An apparatus (10) for producing a three-dimensional work piece, the apparatus (10) comprises a process chamber (12) accommodating a carrier (14) for receiving a raw material powder, an irradiation device (16) for selectively irradiating electromagnetic or particle radiation onto the raw material powder on the carrier (14) in order to produce a work piece made of said raw material powder by an additive layer construction method, a first gas inlet (22) for supplying gas to the process chamber (12) and a gas outlet (26) for discharging gas from the process chamber (12), wherein the first gas inlet (22) and the gas outlet (26) are configured and arranged in such a manner that a first gas flow (F1) across the carrier (14) is generated, a transmission element (34) which allows the transmission of the electromagnetic or particle radiation emitted by the irradiation device (16) into the process chamber (12), and a second gas inlet (38) for supplying gas to the process chamber (12), wherein the second gas inlet (38) is configured and arranged in such a manner that a second gas flow (F2) in a direction facing away from the transmission element (34) is generated.