A gauge pressure sensor for determining the pressure of a medium by means of a housing and by means of a measuring element, which is positioned in the housing, wherein an outwards facing side of the measuring element is in contact with the medium and is exposed to the pressure, which is to be measured. A tube for a reference pressure is provided, which conducts ambient air to the measuring element, and by means of at least one dehumidifying chamber, positioned in the housing, for the collection of air moisture. The dehumidifying chamber contains a moisture adsorbing material or is primarily composed of a moisture adsorbing material, in that the moisture adsorbing material is at least, in sections, enclosed by a wall, which is composed of a first moisture permeable material, or is at least, in sections, free from a wall, and in that the reference pressure supply tube is at least, in sections, fabricated from a first or second moisture permeable material or in that the reference pressure supply tube has an aperture.