The disclosed apparatus can control the cross section of at least one vent opening of an airbag module, through which gases can escape into the environment. The apparatus can include: at least one covering part for at least partially covering the at least one vent opening and an operating mechanism comprising a gas source and an inflatable element in fluid communication with the gas source. The inflatable element can be configured to produce a variation in the outlet cross section of the vent opening in cooperation with the covering part.