IOM: News
Cloud Over Island Paradise:
How IOM helped the people of Montserrat adapt to life after the eruption.
The Soufriere Hills volcano on the West Indies island of Montserrat began erupting in 1995. Plymouth, the island's capital and main population base, is overshadowed by the volcano and now lies under several metres of volcanic ash. It was eventually evacuated in 1996.
Following the eruption, domes of lava formed on top of the volcano and these have continued to grow. Most of the volcanic ash on the island has been created during episodic collapses of parts of these domes. These collapses cause pyroclastic flows - mixtures of hot gases and fine particles that travel downhill at speeds over 100km/hour. The remainder of the ash has been created during volcanic explosions.
Central and southern parts of the island have also experienced frequent ashfalls. These areas were evacuated during 1997 in response to an increased danger from pyroclastic flows and further volcanic explosions.
Soon after the eruption, we were asked to help by the Department for International Development to assess the health risks to the island's residents from exposure to airborne volcanic ash.
Since our initial involvement, we have continued to monitor air quality and assess the risk of exposure on the island. We've been able to provide advice on controlling those risks and have also undertaken some toxicity testing.
The ash itself is composed of a fine silicate material and contains substantial quantities of respirable particles. It also contains unusually large amounts (5-20%) of the crystalline silica mineral, cristobalite.
Exposure to crystalline silica can lead to silicosis and even lung cancer. Exposure to respirable dust can also cause health problems, particularly for those with asthma or other existing respiratory illnesses. Not only that, but tests with cell cultures have shown that the ash is relatively toxic.
An investigation of the health of school children on the island, led by Dr. Peter Baxter of Cambridge University, had already shown that children who lived in more dusty areas were more likely to show asthmatic symptoms.
Our measurements showed that concentrations of airborne ash have been highest in the southern part of the island, close to the volcano. Vehicle movement and activities there, such as cleaning and gardening, disturb deposited ash to create dust clouds, meaning individuals' exposures to airborne dust has depended to a certain extent on their lifestyles.
Most of those who previously lived there would, however, have had to be exposed to volcanic ash for several decades to be at risk of developing silicosis. Since the population moved to the north in October 1997, even those in relatively dusty occupations have been exposed to only low levels of respirable dust and the risks have been greatly reduced.
The volcano has been relatively quiet since February 1998 and rainfall has been unusually high. There is much less ash in the inhabited part of the island and islanders have been able to return to the northernmost part of the area evacuated in 1997. The IOM has provided advice on clean-up procedures in re-occupied areas and undertaken monitoring to provide reassurance as to the air quality.
We've trained the island's environmental health officers on how to monitor dust concentrations and provide warnings of poor air quality for more health-sensitive members of the islands population. About 3,200 residents now live on a crescent of land at the very north of the 39-square-miles British overseas territory. Of the 8,000 others who have fled, 3,000 are in Britain, 3,000 in Antigua, and the remainder elsewhere. Most intend to return after the volcano simmers down which scientists say, could be many years from now.