A huge cloud of corrosive SO2 gas swept across the UK this morning and people were warned to stay indoors to avoid the cloud.

Young children and the elderly are most vulnerable to inhaling SO2 and are advised to stay indoors if possible.

The sulphur dioxide (SO2) cloud was emitted by a volcano in Iceland. It is said to have completely covered the UK from around 4am and engulfed half of the country by 8.45am.

The gas is mainly produced by the combustion of coal or petroleum, but volcanoes also produce large quantities of it when they erupt. Exposure to high doses can lead to inflammation of the bronchi and possibly blockage of the airways.

Symptoms of short-term exposure include sore throat, cough, runny nose, burning eyes, tightness in the lungs and difficulty breathing. The gas is colorless, but the smell is often compared to that of rotten eggs.

The eruption occurred on the Reykjanes peninsula, after which many people in Iceland were evacuated for safety reasons.

Iceland has been preparing for the event for weeks and was expecting an eruption due to ongoing seismic activity at the Sundhnukar volcano. Locals were asked to stay away from the area for their own safety.

The British Foreign, Commonwealth and Development Office (FCDO) has issued a new travel warning following a series of volcanic eruptions in Iceland.

An FCDO spokesman said: “Volcanic eruptions and earthquakes are common in Iceland. Recently there have been a number of volcanic eruptions on the Reykjanes peninsula in south-west Iceland, the most recent on 22 August.”

“This affects the town of Grindavik and the area north of it. The Icelandic authorities advise people to avoid this area. All roads to Grindavik and the surrounding area are closed.”

“It is likely that there will be further outbreaks in this location. Follow local media for updates and follow authorities’ advice on travel to the area.”

“Keflavik International Airport and the road to it are unaffected and are operating normally. The capital Reykjavik and the rest of Iceland are not affected by the outbreaks.”

“Volcanic activity in Iceland’s 32 active volcanic systems is closely monitored for signs of unrest.

“The infrastructure is designed to be robust, but not all events can be predicted and can pose risks to your travel plans, such as travel delays and cancellations, toxic volcanic gases, rockfalls and landslides, and sudden and major flooding.”

In May, Scotland’s capital Edinburgh recorded a dangerous rise in SO2 levels, which experts believe was caused by a volcanic eruption in Iceland.