An\nIntegrated Field Study of Turbulence and Dispersion\nVariations in Road Microenvironments

Traffic-related\nair pollutants (TRAPs) emitted from vehicle tailpipes\ndisperse into nearby microenvironments, posing potential exposure\nrisks. Thus, accurately identifying the emission hotspots of TRAPs\nis essential for assessing potential exposure risks. We investigated\nthe relationship between turbulent kinetic energy (<i>TKE</i>) and pollutant dispersion (<i>D</i>) through an integrated\nfield measurement. A five-year near-road sampling campaign (5 min\nbased) near a light-duty vehicle-restricted roadway and an on-road\nsampling campaign (5 s based) on isolated proving grounds were conducted.\nThe <i>D</i> was first calculated based on vehicle emission\nand pollutant concentrations and then paired with <i>TKE</i> measurements. Here, 198 near-road and 377 on-road measurement pairs\nwere collected. In the near-road measurements, <i>TKE</i> and <i>D</i> showed a positive relationship (<i>R</i><sup>2</sup> ≥ 0.69) with the vehicle flow rate, while they\nshowed similar decay patterns and sensitivity to vehicle types in\nthe on-road measurements. A relationship between <i>TKE</i> and <i>D</i> (<i>TKE</i>-<i>D</i>)\nwas developed through these measurements, demonstrating a robust correlation\n(<i>R</i><sup>2</sup> ≥ 0.61) and consistent slope\nvalues (1.1–1.3). These findings provide field evidence for\nthe positive association between <i>TKE</i> and <i>D</i>, irrespective of the measurement techniques or locations.\nThe <i>TKE</i>-<i>D</i> relationship enables vehicle\nemission estimation with <i>TKE</i> as the sole input, facilitating\nthe identification of emission hotspots with high spatiotemporal resolution.