AS 4312 (Atmospheric corrosivity zones in Australia) has been in use for ten years and is still the only standard of its kind in the world. It enables the user to identify the important factors which influence atmospheric corrosion and determine the ISO corrosivity category for a given geographic location. Since its release, an update to ISO 9223 and related standards has introduced a new extreme corrosivity category Cx. Furthermore, corrosivity research carried out around the world has become available to provide more information to better define the corrosivity of locations. This paper describes some of this new information, how it relates to AS4312 and how it may be used to update and improve the standard. This includes guidelines to indicating the location of the Cx corrosivity category, better delineation of the corrosivity zones, especially near the sea, more information on corrosivity in tropical marine environments and some corrections that may be made to the maps currently in the standard.