UC Irvine

Wildland firefighters experience intermittent and spatially variable particulate matter (PM) exposure during wildfire and prescribed-fire operations, yet current smoke-monitoring systems are not designed to measure worker-scale exposure at the fire line. Regional monitors, satellite aerosol optical depth (AOD), smoke-plume products, and community sensor networks provide important context but cannot consistently resolve near-breathing-zone exposure or determine when respiratory protection is most needed. This dissertation addresses this gap through three linked studies spanning regional smoke assessment, sensor calibration, and wearable field monitoring.First, satellite AOD and surface PM2.5 were evaluated during two coastal California wildfires under contrasting transport conditions. The Mountain Fire occurred during Santa Ana-type offshore flow, whereas the Gifford Fire occurred under onshore marine-boundary-layer conditions. Column-surface coupling depended on boundary-layer structure, transport, topography, and monitor location. During the Mountain Fire, AOD correlated with combined frontside PM2.5 (Spearman ρ = 0.565, p = 0.012), whereas the Gifford Fire showed weaker, non-significant coupling despite higher fire-window AOD. AOD-only models had limited predictive value, but model skill improved when meteorological and smoke-context variables were included.Second, a dynamic cross-sensor calibration approach was developed for low-cost PM1.0 monitoring using an SPS30 optical particle counter and the blue-channel response of an ADPD188BI photometric sensor. Monodisperse polystyrene latex (PSL) sphere and combustion-aerosol experiments showed source- and size-dependent sensor responses. The ADPD188BI-toSPS30 response ratio predicted source-specific calibration behavior (R² = 0.9469) and was used to adjust PM1.0 estimates toward gravimetric-equivalent measurements. The dynamic calibration reduced root mean square error (RMSE) from 783.79 to 121.49 µg/m³, corresponding to an 84.5% reduction in error.Third, a system containing both the dynamically calibrated wearable PM1.0 sensor and an air-purifying respirator with a pressure sensor was evaluated during prescribed-burn operations. The system combined real-time PM1.0 monitoring with in-mask pressure sensing to identify respirator wear periods. Corrected field profiles showed shift-average PM1.0 concentrations of 62.0-151.8 µg/m³ and peaks of 5,930.9-10,148.8 µg/m³. Across pilot burn-day data, APR wear time was strongly associated with estimated PM1.0 reduction (R² = 0.70), with a median reduction of 48 ± 19% corresponding to APR wear time of 40 ± 33 min, or approximately 14% of the burn shift. Together, these studies show that calibrated, wearable, near-breathing-zone PM monitoring can improve upon regional monitoring by providing higher temporal resolution, identifying shortduration high-exposure periods, and alerting wildland firefighters when PM levels are elevated, thereby supporting timely respirator use when most needed and reducing particulate matter exposure.