Method and apparatus for producing a large three-dimensional work piece. In a method for producing a three-dimensional work piece, a layer of raw material powder is applied onto a carrier (16) accommodated within a process chamber (12) by means of a powder application device (14), wherein a plurality of irradiation areas (18a, 18b, 18c, 18d) is defined on a surface of the carrier (16). Electromagnetic or particle radiation is selectively irradiated onto the raw material powder applied onto the carrier (16) by means of an irradiation system (20), the irradiation system (20) comprising a plurality of irradiation units (22), each irradiation unit (22) being associated with one of the irradiation areas (18a, 18b, 18c, 18d) defined on the surface of the carrier (16) and being configured to selectively irradiate electromagnetic or particle radiation onto the raw material powder applied onto the associated irradiation area (18a, 18b, 18c, 18d). Fresh gas is supplied to the process chamber (12) by means of a gas inlet system (30), and gas containing particulate impurities is discharged from the process chamber (12) by means of a gas outlet system (32) such that a gas flow pattern is generated within the process chamber, the gas flow pattern being configured such that each irradiation area (18a, 18b, 18c, 18d) defined on the surface of the carrier (16) is overflown with fresh gas which is supplied to the process chamber (12) via the gas inlet system (30) and which, after having overflown the irradiation area (18a, 18b, 18c, 18d), is discharged from the process chamber (12) as gas containing particulate impurities via the gas outlet system (32).