The Green Party has published this picture, claiming that is shows "why we need a very low emission zone for central London ASAP, not in 2020".
It is a map of nitrogen dioxide (NO2) pollution in the congestion charging zone, put together by Assembly Member Jenny Jones.
It is based on NO2 emissions modelling carried out by Kings College London, not on actual readings.
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Overcrowding at Kings Cross also forced staff to evacuate the station with 14,000 passengers caught up in the chaos.
Low cloud rolling in from the North Sea again bringing mist and murk in the north of the London region.
City Hall plans to issue 100,000 tickets with a £10 admin charge to cover the cost of booking, printing, posting and hiring bouncers.