Background Effective January 1, 2009, the latest version of the Technical Instructions for the Safe Transport of Dangerous Goods by Air issued by the International Civil Aviation Organization (ICAO) added UN serial numbers for dangerous goods, and lithium batteries will be classified as lithium-ion batteries (UN 3090 and UN 3091) and lithium metal batteries (UN 3480 and UN 3481). The regulation states that lithium batteries cannot be transported by air if they do not come with a test report or certificate of approval based on UN38.3.