Linking ambient fire emissions to respiratory effects using gelatin filter sampling

On November 8, 2023, a fire occurred at a chemical plant near Shepherd, Texas. Ambient air monitoring using a novel, biocompatible, gelatin filter alongside proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) with both targeted and non-targeted analysis (NTA) was conducted on November 10, 2023, with seasonally matched monitoring on November 12, 2025. Concentrations of benzene, toluene and ethylbenzene/xylenes were higher near the incident site (Shepherd) compared to downwind (Livingston) following the fire. NTA revealed greater numbers of VOCs, and unique site-specific VOCs, at the incident site versus downwind just after the fire in 2023. In 2025 the number and types of VOCs did not vary across sites, suggesting an apparent site-specific VOC enrichment during the monitoring period in Shepherd post-fire. The gelatin filter, positioned upstream of the PTR-ToF-MS, enabled direct capture of airborne mixtures and subsequent dissolution into cell culture media without additional extraction steps. Trace metal analysis of these filters showed a higher burden of metals, as well as unique (barium, thulium, and samarium) and elevated metals (sodium, magnesium, iron, copper, gallium, strontium, tin, and cesium) in filters collected at Shepherd. The filtrates were then applied to human bronchial epithelial cells. Exposure to incident site filters significantly upregulated the oxidative stress-responsive gene HMOX1. These findings demonstrate that short-term exposure to real-world air pollutant mixtures induces biological responses in airway cells and highlight the utility of integrating air monitoring and novel sampling strategies with in vitro toxicity/biological activity assessment following episodic emission events.