Who Breathes the Detour? A Coupled Traffic-Emission-Dispersion-Exposure Pipeline

Road traffic is among the largest sources of health-damaging air pollution in inhabited areas. Direct measurement of resident exposure at the scale of an entire corridor remains costly, and existing simulation approaches often target either high-fidelity local snapshots or regional averages, leaving the corridor scale underserved. We present a coupled, end-to-end pipeline that links four stages: (i) microscopic traffic simulation with SUMO, (ii) per-vehicle emissions from the HBEFA4 model, (iii) deterministic three-dimensional Eulerian diffusion solved with an implicit finite-difference scheme on a geometric vertical grid, and (iv) resident-level exposure expressed as an air quality index over a synthetic population. The design deliberately trades the fidelity of full CFD dispersion for a workflow that runs end-to-end for the residential areas of several settlements on a single laptop, and the complete implementation is released open source. We showcase the pipeline at the example of the Swiss Gotthard transit corridor, covering the residential areas of six villages, two days, four scenarios, and three pollutants, to enable assessment of congestion mitigation measures. Code & Material: https://github.com/cedriczeiter/zeiter coupled pipeline.