IMPACTS OF TROPICAL PEAT-FOREST SMOKE: URBAN PM2.5 AND TOXICITY IMPLICATIONS

Abstract

To better address the impacts of recurrent tropical peat-forest (PF) burning in the Maritime Continent on regional air quality and public health, this thesis characterizes chemical composition of urban PM2.5. Urban PM2.5 are systematically classified to smoke-dominant (SD) vs. non-SD samples. In-situ pH increases from 1.9 in non-SD PM2.5 to 2.0 and 2.7 in SD and episodic samples, respectively, demonstrating neutralizing effects of PF smoke. Organic carbon ≥6.0 µg/m3 identifies SD PM2.5 with ~90% accuracy and enables hourly assessment. Char-EC/soot-EC ratio of SD urban PM2.5 can infer burning conditions of PF at sources. PM2.5-induced biological effects are investigated using an in vitro model of small airway epithelial cells differentiated at air-liquid interface (S-ALI). Transcriptomic analysis identifies 273 dysregulated genes involving >60 signaling pathways. An alveolar-endothelial co-culture model further demonstrates epithelial exposure to PM2.5 reduces angiogenic ability of endothelial cells through bystander effects, suggesting potentially perturbed ventilation-perfusion ratio and lung functions.