Effects of atmospheric stability conditions on the pollutants dispersion near roads using CFD

Abstract

This study quantifies the effects of atmospheric stability conditions on the concentration of atmospheric pollutants near roads. We used as a base case scenario the resulting concentrations obtained solving numerically the physics equations that describe the dispersion of pollutants emitted from a road located on a flat terrain under neutral atmospheric conditions i.e. uniform temperature and isotropic turbulence. Then, we added to this model the Monin-Obukhov similarity theory (MOST), which describes the complex interactions between solar radiation, earth surface, and local air flows under different atmospheric stability conditions and fixes the resulting profiles for wind velocity, ambient temperature, and turbulence. We found that the near road concentrations of gas and solid phase pollutants under different stability conditions are highly correlated (R2>0.91) to the concentrations observed downwind the road under neutral conditions. However, when the atmosphere is highly stable or stable, these concentrations are 30% and 7%, respectively, higher than the observed under neutral conditions. Similarly, when the atmosphere is extremely unstable or unstable, the concentrations values are 8% and 7%, respectively, lower than the observed under neutral conditions. Our results are of great relevance for the design of living or artificial barriers located on the sides of the road as an adaptive countermeasure to protect the health of pedestrians or residents living near roads.