DAA has confirmed it has increased its buyout offer to residents who will be affected by a planned second runway at Dublin Airport.

A total of 38 residents will be offered 30% above market value for their homes.

This follows the decision by An Bord Pleanála last March to give a five-year extension on permission for the €320 million project, which was due to expire this year.

However many local residents are farmers and point out that the offer only applies to farmland or businesses.

Many other houses in the area only qualify for sound insulation

Joe Kenny of the St Margaret's The Ward Residents Committee said there is also concern at the possiblity of increased nighttime flights, which he said has a proven adverse effect on health.

He said current practice in Europe is to reduce nighttime flights.

DAA hopes to ease restrictions in the 2007 permission which would prohibit nighttime flights on the new runway and limit those on the existing runway to 65 a year between 11pm and 7am.

However Siobhan O'Donnell, head of External Communications with DAA, said nighttime flights have increased since then to 100 a night.

To comply with the 2007 limit would mean 3 million less passengers a day.

She said Dublin Airport does not compare to most other European capitals as it is mainly surrounded by green space.

With improved noise controls and quieter aircraft she said only five houses would qualify for the buyout offer under current readings.

But she said DAA is keeping the offer to the original number 38 houses identified and increasing the above market offer from 20% to 30%.

A separate residents group - the St Margaret's Concerned Residents Group - and 22 St Margaret's Residents are taking a legal challenge against An Bord Pleanála's decision, which is due to be heard in the Commercial Court on 3 October.

Today Ryanair became a notice party to the legal proceedings.

Its director of operations said in a sworn statement that the runway is essential to the airline's expansion and development.

DAA is hoping to have the second runway built by 2020.

However it is facing opposition by residents groups across North County Dublin including Portmarnock, Baldoyle and Swords who have organised an umbrella group - Fingal Organised Residents United Movement (FORUM).