For seven years, people in Britain have been forced to hold their breath and wait for a comprehensive plan to tackle the nation’s toxic air crisis. After a series of humiliating defeats in the courts, Friday’s government plan was meant to finally deliver.

But instead ministers hit the brakes and slammed the policy into reverse – the farcical new strategy has even less detail than the one already ruled illegal. What was the impassable roadblock in the way of finally starting to cut the 23,000 early deaths diesel pollution causes every year? Nothing but pure political expediency.

The only sure way to bring the toxic nitrogen dioxide spewed out by dirty diesel vehicles down to legal levels is to keep them out of cities and towns. The law demands the fastest possible action, which means deterring polluting drivers with charges – as will happen in London. But backing new taxes on drivers in the heat of an election campaign promises a political car crash, so ministers have simply swerved and crashed into the nation’s health instead.

The most shocking aspect is that buried in the documents are candid admissions that the crisis is the “largest environmental threat to public health in the UK” and that it is a “direct result” of car makers gaming emissions tests for years, so that their vehicles pump out far more pollution on the road than in the official lab tests.

Ministers even say: “We will continue to press car manufacturers to develop options for recalling existing vehicles to improve their real world emissions performance.” But unlike in Germany and France, the government’s pressing of car makers has driven precisely zero action.

Rather than tackle air pollution head on, the government has passed the buck to local authorities, daring them to impose the needed charges instead and face the electoral consequences. Ministers suggest councils should penalise any diesel cars more than two years old – most of them – but lack the courage of their convictions.

In place of meaningful action, the government’s plan suggests gimmicks such as removing speed bumps and re-phasing traffic lights, measures as likely to increase traffic and emissions as to cut them.

One of the few good parts of the new plan is funds to clean up older buses, lorries and taxis but even this is old money, already announced in the budget. The much vaunted scrappage scheme is mentioned only as a possibility and even then would only cover 0.1% of all diesel cars.

The new plan will leave the nation gasping for years to come and it seems likely that ClientEarth, the lawyers who have twice had the government’s plans declared illegal, will return to the courts for a third time.

The government is likely to view its manoeuvring as a political success, having buried its feeble plan under the local election results. The government’s cynical calculus is that diesel drivers are more of a political force to be feared than people angry about the health damage being caused to them and their children.