The Scottish Government is proud of its commitment to reducing emissions. It boasts, with justification, of having devised “the most stringent reduction targets in the United Kingdom”. Given claims that exposure to fine particles in our air is causing around 2,000 Scots to die prematurely each year, the issue is more than theoretical.

Among the least desirable fumes created by our attachment to cars are so-called Nox emissions, specifically nitric oxide and nitrogen dioxide. These help to explain why 80 per cent of urban pollution comes from road traffic and why Glasgow, Edinburgh, Aberdeen, Dundee and Inverness endure stubbornly high levels of toxic air; which is to say, according to campaigners, air that persistently breaches regulatory standards Scotland was supposed to meet as far back as 2005.

Stand at a busy city junction on the wrong day and you can only wonder about the efforts of government. At such spots you will be given a taste, literally, of what is meant by toxic air. If you have a mind, you can also admire vehicles bearing the marques of Volkswagen Aktiengesellschaft.

Or perhaps not. The VW group is, aptly, in bad odour around the world for cheating both nitrogen dioxide emissions tests and its customers. Its “defeat device” will undoubtedly prove self-defeating for the car giant once regulators, politicians and lawyers set properly to work. But the confession that 1,189,906 vehicles with hoodwinking software have been sold in Britain is deeply disturbing.

For one thing, if an 8.3 per cent population share is any guide, this means that 98,762 dodgy VWs, Audis, Seats, Skodas and assorted commercial vehicles are on Scotland’s roads and polluting Scotland’s cities. It suggests, albeit unscientifically, that the noble efforts of the Scottish Government to clean up our air have been subverted, at least in part, by a giant of European industry. The blackest irony of all is that cheated VW customers in Scotland are also victims of our tainted air.

Why has this happened? An answer will cost the company billions, as it should and must. That does not explain the failure of European testing regimes to uncover the scandal before the US Environmental Protection Agency, not for the first time, took a hand. Nor does it explain why the British Government seems content to let VW and European officials handle the aftermath. Instead of a full investigation we have Patrick McLoughlin, the Transport Secretary, urging the company to contact customers and explain what steps it will take to “correct the problem”.

That is nowhere near good enough. The US government ordered a product recall on the basis of “just” 482,000 cars. The UK has a 1.2 million vehicle “problem”. Scotland’s share of that, as a small country, is hideously large. Officially, VW must wait for regulators to approve any kind of European recall scheme. But the public will therefore have a simple question: how can the US authorities act instantly while almost 100,000 polluting cars still spew their nitrogen oxide in Scotland?

A wider issue has yet to be broached. What good is it for governments to devise elaborate schemes to cleanse our environment if multi-national companies can treat public trust and standards with contempt? This is not an argument over a vague, catch-all notion of “pollution”. This is specific; the scandal’s cause has a name, a household name. Trust has been forfeited by the guardians of the VW brand. So what consequences will follow?