The House of Lords Science and Technology Committee held an inquiry into air travel and health in 2000. Their findings on the issue of recirculation of air and the transmission of disease are set out below:
1.61 The typical cabin air flow of 20 cfm of air per occupant equates to a full change of cabin air every 2 to 3 minutes, i.e. 20 to 30 times per hour. As half of the air being changed is re-circulated cabin air, this is equivalent to an entire exchange of cabin air with fresh air 10 to 15 times per hour. (Paragraph 5.5)
1.74 On the evidence we have been given, it seems to us that the risk of transmission of infection due specifically to being in the aircraft cabin environment is no greater than elsewhere, provided circulation and filtration systems are working properly. Given the evident success in avoiding transmission of major infections, we do not agree with those who seem keen to attribute any travel-related infectious ailment to augmented transmission within the aircraft cabin environment. (Paragraph 7.17)
1.75 The theory, the facts and the vast majority of our specialist witnesses all support the conclusion that HEPA filtration, if properly installed and maintained, should remove the possibility of cross-infection that would otherwise exist in re- circulatory cabin air systems. We agree that, on the evidence presented to us, the modern aircraft cabin environment generally poses no greater risk of transmission of infection between its occupants than crowded situations elsewhere - and may, indeed, be safer than most of them. (Paragraph 7.25)
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