After reading the last two posts, came across this interesting USAToday article from 2002. Seems Alaska Airlines was involved with a significant number of fume events, with the two AC types. I can imagine what the verdict was. Some further research dates events as far back as 1974 for 8 airlines in the US. BALPA research on 93 757 crews also reported 1600 fume events. I think the pull quote is "Mysteries are cheaper than fixes".
http://usatoday30.usatoday.com/money...-cabin-air.htm