Supporters of Airport Expansion. Basis: Economic Growth

Britain's largest and one of the world's busiest Heathrow airport (one flight every 70 seconds at peak times) is full to bursting. There has been no full-length runway built since the 1940s. The UK's attempts to break into the big and fast-growing markets of the emerging world will be thwarted unless it follows the lead of other European countries and upgrades its aviation infrastructure. Jobs, trade and inward investment all depend on the go-ahead for new capacity. This was the conclusion of the independent airports commission. The government finds the economic arguments compelling and has therefore supported the idea of a new runway in Oct 2016.

Thus, the principal argument stated in favour of expanding Heathrow is to enhance the economic growth of the UK. Govt is keen post-Brexit to make trade with long-haul destinations more attractive. Departure from the EU has made the development of alternative markets for exports an even stronger imperative for ministers, who are keen to show that Britain is 'open for business'.

Opponents of expansion- Basis :Environment

Opponents of airport expansion say that growth isn't everything and that once the extra pollution – from cars as well as planes – is taken into account, the new investment will do more harm than good.  There are many advocacy groups, other groups and prominent individuals who are opposed to expansion on the following grounds:

Greenhouse gas emissions: Environmental campaigners were concerned that the increased CO2 emissions caused by the additional flights will contribute to global warming. They argued that the claimed economic benefits would be more than wiped out by the cost of the CO2 emissions.

The World Development Movement has claimed that the proposed additional flights from Heathrow's third runway would emit the same amount of CO2 per year as the whole of Kenya. But government says that carbon emissions will not actually rise overall in the environment since carbon trading will be used to ensure that these increases from Heathrow are offset by reductions elsewhere in the economy.

Community destruction: Some 700 homes, a church and eight grade II listed buildings would have to be demolished or abandoned, the high street in Harmondsworth split, a graveyard "bulldozed" and the "entire village of Sipson could disappear". John McDonnell, MP for Hayes and Harlington, suggested in 2007 that up to 4,000 houses would actually have to be demolished or abandoned, but government defended the plans, saying anyone evicted from their home as a result of expansion would be fully compensated. BAA has committed to preserving the Grade I listed church and tithe barn at Harmondsworth and has given assurances that the value of properties affected by a possible third runway will be protected.

Air pollution: The Heathrow area has breached air pollution limits every year for the last decade. A third runway can only worsen the problem, but the airport and government are largely reliant on national policies to solve it, such as large-scale shifts to public transport and electric cars.

Noise pollution: Heathrow currently complies with noise rules on its flight paths, helped by planes having become a quieter in recent years. But a new runway would expose 300,000 new people to high levels of aircraft noise. A night flight ban, from 11pm to 5.30am, has been promised by Heathrow: currently 5,800 night flights a year are allowed.

Heathrow third runway plans published for public consultation

A four-month public consultation into the decision to build a third runway at Heathrow is under way.

Plan emphasises that aviation expansion is important for the UK both in boosting its economy and jobs and promoting UK on the world stage. Leaving the EU is a new chapter for Britain and is a great opportunity to forge a new role in the world. UK government is determined to seize that opportunity and have the right infrastructure in place to build a more global Britain.

The consultation will run across the UK, including communities that may be directly affected and people who could benefit from connections. Following the consultation and parliamentary scrutiny, the finalised statement is expected to go to a vote in around a year's time.

This statement will commit Heathrow to meeting pledges and conditions for expansion including more domestic routes, noise mitigation for local homes and schools, legally binding targets on noise, and a ban of six and a half hours on scheduled night flights. The airport must also implement measures to ensure road traffic to the airport does not grow, and will be obliged to compensate homeowners at a rate of 25% above market value plus costs for any compulsory purchases needed.