Grosvenor Place, which runs alongside the Queen's London residence, had the highest level of the toxic gas nitrogen dioxide in 2012.
Researchers found 152 milligrams of the gas per cubic metre of air, with a main contributor being diesel engine fumes. The EU legal limit is 40.
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A drunk man who narrowly escaped death when he lay down between train tracks in Harlow has been given a 12-month community order.
A man from north London has been charged with the manslaughter of Louella Eve Fletcher-Michie, who died at the Bestival music festival.
The mother of Ellie Butler - the six-year-old murdered by her father - has lost a bid to challenge her conviction.