Methods, systems and apparatuses to help control atmosphere in a storage space, such as for example a storage space of a transport unit are disclosed. Generally, the embodiments herein are directed to provide a desired amount of nitrogen to the storage space to replace oxygen and carbon dioxide while removing the same amount of air from the storage space, which can help maintain a pressure balance between the storage space and the ambient atmosphere. Air directed out of the storage space and ambient air can be directed through an air separation device to separate a nitrogen portion. The nitrogen portion can be directed back to the storage space.
