Remediation following Man-made or Natural Disasters -Homeland Security Research

EPA develops procedures and methods to contain and mitigate contamination and to remediate the environment following public health and environmental incidents and disasters. Contamination incidents involving urban areas could require the decontamination of multiple buildings and outdoor areas.  EPA's goal is to protect human health and the environment, and to restore contaminated areas as efficiently as possible.

Contaminant Fate and Transport

EPA investigates what happens to contaminants as they move through indoor and outdoor environments. Limiting exposure to chemical, biological, radiological agents requires a detailed understanding of how contaminants spread: do they spread rapidly as vapors or do they spread as particles that repeatedly settle and become airborne again?

Contaminants can also be carried on skin, clothing, shoes, or tools to areas beyond the original contamination zone. Understanding contaminant behavior allows responders to contain contamination.

Decision-makers require information about contaminant fate and transport to develop decontamination plans. Current research investigates how:

  • contaminants spread through air or move within a structure or the outdoor environment
  • agents spread on skin, clothing, shoes, and tools to areas beyond the contamination zone
  • human activities can spread the contamination
  • environmental conditions affect contaminants
  • contaminants react or interact with or within surfaces and materials

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Indoor and Outdoor Decontamination

City scape
A wide area contamination incident could require the decontamination of multiple buildings and city blocks.

Much of EPA's decontamination research has focused on developing safe and successful decontamination approaches for both indoor and outdoor environments.

The effectiveness of a decontamination technology largely depends on the type of material. What works on one surface does not necessarily work on a different surface. In addition, the concentration of the decontaminant, the contact time of the decontaminant with the material, and conditions such as temperature, sunlight, or humidity all affect decontaminant effectiveness.

To ensure that decontamination methods tested in the laboratory will perform at a large scale, EPA built a room-sized chamber to test methods at a pilot scale. EPA then selected three fumigation methods that proved effective at the pilot scale for testing at field-scale. EPA and several partner agencies performed a field scale decontamination of a building contaminated with a biological agent during the Bio-response Operational Testing and Evaluation (BOTE) Project.

Bio-response Operational Testing and Evaluation (BOTE) Project

The BOTE project not only tested the three decontamination methods on a large scale, but also evaluated the efficiency of all of the interconnected and multi-agency activities involved in a response, from the initial public health and law enforcement response through environmental remediation. The project also included comparative cost analysis for the various decontamination methods and associated activities.

In addition to fumigation, EPA's decontamination research covers a broad range of activities, including investigating the best way to use water (liquid and steam) or other liquids, foams, fumigants, or specialized coatings (such as strippable coatings for materials contaminated with radionuclides) to decontaminate surfaces.

EPA's research on rapid decontamination in the event of the release of a radiological dispersal device, evaluates commercially available technologies for use on buildings, outdoor areas, and contaminated equipment. As with other EPA decontamination studies, minimizing cost and time, minimizing surface damage and secondary waste, and reducing recontamination were considerations for selecting decontamination technologies.

Material Demand and Compatibility

Effective decontamination of large volumes using gasious fumigants requires maintenance of an optimal concentration of fumigant over a certain period of time, along with maintaining optimal temperature and humidity. Vaporized hydrogen peroxide, methyl bromide and chlorine dioxide gas are fumigants used to decontaminate interior surfaces contaminated by anthrax: one of the biological agents of greatest concern for homeland security.

Interior building materials such as concrete, steel, wood, carpet, ceiling tiles, or painted wallboard can interact with a decontaminant through sorption, reducing the amount available for decontamination. This reduction is referred to as material demand.  EPA has studied material demand in an effort to determine the appropriate concentration of a decontaminant to over come material demand and how to maintain the target concentration.

EPA also investigates the compatibility of materials with fumigants.  Researchers have measured changes to physical properties of building materials, recorded changes to the appearance of office equipment, and examined the integrity of electrical circuits and related devices following fumigation studies.

Persistence Studies

EPA investigated the persistence of biological agents, toxic industrial chemicals and chemical warfare agents on various types of building materials under a range of environmental conditions including exposure to ultraviolet light or high humidity. Other studies have included the persistence of chemical warfare agents and microorganisms in the leachates from landfills.

Contaminants also frequently interact with materials such as tile, carpeting, wood, steel, or concrete.  EPA must understand these interactions which can present unique decontamination challenges.

Waste Treatment and Disposal

EPA developed the web-based  I-WASTE decision support tool, which allows users to easily calculate estimates for waste volumes that might be generated during decontamination activities involving multiple types of structures. The tool also organizes large amounts of information related to managing waste after natural disasters or contamination incidents. The tool is not intended to override regulatory or legal requirements, but to provide information on options for removing, transporting, and disposing of contaminated materials. The tool includes databases of facilities such as incinerators, recyclers, and hazardous waste landfills.

Large amounts of possibly contaminated materials might need incineration after a contamination incident. Some building materials inhibit the penetration of heat hindering effective destruction of biological agents. EPA has conducted a variety of studies using thermal destruction systems - for example, a rotary kiln incinerator simulator - and computer modeling designed to predict how well an incinerator might destroy chemical or biological agents.

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