A household refrigerator appliance (100) comprises a cabinet (110), a refrigerator cavity (111) formed inside said cabinet (110) and a crisper compartment (114) formed in said refrigerator cavity (111). A humidity control device (120) is operably associated with the crisper compartment (114). The humidity control device (120) is a knob mounted on a hole allowing fluid communication between the refrigerator cavity (111) and the crisper compartment (114). The knob has an outer ring (121) surrounding a cap (122), said ring (121) and said cap (122) being movable relative to each other in an axial direction between a closed position, where they engage each other to form a seal against passage of fluids, and an open position, where they are spaced apart in the axial direction, thereby selectively allowing a flow of fluids between the refrigerator cavity (111) and the crisper compartment (114).