LONDON, ENGLAND - APRIL 02: The Canary Wharf financial district is seen through smog from the soon to be opened Orbit Tower and the Olympic Park on April 2, 2014 in London, England. Dust from the Sahara combined with pollution from mainland Europe has contributed to one of the worst smogs of the year this week with record levels being recorded in parts of England on Tuesday. The BBC weather centre predicts a potential 8 or 9 out of 10 level of air pollution likely to be found in East Anglia and the East Midlands later today. (Photo by Dan Kitwood/Getty Images)