Campaigners and community groups across north London fear plans for up to 25,000 extra flights to and from Heathrow will herald increases in air and noise pollution over Hampstead and the surrounding area.

The extra flights, unconnected to the proposed third runway, have been mooted in an ongoing consultation over plans for how Heathrow-bound planes use London’s skies. The airport wants to cut time between alternating flight paths so it can accommodate more planes.

Heathrow is also proposing “independent parallel approaches” – when planes land and take off from the same runway – which would involve new areas being covered by flightpaths.

Some of the options could see Hampstead Heath, one of the highest points in London, overflown up to 27 times an hour at low altitudes at the busiest time of day: between 6 and 7am.

Marc Hutchinson, chair of the Heath and Hampstead Society, told this newspaper the society would be working with groups in Putney and Richmond to oppose any increase in flights.

He said: “It’s not so much about the noise as it is about pollution, too.

“These proposals will only make the situation worse for Hampstead. We’ll oppose this in the same way we’d oppose plans which would bring more traffic to Hampstead.”

Patricia Leonard, who lives in Hampstead Garden Suburb, also has concerns about the consultation. She said: “We don’t want 47 flights an hour over Golders Green. I want to know why only some people have been sent letters about this.”

Hampstead campaigner Jessica Learmond-Criqui agreed.

She said: “First of all, for us, the plans would increase noise and pollution above us. Also, it’s a consultation that’s incredibly hard to fully understand – it’s obtuse.”

Last month, the London Assembly released a report criticising the effect of increasing numbers of flights in London’s airspace.

Caroline Russell, the chair of the assembly’s environment committee, said: “The experiences of residents living with the daily nightmare of overhead noise are deeply worrying. There are significant health impacts that follow from an inability to sleep, relax and concentrate.”

At the consultation’s outset in January, Emma Gilthorpe, executive director for

expansion at Heathrow, said the proposals were “crucial” to the airport’s future and its aim “to design a sustainable, fair and more efficient future airport”.

A spokesperson for the airport said: “We’re currently consulting the public on how to modernise the airspace around the airport, whilst at the same time, developing plans for expansion that treat local communities fairly.

“Our submission to the Airports Commission showed how a combination of quieter planes, quieter airport design, quieter operations and a 6.5 hour ban on scheduled night flights will mean that it is possible to expand whilst affecting fewer people by noise than were affected in 2013. The Airports Commission’s own analysis confirmed that this is possible and that’s exactly the plan we will deliver.”

At the moment, the proposals under consultation only concern “envelopes” where flight paths may be located. According to the current schedule, Heathrow will consult on specific flight path options in 2021.

The consultation is running at heathrowconsultation.com until March 4.