Cranfield University's study of cabin air quality has served a useful scientific purpose, even if it is not as useful as the test team might have hoped.
Reliably capturing all the constituents of cabin air that has been delivered from engine compressors is not simple. That was Cranfield's first concern when embarking on the programme, led by Professor Helen Muir, whose analyses of cabin evacuation following accidents revolutionised post-crash cabin drills. To aviation's great loss, Muir died of cancer in March 2010.
One vital achievement of the tests is this: they established beyond doubt that tricresyl phosphate (TCP), a neurotoxin suspected to be present in engine bleed air, was indeed found in cabin air during the test programme. The fact that it was present at low levels currently ruled acceptable in non-aviation environments is not reassuring. Cranfield was unable to sample a fume event at the level that mandates a crew report, because no such event occurred. That makes the whole trial inconclusive. What quantities of TCP, in what isomers, would have been detected if a reportable event had occurred? These do happen in airline operations.
Finally, peer review is likely to challenge some of the figures for different TCP isomers captured, because they do not tally with the proportions in which they normally occur together. The Cranfield report is a step along the way, not the destination.