Flights in Europe returned to normal Thursday, one week after an Icelandic volcano eruption caused the continent to almost completely shut down its airspace.

But some parts in the Scandinavia, including Iceland, were closed due to high levels of ash cloud, which continues to spew out of the Eyjafjjoell volcano.

The airline industry, facing high costs of passenger refunds, continues to question the governments' decision of the shut-down, while observers have begun to analyze the aftermath of this historic air traffic chaos.

All the continent's major air centers were running at close to full capacity Thursday, with some airlines even adding more flights in a rush to clear up the backlog of passengers.

The European air safety coordination body Eurocontrol hoped "almost 100 percent" of scheduled flights would take off or land on Thursday.

"At the current time, almost all European airspace is available, with a few exceptions in northern Scotland and western Sweden," Eurocontrol said in a statement.

"Today Eurocontrol hopes that traffic will be at normal levels of between 28,000 and 29,000 flights," it said.

The airspace in southern Finland, southern Norway, northern Scotland and western Sweden had to be closed again Thursday, as a change in the wind direction brought volcanic ash from Iceland back into Scandinavian skies.

In a twist of fate, Iceland, which had been able to keep its airports open while the rest of European countries have suspended their flights since last Thursday, is now closing its airspace for the first time because the wind has started to blow ash east towards the capital and its airport.

More than 100,000 flights have been canceled since April 14 when European countries enforced the shutdown following the Icelandic volcanic eruption, stranding millions of passengers. The International Air Transport Association (IATA) put the overall cost of the airline industry at 1.7 billion U.S. dollars.

World Bank President Robert Zoellick put the cost of the air travel for African countries alone at 65 million dollars in lost trade.

The European Commission has stressed that all passengers need to be reimbursed for the costs they incurred during the travel chaos, including tickets as well as accommodation and food expenses, after Ireland's lost-cost carrier Ryanair said it would only pay out the cost of canceled flights.

Ryanair CEO Michael O'Leary later agreed to pay the full cost for the passengers, but vowed to continue efforts to change "absurd" EU legislation so reimbursements were "limited to the ticket price paid in the same way they are for train, coach and ferry operators".

Airlines have questioned and slammed the closures, saying the decision was overreacting and based on unscientific data.

Observers have also feared the travel chaos may cause a profound psychological impact on passengers, making them think twice before choosing the plane.

But travel experts have ruled out any long-lasting impact on the air industry, predicting a quick rebound in the number of passengers.

The Eyjafjoell volcano was spewing far less ash on Thursday and the plume of smoke was low. Scientists are also closely observing the neighboring Katla volcano, which is also likely to erupt.