A UV lamp module for the ultraviolet irradiation of a substrate includes a lamp arrangement, a waterproof housing, and first and second airflow zones. The lamp arrangement includes multiple low-pressure mercury lamps each having a longitudinal axis. The waterproof housing surrounds the lamp arrangement and has a bottom side, a top side and at least two side walls connecting the bottom side and the top side to each other, and a beam exit opening on the bottom side which is closed by a beam exit window. The first airflow zone is formed in the housing and has an air supply duct with at least one air-guide for the supply of cooling air to the lamp arrangement. The second airflow zone is separated from the first airflow zone, and is formed in the housing and has an exhaust air duct for the discharge of heated cooling air. When viewed in a cross-section through the housing perpendicular to the longitudinal axes of the low-pressure mercury lamps and in a viewing direction from the bottom side to the top side, the beam exit window, the lamp arrangement and the airflow zones are arranged one after the other.