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Release of hazardous substances may occur during transportation, storage, fire accident or natural disasters and can post danger to the general public and response personnel. It is important to have a standard guideline that can help the emergency service personnel to deal with the hazardous substance after the accident. The Emergency Response Guidebook (ERG), is a guidebook providing protective distance information for substances to the first responders, such as firefighters and police officers. The protective distance is the affected area during the first 30 minutes after a substance is spilled. ERG is used in in the United States, Canada, and Mexico. Similar to a protective distance, the software ALOHA (Areal Locations of Hazardous Atmospheres) is an atmospheric dispersion model maintained by the NOAA's Office of Response and Restoration of USA. ALOHA estimates threat zones for released substances according the toxicological/physical characteristics of the chemicals and in a user defined condition such as atmospheric conditions, and circumstances of the release.
In Taiwan, according to the disaster prevention and protection act, the Environmental Protection Administration, Executive Yuan is the central regulating authority for toxic chemical materials and suspended particulate disaster. However, firefighters are generally the ones who provide the first-line disaster relief after an accident. Having a correct guidance for hazardous substances may protect the public and rescuers from danger when an accident occurred. In this thesis, we compared the estimated threat zone by ALOHA and the protective distance in the ERG.
Nine hazardous chemicals, including aniline, benzo trichloride, propyleneimine, methyl isocyanate, dimethyl sulfate, ethyleneimine, acrolein, allyl alcohol and Phosphorus trichloride, were selected. The software ALOHA was used to estimate the downwind dispersion of a chemical cloud and the threat zone. The estimated results were compared with the protective distance in the Emergency Response Guidebook. The results showed certain differences between the estimated value and the guidance in the ERG. In practice, it’s better to take both of them into consideration.
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