Because of their physical properties, CWA use in a domestic terrorist incident may not be associated with a high-explosive event. Rather, these agents may well be dispersed in a manner that would involve a vapor hazard within a confined space. The type of incident seen in Tokyo, while minimized by the inefficient release of the CWA, is an excellent example of the type of incident expected as a result of terrorist use of CWA. The highest probability of detecting the presence of CWA occurs in cases in which there is a continuing source of vapor. By the time emergency medical personnel arrive at an incident, inevitably the agent will have dispersed significantly. In the case of cyanide and phosgene, and most nerve agents, detection in the environment may not be possible by the time monitoring equipment is in place at the scene. In fact, once casualties of a vapor CWA incident are outside the area of the attack and accessible to medical personnel, the signs and symptoms of the patients may be the only detection method available, and the threat of spread of the CWA hazard from casualties may be minimal. However, in the case of the Tokyo sarin attack, it has been reported that up to 9 percent of EMS workers and a significant number of hospital staff experienced acute symptoms of nerve agent toxicity due to exposure to casualties in unventilated areas (Okumura et al., 1998b). Given the increased threat of CWA terrorism and the various CW agents that can be used, emergency responders must have accurate and timely detection information or the ability to detect and identify a CWA at the time of their response. Again in the case of the Tokyo subway attack, the first identification made was inaccurate, and it was not until three hours post incident that accurate detection of sarin was made and the information disseminated. The medical personnel on site will require equipment capable of detecting the widest range of chemical agents. For medical personnel, detection equipment may include rapid, minimally invasive or noninvasive clinical assays for various chemical agents or for the effects of the chemical agents, that is, cholinesterase inhibition. Without this ability, more individuals may be exposed, including emergency response and hospital personnel attempting to care for casualties. Chemical agent detection will be an essential part of both medical crisis and consequence management. Detection and identification of the chemical agent or agents at the scene of a terrorist incident must not be accomplished at the expense of rapid and appropriate medical treatment of chemical casualties.
An emergency response incident that involves the release of any chemicals or toxic materials will typically be categorized as a hazardous materials (Hazmat) incident. The response to a Hazmat incident is somewhat standardized across the country. Specialized Hazmat teams are normally called in to address these situations. Hazmat teams are typically part of the fire services and will possess a majority of the locality's chemical