Abstract: | Incident-specific data reveal the spatial patterns of two major classes of acute toxic airborne releases in the United States (1982–86): rural agricultural and urban industrial. Rural (primarily truck transport) incidents dominate the distribution in the western US, while rail incidents and fixed site incidents dominate in the east. Using a combination of cartographic and statistical analyses, risk and mitigation measures were calculated to identify high-hazard and low-hazard states. Risk factors, primarily numbers of chemical firms and rail miles per state, best predict the frequency of incidents and their resulting spatial pattern. |