As long as moisture did not get to them too much, the dust should come of relatively easy. If moisture did get to them with the dust, then it tends to "etch" itself on to the model's finish, which could require a bit of polishing into the paint to get rid of. Still in mostly dry conditions, you still need to be careful not to be too aggressive when taking the dust off (blow off as much of the dust, as much as possible.) as the dust and dirt act like an abrasive..... especially on the softer materials like the acrylic molded windshields and windows.....