Discussion

In response to the LA County Wildfires, PHEER leadership convened a task force of PHEER members, Los Angeles-based researchers, and members of the National Institute of Environmental Health Sciences (NIEHS) Disaster Research Response (DR2) network in January 2025 to discuss what type of mobilization would be most helpful to the local research and public health practice community. These groups identified a need for coordination among researchers interested in collecting data on the wildfires. To aid in this coordination, PHEER developed a wildfire health exposure map in ArcGIS Online that is freely available to the research, practice, and policy communities.Reference Cutler, Epstein and Morris ⁶ The objective of the map was to collect and curate critical exposure measurements, including environmental exposures from the fire and smoke as well as secondary hazards associated with contaminated soil, air, water, and debris. Researchers may integrate these exposure data with health outcome data to study the health impacts including disease incidence and healthcare utilization. PHEER also partnered with the Natural Hazards Engineering Research Infrastructure’s (NHERI) Natural Hazards Reconnaissance (RAPID) facility at the University of Washington to collect perishable hyperspectral imagery in select census blocks within the burn areas of the Palisades and Eaton Fires in March 2025. These data will be publicly available in 2026 on the NHERI DesignSafe data curation platform, which provides tools for researchers to manage and share natural hazards data. PHEER also awarded a grant to a team of researchers to process the hyperspectral data and analyze the spatial impact of contaminants in the burn zones.

After the fires, the Los Angeles County Department of Public Health (LACDPH) created an online dashboard to share information on active or proposed environmental and health assessments. PHEER gathered information from this website and from an ArcGIS-based survey sent to the PHEER leads’ networks. When available, PHEER recorded assessment type (soil, water, outdoor air, indoor air, debris water, biological, or ash), assessment targets (particulate matter, heavy metals, or other contaminants), study site(s), and the estimated timeline for each study. Additionally, PHEER and LACDPH aligned their efforts, deciding that the tools would serve the research community and the public, respectively. In March and April 2025, PHEER attended several of LACDPH’s “Wildfire Impact Monitoring Dashboard Implementation Team” meetings to share progress on the map with partners and researchers collecting wildfire data.

After gathering information on the studies, PHEER created an ArcGIS Online Web Application using the Experience Builder tool. The web application hosts a map of the study locations as well as publicly available secondary datasets including the California Department of Forestry and Fire Protection (CAL FIRE) Damage Inspection (DINS) dataset, current AirNow air quality monitoring sites, Environmental Protection Agency (EPA) parcel clean-up data, wildfire perimeters, and the Centers for Disease Control and Prevention’s (CDC) 2022 social vulnerability index (SVI) data. PHEER added the census blocks layer to encourage a standard geographic unit of analysis for future research. The links to these data sources are provided in the supplemental table. Studies were added to the map as investigators shared information with PHEER directly, when a spatial file was added to the LACDPH dashboard, and from internal web applications, ArcGIS online accounts, or websites. A few studies on the LACDPH dashboard did not provide any information on their data collection locations, so they were not included on the map. The conceptualization and development of the map took place from January to November 2025, and the PHEER team will add future studies to the map if relevant (Figure 1).

Figure 1. Timeline of map development and collaboration process.

Studies were categorized as surface studies (including soil, debris, and indoor contaminants), water studies, outdoor air studies, and indoor air studies. The studies with point data within each category were visualized with a distinct symbol that represents the study type (e.g., park bench for outdoor air, home for indoor air). Polygonal data were visualized with outlines or transparent shapes to ensure readability of the map, and color consistency was prioritized throughout the studies within each category. Clicking on a data collection location prompts a pop-up with information about the study, including study team names, study affiliation, study assessment type and targets, primary point of contact email, and a link to the study website or section on the LACDPH dashboard. Finally, a spreadsheet with information about each study that is linked in the web application is provided so users can easily sort and filter study types in a tabular format.

While the map was generated to address gaps in coordination related to exposure assessment, it was challenging to explain the mission and capabilities of PHEER to researchers and practitioners who were immersed in the response and often personally affected by the fires. Initially, PHEER planned to host the data from each study on this map or the DesignSafe platform so investigators could directly download and use data from other studies. A few researchers expressed a willingness to share their data in this way, though several of their data sources were already publicly available. Partners and researchers attending LACDPH’s wildfire data meetings expressed hesitancy about sharing data publicly because combining household-level datasets might compromise privacy. There were also concerns that the presentation of data at the parcel level could have unintended negative consequences on affected community members, such as effects on real estate values. Moreover, even if sharing or resharing data from a single source on a map interface had limited risk, bringing multiple sources together could facilitate triangulation of information that could potentially be harmful. To address this concern, PHEER chose to display the locations and types of data being collected, rather than the data itself. Map users can download publicly available data from the agency that collected it or contact the researcher directly if they are interested in accessing research data. Additionally, to ensure that data collection locations could not be linked to specific parcels, the map symbols are only visible at the street level, rather than the parcel level. More conversations among the disaster science and practice communities, inclusive of those impacted by disasters, are necessary to identify pathways for negative consequences of data sharing, mitigation opportunities, and standards of practice.