ISO 15906:2007 describes a method for the measurement of the air permeability of baked anodes, by determining the resistance to airflow of a specimen of specified volume at room temperature, within the range of air permeability between 0,01 nPm (nanoperms) and 10 nPm.

"Green" anodes are considered to be impermeable to gas. Therefore, this test is most applicable to "baked" carbon material.