Five judicial reviews challenging the legality of the government’s decision to allow a third runway at Heathrow airport have begun in the high court.

Protesters against the decision by the transport secretary, Chris Grayling, to approve the expansion demonstrated outside the Royal Courts of Justice on Monday before the start of the hearing.

One of the legal actions is being taken by a coalition of Greenpeace, the mayor of London and local councils – including the prime minister’s local authority, Windsor and Maidenhead – which will be affected by noise and pollution from the increased flights.

In another action, Friends of the Earth is alleging that the government’s decision to allow the expansion is unlawful because it failed to take account of the need to mitigate climate change under the Paris agreement.

Nigel Pleming QC, representing the boroughs, said the plans could see the number of passengers using the airport rise to an estimated 132 million, an increase of 60%.

He told the court Heathrow is the “busiest two-runway airport in the world” and is situated in a densely populated area. Pleming said: “If the [third runway] is the means of achieving expansion, there will be widespread consequences. There will be hundreds of thousands of additional flights each year across central London, and also affecting the south-east.

“Thousands of people’s homes will be demolished. Hundreds of thousands will experience increased noise, worsened traffic and harmful air pollution.”

Shirley Rodrigues, deputy mayor for environment and energy in London, said: “Toxic air pollution leads to thousands of premature deaths in the capital every year and stunts the development of children’s lungs.

“Heathrow expansion would worsen air quality further, with dire consequences on the health and quality of Londoners’ lives. There is no commitment to new rail infrastructure and expansion is expected to result in at least 40,000 additional vehicles on the roads every day.”

The five judicial reviews are expected to take two weeks to be heard in court, after which the judges will make a decision on the legality of Grayling’s airports national policy statement (NPS).

The government has repeatedly been defeated in the high court in unlinked cases over its attempts to clean up illegal levels of air pollution, with judges saying government plans are so poor as to be unlawful.

Lawyers for the coalition will argue the third runway would involve large increases in road traffic, which would increase already illegal levels of air pollution, and that the increased greenhouse gas emissions from 700 more planes each day would exacerbate climate change.

John Sauven, executive director of Greenpeace UK, said: “Of all Chis Grayling’s bad decisions as transport minister, this one will cost us the most.”

“The idea that yet another runway might be worth the environmental and health costs we all have to pay is ludicrous.”

The go-ahead for a third runway at Heathrow was made through the NPS), the policy framework for expansion at the airport devised by Grayling.

The legal firm Leigh Day, which is representing Friends of the Earth, alleges the policy is unlawful because it amounts to a breach of the UK’s climate change commitments and its duties towards sustainable development.

Laura MacKenzie, climate change campaigner at Friends of the Earth, said the third runway was a “pending emissions disaster”.

“An expanded Heathrow airport would put 700 extra planes a day into our skies, pumping millions of tonnes of carbon into our atmosphere. With the impacts of climate chaos already being suffered by millions around the world we simply cannot allow this to go ahead.”

Leigh Day said the government had already been forced to admit – at a hearing in January – that it held material which indicated more stringent emissions targets were likely to be necessary in light of the Paris agreement before making its decision to approve the third runway.

Rowan Smith, from Leigh Day, said: “The absurdity of the government giving the green light to airport expansion, when all the signs it ignored pointed to the need to make even deeper CO2 cuts in order to avoid catastrophic climate change, is clear.

“All this goes to show that the government fell dramatically short of its sustainable development duties and the decision to give the go-ahead to the third runway was unlawful.”

A spokesperson for the Department for Transport said: “Expansion at Heathrow is a critical programme which will boost the economy, increase our international connections and create tens of thousands of new jobs.

“As with any major infrastructure project, the government has been anticipating legal challenges and will robustly defend our position. We recognise the local impact of any expansion, which is why a world class package of mitigations would need to be delivered.”