Diesel cars account for 44% of traffic in Belfast
Tens of thousands of diesel cars and vans are still clogging up Belfast's roads, despite drivers being encouraged to move away from them in favour of cleaner fuels.
Figures from the Department for Transport and the DVLA show that 49,812 new and existing diesel cars were registered in 2017 in the area - 44% of all cars. There were also 8,725 registered diesel vans.
Despite the questions asked of diesel technology following 2015's Volkswagen scandal, in which the German manufacturer was found to be cheating emissions tests, 1,223 more diesel-powered cars were registered in Belfast last year than in 2016.
The UK government has since announced proposals to ban sales of new diesel cars from 2040, as well as exclusively petrol-powered vehicles.
Around 40,000 premature deaths every year are linked to the country's poor air quality.
It signals a remarkable turnaround in the popularity of diesel, with Gordon Brown introducing tax breaks on new diesel-powered vehicles as recently as 2001.
RAC spokesman Simon Williams said: "The number of registered petrol cars reached a peak in 2004 and then began to fall as more people opted for diesel, to the point where we now have 12.3 million on Britain's roads.
"The tide has now begun to turn as motorists go back to petrol, or choose an alternatively fuelled vehicle, as a result of emissions from diesel vehicles being found to be harmful to health.
"We are unlikely to see the number of registered diesel cars peak for a few years as, while sales of new diesels have declined, they are still contributing to their overall numbers rising as they far outweigh those being scrapped."
In total, 128,732 vehicles were registered in Belfast last year, 1,817 more than in 2016.
There were 643,550 diesel cars and vans registered across Northern Ireland in 2017, and 16.8 million across the UK - an increase of 3% on 2016.