The Aviation Health Institute seems more concerned that the quality of the air in the cabin is usually set at a mixture of 50% "pure" and 50% recycled air. It suggests that the recycled air may not have all the harmful elements removed should the filtering system be working at less than normal capability.. .. .This time last year, two surveys were announced into passenger health. The UK govt. announced a study into the risk of air travel-related DVT and the quality of air on board aircraft. Other subjects include the transmission of infection, cosmic radiation and the effects of jet lag and work patterns. The results were published in the autumn 2001. There are two reports, the second makes for interesting reading:. .<a href="http://www.aviation.detr.gov.uk/healthcab/aircab/index.htm" target="_blank">http://www.aviation.detr.gov.uk/heal thcab/aircab/index.htm</a>. .<a href="http://www.aviation.detr.gov.uk/healthcab/cabinhealth/index.htm" target="_blank">http://www.aviation.detr.gov.uk /healthcab/cabinhealth/index.htm</a>. .. .The second survey was a three year study to be co-ordinated by the UK Buildings Research Establishment(no kidding!). Tests were going to be carried out on short- and long-haul flights on British Airways, SAS and KLM aircraft. This appears to have been delayed according to this press release:. .. .<a href="http://www.bre.co.uk/press/2002/february/010202cabinair.html" target="_blank">http://www.bre.co.uk/press/2002/fe bruary/010202cabinair.html</a>. . . . <small>[ 13 March 2002, 09:41: Message edited by: newswatcher ]</small>