Background: Wildfire severity and frequency have increased in the last two decades, as have their consequences and public attention toward these disasters. Wildfires have led to community evacuations, social disruptions, significant property damage, loss of life, and impacts on economic activity in communities across California. However, the effect of fires on individual healthcare facilities and the health system has received comparatively less attention. There is a lack of empirical assessments on how this risk affects the operations of healthcare facilities and the spatial trends of actual wildfire exposure. We use historical wildfire perimeter data, and inpatient healthcare facility data to assess trends by county in observed exposure to wildfire between 2001 and 2023 in California.

Methods: Inpatient facility data was collated from the California State Department of Health Care Access and Information. Data on annual wildfire perimeters was retrieved from the California Department of Forestry and Fire Protection. Inpatient facility data from the pre-2008 era did not include geospatial coordinates for facility locations. However, they included street address data which was geocoded using a Google Maps API in R, and supplemented with manual geocoding. The ‘sf’ package in R was then used to compute the nearest distance to a wildfire perimeter each year for each licensed and open facility (closed facilities were excluded from analysis). The proportion of facilities that were within ten miles of a wildfire perimeter were summarized, by year, and by county.

Results: Between 2001 and 2023, 20 of California’s 58 counties had at least an average of 50% of inpatient facilities within ten miles of a wildfire perimeter. For three counties, Placer, Shasta, and Ventura, more than 75% of inpatient facilities experienced wildfires within ten miles of the facility site between 2001 and 2023. While all but two counties experienced a wildfire within ten miles of an inpatient facility at some point, the frequency of wildfires near inpatient facilities is not evenly distributed across the state.

Conclusion: Addressing the threat to healthcare facilities will require action at multiple scales. Policies to address the root causes of the increase in wildfire exposure are essential; these may include policies directed at reducing wildfire ignition, improving land-use management, guiding future development decisions, and mitigating future climate change through reductions in fossil fuel use and greenhouse gas emissions. Empirical data such as the results of this study may help prioritize wildfire adaptation investments for healthcare facilities in specific California counties.