Diesel Car Emissions Are Higher by 30 Percent on Hot Summer Days

A new research conducted by The Real Urban Emissions (TRUE) Initiative in the French capital Paris is confirming the findings of Dieselgate 2015: in real-world conditions, diesel cars and some two-wheelers tend to emit more air pollution.
Research in Paris shows even newer diesel cars pollute by up to 30% more on hot summer days 12 photos
Photo: Daxtell / Wikimedia Commons
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Studies done in laboratory conditions prior to Dieselgate 2015 included temperatures between 20 and 30C. This summer, however, in Paris, temperatures have topped 30C on 20 different days and, on those days, emissions from diesel vehicles rose by up to 30 percent, TRUE says. Car manufacturers must change their policy to include real-world testing for NOx emissions on a larger scale, the Initiative adds.

Even newer models of diesel cars, marketed as cleaner than their predecessors, still emit more air pollution than they do in laboratory conditions – up to 18 percent more on hotter days. It’s not just diesel passenger cars that pollute more, the research has found: motorcycles, which are often considered cleaner vehicles, also “greatly exceed” averages for both gas and diesel cars.

The research was conducted with support of Paris mayor Anne Hidalgo and analyzed emissions from 180,000 vehicles, including passenger cars and light commercial vehicles, but also buses, mopeds, motorcycles and trucks.

“Dirty diesel vehicles have knowingly been manufactured and sold for decades and these excess emissions alone are responsible for some 38,000 deaths each year,”
Sheila Watson, Deputy Director of the Fédération Internationale de l'Automobile (FIA Foundation), says of the findings of the research.

“These new results show the legacy of that deception and the growing challenges cities face. The unacceptable urban health burden caused by diesel vehicles increases as cities get hotter in terms of both the level of emissions and the health impact of those emissions. This poses huge implications for cities all around the world as we face hotter and hotter summers in a climate crisis to which transport it a major contributor. It also shows that two- and three-wheelers are neither the answer to urban air quality nor traffic issues,” Watson adds.
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About the author: Elena Gorgan
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Elena has been writing for a living since 2006 and, as a journalist, she has put her double major in English and Spanish to good use. She covers automotive and mobility topics like cars and bicycles, and she always knows the shows worth watching on Netflix and friends.
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