It emerged this week that Volkswagen rigged software in 11 million "clean diesel" vehicles so that they only passed emission standards when tested.
Since 2009 the cars may have been producing up to 40 times as much harmful smog-forming compounds and particulates than allowed - and analysis suggests an extra 1 million tonnes of air pollution have been added to the atmosphere every year as a result.
The Guardian reports that this is equivalent to roughly the same amount of pollution as is emitted by all of the UK's entire industry and agriculture sectors, power stations, and vehicles on the road.
Volkswagen Group CEO Martin Winterkorn, who is under pressure to resign
Professor Martin Williams of King’s College London told the Guardian that emissions from diesel cars cause roughly 5,800 premature deaths in the UK each year.
If you were to make the cars emit at the legal limit you could reduce those deaths by at least a factor of two and maybe more. Maybe a factor of five.
Professor Martin Williams, King’s College London
In the US, the Environmental Protection Agency has said that Volkswagen has clearly violated the Clean Air Act, and the Department of Justice is considering criminal charges.
The company has had to recall more than 482,000 cars and is looking at £11.7billion in fines.
So why did they cheat? Volkswagen is yet to give a reason why it gamed the emissions tests, but it has been suggested that the company was trying to balance out the negative effects of emission controls on milage and acceleration performance.
The company board is meeting today to discuss Volkswagen's future actions in light of the scandal.