The air drag force on a deposited spherical particle which is present inside the slider airbearing of a computer disk drive has been found to be very substantial. A critical moment model has been proposed for determining the critical condition to detach a smooth spherical particle from a smooth solid surface. Using the model, it has been found that the detachment of submicron particles from computer disk surface by a slider air-bearing is possible. The critical speed for particle detachment from disk surfaces has been calculated, which depends on the adhesion parameter, surface energy and particle size. This model can be experimentally validated using computer disk drives.