Here’s a conundrum for you: In June of this year, the International Agency for Research on Cancer (IARC), part of the World Health Organization, issued a report that raised the classification of diesel engine exhaust and “fumes” to its most deadly level, labeling such fumes “Group 1” carcinogens. It noted that exposure significantly raises the risk of lung cancer, as well as bladder cancer.

IARC made another, perhaps bigger, statement as well: It placed diesel fumes into the same risk category as tobacco and mustard gas. Okay … mustard gas? Really? Last time I checked, this chemical agent packed a vicious punch nowhere near that of diesel fumes. As one of the most infamous and feared weapons devised for the battlefield, mustard gas inflicted severe skin ulcerations, blindness, and respiratory burns on its victims. And now diesel is being placed in the same league as this horrific chemical, despite the hundreds of millions of dollars spent developing emissions control systems to remove harmful pollutants from diesel exhaust?

“Increasing environmental concerns over the past two decades have resulted in regulatory action in North America, Europe and elsewhere with successively tighter emissions standards for both diesel and gasoline engines,” IARC noted in its report. “However, while the amount of particulates and chemicals are reduced with these [technological] changes, it is not yet clear what the quantitative and qualitative changes may translate into.”

Now here’s the rub. The National Petroleum Council (NPC) issued a report dubbed Advancing Technology for America’s Transportation Future, the result of a two-year inquest done at the behest of U.S. Energy Secretary Stephen Chu.

“Diesel engines will remain the powertrain of choice for HD vehicles for decades to come because of their power and efficiency,” the report noted. Indeed, “internal combustion engines will remain dominant because of their lower cost and use in a diverse set of vehicle platforms: conventional gasoline and diesel liquid ICEs, hybrid electric vehicles, plug-in hybrid electric vehicles, and compressed natural gas vehicles.”

Consider this statement in the report as well: “Hydrocarbon liquids have unique properties that make them well-suited as transportation fuels including high energy density, liquid form with easy transport, adjustable combustion characteristics for use in a wide range of engines, and consumer familiarity and risk acceptance,” NPC noted. “For these reasons, they are expected to continue to play a key role in the future U.S. transportation system.” Wow! Guess diesel must be doing something right after all.

“The NPC findings confirm what transportation officials and industry leaders have already long determined—that the continued advancements in clean diesel technology will continue to make diesel the dominant power source for heavy-duty trucks throughout the U.S. for decades to come,” noted Allen Schaeffer, executive director of the Diesel Technology Forum. Something we should keep in mind as the debate over the future of diesel heats up.