A process for reducing the volatile and semi-volatile organic compounds (VOC and FOG values) of a polypropylene composition to below 150 μg/g (VOC, VDA 278 October 2011) and below 350 μg/g (FOG, VDA 278 October 2011), the polypropylene composition including a polypropylene homopolymer and/or a polypropylene random copolymer, the process comprising the steps of a) providing an aeration vessel having - at least one inlet for aeration gas, - at least one outlet for exhaust gas, - an inlet for a raw polypropylene composition at the top of the aeration vessel, - an outlet for the polypropylene composition at the bottom of the aeration vessel; wherein the polypropylene composition is present as a packed bed. b) initiating a counter-current flow of the polypropylene composition and aeration gas c) by - feeding the raw polypropylene composition showing a VOC value of greater than 150 μg/g and an FOG value of greater than 350 μg/g (VOC and FOG values according to VDA 278 October 2011), into said aeration vessel from the top, - feeding the aeration gas into said aeration vessel via the at least one inlet at the bottom; - withdrawing the exhaust gas via the outlet for exhaust gas; - withdrawing the aerated polypropylene composition via the outlet at the bottom of the aeration vessel d) maintaining said aeration gas flow for an aeration time of from 3 to 96 hours, wherein, the temperature of the aeration gas is from 100 °C to 140 °C, and wherein the Reynolds number of the gas flow is from 5 to 150, whereby the Reynolds number for the flow of aeration gas through the packed bed is defined by formula. Re = ρ v s D / μ where: - ρ is the density of the aeration gas at the temperature used (kg/m 3) - μ is the kinematic viscosity of the aeration gas at the temperature used (kg /m s) - v s is the superficial velocity, defined as Q/A where Q is the volume flow rate of the aeration gas, (m 3 /s) and A is the cross sectional area (m 2) - D is the diameter (m) of the particles. a) providing an aeration vessel having - at least one inlet for aeration gas, - at least one outlet for exhaust gas, - an inlet for a raw polypropylene composition at the top of the aeration vessel, - an outlet for the polypropylene composition at the bottom of the aeration vessel; wherein the polypropylene composition is present as a packed bed. - at least one inlet for aeration gas, - at least one outlet for exhaust gas, - an inlet for a raw polypropylene composition at the top of the aeration vessel, - an outlet for the polypropylene composition at the bottom of the aeration vessel; wherein the polypropylene composition is present as a packed bed. b) initiating a counter-current flow of the polypropylene composition and aeration gas c) by - feeding the raw polypropylene composition showing a VOC value of greater than 150 μg/g and an FOG value of greater than 350 μg/g (VOC and FOG values according to VDA 278 October 2011), into said aeration vessel from the top, - feeding the aeration gas into said aeration vessel via the at least one inlet at the bottom; - withdrawing the exhaust gas via the outlet for exhaust gas; - withdrawing the aerated polypropylene composition via the outlet at the bottom of the aeration vessel - feeding the raw polypropylene composition showing a VOC value of greater than 150 μg/g and an FOG value of greater than 350 μg/g (VOC and FOG values according to VDA 278 October 2011), into said aeration vessel from the top, - feeding the aeration gas into said aeration vessel via the at least one inlet at the bottom; - withdrawing the exhaust gas via the outlet for exhaust gas; - withdrawing the aerated polypropylene composition via the outlet at the bottom of the aeration vessel d) maintaining said aeration gas flow for an aeration time of from 3 to 96 hours, wherein, the temperature of the aeration gas is from 100 °C to 140 °C, and wherein the Reynolds number of the gas flow is from 5 to 150, whereby the Reynolds number for the flow of aeration gas through the packed bed is defined by formula. Re = ρ v s D / μ where: - ρ is the density of the aeration gas at the temperature used (kg/m 3) - μ is the kinematic viscosity of the aeration gas at the temperature used (kg /m s) - v s is the superficial velocity, defined as Q/A where Q is the volume flow rate of the aeration gas, (m 3 /s) and A is the cross sectional area (m 2) - D is the diameter (m) of the particles. - ρ is the density of the aeration gas at the temperature used (kg/m 3) - μ is the kinematic viscosity of the aeration gas at the temperature used (kg /m s) - v s is the superficial velocity, defined as Q/A where Q is the volume flow rate of the aeration gas, (m 3 /s) and A is the cross sectional area (m 2) - D is the diameter (m) of the particles.