Wearable Personal PM _2.5 Monitoring During Wildfire Smoke Episodes in Metro Detroit

Wildfire smoke has increasingly affected air quality across North America, raising concerns about the health effects of fine particulate matter (PM _2.5 ) exposure, including potential impacts on brain health. However, relatively few studies have characterized personal PM _2.5 exposure during these events using wearable monitoring. We examined daily personal PM _2.5 concentrations during wildfire smoke episodes in southeast Michigan alongside neighborhood outdoor PM _2.5 estimates. Four participants (one adolescent and three adults) wore AirBeam3 personal monitors during ongoing studies. Neighborhood outdoor PM _2.5 was estimated using the average of three nearest PurpleAir outdoor air quality sensors, and wildfire smoke days were identified using state air quality advisories. Group-level descriptive statistics summarized personal and neighborhood outdoor PM _2.5 and self-reported time spent outdoors. Exploratory within-participant analyses quantified associations between neighborhood outdoor and personal PM _2.5 concentrations on smoke and non-smoke days. Neighborhood outdoor daily PM _2.5 concentrations were higher during wildfire smoke days than non-smoke days (87.6 ± 80.2 vs. 12.3 ± 7.0 µg/m ³ ). Personal PM _2.5 concentrations were more than five times higher during wildfire smoke days (28.2 ± 20.0 vs. 5.1 ± 4.7 µg/m ³ ) than non-smoke days. Within participants, every 10 µg/m ³ increase in neighborhood PM _2.5 was associated with 2.3 µg/m ³ increase in personal PM _2.5 concentrations. Wearable PM _2.5 monitoring captured elevated personal exposures while providing individual-level exposure information beyond neighborhood outdoor air quality estimates. These findings demonstrate that wearable monitoring complements neighborhood air quality measurements by capturing individual-level exposure, providing a more comprehensive assessment of real-world wildfire smoke exposure for future studies examining the effects on brain health.

Wildfire smoke is becoming more frequent and severe, exposing millions of people to unhealthy levels of fine particulate matter (PM _2.5 ). Most public air quality information comes from outdoor monitoring stations, but these measurements do not necessarily reflect the amount of pollution an individual breathes. In this study, personal PM _2.5 concentrations were generally lower than neighborhood outdoor air quality estimates, yet they increased more than fivefold during wildfire smoke events, even though participants reported spending relatively little time outdoors. Overall, more than 25% of participant-days exceeded the United States Environmental Protection Agency (EPA) 24-hour PM _2.5 standard. These findings suggest that reducing time outdoors may lessen, but not completely eliminate, wildfire smoke exposure. As evidence continues to emerge linking wildfire smoke exposure to respiratory, cardiovascular, and brain health, combining wearable personal air pollution monitors with neighborhood air quality measurements may help researchers and public health officials better understand individual exposure, support the evaluation of protective strategies such as indoor air filtration and cleaner-air spaces, and inform recommendations that better protect communities during future wildfire smoke events.