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.
More top news
When you're trying to concentrate even the slightest sound can be a distraction.
The court heard how Roland McKoy killed his 22-month-old daughter Jahzara out of 'spite and resentment'.
Richard Deakin, the chief executive of NATS, was being grilled by MPs from the House of Commons Transport Committee.