As far as fumes go, the BALPA study was actually directed at 757,737 and A320 air quality - see
http://www.aopis.org/BALPA757SURVEYp253-262.pdf
The 146 has a longer documented history of fumes, which merely prompted everyone to look at other types. It is interesting that in the Balpa list of the worst offenders, the 146 was second behind the 757. In terms of numbers, the 757 has affected far more people than the 146 has (owing to numbers in service and number of pax carried). The 757 was clearly the focus of concern, no doubt driven by the many BA pilots who have experienced fume problems.
More to the point, the number of fumes incidents on the 146 declined dramatically once the problem was understood, and proper maintenance procedures put in place. Our company was particularly picky about making sure the ducts were clean.
Personally, I think it is outrageous that more has not been done in the way of filters etc, but there you go.
I'd still far rather fly the 146 than the Q400.