Diesel is now better than gas in polluting air

The study, led by researchers in Switzerland and Norway of diesel cars polluting air, with help from Hayes and colleagues in Italy. France and the U.S. looked at carbonaceous particulate matter (PM) emitted from the tailpipes.

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Modern diesel cars emit less pollution generally than cars that run on gasoline. A new six-nation study published in Scientific Reports. The groundwork laid in part by an American chemist now working at Université de Montréal. And since diesel is so much cleaner than before. Environmental regulators should increasingly shift their focus to dirtier gasoline-powered cars and other sources of air pollution, says the UdeM scientist, Patrick Hayes.

"Diesel a bad reputation because see the pollution, but actually the invisible pollution that comes from gasoline in cars worse," said Hayes, 36, an assistant professor at UdeM.

Vehicles required to equip with diesel particle filters

In the lab (at the Paul Scherrer Institute, near Zurich in Switzerland), "gasoline cars emitted on average 10 times. More carbonaceous PM at 22°C and 62 times more at -7°C compared to diesel cars," the researchers noted in their study.

The increase in emissions at lower temperatures is related to a more pronounced cold-start effect. Gasoline engine is less efficient because not yet warned up and its catalytic converter is not yet on, the study noted.

Carbonaceous PM made up of black carbon. Primary organic aerosol (POA). Especially, secondary organic aerosol (SOA), known to contain harmful reactive oxygen species. Also can damage lung tissue. In recent years, newer diesel cars in Europe and North America have been required to be equipped with diesel particle filters (DPFs). Significantly cuts down on the pollution they emit.

These results challenge the existing paradigm diesel cars associated. In general, with far higher PM emission rates, reflecting the effectiveness" of engine add-ons like DPFs to stem pollution.

That said, it is true that older diesel cars do pollute more than gasoline cars. Because they don"t have DPFs, and diesel cars in general emit far more nitrogen oxides. This cause smog and acid rain, the study also noted.

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Over four weeks in a parking lot of the California Institute of Technology, in Pasadena. Hayes analyzed air coming from nearby traffic-heavy Los Angeles, drawn through a tube in the roof of a modified construction trailer.