There are many man-made and natural threats to public health. These can impact on human health, economic and political stability, trade and tourism and affect our access to goods and services. One such threat was the fall-out from the volcanic eruption in Iceland early in April 2010. The explosive eruption of the Eyjafjallajokull volcano blew a dense ash cloud over Iceland that reached heights of between 6 to 11 kilometres into the upper atmosphere [1] and the wind blew the ash towards the UK and other European countries. Due to previous experiences associated with aircraft flying through dense volcanic ash, all airports in Britain and Northern Ireland were closed. Edinburgh Airport activated its emergency arrangements to deal with stranded passengers, with advice being given via the media. There was widespread anxiety about the disruption of air travel, how long it would last and whether volcanic ash would have an impact on human health when it settled on the ground. At national and local level multi-agency arrangements to respond to an emergency were put into action. This event was unusual because it caused disruption in high income countries.

Volcanic ash and SEPA

The Scottish Environment Protection Agency (SEPA) is responsible for protecting and improving the environment in Scotland [2]. They regulate activities that may pollute the physical environment, for example, air, water or soil. Volcanic ash contains potentially harmful substances in the form of water-soluble materials, mostly acids and salts, which cling to the particles and have the potential to become an environmental hazard. When an incident such as an ash cloud occurs a systematic hazard assessment is undertaken as quickly as possible to assess the size and composition of ash particles so that the risk of harm can be assessed in different regions. Decisions are then made on whether there are immediate risks to health, whether people or animals staying in affected areas are at risk following an eruption, and whether crops and natural resource, for example, water, remain fit for consumption. The potential risk varies with the weather so local knowledge of the hazard and plans to minimise risk are important.

Air quality monitoring, laboratory and modelling studies have produced national and international air quality standards and limits to the acceptable concentrations of specific airbourne hazards. In the first week of the volcanic ash incident rain/ snow samples were submitted to SEPA for analysis. A microscopic examination of the samples collected on the ground in Scotland showed that the dust contained particles typical of volcanic material. The concentration of chemicals in the air, close to the ground and in the particles that settled on the ground, was so small that they were unlikely to cause significant health impact. The Automatic Urban and Rural Network (AURN) air quality monitoring station at St Leonards, Edinburgh measures particulate matter concentrations at ground level. On 10th April 2010 it picked up volcanic ash particulate levels that were not hazardous to health. The picture was similar across the rest of the UK as well.

The information and modelling generated by SEPA and Met Office enabled Health Protection Scotland to provide information to policy makers and health advice to the general public. In Scotland, volcanic ash caused few health problems, because the ash cloud kept very high up in the atmosphere and only small quantities of dust settled at ground level, but did generate much anxiety and, as we have seen in the case of Eyjafjallajokull, caused major disruption to travel and transportation services.

Air quality monitoring for airborne hazards

The recent volcanic eruption, with the widespread effect on air transport and the uncertainty on the health impact, illustrates the need for real time air quality monitoring to inform decision making. Following the Buncefield petro-chemical fire in December 2005, it was recognised that new ways of assessing the risk of potential adverse events was required as the previous method of risk assessment had not identified the main threats to health found in this fire: vapour cloud formation, flash fire and explosion [3]. Over the last five years, the Directorate of Public Health and Health Policy in NHS Lothian has increased its focus on the role of the physical and built environment on the public’s health. We have developed a process for assessing planning applications that are subject to pollution prevention and control regulations and respond to concerns from local residents and partner organisations.

Box 1

Large scale factory fire in West Lothian

In the early afternoon on Thursday 16th September 2010 the peace and quiet of West Calder was shattered by the sirens of 12 fire engines racing to Brucefield Industrial Estate. A large scale fire had taken hold in a print factory and about 70 firefighters were needed to tackle the blaze.

This was a significant incident that required the evacuation of many local businesses and the re-routing of local rail services.

Residents in Murieston were advised to stay indoors and keep windows closed.

Mutual aid was provided by Fife, Central, Tayside and Strathclyde Fire and Rescue Services and further resources were provided by Lothian & Borders Police, the Scottish Ambulance Service, NHS Lothian Public Health and Health Policy Directorate, Network Rail, SEPA, Edinburgh Scientific Services, Scottish Water and the WRVS.

It took about six hours to bring the blaze under control and surrounding roads in the area were closed until the following day.

In addition to the proposal for changes in the approach to planning the location of facilities with the potential to have an adverse impact on health, a committee of air quality specialists called an ‘Air Cell’ has been established. The role of the committee is to improve and provide risk assessment, monitoring and alerting capabilities in England and Wales and provide advice for action. Scotland has developed a similar system called ‘Airbourne Hazards Emergency Response’ (AHER) an air quality monitoring and modelling service for responding to incidents and emergency situations. This will enable SEPA, Health Protection Scotland, Health Boards and other agencies to carry out rapid and high quality public health risk assessments based on real time air quality monitoring and complex modelling data. The information generated will enable responding agencies to provide more appropriate and timely responses, particularly during an incident. NHS Lothian represents Scottish Health Boards on the liaison group. It is hoped that when fully established the AHER services will be used to support response to small incidents such as the recent fire at the printing factory (see Box 1) in Livingston, West Lothian.

The main outputs from this initiative will be:


The Eyjafjallajokull volcanic eruption was a large scale event with little actual health impact on the physical health of the public. There was, however, an immediate social and economic impact on many individuals, organisations and countries, and the effect was felt globally. The event was a reminder of the effect a large scale disaster can have on every day life, and its potential to affect large numbers of people. This scenario could have arisen if the gases had been poisonous and found in the air close to the ground. The management of such a disaster would have required timely air quality modelling information to support the complex coordination, management and control of the health effects.

Key points

Source: Walter Hays [4]

*Pyroclastic flow: a fast-moving current of super-heated gas (up to 1000C) and rock which reaches speeds moving away from a volcano of up to 450 mph.

*Lahar: a type of mud flow composed of a slurry of pyroclastic material, rocky debris and water.


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