Manufacturers’ lies about how much pollution diesel cars emit have had a role in the Netherlands’ failure to reach European clean air standards, environmental lobby group Milieudefensie says.

If car emissions were actually in line with manufacturers’ official calculations, most parts of the country would meet the target for nitrogen dioxide, the organisation says in Tuesday’s Volkskrant. Milieudefensie bases its claims on figures from the public health institute RIVM.

Diesel cars have been found to emit up to six times the amount of nitrogen dioxide claimed by the manufacturers and the amount of the pollutant in the atmosphere is far higher than would have been expected if the figures were honest.

In particular, people living close to busy roads have been the victims of the cheating, Milieudefensie says. ‘These people will live on average 2.5 months less because of the way the figures have been fiddled,’ spokeswoman Anne Knol said. ‘Their health is suffering.’

However, Eindhoven University researcher Bert Somers told the Volkskrant he had doubts if the air quality at busy traffic hotspots would be much better if diesel car makers had not lied.

‘I can imagine that traffic jams have an enormous impact on the amount of nitrogen dioxide in the atmosphere,’ he said. Diesel cars with idling motors emit a relatively large amount of pollutants, he said.