The objective of this assessment is to determine what level of cleanup will be required to meet regulatory and stakeholder needs in the case of a chemical and/or biological incident at a civilian facility. A literature review for selected, potential chemical and biological warfare agents shows that dose information is often lacking or controversial. Environmental regulatory limits or other industrial health guidelines that could be used to help establish cleanup concentration levels for such agents are generally unavailable or not applicable for a public setting. Although dose information, cleanup criteria, and decontamination protocols all present challenges to effective planning, several decontamination approaches are available. Such approaches should be combined with risk-informed decision making to establish reasonable cleanup goals for protecting health, property, and resources. Key issues during a risk assessment are to determine exactly what constitutes a safety hazard and whether decontamination is necessary or not for a particular scenario. An important conclusion is that cleanup criteria are site dependent and stakeholder specific. The results of a modeling exercise for two outdoor scenarios are presented to reinforce this conclusion. Public perception of risk to health, public acceptance of recommendations based on scientific criteria, political support, time constraints, and economic concerns must all be addressed in the context of a specific scenario to yield effective and acceptable decontamination.

Decontaminating civilian facilities or large urban areas following an attack with Bacillus anthracis poses daunting challenges because of the lack of resources and proven technologies. Nevertheless, lessons learned from the 2001 cleanups together with advances derived from recent research have improved our understanding of what is required for effective decontamination. This article reviews current decontamination technologies appropriate for use in outdoor environments, on material surfaces, within large enclosed spaces, in water, and on waste contaminated with aerosolized B. anthracis spores.

Recent terrorist events underscore the urgent need to develop a comprehensive set of health-protective cleanup standards and effective decontamination technologies for use in the restoration of civilian facilities. Accurate scientific information remains limited in the area of biological warfare agents. However, new guidelines and calculated cleanup values are emerging for initial re-entry and long-term reoccupation following use of chemical warfare agents. This article addresses airborne, soil, and surface exposures following release of G-type chemical warfare agents and VX. Cleanup goals should be tailored to the type of population that may be exposed, potential exposure times, and other scenario-specific considerations. Three different airborne concentrations are proposed for cleanup of public sector facilities. One value is recommended for initial re-entry; a more conservative value is recommended for long-term monitoring and increased public confidence; and a third, even more conservative concentration represents essentially a no-effect level for round-the-clock airborne exposure. Health-based cleanup levels are provided for contaminated residential and industrial soil. Results are presented on the outcome of a preliminary risk assessment to determine safe surface levels (e.g., walls, floors, and handrails) for cleanup after exposure to the G agents and VX. Because specific cleanup criteria for most biological warfare agents remain problematic, recommendations are made for filling the knowledge gaps.

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To evaluate potential health effects from a radiological, chemical, or biological agent following intentional contamination—whether to water, air, or environmental surfaces—some type of health risk assessment is necessary. Risk assessment parameters are defined in the context of “risk informed” decision‐making. A risk‐based approach means that cleanup goals should be based on a defined, “acceptable,” or “tolerable” level of risk to health. For weapons of mass destruction, regulations and guidelines for what constitutes an acceptable human dose are clearest for radiological agents, less clear for chemical agents, and least codified by far for biological agents. The Environmental Protection Agency (EPA) has developed an updated Protective Action Guides to help authorities make radiation‐protection decisions during the phases of an emergency. No uniform set of cleanup standards for radionuclides exists at present, but the Department of Homeland Security has posted proposed guidelines in the Federal Register to address response operations. The consensus for item clearance criteria (a voluntary standard) is currently 1 mrem/year (or 10 μSv/year) total effective dose equivalent above background. EPA standards for concentrations of various radioactive isotopes in groundwater and drinking water are reviewed along with primary drinking water standards. For chemical warfare agents and toxic industrial chemicals, several authorities have published quantified, health‐based guidelines that can be used as “accpetably safe” clearance goals, and these values are reviewed. For example, both the EPA and the military use maximum contaminant levels as enforceable guidelines for chemical agents in drinking water. Although nearly all biological warfare agents are intended for aerosol application, many have a strong potential as waterborne threats and could inflict heavy casualities if ingested. Scientific investigations have led to recommended guidelines in drinking water for only some of the biological warfare agents that have been identified as priority microbes or microbes of medical importance in water. Most researchers agree that there is currently insufficient information to develop; an infectious dose and to quantify a “safe” amount of residual biological agent in a decontaminated facility or outdoor environment. There is even less information regarding safe levels for water resources. Education should not be underestimated when considering what risk the public is willing to accept. Individual states have drinking water relations based on their stakeholders, and such information must be considered when trying to determine guidelines applicable to an unnatural even. Major gaps, critical needs, and future directions associated with evaluating risks to human health following a terrorist attack are summarized.