Five African countries have announced they will reject shipments of high sulphur diesel from Europe. Ghana, Ivory Coast, Togo, Nigeria and Benin have also demanded they begin receiving cleaner diesel fuel like that available in many other regions of the world.

In contrast, the mayors of four cities – Paris, Madrid, Mexico City and Athens – announced they had pledged to remove diesel vehicles from their cities by 2025.

Allen Schaeffer, executive director of the Diesel Technology Forum (USA), said that the pledge by the four mayors to ban diesel or any other technology ran against the popular consumer choice, may make air quality worse, and is likely to put achieving climate change objectives further out of reach.

“In the United States, cleaner diesel fuel and new diesel engines now achieve near-zero emissions and are an important part of the strategy to achieve cleaner air and reduce greenhouse gas emissions. The new diesel technology also meets the high fuel economy needs of consumers without sacrificing vehicle performance or mobility.”

Schaeffer said the International Council on Clean Transportation and the Climate and Clean Air Coalition, an initiative of the U.N. Environment Programme, has identified policies to promote access to clean diesel fuel and the introduction of modern diesel engines as important elements to generate clean air benefits while substantially reducing greenhouse gas emissions.

“All sources of emissions, including vehicles, stationary and industrial sources, contribute to the emissions challenge of all metropolitan areas and nations. Rather than singling out one fuel and technology, city leaders should be pursuing a holistic approach that accelerates the retirement of older, high emission vehicles regardless of fuel type.”

In France, Spain and Greece, diesel cars make up more than 50 percent of all car registrations, and Schaeffer said to deny them the opportunity to choose the vehicle of their choice and the cleanest diesel technologies available is a short-sighted and ill-conceived policy.

“Manufacturers have already stated that the low-CO2 performance of the newer diesel cars will be a key strategy in meeting the Paris accord. This makes the pledge by these four mayors even more confusing.”

While technologies like electric or hydrogen vehicles may provide new options for consumers at some point in the future, Schaeffer said they were not likely to be available in the timeframes and scale that these cities need to achieve continued reductions in CO2.

He said most major cities faced the mounting pressures of more vehicles on the road, growing congestion, and emissions problems, but moving to ban diesel vehicles was not the answer. He found it ironic that Mexico City had joined the pledge as it had promised and failed to bring cleaner diesel fuel into the country.

“This serious policy failure severely limits the region‘s ability to introduce on a wide-scale regional basis the very clean diesel engines and vehicles that would ensure progress toward clean air objectives.”

Schaeffer said while four city leaders were rejecting new technology, five African countries were taking action that would enable them to dramatically improve air quality and the health of their citizens through embracing clean diesel fuel and technology, not banning it.