A Supreme Court ruling forcing the Government to do more to tackle dangerously high levels of air pollutants has entrenched divisions over the the proposed Silvertown tunnel.

The ruling came after environmental lawyers ClientEarth took the Government to court for being in breach of European law.

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The result is that measures to tackle nitrogen dioxide (NO2) need to be speeded up, moving to compliance by 2020 – or sooner – not 2030 as originally planned.

In between those dates, around 2021, the Silvertown Tunnel would open – if Transport for London can fend off legal challenges.

The tunnel would aim to take the pressure off Blackwall tunnel and would be the start of a run of east London crossings, including one at Gallions Reach.

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Green campaigners argue that the answer to reducing NO2 – which is a particular byproduct of diesel vehicles – can never be the building of more roads that take more polluting cars.

Friends of the Earth campaigner Jenny Bates said: “In order to meet limits in the shortest possible time we have to be looking at all measures to bring emissions down. We shouldn’t be adding to it.

"We need to rethink things that deliberately add to traffic such as the east London river crossings.

“There has not been a full package looked at for non-road options. We can find solutions that help the economy and respect the environment.

“The directive is clear. The limits have to be met absolutely, irrespective of cost. Effectively, having to fail to meet these limits by 2010 and now 2015 we’re in special measures.”

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The Mayor of London’s senior adviser on environment and energy Matthew Pencharz disagrees. He said: “The Blackwall tunnel is one of the worst pinch points in the entire UK, not just London.

“A lot of the air pollution is caused by the stopping and starting of all that traffic backed up through Greenwich and it is right not only economic development grounds to ease that particular pinch point but also on air pollution grounds.”

Mr Pencharz admits that there will be some areas that would suffer increased pollution as a result of the tunnel but there would have to be a net reduction.

He said: "[The tunnel] is not going to get permission with all the legal challenges that we will inevitably get unless there is an overall reduction in the air pollution impact.

“We’re inevitably going to be [judicially reviewed] over the building of the Silvertown Link and we’re going to have to show to the judges and wider society why it would result in a reduction in air pollution impacts.”