I googled about this subject and it seems that the info, that I deleted, was from a Boeing website and exaggerated how safe airplane air is. Read this WSJ article: http://blogs.wsj.com/middleseat/2009/05/01/swine-flu-and-travel-qa-on-infectious-diseases-in-airline-cabins/ Airplane air is not as safe as air in your home or in an industrial "clean room", this is corporate propaganda. Read from that link about all those flights where SARS or the flu for example spread among lots of passengers even on flights as brief as 3 hours.