Dublin Airport handled passenger traffic of 1.1 million in January 2010, a 17% decline compared to the same period last year, according to the Dublin Airport Authority.
The decline in passenger traffic was mainly due to industrial action by air traffic control staff in Ireland and severe winter weather, which caused airport closures.
In January, the airport's passenger traffic to and from continental Europe declined by 17%, with 575,000 passengers travelling to European destinations.
UK traffic dropped 17% with 475,000 passengers travelling during the same month.
On domestic routes, 31,000 passengers travelled from Dublin Airport, which is a 42% decline from the previous 12 months.
Passenger volumes to and from North America decreased by 15% with 85,000 passengers travelling from the airport in January.
International traffic, mainly to the Middle East, decreased by 8% with 20,000 passengers travelling from Dublin Airport.