Britain has staved off the threat of £300m fines over air pollution in London. The European commission has agreed to give the UK a time extension to meet a key air quality directive, subject to short-term action taken by the UK.

Critics point out the extension offers only a temporary reprieve for the UK and should serve as a "big wake-up call" to Boris Johnson, the London mayor, and the government.

The commission’s environment commissioner, Janez Potocnik, said on Friday morning that the extension on meeting limit values for PM10s – dangerous airborne particles that contribute to thousands of premature deaths in the capital each year – has been granted until 11 June.

But that is on the condition that Boris Johnson’s air quality strategy is revised by June and submitted to the commission for scrutiny by November this year.

London is the only region still in breach of the directive on limit values for PM10s, six years after the standard was first agreed in Europe.

Potocnik said short-term measures will have to be introduced to control "or, where necessary, suspend activities", which contribute to the risk of the limit values being exceeded.

"Air pollution from PM10 has serious impacts on human health. That is why EU legislation sets strict standards. The commission expects member states to clearly demonstrate that they are doing their utmost, in the interests of their citizens, to comply with the standards in the shortest possible time."

Johnson, the Conservative mayor, published his third and final draft of his air quality strategy for the capital in December in the firm belief that it would meet the limit values for PM10s by 2011, despite critics who claimed the plan was "not fit for purpose".

Johnson published figures showing the health impact of poor air quality, which in 2008 contributed to 4,300 premature deaths.

Simon Birkett, the founder and director of Clean Air in London, said: "The mayor has stumbled and fallen after backward steps on air quality. This is a big wake-up call to the mayor and the so-called ‘greenest government’ in the run-up to the London 2012 Olympics."

He added: "Clean Air in London hails the European commission’s temporary and conditional time extension as an ideal mechanism to maximise pressure on the UK to comply with health-based laws. It requires urgent air quality action in London and ‘freezes’ the current enforcement process."

The commission began legal proceedings against the UK in January 2009 for failing to meet air quality standards that came into effect at the end of 2004.

The UK government turned down a first request for an exemption in December 2009 on the grounds that insufficient information had been provided to allow the commission to assess whether the limit values for PM10s could be met by the deadline.

It issued the UK government with a second and final written warning last June to clean up London’s air or be taken to the European court of justice and face fines of up to £300m.

Just days before losing power, the Labour government reapplied for a time extension, granted on Friday.

The decision states that the government’s re-submission "satisfies the conditions set in the directive", with the caveat of short-term measures being put in place.

"It is up to the UK to decide which specific actions to introduce," the commission says. "These could include measures in relation to traffic, construction work, ships at berth and the use of industrial plants or products and domestic heating. London’s air quality plan will need to be revised by 11 June 2011 to include the short-term measures and submitted to the commission."

City hall claims the commission has not seen the full range of measures drawn up because the government submitted its application in May 2010.

A spokeswoman for the mayor said: "This is a welcome recognition of the serious steps that the mayor has taken to reduce PM10 pollution in order to confront the legacy of poor air quality he inherited and that led to this issue being taken to the European commission in the first place.

"We look forward to working with the government to further reassure the commission, and more importantly people in London, that we have robust, sensible and proportionate measures in place to reduce pollution levels ensuring that the capital is as healthy and clean as possible."

The decision gives the UK only breathing space, since the commission has not withdrawn the previous written warnings and can take the government to court if it fails to reduce pollution this year in a fast-track process that could lead to an estimated £300m fine.

Darren Johnson, a Green party member of the London assembly, said: "The reason the European commission have taken the unprecedented step of requiring a set of emergency plans to be drawn up is that they simply don’t trust the UK government and mayor to protect the health of Londoners.

"This country negotiated and agreed these limits on pollution over a decade ago, but politicians at all levels of government have subsequently failed to act. By refusing to withdraw the written warnings the commission has shown that it is prepared to take a tough stance on a problem."

Johnson was heavily criticised by opposition parties for unravelling environment policies put in place by his predecessor, Ken Livingstone, such as his decision to delay by 15 months the introduction of phase three of the Low Emission Zone (Lez), which fines the most polluting vans, and the scrapping of the western extension of the congestion charge zone last Christmas.

But some have sympathy for his claim that the previous Labour government failed to do enough to ensure London was in compliance with air quality directives in the first place.

Murad Qureshi, Labour’s environment spokesman on the London Assembly, said: "If Boris Johnson hadn’t halved the size of the congestion charge zone, cancelled taxi inspections and suspended fines for the most polluting vehicles, London and Britain would be in a much healthier state today. Dirty vans and minibuses would have been off our roads by now but for the actions of this mayor. He has taken London backwards in the fight to improve the city’s air and should take urgent action now to put this right."

Mike Tuffrey, the Liberal Democrat London Assembly environment spokesperson, said: "The case for urgent action on London’s appalling air quality never rested on the views of the EU commission. Londoners’ health is at grave risk and that alone is the reason action [is needed] to tackle air pollution. We need a Clean Air Zone for central London, as cities like Berlin do, and rapid action to clean up buses and taxis. Now more than ever the mayor must act."

http://www.guardian.co.uk/environment/2011/mar/11/britain-300m-fine-london-air-pollution