What do you think of the plans?
MPs have said the new Heathrow expansion cannot be justified if it breaches law on climate change and pollution.
Ministers have said the third runway will not exceed environment limits.
The Commons Environmental Audit Committee have said that ministers must show that the new expansion will not fuel climate change.
Committee chair Mary Creagh told BBC News: “There’s plenty of talk about how the government wants to solve environmental problems at Heathrow, but a total absence of any policy guarantees.”
“The implication of this is that they think other sectors of the economy like energy and industry are going to have to cut their carbon emissions even more so people can fly more – but the government’s been told by its own advisors (the Committee on Climate Change) that’s not possible.”
The MPs also heavily attacked the government’s projection of the use of electric cars to help keep pollution levels down.
Creagh said: “The government has missed already its targets for electric vehicles,”
“Our committee has no confidence it will meet its target for 2020 or 2030. Ministers have got to put proper policies in place instead of relying on magical thinking.”