How many countries did eyjafjallajokull's eruption in 2010 effect?

The eruption of Eyjafjallajökull in 2010 significantly affected air travel across Europe, leading to the cancellation of over 100,000 flights. The ash cloud spread across many countries, with the most severe impacts felt in the UK, Ireland, France, Germany, and other parts of Northern and Western Europe. In total, the disruption affected air travel in more than 20 countries, causing widespread travel chaos.