A modified E-∈ non-hydrostatic model with non-equilibrium level 2.5 closure was applied to the flow and pollutant dynamics in the sea-breeze. The model predicts key observed characteristics of the sea-breeze, such as midday slowing of inland penetration, fast and deep inland penetration in late afternoon, and detachment of the sea-breeze from the feeding flow in early evening. In late evening when the turbulent mixing over the land subsides due to the surface cooling, a frontal density current is formed and the predicted structure is in good agreement with observations and laboratory experiments of density currents. Turbulent mixing over the land is a key parameter that controls midday slowing and late afternoon frontal development. The calculated thermal internal boundary layer and fumigation of an elevated line source show good agreement with observations and similarity theory. Calculations suggest that the residual plume aloft over the sea returns onshore at ground level during the afternoon sea-breeze and has a large impact on ground-level concentrations during the following day.