PHIREWISE: Public Health Impact and Response on Wildfire Exposure and Health Support and Evaluation

Abstract

University of Washington Abstract PHIREWISE: Public Health Impact and Response on Wildfire Exposure and Health Support and Evaluation Lilian Liu Chairs of the Supervisory Committee:Elena Austin, ScD, MS Edmund Seto, PhD, MS Department of Environmental and Occupational Health Sciences Background: Extreme events including wildfire (WF) and wildfire smoke (WFS) have increased in frequency, duration, and intensity in the U.S. as well as globally. Exposure to WFS fine particulate matter (PM2.5) leads to significant health impacts and disproportionate burdens in vulnerable communities. This research aims to: 1) adapt portable exposure tent system to respond to WFS exposure concerns faced by impacted communities using approaches such as gatherings, community-specific handouts, educational videos, and hands-on demonstrations, 2) support the rapid acquisition of questionnaire based health and exposure data by developing a decision-support framework developed from validated questionnaires, and 3) describe patterns in WFS exposures in older adults compared with the general population and discuss implication for aging epidemiology research. Methods: For Aim 1, we gathered WFS, air quality, and indoor air treatment information from credible sources (e.g., Centers for Disease Control and Prevention, World Health Organization, Washington State Department of Health, and peer-reviewed articles). We prepared educational handouts and a video demonstration and critically evaluated the effectiveness of a DIY box fan filter with a MERV-13 rated filter in removing particles by measuring the clean air delivery rate (CADR). To share and translate the findings to impacted groups, we participated in a community-engaged event to demonstrate DIY box fan filter particle removal effectiveness using a novel low-cost tent exposure system (333 ft³ mylar-lined grow tent) paired with low-cost particle sensors (Dylos DC 1700 and PurpleAir Classic). For Aim 2, we conducted a PRISMA-guided systematic review to identify WF studies using self-reported exposure and health questionnaires. We acquired additional health and exposure questionnaires via REDCap and the National Institute of Environmental Health Sciences Disaster Research Response (DR2) portal and DesignSafe, a National Science Foundation-supported research platform. Extracted questionnaires were curated into two structured libraries: a WF exposure questionnaire (WEQ) library compiling surveys on exposure characterization and mitigation strategies, and a WF health questionnaire (WHQ) library encompassing instruments for various health conditions. These libraries were integrated into a REDCap-based decision-support framework employing branching logic to tailor questionnaire recommendations to study needs. For Aim 3, we performed a rigorous evaluation of WFS PM2.5 census tract level exposure metrics based on either total population or age-specific population weighting. We started with daily 10-km gridded WFS PM2.5 modeling estimates from the Stanford ECHO Lab and re-aggregated the exposure data to census tract exposure estimates that are specific to older adults (i.e., 65 years and older) or the general population living in the contiguous United States (CONUS) from 2006 to 2023. We investigated the exposure estimate summaries using summary statistics and the Wilcoxon paired rank sum test, compared the estimate differences using a Bland-Altman analysis. We additionally, we identified factors that explain the exposure estimate difference through linear regression models, model selection using Akaike Information Criterion (AIC), and estimation of marginal means for WFS PM2.5 estimate discrepancies across census divisions in CONUS. Analyses and visualizations for all three aims were performed in R. Results: For Aim 1, the in-lab evaluation of the DIY box fan filter turned on at the highest fan speed resulted in a CADR of 116.1 ft³/min, which was comparable to previous literature describing a DIY box fan with a MERV13 filter with a CADR of 111.2 ft³/min and a commercially available HEPA-based air purifier with a CADR of 118.9 ft³/min. At the community-engaged event where the efficacy of the DIY box fan filter was demonstrated with our novel low-cost tent-exposure system, participants, especially juniors and seniors, expressed interest in the live demonstration and appreciation for the shareable public health resources on WFS educational materials. Participants expressed increased confidence and preparedness to protect themselves during future WFS events. For Aim 2, 30 eligible studies were identified and reviewed. The initial query returned 42 health questionnaires, which were expanded to 109 health instruments across multiple domains including mental health, respiratory health, sleep and cardiovascular health. The initial query also returned 3 exposure questionnaires and were expanded to 6 exposure resources covering sensory smoke perception, evacuation experiences, time–activity modifications, residential proximity, property damage, and exposure mitigation behaviors upon a structured secondary search. The decision-support framework can help researchers rapidly generate customized, study-ready questionnaire sets, and address common rapid-response needs, including use case screening, questionnaire topic areas, research objectives and participants. For Aim 3, we observed overall increases in WFS PM2.5 concentration, spatial coverage, and smoke wave duration from 2006 to 2023. Comparing exposure estimates for older adults and the general population, we found a statistically significant difference between WFS PM2.5 estimates, but the magnitude of difference was generally small at the national level. However, the stratified Bland-Altman analysis showed the biggest discrepancies between older adult vs. general population-weighed exposure estimates in the Pacific census division ranging from -4.3 to 5.9 μg/m3 on an annual basis and from -147.9 to 145.3 μg/m3 on “intense” smoke days. The correlation analysis and estimated marginal mean results also confirmed differential exposure estimates in the Pacific division, where the exposure metric for older adults systematically estimated higher smoke concentrations, particularly when the smoke levels were high. Conclusion: This dissertation will directly support the preparedness of communities and research teams with practical and generalizable tools and approaches. The analytical results will also provide critical support in aging epidemiological studies. Our findings fill gaps that advance WF and WFS research and practice in community-based settings, disaster contexts, and environmental exposure science and public health.