Like any internal combustion engine, an ICE running on hydrogen may produce nitrous oxides and other pollutants. Air input into the combustion cylinder is approximately 78% nitrogen, and the N2 molecule has a binding energy of approximately 226 kilocalories per mole. The hydrogen reaction has sufficient energy to break this bond and produce unwanted components such as nitric acid (HNO3), and hydrogen cyanide gas (HCN), both toxic byproducts.