Direct and indirect wildland fire exposures and impacts in California’s wildland–urban interface

Background People who live in the wildland–urban interface (WUI), where human development overlaps or neighbors wildland vegetation, are at risk of adverse public health consequences caused by wildland fires. Aims We evaluate the direct and indirect exposures and impacts of WUI communities in California, US, to wildland fires from 2008–2018 by evaluating burned area, building damage, civilian fatalities, air pollution and long-term mortality associated with smoke. Key results Most of California’s burned area (95%) is in uninhabited (non-WUI) areas, but nearly all (~99%) building damages and civilian fatalities occurred in the WUI. People living in the WUI are also consistently exposed to smoke pollution, ranging from 0.3 to 3.2 µg/m3 in annual smoke-contributed fine particulate matter (smoke PM2.5) concentrations, with long-term health consequences. Less vulnerable WUI communities, as identified by an environmental justice screening tool for California, tend to experience more direct fire exposures and impacts, with indirect exposures more evenly distributed. Conclusions Most of the adverse direct fire impacts considered in this study occur within WUI areas, while indirect fire impacts are more distributed across WUI and non-WUI areas. Implications Targeted community preparedness efforts in at-risk communities need to address the comprehensive public health threats associated with wildland fires.