Now a days it is well recognized that the transport of chemical species through the Planetary Boundary Layer (PBL) of the atmosphere is a key of global change problem (Lenschow and Hill, 1989) and needs more reliable parameterization (Wyngaard, 1990). Also very recently, in the air pollution meteorology, the usual practice of neglecting the concentration correlation in the atmospheric photochemical reaction has been recognized as a source of serious error. The practical application of concentration fluctuations of chemical flow occur whenever the processes of turbulent flow and chemical reaction are merge, particularly when the reactant species are nonuniformaly distributed. The urban air pollution is an interesting case of this problem because the pollutants are introduced in the atmosphere at the various locations so that large concentration inhomogeneities exist before the pollutants are brought togather by movements and mixing large scale masses by atmospheric turbulent winds. This is common in the case of auto exhausts when the pollutants are discharged and subsequently mixed and react in the atmosphere. So, it is important to study the various aspects of the concentration correlation with photochemical reaction. In this study a model of concentration correlation spectrum with photochemical reaction is constructed using the closure model of turbulence given by Hill (1980). The result of this study shows that in the case of pure mixing (without chemical reaction) the concentration of air pollution decays in a natural manner, but if the concentration selected is that of chemical reactant, then the effect is that the dispersion of the concentration of air pollution is much more rapid. The similar results were also obtained by Kumar and Patel (1974, 1975) and Patel (1974, 1975, 1983, 1984, 1992, 1995, 1998, 1999, 2000, 2001) by using different closure models of turbulence.