Sayeth the BBC: “Diesel engines contribute to the problem in two key ways - through the production of particulate matter (PM) and nitrogen oxides (NOx). Very fine soot PM can penetrate the lungs and can contribute to cardiovascular illness and death”
Diesel engines don’t produce “very fine soot PM”, petrol engines do. Diesel cars have had soot filters fitted to them for years, but it’s only now that there’s a requirement for petrol engined cars to do so.
The technology for reducing NOx has come on leaps and bounds in recent years, but it’s not particularly helped by CERTAIN VEHICLE MANUFACTURERS not implementing them properly, for a better consumer experience. This is a mostly solved problem if there is the will to solve it.