Dream Buster - well, as it happens I have been flying the 146 for the last ten years or so. Unfortunately, I have a slightly different tale to tell. My experience is that normally, you only get fumes on APU start if the APU is worn, the ducts are covered in oil, or whoever set the temp controllers screwed up by trying to get the packs to warm up too quickly on a cold day. The 146 I currently fly has yet to produce any visible fumes at all, over the last six months at any rate. More to the point, you need to distinguish between the risks of exposure to the short-lived event that you mention, and long-term exposure to smaller, but longer lived, fume concentrations that occur during flight. Yes, if you deliberately select an old APU and then deliberately misuse the controls, you could induce fumes... but to suggest that this is a normal scenario is somewhat disingenuous, to say the least. And resting your case on a single "expert" is hardly convincing...