Heathrow Airport has promised to reduce night flights and curb both noise and pollution if it is allowed to build a new, third runway.
The pledge comes ahead of a government decision expected this summer on whether to expand Heathrow or Gatwick.
Last year, the Davies Commission recommended expanding Heathrow, but with strict environmental restrictions.
But, Gatwick Airport is still fighting, saying it remained the "only expansion plan that could deliver for the UK".
Heathrow said it will allow a longer quiet period overnight, with flights not allowed to land between 11pm and 5:30am, from their current 11.30pm finish and 4.30am start.
The offer falls short of the recommendations made by Sir Howard Davies' inquiry, which wanted a ban on night flights between 11.30pm and 6.00am.
However, it is promising to meet his calls for limits to overall noise and guarantees that local pollution would not get worse.
No guarantee
John Stewart, chair of the anti-noise group HACAN ClearSkies, accepted Heathrow was offering a concession on nights flights but said it was disappointing it would not be extended to 6.00am.
He also questioned whether Heathrow was in a position to reduce air pollution.
"The bigger problem with air pollution is most of it comes from traffic and it's out of Heathrow's control to deal with air pollution from traffic. They can't really guarantee that air pollution levels can be brought down to EU legal limits," he added.
'Cleaner, quieter'
John Holland-Kaye, chief executive at Heathrow Airport Holdings said the airport was going beyond the recommendations of the Davies Commission and he was confident they could create a "cleaner, quieter Heathrow delivering more for the UK economy and that clears the way for the prime minister to make the right choice to expand Heathrow and deliver a stronger economy".
He said more investment in public transport and the use of electric and hybrid cars in the future would limit the impact from traffic pollution.
Mr Holland-Kaye blamed diesel vehicles for air pollution and said he was writing to the new London Mayor, Sadiq Khan, to request that he extended the ultra-low emission zone to the M25.
Mr Khan's manifesto stated that he would oppose a third runway at Heathrow and he favoured Gatwick as the more viable option.
The airport has pledged to create an ultra-low emissions zone for airport vehicles by 2025 and develop an emissions charging scheme for all vehicles accessing the airport.