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Thesis
Estimating risk of exposure to Bacillus anthracis based on environmental concentrations
Master of Science (M.S.), Drexel University
May 2009
DOI:
https://doi.org/10.17918/etd-3012
Abstract
In many cases human health risk from biological agents is associated with aerosol exposures. It is suggested that concentrations found on surfaces may be used to infer future or past aerosol exposures. When these concentrations indicate that aerosol exposures exceed specified values, they would trigger response actions, such as remediation (to avoid future risks) or prophylactic antibiotics (to mitigate risks of past exposure). In this paper, two scenarios are modeled. The first scenario assumes a release of aerosolized Bacillus anthracis spores. This scenario is termed a retrospective risk scenario as the environmental samples would be used to infer past risk to occupants of the building. Analytical equations are developed a) to relate the past risk of mortality to the concentration of spores on six surfaces (1. tracked floor, 2. untracked floor, 3. walls, 4. HVAC filters, 5. ceiling, and 6. in nasal passages) that could be sampled after the release; b) to estimate the minimum sampling area required for negative results to establish that risks are below a specified level. The second scenario assumes that the spores are initially on a tracked surface. This scenario is termed prospective risk, as environmental samples would be used to estimate future risk to occupants of the building as a result of re-aerosolization. Analytical equations were developed to estimate minimum sampling area and relate future risk to the concentration of spores initially present on the tracked surfaces. For the retrospective simulation, the risk of mortality can be linked with the concentration of Bacillus anthracis spores on a given surface without dependence on the room dimensions which creates a shortcut to estimating the risk level; for prospective simulation, the risk of mortality is related to the amount of spores released at the initial point and the dimensions and the characteristics of the room. The minimum sampling area has an inverse relation to surface concentration and particle diameter, which indicates that accurately measuring these risk levels for the smallest size fraction of B. anthracis (diameter of 1 [mu]M) will be problematic.
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Details
- Title
- Estimating risk of exposure to Bacillus anthracis based on environmental concentrations
- Creators
- Tao Hong - DU
- Contributors
- Patrick L. Gurian (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- Civil (and Architectural) Engineering [Historical]; College of Engineering (1970-2026); Drexel University
- Other Identifier
- 3012; 991014632613704721