982496 - Dispersion Modeling of Gaseous Emissions from Mobile Area Sources by Incorporating Wind Shear Near the Ground

The vehicles that are normally operated on highways including cars, motorcycles, buses, and trucks are significant pollution sources in urban areas. The emissions from these sources vary based on the type of combustion, fuel category, the grade of fuel, and age of moving vehicles. Exposure to these emissions has been associated with adverse health effects. The level of exposure can be estimated by predicting these emissions and the estimation of the ground-level concentration of pollutants, which involves numerous complexities. This paper presents a dispersion model by considering the mobile sources as an area source. The model uses an analytical solution of the convective-diffusion equation for an infinite area source. The existing models in this category do not consider directly the effect of wind shear (magnitude) near the ground. The model development includes the specification of associated dispersion coefficients based on atmospheric turbulence work. The input data for the source, meteorology, and atmospheric turbulence are discussed under different atmospheric conditions. Vertical dispersion coefficients for different atmospheric conditions include a term for additional spread due to the vehicular wake. The sensitivity of the model is examined to compute the ground-level concentrations of gaseous pollutants for different downwind distances.