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Modeling Shelter-in-Place Including Sorption on Indoor Surfaces
"Intentional or accidental large-scale airborne toxic releases (e.g. terrorist attacks or industrial accidents) can cause severe harm to nearby communities. The purpose of this work is to quantify the level of protection offered by existing houses, and the importance of sorption/desorption to and from surfaces on the effectiveness of SIP."
Lawrence Livermore National Laboratory
Price, Phillip N.; Gadgil, Ashok; Chan, Wanyu R.
2003
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Assessing the Effectiveness of Shelter-in-Place as an Emergency Response to Large-Scale Outdoor Chemical Releases
"Large-scale outdoor chemical releases can cause severe harm to people in nearby communities. Sheltering in buildings may be used as a temporary measure to reduce health risk from exposure to the toxic materials. Shelter-in-place (SIP) is relatively straightforward to implement because most people are already in buildings most of the time, and so exercising the emergency response simply means closing windows and doors, and turning off ventilation fans. However, air leakage variability in the building stock can lead to considerable differences in the effectiveness of buildings in protecting occupants against outdoor releases. The effectiveness of SIP for the community can also vary for different release conditions. This dissertation identifies and assesses the key factors that affect community-scale SIP effectiveness. Large-scale airborne toxic chemical releases are simulated to assess the potential acute health effects for the exposed population. Modeling of the distribution of indoor concentrations is accomplished through detailed analysis of the air leakage of 2 residential and non-residential buildings and simulation of their air infiltration rates. The expected outcome for a population that shelter indoors is quantified by a community-based metric that captures the variability among buildings. Sensitivity of SIP effectiveness to model parameters is evaluated under different release scenarios by comparing changes in the casualty reduction estimates."
Lawrence Berkeley National Laboratory
Chan, Wanyu R.
2006-05
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Effectiveness of Urban Shelter-in-Place II: Residential Districts
"In the event of a short-term, large-scale toxic chemical release to the atmosphere, shelter-in-place (SIP) may be used as an emergency response to protect public health. We modeled hypothetical releases using realistic, empirical parameters to explore how key factors influence SIP effectiveness for single-family dwellings in a residential district. Four classes of factors were evaluated in this case-study: (a) time scales associated with release duration, SIP implementation delay, and SIP termination; (b) building air-exchange rates, including air infiltration and ventilation; (c) the degree of sorption of toxic chemicals to indoor surfaces; and (d) the shape of the dose-response relationship for acute adverse health effects. Houses with lower air leakage are more effective shelters, and thus variability in the air leakage of dwellings is associated with varying degrees of SIP protection in a community. Sorption on indoor surfaces improves SIP effectiveness by lowering the peak indoor concentrations and reducing the amount of contamination in the indoor air. Nonlinear dose-response relationships imply substantial reduction in adverse health effects from lowering the peak exposure concentration. However, if the scenario is unfavorable for sheltering (e.g. sheltering in leaky houses for protection against a nonsorbing chemical with a linear dose-response), the community must implement SIP without delay and exit from shelter when it first becomes safe to do so. Otherwise, the community can be subjected to even greater risk than if they did not take shelter indoors."
Lawrence Berkeley National Laboratory
Gadgil, Ashok; Price, Phillip N.; Nazaroff, W. W. . . .
2006-12
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