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Containing the Effects of Chemical and Biological Agents in Buildings

For three years, researchers in EETD's Airflow and Pollutant Transport Group have been studying the dispersion and fate of chemical and biological agents released in buildings, with an eye to developing strategies to minimize casualties. The events of September 2001 have increased the urgency of this work. This research builds on 25 years of R&D at Berkeley Lab on the indoor environment. Three recent projects illustrate this group's capabilities.

The Secure Buildings Website

The Secure Buildings website is intended for emergency personnel and building operators. It contains advice for handling a biological or chemical release in a building, and will be updated as understanding changes. The recommendations on this site are appropriate for small and medium-sized releases such as those expected from a terrorist attack, not for industrial-scale releases such as those that occurred at Bhopal, India, or Chernobyl, Ukraine. The website addresses both pre-event planning (immediate and long-term steps), as well as actions recommended to be taken during various types of releases.

Illustration showing how the HVAC system spreads contamination through a building horizontally.

Interpreting Chemical/Biological Sensor Data in Real Time

We have developed the ability to process data arriving in real time from multiple airborne toxic sensors within a building. New software provides a probabilistic interpretation that tells responders where and how much of the chemical or biological agent may have been released in a building, when it was released, and where in the building the agent is likely to spread. As additional data arrive, the software narrows down the probable answers to these questions, increasing the confidence that responders have the correct information. This helps them to devise a containment response and rescue strategy. The system has been tested using synthetic data, and field tests are in progress using real data from the U.S. Army's Dugway Proving Grounds.

Anth-Trax

Illustration showing how the HVAC system spreads contamination through a building vertically.

A computer model now exists that can simulate the release and dispersion of anthrax spores within a building. The model predicts where the spores go-what fraction settles on floors, in carpets and on walls, how much is resuspended in the air from footfalls, how much is caught in the duct system and air filtration elements, and how much leaves the building through cracks, doors and windows. It also estimates human dosages, and helps assess which strategies might work best to contain the agent. The model is currently being used to examine the anthrax release at Washington, D.C. area's Brentwood mail-processing facility. Anthrax-laden letters sent to Congressional offices passed through this building last fall.

Additionally, the Airflow and Pollutant Transport Group is continuing ongoing work (a) to test and apply computational fluid dynamics to study the dispersion of airborne toxic chemicals in large indoor spaces; and (b) to upgrade the COMIS (Conjunction Of Multizone Infiltration Specialists) computer model, which simulates pollutant airflows within buildings.

New Work

Two new projects are also underway:

Enhancing predictive powers of the LLNL National Air Release Advisory Capability (NARAC)
In cooperation with Lawrence Livermore National Laboratory (LLNL), we are developing a model to predict the indoor concentrations resulting from an outdoor toxic gas or aerosol release in the vicinity of a residential community. Already, select federal and state emergency services officials can register with LLNL's NARAC, which provides real-time simulation of the dispersion and movement of toxic plumes outdoors, such as might be released in nuclear reactor, chemical industry, or oil refinery accidents.
Our research will extend this capability to predicting the infiltration of these plumes indoors. For example, if a toxic cloud passes through a residential neighborhood, the real-time computer simulation can guide first responders (police and fire agencies) about where to look first for injured parties who need medical assistance, and where the safe zones and areas of maximum exposures are located. It also provides information on when it is safer for the exposed populace to seek shelter indoors, when to leave the house, and which escape route to choose.
Entry of airborne toxic plumes into commercial buildings
We are developing an end-to-end computer modeling capability that simulates a toxic release from the beginning of the incident to its end, using an existing outdoor plume dispersion model. It will track the motion and dispersion of the plume outdoors. This Berkeley Lab research will then provide predictions of entry of the toxic plume into specific commercial buildings, e.g., through window cracks, doorways, or fresh air intakes. The toxic plume will be tracked as it propagates into the building's interior. The simulation will assess exposure of building occupants under various outdoor release scenarios and building responses, including assessing the safety of areas of safe shelter throughout the duration of the incident, and provide guidance on the consequences of different strategies for taking shelter (remaining indoors, evacuating immediately, or after a delay), for different types of toxics. The software will incorporate existing toxic dose-response estimates for humans.

— Ashok Gadgil

For more information, contact:

  • Ashok Gadgil
  • (510) 486-4651; fax (510) 486-6658

http://securebuildings.lbl.gov

This work is supported by the U.S. Department of Energy, Office of Chemical Biological Non-Proliferation Program.

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