Rolling coal is one of those idiotic expressions of personal freedom things so beloved by the wingnut peanut gallery and we've got quite enough of that already.
I'm pretty sure that if I go out and remove the catalytic converter from my vehicle, and then drive it, thst it's a $2,500 fine. (Im in the US.)
Perhaps a similar fine is in order for people who have made their diesel engine intentionally run dirty.
Now I will blame part of this issue on the difficulties associated with keeping diesel engine emissions equipment alive. I feel these systems could be made more durable.
Funnily enough, removing your cat. converter is illegal, but getting caught without one isn't. Unless the Fed watches you remove it, they won't fine you.