Announcing the decision, Lord Carnwath said: “The new government, whatever its political complexion, should be left in no doubt as to the need for immediate action to address this issue.”

The group is now calling for widespread adoption of low emission zones, congestion charging and other economic incentives targeting the worst polluting diesel vehicles.

ClientEarth lawyer Alan Andrews said: “This ruling will benefit everyone’s health but particularly children, older people and those with existing health conditions like asthma and heart and lung conditions.

“The next government, regardless of the political party or parties which take power, is now legally bound to take urgent action on this public health crisis.”

A spokesperson for the Department for Environment, Food and Rural Affairs (Defra) said: “Air quality has improved significantly in recent years and as this judgement recognises, work is already underway on revised plans (since February 2014) to meet EU targets on NO2 as soon as possible.

“It has always been the government’s position to submit these plans before the end of this year. Meeting NO2 limits is a common challenge across Europe with 17 member states exceeding limits.”

Mike Hawes, SMMT chief executive, said: “Policies to improve air quality should focus on encouraging the uptake of the latest low emission vehicles, while also addressing other sources such as electricity generation and heating, which between them account for more than half of NOx emitted in the UK (Defra). Today’s diesel engines are the cleanest ever: high tech filters capture 99% of particulates and NOx emissions are down 84% since 2000.”