Re: I wonder
Older diesels produced visible soot, which although hardly good for you might not be as bad as the smaller particulates made by newer 'clean' diesels.
No idea about NOx levels in older cars.
Plenty manufacturers still making cars which are allegedly EU6 compliant without additives. I'll be more surprised if more manufacturers aren't caught out for cheating.
Peugeot was raided not long ago was it not?