Pollen Dispersion and Deposition in Real-World Urban Settings: A Computational Fluid Dynamic Study

Due to concern with the health and environmental impacts of allergic pine pollen on an urban community in Las Vegas, Nevada, a computation fluid dynamics (CFD) modeling framework was established for investigating the dispersion and deposition of pollen emitted from inventoried pine trees. The framework employs a Eulerian–Lagrangian approach with mesh grids of < 10 m to simulate wind flows and track pollen particle movements around real-world building blocks. The initial assessment focused on a spring pollen episode and a low period following the episode. Model results highlighted that building structures constrained pollen transportation by reducing wind speeds, especially during the low period, and altered pollen distributions, creating hot spots and cold spots at the windward and leeward sides of buildings, respectively, on the pollen trajectories. The majority of pollen particles appear to deposit onto the ground or buildings 1–3 km downwind from the sources through gravitational settling. Multiple model validations are presented, while limitations and potential applications are discussed.