Letter from Iceland

Volcano eruptions occur around the globe. They can affect human health in many ways. This can happen both around the globe but also locally in part of the world. This can occur as a result of airborne dispersion of toxic gases and ash but also through impact on climate.1 Volcanoes are most commonly associated with tectonic plate margins and can therefore be found in many different locations of the world. It is estimated that more than half a billion people worldwide live within a potential exposure range (100 km) of a volcano that has been active within recorded history. Volcanic eruptions can also affect areas thousands of kilometres away from the volcano itself. This can be on a global scale because of impacts on climate or as a result of airborne distribution of ash and gases.2 Volcanic activity can be broadly defined as either explosive or effusive (predominantly quiet emission of lavas).1 Explosive eruptions are of two types. One is magmatic eruptions where the explosive fragmentation is mainly caused by the expansion of magmatic gases and phreatomagmatic eruptions where fragmentation results from the interaction of magma with water.3 Volcanic gases expelled during volcanic eruptions can be highly toxic for humans. They can irritate the mucus membranes of the upper respiratory tract and the eyes at lower concentrations and the lower respiratory tract at higher concentrations. In addition, they can also be very irritating to the skin. The list of volatiles that can be emitted during volcano eruptions includes CO, CO2, SO2, HCl, HF, H2S and radon.1 Volcanic ash refers to fragmentary material emitted from volcanos where particles are less than 2 mm across in size. This ash is irritating for the mucus membranes of the eyes and upper respiratory tract. The alveoli of the lungs can be reached by the smallest particles of volcanic ash as can the bronchial tree. The acute respiratory manifestations after ashfall occurs include nose and throat discomfort in addition to irritation of the chest. Acute exacerbations of obstructive lung diseases such as asthma, chronic obstructive pulmonary disease are seen in addition to episodes of bronchitis. The presenting symptoms commonly are increased cough, breathlessness, wheezing and chest tightness. Inhalation of fine ash can also exacerbate other diseases such as chronic heart problems including ischemic heart disease.3 Volcanic eruptions are common in Iceland and have been since the settlement of Iceland in about 870 AD. They occur every 3–4 years on average. In Iceland, phreatomagmatic explosive eruptions are most common. These often occur in volcanic systems that are partly covered by glaciers.2 Craters of Laki is a volcanic fissure situated in the south of Iceland. On 8th June 1783, a fissure with 130 craters opened.4 The eruption continued until February 1784. It has been estimated that it produced 14 km3 of lava, and the total volume of fragmentary material emitted was 0.91 km3. Gases produced included an estimated 120 million tons of sulphur dioxide and 8 million tons of hydrogen fluoride. This outpouring of gases gave rise to what has since become known as the ‘Laki haze’ across Europe. Throughout the summer of 1783 sulphurous air pollution was widely reported in Europe. Acid deposition and poor air quality caused damage to vegetation and crop failures that was widespread throughout Europe. Extensive asthma-like symptoms and eye irritation were reported in humans.3 In England there were 10,000 more deaths than would be expected for an average year and mortality was more than 10% in excess of the 50-year mean.4 In Iceland over 50% of livestock was killed. This lead to famine that killed approximately 25% of the population of Iceland.2, 3 Geldingadalir Volcano, near Grindavik, Iceland (photo by Miha Rekar on Unsplash.com). More recently there have been volcanic eruptions occurring less than 50 km from Reykjavik and less than 10 km from Grindavik, a fishing village on the southwest coast of Iceland. A volcanic fissure opened in March 2021 after several weeks of earthquakes and it was estimated to be 180 m long. The lava flow soon concentrated in two craters. This volcano produced no ash. The eruption turned out to be an effusive fissure eruption, that released volcanic gases and produced a steady outflow of lava that build up around the volcano. The eruption came to an end in late September, 2021. On 3 August 2022 an eruption started again in the same area but it did not last very long. These two eruptions were very popular by tourists and tens of thousands hiked to see them. Nobody got injured by the eruption itself or by volcanic gases but exhaustion and hypothermia were common in hikers that went there in all kinds of weather. A close surveillance was on the respiratory health of those that were living close by the volcano. An extensive monitoring system was also established to monitor volcanic gases and their distribution. Despite multiple volcanic eruptions during the last decades in Iceland mortality has been low and effects on human health have been limited. However studies on long-term effects are lacking.1-3 These most recent volcano eruptions have not lead to increased hospitalizations or mortality but those with respiratory diseases have reported more symptoms and the sales of respiratory medications increased. The Directorate of Health in Iceland and other services have responded promptly to these recurrent volcanic eruptions over the last few years and given detailed instructions on how to minimize the effects on the public health. Further works for that are ongoing. None declared.