We will identify individuals who lived in the area during the blowout but have since left using multiple data sources and methods including mobility tracking and health utilization data. We are actively seeking legal settlement information and welcome the community’s input to comprehensively account for these changes. Individuals who have moved away or died since the blowout will be included in the analysis of the California Health Interview Survey and health care utilization data. Individuals who moved away since the blowout may also be eligible to participate in the focus groups.