I've worked in trucking (specifically fixing them, in large fleets) for a long time.
Long enough to remember the "smell" of the yard with the trucks starting up in the morning. My passat smells the same way at startup, as it is not equipped with a DPF. Years ago when I would walk through the yard of the trucking company I worked at, the only smell you could sense was that permeating diesel truck smell - it was everywhere. It was even comforting - to me it was the smell of gainful employment, of accomplishing something - that smell meant we were keeping trucks on the road, that I was part of the machine keeping the economy working. As the saying goes, Everything you eat, that chair you're sitting in, that screen allowing you to post your thoughts on the internet... All of it came in a truck.
Every morning I walk through the yard of the trucking company I work at, and you know what I smell these days? Nothing.
Rather I do smell the ambient smells of the surrounding vegetation (we border greenspace), the rotting leaves smell in the fall, the "new" smell of freshly fallen snow etc. Just normal smells.
The reason why I am able to smell those instead of the trucks is all of the emission equipment, most notably the DPFs.
That smell... in the absence of a DPF, is soot, or particulate matter / PM.
Particulate matter is long been correlated with many cancers:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6922579/
It's long, and I honestly don't understand a lot of it, even with a background in statistical analysis. It's a good one, as it aggregates together a number of previous studies, all looking to find the answer to the following - does PM cause cancer?
The answer is yes.
In this brave new world of increased complexity due to emissions equipment on cars and trucks, yes, these trucks are more complex, and have many equipped parts which can cause a shutdown if they fail. However, they don't fail any more often than an old Pete 389 with a CAT C15, they just go off to the side of the road for different reasons.
I have to pay more to repair and maintain my fleet, this requires me to employ more mechanics. Paying them for their work spurs the economy.
The increased cost gets added to the cost of business, and you pay a few cents more for that cup of coffee, or a few $ more for that Television.
The small increases are paid for by the reduction in overall healthcare costs not treating as many cancer patients, and I sleep a little easier each night knowing this is the case.