Now consider that if you inhaled diesel fumes the way one would a cigarette, you would run a high risk of death. You know, like running the car in the garage could easily kill you.
Excuse me, but when did anyone say that you inhale diesel fumes the way a smoker inhales cigarette smoke? If you inhale diesel fumes, you inhale them more in the style of catching a whiff of a straw man being torched. (Incidentally, diving head first from the 10 meter platform into an empty pool could also easily kill you. Amazingly, it's also irrelevant to this conversation.

)
But, you're telling me that just the aroma of a smoker gives you a piercing headache,
It is not the "aroma" of a smoker that gives me a piercing headache. It is a physical reaction to some compound or other in tobacco smoke. The chemicals in cigarette smoke (and I use the term "chemicals" in its scientific form, not in the enviro-nut "Ban DHMO!" manner) are adsorbed to or absorbed by the fabric, and just as you off-gas nitrogen when a pressure gradient exists, when the smoker and his clothes are in my nice non-smoking office, the chemicals are desorbed.
Now, if you want me to stick a heavy smoker in a man trap; sample the gases after a given time period; perform mass spectroscopy, gas chromatography, or other expensive tests; and apply the results to studies of exposure to the various constituents in controlled laboratory studies, I don't have the funding for that. If you want to expose me in controlled conditions to clothing that has been saturated with tobacco smoke (and clothing that has not, and possibly dirty clothes, as an additional control group), all the while measuring my heart rate and blood pressure (and, optionally, doing something like functional MRI or other expensive tests [if necessary, drawing a *little* blood is acceptable -- although I *really* hate needles, this is for science]), I will submit myself for study, provided it is not at *my* cost.
and a puff of diesel just makes you a BIT queasy.
I reject your attempt to misinterpret the word "puff". Replace it by "whiff" if it makes you feel better. Would "Catching a whiff of diesel fumes makes me a bit queasy." make you feel better?
I gotta tell ya, it IS in your head. I believe that you are just mentally making yourself sick.
By your post, I assume you are a smoker? That is indeed some of the best straw-man, misdirection, and denial I've seen in a while. Excellently done, sir, but it serves no useful purpose.
If you're really serious about showing that it *is* all in the heads of the non-smokers, I am at your disposal. I consider myself a man of science, so let's do this thing, and if it's true, I will be more than happy to go on record about that after the study. It is not necessary, of course, but might you wish to wager something as well?