The government should not approve expansion at Heathrow until the airport can demonstrate it comply with key environmental conditions, says the Environmental Audit Committee.
In a new report, the committee says plans to expand the airport in west London by building a third runway, which were backed by the Davies Airports Commission, should only go ahead if it can be demonstrated that a larger Heathrow can meet legal air pollution limits and be less noisy than the existing operation.
The inquiry by MPs was set up to examine the implications of the commission's recommendations for dealing with the impacts of a third runway on climate changing emissions, air quality and noise.
According to the committee, the additional traffic generated by a third runway would significantly increase local air pollution. It calls on the government to reject the commission's claims that this would be allowable under the Air Quality Directive because of worse pollution performance elsewhere in London.
Huw Irranca-Davies, chair of the committee, said: "The government has a duty to reduce illegal levels of air pollution in London to protect the health and wellbeing of its population. The communities living near to the roads around Heathrow already put up with noise and extra traffic, it would be quite unacceptable to subject them to a potentially significant deterioration in air quality as well. Increased pollution should certainly not be permitted on the grounds that other areas of London are even more polluted."
On carbon emissions, the committee found a significant gap between the commission's theoretical model, which shows the expansion could be achieved within CO2 limits, and the UK's current policy commitments on emissions. The report says the government should set out its approach to international negotiations on aviation emissions and put in place a strategy to deliver aviation emissions no higher than 2005 levels by 2050.
"Even without expansion, aviation is on track to exceed its climate change target," said Irranca-Davies. "We heard evidence that those targets might be met in theory, but at present there is a policy vacuum and evidence-based scepticism as to whether they can be met in practice."
The MPs endorse the commission's proposed ban on night flights but urges the government to establish an independent aviation noise authority, whether or not it proceeds with the expansion at Heathrow.
Responding to the report from MPs, Simon Clydesdale, aviation campaigner for Greenpeace UK, said; "To the surprise of absolutely no-one, the committee has discovered that when you build more runways and fly more planes, carbon emissions, noise and air pollution rise. The Davies commission's insistence that this is not necessarily the case is based on hot air and not facts."
If the government decides to accept the commission's recommendation on expansion at Heathrow, the committee says it will ask the transport secretary to explain how the government intends to deal with the issues raised by the inquiry.
