Look, I'm a vehicle engineer and driving enthusiast, and I have been following car emisison science since 1997 and worked with it at some point in my career too.
I'm just giving the information, the whole holier than you is on part of the receiver.
I could also turn it around, on what moral high ground do you think you have the right to (illegally) remove emission devices, and pretend nothing happens just because you don't see the victims and deny the link? Unlike smoking that hits the mostly the one doing it, this hits indiscriminately.
And no, it's not zero, far from. Euro6/7 allow 600 billion particles per driven kilometer, or 600 thousand per driven mm, to put it in units we can grasp. Without GPF that is roughly 10x that, or the same as 10 cars with GPF. On what basis do you think you have the right to make your car as bad as 10 others combined?
Now, I'm not actually taking this stance, it's just how actual preaching could look like.
Pointing the fingers at others doesn’t help. Shipping has through IMO 2020 Global Sulphur Cap and IMO tier I, II and III standards for NOx massively reduced their emissions globally. And new rules will be inforced the coming years also. China, the typical scapegoat, is also making large improvements in may areas.
Neither does playing the victim. Don't see what poor has to do with it, when you're spending money to make it worse....
So everyone has to do their part.
I don't expect people's to put it back, but maybe make an informed decision on the posisble consequences if considering removing it. Also see
post 2 in this thread. Which I made 4,5 years ago, well before I became "holy" lol...