Packaging machine and method for filling dusting product such as bulk material into open-mouth bags via a filling process. The filling process is controlled by weight via a control device and a weighing device. A batching element conveys product and introduces it through a filling spout into an open-mouth bag appended for the filling process. The filling spout is connected with a collecting tank through a flow connection such that a pressure surge occurring during the filling process is utilized for transferring into the collecting tank the displacing air contained in the open-mouth bag and including the dusting product to receive and settle the displacing air in the collecting tank and to deposit at least part of the dust content of the displacing air in the collecting tank as deposited product.