Abstract
The effects of using solid barriers on the dispersion of air pollutants emitted from the traffic of vehicles on roads located over flat areas were quantified, aiming to identify the geometry that maximizes the mitigation effect of air pollution near the road at the lowest barrier cost. Toward that end, a near road Computational Fluid Dynamics (NR-CFD) model that simulates the dispersion phenomena occurring in the near-surface atmosphere (<250 m high) in a small computational domain (<1 km long), via Computational Fluid Dynamics (CFD) was used. Results from the NR-CFD model were highly correlated (R2 > 0.96) with the sulfur hexafluoride (SF6) concentrations measured by the US-National Oceanic and Atmospheric Administration (US-NOAA) in 2008 downwind a line source emission, for the case of a 6m near road solid straight barrier and for the case without any barrier. Then, the effects of different geometries, sizes, and locations were considered. Results showed that, under all barrier configurations, the normalized pollutant concentrations downwind the barrier are highly correlated (R2 > 0.86) to the concentrations observed without barrier. The best cost-effective configuration was observed with a quarter-ellipse barrier geometry with a height equivalent to 15% of the road width and located at the road edge, where the pollutant concentrations were 76% lower than the ones observed without any barrier.
Highlights
In urban centers, vehicles are the main source of fine (d < 10 μm) and ultrafine (d < 100 nm) particles, black carbon, carbon monoxide (CO), and nitrogen oxides (NOx ) [1,2].These air pollutants cause respiratory and cardiovascular problems, chronic diseases, and early mortality in the people exposed to these pollutants [3,4]
These results demonstrate (Figure 4b) for both cases, with and without barrier. These results demonstrate the capacity of the near road Computational Fluid Dynamics (CFD) (NR-CFD) model of reproducing short-term experimental measurements
Via CFD, the governing equations that describe the dispersion of air pollutant emitted by the transit of vehicles in roads in the near-ground atmosphere under neutral conditions, the effects of the presence of solid barriers on the nearby resulting concentration were systematically evaluated
Summary
Vehicles are the main source of fine (d < 10 μm) and ultrafine (d < 100 nm) particles, black carbon, carbon monoxide (CO), and nitrogen oxides (NOx ) [1,2]. These air pollutants cause respiratory and cardiovascular problems, chronic diseases, and early mortality in the people exposed to these pollutants [3,4]. Studies have shown that within urban regions, pedestrians and people living near roads (
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