01:32DiscoveryThin AirEpisode 2BBC World Service Duration: 27 minutes Thu 27th Jan 2011, 01:32 on BBC World Service OnlineAvailable for over a yearListen nowWe not only live in the atmosphere, we live because of it. It is a transformer and a protector, though ultimately also a poison.GenresFactualScience & NatureFormatsDocumentariesBrandDiscoverySeriesDiscovery: Thin Air Source: BBC Online