Volkswagen case: Road transport exhaust emissions disparity 'was known'

The gap between official estimates and actual recorded air pollution was known to scientists before Volkswagen's admission that it deceived US regulators in exhaust emissions tests.

Professor Alistair Lewis of the UK's National Centre for Atmospheric Science said that evidence had emerged over the last five years to suggest that road transport was under-reporting its emissions.

He told the BBC that he was "not surprised" that evidence was found for higher emissions but that people would be surprised at the "lengths the company went to" to pass the tough US test.