Ash, gases and particles emitted from volcanic eruptions cause disruption to air transport, but also have negative impacts on respiratory and cardiovascular health. Exposure to sulphur dioxide (SO₂) and sulphate (SO₄) aerosols increases the risk of mortality, and respiratory and cardiovascular hospital admissions. Ash and gases can be transported over large distances and are a potential public health risk. In 2014-15, the Bárðarbunga fissure eruption at Holuhraun, Iceland was associated with high emissions of SO₂ and SO₄, detected at UK monitoring stations.

We estimated the potential impacts on the UK population from SO₂ and SO₄ associated with a hypothetical large fissure eruption in Iceland for mortality and emergency hospital admissions. To simulate the effects of different weather conditions, we used an ensemble of 80 runs from an atmospheric dispersion model to simulate SO₂ and SO₄ concentrations on a background of varying meteorology. We weighted the simulated exposure data by population, and quantified the potential health impacts that may result in the UK over a 6-week period following the start of an eruption.

We found in the majority of cases, the expected number of deaths resulting from SO₂ over a 6-week period total fewer than ~100 for each model run, and for SO₄, in the majority of cases, the number totals fewer than ~200. However, the 6-week simulated period with the highest SO₂ was associated with 313 deaths, and the period with the highest SO₄ was associated with 826 deaths. The single 6-week period relating to the highest combined SO₂ and SO₄ was associated with 925 deaths. Over a 5-month extended exposure period, upper estimates are for 3,350 deaths, 4,030 emergency cardiovascular and 6,493 emergency respiratory hospitalisations. These figures represent a worst-case scenario and can inform health protection planning for effusive volcanic eruptions which may affect the UK in the future.