A device for subjecting air to UV(C) radiation comprises a UV(C) treatment chamber comprising a UV(C) source, a measuring device comprising one or more of a temperature sensor which measures the temperature on the wall of the UV(C) source; two temperature sensors downstream and upstream of the UV(C) source; and a UV(C) sensor for determining the intensity of the UV(C) radiation. The UV(C) source comprises at least one UV(C) lamp which is held by a lamp holder. The lamp holder comprises positioning elements for holding the measuring device and the lamp(s) in a fixed position. Electrical supply wires and signal wires are arranged such that they are shielded from the radiation from the UV(C) lamp(s).