A bid by the Government to delay publishing its plans to tackle illegal air pollution until after the General Election is being heard by the High Court today.
Ministers were given until 4pm on Monday April 24 to set out draft measures on reducing illegal levels of nitrogen dioxide pollution after the court ruled last year that existing plans to meet EU-mandated air quality limits were inadequate and must be improved.
But days before the deadline, the Department for Environment, Food and Rural Affairs (Defra) lodged an application with the High Court to postpone publication of the draft clean air plan until after the June 8 poll.
Mr Justice Garnham will hear the Government's application in London.
Defra said a delay was necessary in order to comply with "purdah" rules on government announcements during the election period.
Environment Secretary Andrea Leadsom told MPs it was "not appropriate" to publish the plan during the pre-election period and pledged to unveil the draft proposals on June 30.
Responding to an urgent question from Labour in the Commons, Ms Leadsom said the move would not delay the implementation of the plans and insisted ministers were deeply committed to improving air quality.
But the move prompted critics to accuse the Government of "pure political expediency" in missing the deadline.
There has been speculation the clean air plan could include potentially controversial measures such as charges for motorists to drive diesel vehicles, which cause much of the pollution, in towns and cities, or a diesel scrappage scheme.
James Thornton, chief executive of environmental law firm ClientEarth, which originally brought the case over the Government's failings on air pollution, said: "This is a public health issue and not a political issue.
"Urgent action is required to protect people's health from the illegal and poisonous air that we are forced to breathe in the UK.
"This is a matter for the court to decide once the Government has made its arguments because it is the Government which has not met, and instead seeks to extend, the court's deadline for the clean air plan to clean up our air."
At the High Court last November, Mr Justice Garnham declared that the 2015 Air Quality Plan (AQP) was legally flawed.
He gave the Government until April 24 this year to produce a draft plan, and July 31 to deliver a final one.
Limits for nitrogen dioxide (N02) were introduced by EU law in 1999, and were to be achieved by 2010. ClientEarth launched its legal action in 2011.
Air pollution is linked to an estimated 40,000 early deaths a year in the UK, and some 37 out of 43 regions of the country are in breach of legal limits for nitrogen dioxide.