Wearable measured physiological stress and activity patterns changes after 2025 Los Angeles wildfire among older...

The wildland-urban interface (WUI) fires have adverse effects on both physical and mental health. However, early biosignals changes related to fires are not well understood. Digital wearables can capture real-time changes in physiological stress and activity patterns, providing insight into the mechanisms of health effects of WUI fires and identifying vulnerable populations during and after WUI fires. This study aimed to assess the immediate and sustained changes in physical activity patterns and physiological stress markers during and after the 2025 Los Angeles wildfires. We conducted a longitudinal study of 15 older adults (mean age 73.2 years) during the 2025 Eaton Fire in Los Angeles, using the digital Oura Ring (Gen 3) continuously. Data were collected at baseline (Dec 9th, 2024 to Jan 6th, 2025), during the fire (Jan 7th, 2025 to Jan 12th, 2025), and after the fire (Jan 13th, 2025 to Jan 27th, 2025). Daily activity patterns (physical activity and sleep duration) and physiological stress (sleep heart rate, heart rate variability, sleep fragmentation, and breath rate) were collected, and linear mixed-effects models were used to investigate how these biosignals changed and how evacuation alerts impacted these changes. During the fire, six out of fifteen participants received evacuation alerts. We observed a 41-minute increase in sedentary time (P = .007), a 34 min reduction in sleep duration (P = .002), and a 0.4 BPM increase in sleep breath rate (P = .009). Although activity patterns returned to baseline post-fire, markers of physiological stress, including sleep heart rate and breath rate, remained elevated. Among participants who received evacuation alerts, the immediate and prolonged impacts are larger. The changes in activity patterns and increases in physiological stress during and after the 2025 Los Angeles wildfire in this cohort can indicate potential health effects. Digital bio-signals may serve as early indicators of adverse health outcomes following a wildfire.