More than 2 million people would be exposed to additional aircraft noise if Heathrow builds a third runway, according to a government analysis.
Ministers have argued that Britain’s biggest airport will affect fewer people with noise in future, due to quieter planes. But government calculations suggest a new runway would still have a negative impact on nearly a million households, or 2.2 million people.
Department for Transport documents, released by the Civil Aviation Authority after a freedom of information request, show the government expects 973,000 households around Heathrow to experience increased daytime noise by 2050 after a third runway is built.
It said 673,800 households affected by Heathrow’s two runways will experience less noise once expansion takes place, making a net 300,000 worse off.
The DfT work was carried out for a revised national policy statement published last year, which gives the green light to Heathrow expansion if approved by a parliamentary vote expected this summer.
Campaigners and parliamentary opponents of expansion accused the government of attempting to bury the figures.
Paul McGuinness, the chair of the No 3rd Runway Coalition, said: “It has long been clear that the DfT have understated the numbers who will be impacted by an expanded Heathrow’s noise.
“So it’s hardly surprising to learn that these calculations were not presented to the public and parliament. The DfT wish to conceal the true impact of expanding this highly disruptive airport.”
According to the Heathrow anti-noise group Hacan, households in Heston, Osterley Park, Brentford and parts of Chiswick and Hammersmith would be brought directly under a new flight path.
When announcing the government’s backing for a third runway in 2016, the transport secretary, Chris Grayling, told the House of Commons: “Even with expansion, fewer people will be affected by aircraft noise than today.”
In February, he told the transport select committee: “If you look ahead 20 years, I expect an expanded Heathrow airport to be quieter than the existing two-runway airport.”
The policy statement acknowledged that 92,700 more people around Heathrow would by 2030 be affected by noise at levels recognised as causing disturbance, although it said the numbers would diminish as plane technology improved.
The DfT said increased noise would be addressed by home insulation and compensation. “We have been clear that expansion at Heathrow would not be allowed to proceed without a world-class package of compensation and mitigation measures for local communities,” a spokesperson said.
“This includes noise insulation for homes and community buildings and a community compensation fund worth up to £50m per year. We have consulted extensively on the options for airport expansion and will continue to engage with MPs and their communities as the proposals develop.”
Heathrow insisted fewer people would be affected by noise than at present, even with another runway. “We stand by our commitment to expand Heathrow while reducing the number of people affected by noise, compared to today. We are currently consulting with our local communities on airspace modernisation, which will redesign how planes fly over Heathrow in coming years,” a spokesperson said.
“Any future modelling of noise impacts must take into account these changes, as well as the stringent mitigation and insulation plans Heathrow will put in place, which will continue to reduce the number of people affected by our operations.”
The airport has managed to double passenger numbers and decrease its noise footprint in recent decades, as the oldest and loudest planes have been phased out. It expects to be held to a 6.5-hour night flight ban as a condition of building a third runway.
Airspace around Heathrow is also to be redesigned, which could see fewer newly affected households, although with 50% more flights, taking the total number to up to 740,000 a year, limiting additional flightpaths would concentrate the burden on areas that are already overflown.
