It is a well-known fact that when meteorite hits surface of the Moon, a part of debris can end up on Earth because the escape velocity for Moon is low - 2.38km/s. A similar effect can be achieved by landing spacecrafts on the surface of the Moon because the speed of rocket exhaust gases in a vacuum are in the range 3.0 - 4.5km/s. Besides launching debris in space, there is a possibility to make them orbit the Moon because orbit velocities for Moon are from 0.92 - 1.082 km/s.
What is the danger of creating an impenetrable cloud of micrometeorites around the Moon if the landings on its surface become frequent?