Funded by a DGHI Pilot Grant, this project investigates how air pollution contributes to posttraumatic stress disorder (PTSD). Using a South African longitudinal cohort of individuals with PTSD and trauma-exposed controls, we are testing whether PM2.5 influences symptoms through changes in the gut microbiome or systemic inflammation. The goal is to identify modifiable biological pathways to inform PTSD prevention strategies. We were recently awarded an IBRO–Wellcome Neuroscience Capacity Accelerator grant to expand this work, including conducting lived-experience focus groups and launching the African Exposome and Mental Health Network.