Ireland's air travel is more exposed compared to any other EU member state in the wake of Brexit, according to CEO of the DAA Kevin Toland.
Mr Toland told the Seanad committee that tourism from the UK to Ireland is already in "freefall".
Meanwhile an all-time high of passengers travelled through Dublin Airport in May, according to a DAA news release.
The record figure of 2.6 million passengers who passed through the airport was a 5% increase compared to May of last year.
European passenger volumes to and from the continent rose by 4% as almost 1.4 million travelled between Dublin and European destinations last month.
Over 843,000 passengers travelled to UK destinations, a 1% increase from last year. Flights to and from the UK account for 39% of air travel, according to the DAA.
Transatlantic traffic to and from North America increased by 18% as almost 321,000 passengers travelled this route sector in May.
Remaining international traffic, mainly to the Middle East, increased by 3% with over 56,000 passengers travelling to Dublin.
Domestic passenger numbers decreased by 9% compared to 2016. Last month, 8,000 passengers travelled on domestic flights.
In the first five months of this year, more than 10.9 million passengers have travelled through Dublin Airport.
Between January and May, the airport welcomed an additional 640,000 travellers, a 6% increase compared to the same period in 2016.
More people also used Dublin Airport as a hub to connect to another destination as 330,000 passengers did so in the year to date, a 51% increase.
Despite May's record traffic, Mr Toland expressed his regret to the Seanad committee that the UK will no longer be part of the open skies arrangement which enables any EU airline to go from one country to another without impediment.
He said the DAA will need to focus on developing long haul connectivity and called for the new northern runway at Dublin Airport to be developed.
