Aviation officials have opened up the possibility of some transatlantic flights resuming as the volcanic ash cloud continues to cause travel chaos.
The cloud has prevented nearly all flights from entering or leaving the UK since noon on Thursday - wrecking travel plans and leaving thousands stranded.
Air traffic control company NATS said flights in and out of England and Wales would remain grounded until at least 7am on Saturday
But the company added it was lifting flight restrictions in a large part of Scottish airspace, including at Scottish airports, the Shetlands and Orkneys, and in Northern Ireland. This means some North Atlantic services could operate to and from these points.
Health advice has been issued as ash from the volcanic eruption in Iceland fell towards the ground in some parts of the UK. Particles are expected to reach ground level in Scotland later before moving south.
The Health Protection Agency (HPA) said the ash should not cause serious harm but could cause irritation, particularly to those with respiratory conditions.
It advised people with conditions including asthma and chronic bronchitis to carry inhalers and medication with them and those who noticed symptoms, including itchy or irritated eyes, runny nose, sore throat or dry cough, should either return to their homes or "limit their activities outdoors".
But the Met Office said any ash which did reach ground level would be barely visible and the public should not be concerned.
The HPA said weather patterns indicated a "small fraction" of the volcanic plume in the UK's airspace, which could include low levels of sulphur dioxide.