ClientEarth will challenge the UK government in court for a third time next month following the release of its “incredibly inadequate” air quality plan.

Speaking at the LowCVP annual conference in London yesterday, ClientEarth chief executive James Thornton confirmed the next court case is scheduled for 5 July.

ClientEarth has defeated the government in two legal battles over its plans to tackle air pollution, and Thornton said the revised version the firm demanded after the most recent case still fell short of the mark.

He said: “As great as London is, it’s not yet a very good place to breathe, although the mayor is tackling that. The government could be taking care of it, but it isn’t.”

As an example of what ClientEarth sees as the latest plan’s failings, Thornton told delegates that the appendix of the document states the most effective method of tackling air pollution would be to remove diesel vehicles from city centres.

The main body of the document, however, “says under no circumstances may you restrict vehicles coming into London in this way. So we’re back in court on July 5th”.

Thornton added that even though it is illegal to use economics as a legal defence against improving air quality, the government’s own documentation proves how financially beneficial it would be to clean up the UK’s pollution.

He said: “When you ask the question 'why is the government so neglectful', the answer comes back, for economic reasons. Actually the law specifically prohibits economic answers because it’s a health case standard.

“But even according to the government’s own numbers, air pollution is costing our economy £27.5bn every year.

“Even the government’s new incredibly inadequate plan that we’re fighting in court, they say it will save the economy £555m over 10 years. There aren’t many opportunities to save your own economy £27.5bn a year.”