Addison Bain is a retired NASA scientist and founding member of the National Hydrogen Association who is credited with postulating the Incendiary Paint Theory (IPT), which posits that the Hindenburg disaster was caused by the electrical ignition of lacquer- and metal-based paints used on the outer hull of the airship. Thus Bain believes that the hydrogen in the airship had no part to play in the initiation of the disaster. This theory, which was proposed in 1997 and recently updated in his 2004 book, The Freedom Element: Living with Hydrogen, has been generally accepted by people interested in promoting hydrogen as a transportation fuel, and generally rejected by people involved with airships and their history.}}[citation needed]