Good to know

"The United States and other wealthy nations have less of a problem because they require modern diesel engines to burn much cleaner than they did even a decade ago. Most industries, like mining, already have limits on the amount of diesel fumes to which workers may be exposed."

The risk may be more about those who are heavily exposed to diesel exhausts, such as miners, highway toll booth collectors and some of truck drivers.  If diesel exhaust causes higher rate of lung cancer, europeans should show that as they have much higher diesel cars on the road.  does europeans prove that theory?