text: One of the most notable surveillance projects was the Hazardous Substances Emergency Events Surveillance (HSEES) program, which lasted from 1990 to 2009. ATSDR partnered with 15 states to collect information for HSEES in order to track, report, and study  chemical spills. The information in the HSEES system was used to plan for emergency events involving hazardous substances (including terrorist attacks). States also used the information to develop policies and programs to strengthen public health and reduce illnesses and deaths that can result from exposure to hazardous substances. For example, states used HSEES data to support legislation addressing the problem of hazardous chemicals at illegal methamphetamine labs. Other states used HSEES data to implement programs designed to minimize exposure to hazardous chemicals and mercury at schools. More than 50 published studies were conducted using HSEES data.