It is a serious crime. Diesel fumes are very damaging to the lungs and heart. Imagine a pregnant woman being exposed to them. There is no logical way to make light of it.
From your link:
> the practice can increase nitrogen oxide emissions as much as 310 times, non-methane hydrocarbons 1,400 times, and carbon monoxide 120 times
From your link:
> the practice can increase nitrogen oxide emissions as much as 310 times, non-methane hydrocarbons 1,400 times, and carbon monoxide 120 times