We developed an integral concentration and diffusion model based on the aerosol theory. We studied the representation method and actualization process for pollution substances under stable and unstable status using the integral concentration model. We studied modeling and computing processes based on reflecting and absorbing barriers using the diffusion model. The model we developed can improve understanding of the change and distribution rules of inner pollution particles in transition rooms. Moreover, it provides a reference for environmental quality control and evaluation, and troublefree operation of the laser experimental system.