Abstract: The present invention relates to a spray drying system provided with a gas filtering system, which system is intended for use in the pharmaceutical industry for aseptic production of sterile pharmaceutical products or in other industries e.g. production of food, where an intake of sterile air for the drying process is necessary. The spray drying system for providing a particulate material comprises a spray drying chamber (3), after treatment equipment (4, 5) placed downstream of the spray drying chamber and a process gas heater (2) placed upstream in relation to the spray drying chamber (3), wherein an inlet filter (1) capable of removing microorganisms at a temperature below 140° C., is placed upstream of the process gas heater (2) and that the process gas heater (2) is a non-flaking heater.