Investigation is presented of the evolution of debris clouds generated by the EVOLVE model which has been recently updated. Simulation of debris clouds assumes perturbations due to the Earth's gravitational potential to degree 4, and aerodynamic drag. It is found that above an altitude of 700 km, a debris cloud has sufficient time to become fully developed, and that the orbital elements of Right Ascension of the Ascending Node and the Argument of Perifocus at epoch are lost. These conditions are those necessary for the Direct Simulation Monte Carlo method used to model debris risk. Below 700 km the methodology is still found to be justified when there has not been a recent injection of a substantial volume of debris below 700 km.