Modelling the dispersion of motor vehicle exhaust gases, including building effects, and its application to the calculation of NOx concentration in Osaka City

This paper presents a model for dispersion of NOx from motor vehicles and stationary sources in urban areas. Annual average NOx concentrations from these sources were calculated using the Gaussian plume model. The calculated concentrations were compared with the observed concentrations at 67 air monitoring stations located in Osaka Plain. The effect of mechanical turbulence resulting from buildings is modelled using the vertical dispersion parameter, σz, including surface roughness and initial dispersion spreads given as a function of building height and building–to–land ratio.