It just moves the TCO to the lungs of everyone else.

Why is it impossible to say <thing happens> without everyone around here reading it as <thing happens and I approve>?

My comment intentionally no value judgement yet everyone assumed one.

How much does it increase the TCO?

From a European perspective pretty much any diesel car here that has done over 200,000km will have had the DPF removed. In most countries it's illegal, but it's also not tested as part of the emissions tests (particulate matter in general is not tested, other than 'is there black or white smoke? nope, you pass').

Above this mileage it will become clogged and need to be replaced. If it isn't it will increase fuel consumption, reduce power, and damage the engine if left long enough. They are not off-the-shelf parts you can buy (not that they couldn't be, but nobody buys them), so you need to get a 'reconditioned' one which isn't going to last anywhere near as long. For €2500 or more for parts and labour it doesn't make financial sense, especially when your car is probably valued at a similar amount.

I live in a city center next to a relatively busy road and whenever I replace the filters in my apartment ventilation system every 3-6 months they are always thick black. We don't really have any heavy industry in this city, so I assume most of that is from vehicles.

Looks like this is a problem to be solved with the application of law and order. If a few extrajudicial executions happen along the way, it's just the price we pay for an orderly society.

After all, all lives matter.

Isn't it a little hypocritical to call for law and order and condone vigilantism in the same sentence?

Obviously I'm being sarcastic. The extrajudicial executions are administered by the police, in case that wasn't clear.