A third runway at Heathrow would triple the number of early deaths from pollution linked to the airport, a new study claims.
In contrast, moving London's main airport to the Thames Estuary would cut the number of deaths, the report by the Massachusetts Institute of Technology and Cambridge University says.
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Tubes, trains, trams, buses, cable cars, river buses, taxis and going by foot - your guide to getting around during the strike.
Union officials rejected a revised offer from Underground managers during a meeting at the conciliation service ACAS this afternoon.
Train drivers were offered £200 a shift to work on the new 'Night Tube' in a bid to halt the threatened walkout.