Sue, and the rest of you,
The main problem with 146 air quality was that folk used to "burn off" the oil accumulated in the APU through seal leakage overnight, and the old practice of letting the ducts get hot first thing led to a lot of problems. This practice was weeded out a long time ago, and every 146 jockey I know spends more time looking at duct temps than his wallet.
Keeping them under 40' stops the problem and I also not running both packs on the APU makes a lot of differnece as the poor thing isn't running itself to death that way either.
The Q400 has HEPA filters in the recirc, and a very good record on air quality, the 146 is about to be phased out, RIP bless it, and the 195 is pretty much state of the art now, so any problems that did exist are unlikely to resurface.
I can't speak of the 757 cause I know nothing about it, except never sit in 17A if you can help it, but as far as Flybe goes, then except for scaremongerers and agitators, the problem has long gone.
I had 6 years on the 146 with no problems BTW.
Come on in, if you do want to fly, then at least do it with a company that is making money!