Me, me me... I've done this, I've done that..
The problem with the air quality in aircraft is varied so much that everyone is scratching their head over it, and it isn't dependent on the type of aircraft.
All aircraft use the same type of systems/design with parts manufactured by same people.
All engines leak oil passed internal seals at one time or another, hell some of that 1 qtr-3qtr a day used must find it's way in to the air system?
some aircraft have catalytic converters, ie some 146's, and they do work.
Maintenance? you mean heavy maintanance? All depends on the operator and cost, which will affect how well the packs and the engines are maintained.
Any way i've seen, (been with) crew who had a heavy night, jumped in to an aircraft, they were so ill they grounded the aircraft on the basis of oil smell in cabin which caused them illness!!
same aeroplane Was tested for two days using air quality test equipment.nothing.
Hmmm. too many variebles me think.