Ryanair and Aer Lingus have cancelled a number of flights because of a national strike in France.
Up to two million people are taking part in the action over pension reforms and a crackdown on illegal immigrants.
French trade unions have said everything from public transport to schools and telecommunications will be affected by today's strike.
There is severe unrest at President Nicholas Sarkozy's intention to raise the retirement age to 62 from 60.
Thousands of people have also protested in French cities against a crackdown on illegal Roma immigrants.
Ryanair said many of its flights will not run as scheduled today with numerous cancellations and delays both to and from French airports and to flights that overfly France.
It has already cancelled a number of flights for today.
Aer Lingus has cancelled two flights this morning both to and from Dublin and Paris and it is warning of news of more delays for the rest of the day.
Passengers are advised to travel to the airport as normal.
But the airlines have said they will do everything possible to minimise disruption.