EVALUATING THE SENSITIVITY OF HAZARDOUS SUBSTANCES EMERGENCY EVENTS SURVEILLANCE - A COMPARISON OF 3 SURVEILLANCE SYSTEMS

This study evaluated the sensitivity of the active, state-based Hazard ous Substances Emergency Events Surveillance (HSEES) system by compari ng it with two passive systems. Incident reports for the passive repor ting systems were sent to participating HSEES states during a two-year period. The states evaluated these hazardous substances spill events according to whether an event was detected by the HSEES system and whe ther it met the HSEES case definition. These data were analyzed to det ermine the sensitivity of the HSEES system. HSEES detected 61.7% (31.2 % surveillance and 30.5% nonsurveillance) of hazardous substances spil l events documented by the combined passive reporting systems; HSEES d id not detect 38.3% (4.4% surveillance, 20.2% nonsurveillance, and 13. 6% unknown) of events. The HSEES system recorded more events than both passive reporting systems combined. Event reporting differences can b e attributed to differences in each system's approach to surveillance. HSEES detects events inside and outside the limits of the passive rep orting systems. Comparing surveillance systems that collect related in formation is very useful in measuring system effectiveness, locating d ata gaps, and identifying new data sources.