Icelandic airspace was closed over the weekend . Ash cloud prompts cancellation of dozens of flights , . Score: 6 Scientists say ash particles produced by Grimsvotn volcano are less hazardous than those from Eyjafjallajokull .
Ash cloud prompts cancellation of dozens of flights , . Score: 6 Scientists say ash particles produced by Grimsvotn volcano are less hazardous than those from Eyjafjallajokull .