Volcanic ash cloud – the latest news from SEPA – update 5

  20 April 2010

The Scottish Environment Protection Agency (SEPA) is monitoring the situation regarding the volcanic ash cloud currently affecting the UK and its possible impact on Scotland's environment.

SEPA's Director of Science and Strategy, Professor James Curran, said:

The greatest environmental concern from volcanic ash, and the most significant risk to grazing livestock would be fluoride content in ash deposits. Information from SEPA's analysis of Scottish dust samples, and from similar analysis in Norway, indicates low levels of fluoride in the current Icelandic ash plume.

"The latest rainwater samples analysed also indicate no cause for concern - pH levels are entirely consistent with normal rainwater in Scotland.

"We believe, on the basis of the expected deposition patterns and the nature of the ash, that there is a minimal risk to the environment."

Ongoing monitoring

SEPA has been carrying out monitoring and analysis on four areas of the Scottish Environment – ambient air quality; rainwater; deposited ash particles; and vegetation. Samples collected covering all these areas are being conveyed to SEPA laboratories by SEPA staff, Met Office volunteers and partner organisations such as the Scottish Agricultural College (SAC). Ongoing analysis is being supported by the Macaulay Institute, Edinburgh University and the Scottish Avalanche Information Service (SAIS).

Air quality

The Scottish Air Quality Database (SAQD) contains the most up-to-date continuous ambient monitoring information across Scotland. Members of the public can access this information at www.scottishairquality.co.uk.

SEPA's most recent assessment of sulphur dioxide (SO2) at 0600 this morning (20 April) was that concentrations remain low across Scotland and there have been no significant increases in pollutants. Therefore, there remains no cause for concern.

Radiation measurements are taken across the UK and Europe via the RIMNET monitoring network. Readings show no evidence that the volcanic ash contains radioactive materials of any significance.

Rainwater analysis

Preliminary analysis of 13 samples, 11 from rainwater and two from snow, have been carried out for pH and fluoride levels. pH measures the concentration of hydrogen ions in solution and is the commonly accepted measure of acidity and alkalinity, using  pH units that range from 0 to 14, with 0 to 7 reflecting acidic conditions, 7 neutral and 7-14 alkaline conditions.

Rainwater in Scotland is normally between 4 and 7 pH units. Occasional acidic events are observed in Scotland and pH readings can be as low as 2.5.

The results from the samples analysed by SEPA yesterday are all between 4 and 7 pH units and as such are typical of normal Scottish rainfall.

Currently, a selection of the rainwater samples have also been analysed for fluoride. Results indicate that levels present in the sample are less than 0.05 milligrams per litre. This is very low and is more than an order of magnitude lower than the UK safe levels for drinking water. The national and international drinking water standard is 1.5 milligrams per litre.

All of the results above indicate that there is no cause for concern.

Deposited ash analysis

SEPA is monitoring deposits of ash right across the country and deposition rates remain low.

Photographs of volcanic ash deposits are available to download from our media gallery.

The majority of the particles examined revealed a glassy type material which was angular with conchoidal fractures and which comprised a more complex composition than quartz. The morphology and composition was similar to that of samples which had been previously analysed. A few crystallised silicate grains (quartz) were also evident and these exhibited a very simple composition of Si and O. The latter are most likely to be background contamination.


On behalf of SEPA, the Scottish Agricultural College (SAC) is collecting samples of grass from across Scotland. SEPA scientists will wash the samples and analyse the run off to ascertain if there are any potential hazards for grazing animals and the wider environment.  Given that no adverse effects have been observed in rainwater and dust deposits, we do not expect to see any issues on concern.

Future work

Although it is Spring, there have been recent snowfalls in upland areas across Scotland! Snow is a particularly good medium for absorbing dust particles from the atmosphere. The Scottish Avalanche Information System (SAIS) is now collecting samples of snow on behalf of SEPA and transporting them to our laboratories. As we have already analysed two samples of snow, again we do not expect to find any areas of concern, but this will allows us to provide further reassurance about the environmental impacts.

We will continue our environmental monitoring until the Icelandic eruption subsides.


Notes to editors

Environmental monitoring sites include 75 sites air quality monitoring sites (results available live on www.scottishairquality.co.uk). SEPA also uses data from other local air quality monitoring sites across Scotland.

SEPA evaluates the results from 25 radioactivity monitoring sites across the country. Some locations also have dust filters that are being collected for analysis not only for their normal purpose but also to provide additional samples for volcanic dust analysis.