I never understood how these so-called studies can draw such a definite conclusion. How do the people who ran these studies know for sure that these people who died didn't die from overeating junk food, lack of exercise or by inhaling gasoline exhaust from some old POS pickup truck? Carbon monoxide is the most lethal poison folks, and gasoline engines produce many more times the amount that diesel engines do. The other flaw in this study that I see is that they call buses, trucks and construction equipment "diesels", thus giving diesels a bad name, including passenger cars running on diesel fuel. If diesels are so filthy, then why doesn't anyone install gigantic gasoline engines in buses, trucks & construction equipment? I'm sure they would be a lot cleaner.
