Earlier quoted context omitted.
There's a big difference between general "emissions" which a lot of people take colloquially to just mean greenhouse gases (and CO2 in particular with combustion engines), and then the small particulates and other things (like NOx) that create worse local air conditions[1]. Most "modern" diesels in use do still have the latter problem. I think at the very cutting edge, if you maintain a very good filter and operate i…
Most local air pollution, counterintuitively, doesn't even come from exhaust. Wear on tires, brakes, and the road each contribute more individually. There's another process called resuspension that dwarfs even these. Cars grind down large particles sitting on the road, making heavy particles light enough to float in the air. Then the cars' wake kicks those newly light particles into the air, suspending them in the ai…
https://maps.luftdaten.info/#2/0.0/0.0
Building and deploying your own sensor is pretty easy: https://bergie.iki.fi/blog/microflo-particulate-sensors/