Purification device for inactivating microorganisms, such as bacteria, germs, mold and/or viruses, present in a medium flowing through the purification device , namely air, with an irradiation device for UV irradiation, in particular UV-C irradiation, of the medium, wherein at least one radiation source is provided in the irradiation device for irradiating the medium and/or the partial flow flowing through the irradiation device , wherein at least one radiation source emits UV radiation in a wavelength range of 250 to 285 nm, wherein a guiding means flow-connected to the irradiation device is provided for supplying a partial flow of the flow of the medium flowing through the purification device to the irradiation device , wherein at least one further guiding means is provided for guiding a further partial flow and wherein the further guiding means does not open into the irradiation device and is guided past the irradiation device and is spatiallyand flow-wise separated from the irradiation device , wherein a blower device is provided for sucking in and/or blowing out the medium, wherein the purification device is designed such that the partial flow emerging from the irradiation device has a higher velocity, preferably by at least 20 %, more preferably by at least 40 %, preferably by at least 50 %, than the at least one further partial flow, wherein the blower device has an actuating means , in particular a valve and/or a butterfly valve, for controlling the volumetric flow of the partial flow guided into the guiding means and at least one further actuating means , in particular a valve and/or a butterfly valve, for controlling the volumetric flow of the at least one further partial flow guided into the at least one further guiding means , wherein a control device is provided for controlling, connecting, disconnecting and/or regulating the volumetric flow of the partial flow and/or the at least one further partial flow. wherein a guiding means flow-connected to the irradiation device is provided for supplying a partial flow of the flow of the medium flowing through the purification device to the irradiation device , wherein at least one further guiding means is provided for guiding a further partial flow and wherein the further guiding means does not open into the irradiation device and is guided past the irradiation device and is spatiallyand flow-wise separated from the irradiation device , wherein a blower device is provided for sucking in and/or blowing out the medium, wherein the purification device is designed such that the partial flow emerging from the irradiation device has a higher velocity, preferably by at least 20 %, more preferably by at least 40 %, preferably by at least 50 %, than the at least one further partial flow, wherein the blower device has an actuating means , in particular a valve and/or a butterfly valve, for controlling the volumetric flow of the partial flow guided into the guiding means and at least one further actuating means , in particular a valve and/or a butterfly valve, for controlling the volumetric flow of the at least one further partial flow guided into the at least one further guiding means , wherein a control device is provided for controlling, connecting, disconnecting and/or regulating the volumetric flow of the partial flow and/or the at least one further partial flow. <EOS>