hart Building by tracing the route back to the Dirksen Senate Office Building (where the mail for the Senate is processed), to the P Street Warehouse (a restricted mail inspection facility overseen by the Capitol Police where congressional mail is inspected), and finally to the Brentwood postal facility (the U.S. Postal Service mail processing and distribution center for Washington, D.C.). Samples from 7 of the 26 buildings were found to contain anthrax, which required that these 7 undergo more thorough sampling, followed by decontamination, and followed then by resampling to confirm that the anthrax had been eradicated. In total, approximately 10,000 samples were taken at the Capitol Hill site, about half of them from locations in the Hart Senate Office Building. EPA advised the Capitol Police Board’s incident commander about the extent to which buildings needed to be cleaned to make them safe. EPA, along with the Centers for Disease Control and Prevention, the Agency for Toxic Substances and Disease Registry, the National Institute for Occupational Safety and Health, and other relevant authorities, determined that the cleanup standard that would be fully protective of public health and the environment was “no detectable, viable anthrax spores.” The seven buildings that required decontamination were the Dirksen, Hart, and Russell Senate Office Buildings; the Ford and Longworth House Office Buildings; the U.S. Supreme Court Building; and the P Street Warehouse. Six of the seven buildings were cleared for reentry by the end of January 2002. The P Street Warehouse was cleared for reentry in March 2002. According to the lead EPA on-scene coordinator, no one became sick as a result of exposure to anthrax or chemical agents used during decontamination. EPA performed its work on the Capitol Hill anthrax cleanup under its Superfund program pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the National Oil and Hazardous Substance Pollution Contingency Plan (NCP). Provisions of CERCLA, as amended, promote a coordinated federal, state, and local response to mitigate situations at sites that may pose an imminent and substantial threat to public health or the environment. The NCP is the federal government’s blueprint for responding to both oil spills and hazardous substance releases. It requires that an on-scene coordinator manage the federal response at the scene of a discharge of oil or a release of a hazardous substance that poses a threat to public health or the environment. The on-scene coordinator coordinates all federal efforts with, and provides support and information to, local, state, and regional response communities. Depending on where an incident occurs, the on- scene coordinator may be either an EPA or U.S. Coast Guard employee. EPA’s Superfund work typically involves using agency personnel and contractors from 1 of 10 EPA regions located throughout the country that have experience with the hazardous substances involved in the incident and the methods required to remove them. Removal actions are generally short-term, relatively inexpensive responses to releases or threats of releases of hazardous substances, pollutants, or contaminants that pose a danger to human health, welfare, or the environment. CERCLA generally limits the cost of a removal action to $2 million and the duration to 1 year. However, CERCLA exempts certain removal actions from these limitations, such as when continued response is required immediately to prevent, limit, or mitigate an emergency. EPA approved an emergency exemption to the $2-million statutory limit for the Capitol Hill anthrax cleanup on November 5, 2001. Typically, EPA provides one on-scene coordinator for a removal site to perform an initial assessment of the cleanup work needed, monitor the more detailed technical assessment and cleanup work being performed by EPA personnel and one or two contractors, and evaluate the results. However, the Capitol Hill site response was different from most hazardous materials emergency responses in its size and complexity, the nature of the contamination, and the requirement that the closed congressional buildings be reopened as soon as possible. As a result, EPA had to use a large number of on-scene coordinators, major contracts, and other federal agencies for assistance. In this case, EPA’s Mid-Atlantic Regional Office (Region III) provided the lead on-scene coordinator, who led the agency’s cleanup efforts. Region III, along with eight other regions, also provided about 50 other on-scene coordinators. Further, unlike most EPA cleanups, the lead on-scene coordinator was not in charge of the overall operations but instead reported to the incident commander, who in turn reported to the Capitol Police Board and House and Senate leaders. A substantial portion of the cleanup work at the Capitol Hill site was performed from October 2001 through January 2002, with most of the remaining work finished by April 2002. However, some additional costs have been incurred, and EPA personnel continued to work on activities related to the cleanup after April 2002. For example, the final disposal of items used at the cleanup continued after the buildings had been reopened. In addition, EPA conducted several internal reviews to identify lessons learned from this experience to help the agency prepare for responses to other potential biological or chemical weapons attacks. According to EPA, the agency expended about $27 million on the Capitol Hill anthrax cleanup, using Superfund program funding. Through fiscal year 2002 supplemental appropriations acts, the Congress provided EPA with additional funding for activities related to terrorism, and EPA allocated about $23 million of these funds to reimburse the Superfund program for expenditures associated with the Capitol Hill anthrax cleanup. Overall, EPA dedicated what it describes as unprecedented resources—contract staff and EPA personnel—to accomplish the cleanup of the anthrax site safely and effectively. Ninety-three percent of the $27 million in costs were incurred primarily by EPA contractors who, among other things, conducted technical assessments and performed the decontamination tasks at the various Capitol Hill sites; the remaining 7 percent of costs were incurred by EPA personnel, largely for planning and overseeing the work of the contractors in accordance with the direction provided by the Capitol Police Board. Over the course of the cleanup, EPA revised its cost estimates several times as the nature and extent of the contamination became fully known and the solutions for removing and properly disposing of the anthrax were agreed upon and carried out. EPA’s various cost estimates covered the contracts and government agreements and generally do not include the payroll and travel costs associated with EPA personnel assigned to the Capitol Hill site.