Unfortunately, sensible discussion of cabin air contamination was hijacked on this website last year by a group which appeared to have an axe to grind banging on about 'CO contamination', a very unlikely contaminant in a modern jet transport.
As far as I am aware the most likely source of contamination would be lub oil from a leaking forward compressor bearing seal.
I do not believe that I have ever suffered from contaminated cabin air but I did, at one time, have an ongoing lung problem. It was co-incident with spending long periods of time in Hong Kong.