Jeff Kleb said:
It all depends upon how you measure the pollution, though. While diesels are often lower in noxious gases, they put out a lot more particulates (soot, etc.) than a gasoline engine.
When the new diesel standards (15 ppm sulfur content versus 300 ppm of recent years) are integrated into the market, you will likely see more and more of them - as is the case in Europe. Over there, diesel is taxed at a lower level than gasoline; which makes oil-burners more economical.
It also is an advantage to diesels that it costs less to produce/refine diesel fuel than gasoline, and diesel vehicles typically get 15 to 20 percent more miles on a gallon.
Soot is far more dangerous than plain CO, it has arsenic and heavy metals present along with the average culpruts such as sulfates and ammonium. And that isn't even mentioning NOx, which will kill you faster than about anything else. I don't know how these new regulations will fare when everyone seems to pander to the semi-truck drivers. To know what soot particles do just drive to Riverside, CA, climb a hill and look towards LA.
<----Stepping down from the soap box