Ornl-6615 Evaluating Protective Actions for Chemical Agent Emergencies

In the process of completing a Congressionally mandated destruction of the U. S. stockpile of unitary chemical weapons, the U.S. Army decided that enhanced emergency planning was needed to reduce the consequences of an accidental release of agent. In cooperation with the Federal Emergency Management Agency, other federal agencies, and affected state and local governments, the U.S. Army is in the process of implementing an enhanced emergency preparedness capability. This research supports that effort by developing a method of evaluation for the principle protective action alternatives–evacuation, in-place shelter, and respiratory protection. In addition this research examines these alternatives for a limited set of scenarios to both "validate" the method's utility, and make some preliminary program recommendations regarding protective action strategies. A model was developed to examine the effect various protective actions have on expected exposure under a variety of release and meteorological conditions. The model compares the expected exposure without protection, with the expected exposure given a specified emergency response system, and the capacity of the selected protective action to protect (assuming that all people to be protected have implemented the protective measure). These exposure estimates are graphically displayed over time from the beginning of the event in the context of their anticipated acute human health effects. This report analyzed a total of 1134 scenarios–504 evacuation, 378 in-place sheltering, and 252 respiratory protection scenarios. This preliminary analysis focused on 14 classes of accidents (i.e., 5 GB, 5 VX, and 4 H/HD), for a range of meteorological condition (involving winds averaging 1, 3, and 6 m/s), and for a series of downwind distances (3, 10, and 20 km). These 126 accident scenarios were examined for emergency responses involving evacuation (clearing the area in 1, 5, 10, and 20 min), in-place shelter (expedient, enhanced and pressurized shelters), and respiratory protection (NATO civilian and U.S. military standard masks). All of the scenarios examined assumed that the protective actions would be implemented in the context of a state-of-theart emergency response system. Such a system is characterized as being able to (1) detect and assess an accident, communicate that to off-site officials and make a decision to warn the public in five minutes or less; (2) have both indoor and outdoor emergency warning systems, such as siren and telephone ring-down systems; (3) stimulate public response at a rate that is 25% faster than previous disasters (empirically documented), including response to five chemical evacuations.