Andrew Masterson
Andrew Masterson is a former editor of Cosmos.
About 5000 people across Europe die prematurely every year because of discrepancies between certification tests and real-world driving conditions for diesel vehicles.
That’s the disturbing conclusion arising from a study by scientists from the Norwegian Meteorological Institute (NMI), Austria’s International Institute for Applied Systems Analysis, and Chalmers University of Technology in Sweden.
The finding is the latest to emerge from separate research teams that have all established that diesel vehicle emissions standards are engineered to meet exacting laboratory test standards rather than authentic driving conditions.
As a result, diesel engine contributions to air pollution are much higher – in some cases, the latest study finds, up to seven times higher – than their official certification states.
And this discrepancy, the scientists report, costs thousands of lives each year.
The research, led by the NMI’s Jan Eiof Jonson, found that air pollution in Europe accounts for 425,000 premature deaths every year. Most of these deaths are through respiratory and cardiovascular failure caused by exposure to fine particulate matter – of which various nitrogen oxides (known collectively as NOx) are a key precursor and the principle pollutant emitted by diesel engines.
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Nitrogen oxides from diesel engines are responsible for 10,000 premature deaths every year – but Jonson and colleagues found that roughly half of these were caused by the discrepancy between claimed and actual emissions.
Vehicles in this category are emitting way above the maximum legal limits, but are permitted to do so because their certified emission levels fall beneath the threshold in highly artificial test conditions.
Although over-emitters are being driven across Europe, the particulate matter density differs from region to region. The study found it was at its worst in Germany and Italy.
“This reflects the very adverse pollution situation, particularly in highly populated northern Italy,” says Jonson.
Diesel-powered vehicles are increasingly popular, but especially so in the EU, which is now home to more than 100 million of them – twice as many as the rest of the rest of the world put together.
Ironically, the petrol-driven vehicles they are replacing are, in the matter of NOx emissions at least, much less toxic.
“If diesel car emissions were as low as petrol car emissions, three quarters, or about 7,500, premature deaths could have been avoided,” says co-author Jens Borken-Kleefeld.
The study, published in the journal Environmental Research Letters, adds detail to findings from previous research into NOx emissions and diesel vehicles.
Notably, in the journal Nature in 2016, a team led by Susan Anenberg of Environmental Health Analytics in Washington DC, US, found that one-third of heavy diesel vehicles and half of light ones in 11 markets across the globe exceeded emissions certification limits.
The geographic markets covered by Anenberg’s team accounted for about 80% of annual sales of new diesel vehicles.
The scientists calculated that if lab-test emissions limits were effectively enforced in the real world then diesel-related NOx emissions could be nearly eliminated.
If this was done, they calculated, approximately 174,000 premature deaths could be avoided in the year 2040.
