The Government will not appeal against a High Court ruling on its strategy on pollution from vehicle emissions and will publish the plan by the deadline of May 9, a Downing Street spokesperson has said.
Mr Justice Garnham said a draft plan must be published on May 9 with the July date for publication of the final plan unchanged.
The Government had been seeking a later publication date because it said the report would drop a "controversial bomb" into the mix of local and national elections.
Environment Secretary Andrea Leadsom had told MPs it was "not appropriate" to publish before the election and pledged to unveil the draft proposals on June 30.
But lawyers for campaign group ClientEarth said there were not sufficient grounds to justify the proposed delay, which could cost lives by allowing excessive pollution to continue for longer.
Air pollution causes 40,000 unexplained deaths in the UK each year and associated health complications costs the NHS £20bn per year.
On Monday a spokesperson for Mrs May's said: "We have looked at the judgment from last week and we will not be appealing.
"The court deadline was May 9 and we will be meeting that deadline.
"We will publish at the earliest opportunity after local election purdah is over and before the deadline."
Ministers had been given until 4pm on Monday April 24 to set out draft measures on reducing illegal levels of nitrogen dioxide pollution.
But days before the deadline, the Department for Environment, Food and Rural Affairs (Defra) applied to postpone publication of the draft clean air plan.
It followed the judge's ruling last year that existing plans to meet EU-mandated air quality limits were inadequate and had be improved.
The judge ruled that purdah was in no sense binding on the courts and was not a "trump card" to be deployed at will by a litigant.
There were 64 deaths each day of the year in the UK and that alone constituted circumstances which were "wholly exceptional" and made immediate publication of the plan essential.
Limits for nitrogen dioxide (NO2) were introduced by EU law in 1999, and were to be achieved by 2010.
There has been speculation the government's clean air plan could include potentially controversial measure such as charges for motorists to drive diesel vehicles, which cause much of the pollution, in towns and cities.