The biggest disadvantage of AFCs is their high sensitivity to contaminants, especially CO2 which reacts with KOH to form K2CO3, degrading the cell performance and durability. This poisoning has required pure hydrogen and oxygen to be used instead of air, for the CO2 to be removed via absorbers (soda lime, molecular sieves) or by electrolyte recirculation where the electrolyte is passed through a cleaning system to remove carbonates. Using an alkaline membrane as a portion of the electrolyte helps, allowing a lower susceptibility to CO2 poisoning. However, carbon dioxide still affects the performance of the Alkaline Membrane Fuel Cells (AMFC) .