The device for the treatment of a gaseous medium according to the invention comprises in flow direction of the gaseous medium a plasma-generating device for the generation of a plasma in the gaseous medium. The plasma comprises in particular excited molecules, radicals, ions, free electrons, photons and any combination thereof. Furthermore, the device according to the invention comprises at least one dielectric structure, in particular at least one fused silica tube. The plasma is conveyable into the at least one dielectric structure, in particular after generation in the plasma-generating device.