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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Here is a timeline of some of the key events in the debate over expansion of airport capacity.
More than 700 households were today bracing themselves for a government decision which could see their homes bulldozed.
Dozens of cats bear the hallmarks of the cat murderer who is suspected to have killed upwards of 100 cats, mostly in the south London area.