It was hardly a consideration for former health minister Micheal Martin when he introduced the smoking ban last year. But one unintended by-product of his legislation is that it serves as a useful tool in gauging the crowds at Dublin airport, writes John Downes

Whereas before you could smoke in the airport's bars and restaurants, the smoking ban has meant that both the entrances and exits to the country's largest airport are now official and unofficial smoking areas.

So - as was the case for most of yesterday morning - if there are a lot of people smoking by the front entrance to the departures lounge, then it is bound to be pretty busy inside.

Dublin airport is under stress. Sometimes that stress can be crippling, and is reflected in the faces and anxious minds of people who arrive into a sea of shapeless humanity, without any indication of where a check-in queue might begin or end. Traffic through the airport has gone from 14.3 million a year in 2001 to 18.4 million expected this year, a huge jump.

Latter-day national prosperity and competition in the cheap-flight sector have meant thousands who would once have holidayed annually in Brittas are taking several overseas breaks a year.

Bank holiday traffic has gone up 50,000 in four years, from 275,000 to 325,000. Yesterday was one of the busiest days of the airport's year, with an estimated 78,000 to 80,000 people expected to arrive and depart. The day before, Sunday, was the busiest in the history of the airport, with 86,000. But, to be fair, there seemed little panic, and responses to the state of the place varied significantly.

Some people were glad to be getting away on, or returning from, relaxing holidays. Others were unhappy with the level of "flash" congestion which appeared from time to time, and with relatively little notice. But the airport building was only moderately busy for most of yesterday morning. The horror stories of jam-packed departure halls, even at 5.30 am in the off-season, were not repeated.

However, at the check-in desk, the much-maligned security channel or at the boarding gates, patience was definitely a virtue.

Throughout the morning, areas 10 and 11 (mainly for City Jet, Air France flights and charter flights) and the neighbouring areas 12 and 13 (for transatlantic and other charter flights), saw huge lines of people. The Ryanair and BMI check-in desks further along the way were also busy most of the time.

The result? Queues trailing snake-like around the corner, so that anyone entering the airport got the distinct impression of disorganised chaos.

Cordula Mullerke, from Ardennes in France and flying to Paris after a 10-day visit to Ireland, was watching the scene near area 10 with interest.

"People are waiting for area 11. And people who want to access area 10 can't get through . . . it all seems haphazard," she said. "Although I suppose every airport in the world is like this."

Extra customer-service agents in yellow T-shirts, deployed by the Dublin Airport Authority (DAA) for the weekend, tried their best to deal with the situation. The DAA says the problem is partly due to people arriving too early for their flights. But that was too often compounded by the fact that only one or two check-in desks were in operation to deal with upwards of a hundred passengers.

A spokeswoman for the DAA acknowledged as much. Some airline agents are more responsive than others to the need to open up more check-in desks, she said. The airport building does not have enough depth to install horizontal check-in desks, which might help eliminate some of the congestion, she added.

Later, standing at the group meeting point in the arrivals area, Trevor Foster from Australia, making his first trip to Ireland with a group of friends, said the arrivals hall was "chaos".

"Everybody seems to be going left, right and centre. Nothing seems to be organised," he said. "There's also only one place for people to come out as well. It's too cramped - but I suppose back in Sydney it's probably something similar."

The overall negative image of Dublin airport owes something to the campaign fronted by the flamboyant Ryanair chief, Michael O'Leary. O'Leary has labelled Dublin airport the "black hole of Calcutta". Ryanair has also launched a High Court challengeto the decision to award ownership of the proposed second terminal to the DAA.

The company says it is concerned the DAA will build "over-specified facilities" which will increase debts and charges, imposing additional costs on Ryanair and other airport users.