In the present study, the particle formation and evolution processes, and concentration field in the wake region of the studied ground vehicle for stationary (i.e., low idling mode) and moving (i.e., 10 and 30 km/h modes) conditions in a typical high densely urban road microenvironment were investigated numerically using large eddy simulation (LES) with the aerosol dynamics and dispersion model based on the direct quadrature method of moments (DQMOM) approach. The turbulent dilution and dispersion characteristics, and the complex formation and growth dynamics of exhaust particles behind the studied ground vehicle to the atmosphere were taken into consideration. The results show that the processes of nucleation and coagulation are completed in a short distance away from the vehicular exhaust tailpipe exit of the studied ground vehicle. Due to the nucleation, coagulation and strong dilution by the turbulent exhaust plume that take place behind the studied ground vehicle. the characteristics and behavior of the average diameter, and the number and volume concentration of the particles are quite different with respect to the studied driving conditions. (C) 2010 Elsevier Ltd. All rights reserved.