Even though the amount of airborne Saharan dust carried towards the Atlantic has decreased since the 1980s, the intensity of the haze in the Canaries has been increasing since 2020
Scientific studies carried out in the Canary Islands to analyse the physico-chemical properties of this dust have proven that the Saharan dust haze, known as calima, affects health, the environment and the climate.
Sergio RodrÃguez, a Lanzarote scientist at the Spanish National Research Council (CSIC) and expert in atmospheric sciences, points out that ‘Whilst the frequency of Saharan haze carrying dust towards the Atlantic has decreased since the 1980s, its intensity is on the rise. Since February 2020, the Canary Islands have suffered several short (lasting a few days) but extraordinarily intense periods of Saharan dust hazes called supercalimas, bringing with them between 1,000 to 4,000 micrograms (µg)/m3 of breathable particles less than 10 microns (PM10) in size.
‘On days when there’s no haze,’ explains RodrÃguez, ‘the concentration of breathable particle matter (PM10) is usually between 25 and 30 (µg)/m3, while during a normal haze in the Canary Islands, this figure usually reaches between 50 and 300 (µg)/m3. Since February 2020, however, we have experienced five extraordinarily intense super hazes. The one in March 2022 affected mainland Spain for the first time. We are now studying why they occur, their behaviour
and trends.’
Calima is beneficial for marine ecosystems, especially open ocean waters because it provides fertilisers such as iron and phosphorus. Nevertheless, it is harmful to humans. Studies by the CSIC and the Cardiology Unit of the Canary Islands University Hospital (Tenerife), published in 2020 in scientific journals Translational Research and Journal of Clinical Medicine, revealed that inhaling this dust causes inflammation of the respiratory tract and increases the risk of cardiovascular death at a rate of 2% for every 10 (µg)/m3 of suspended dust particles inhaled. Over four years, this translates to 86% of in-hospital deaths (patients admitted to hospital) due to heart failure were associated with admissions made during days of Saharan dust haze. The higher the dust concentration, the higher the incidence.
Other studies carried out at the Izaña Atmospheric Observatory (Tenerife) have shown that this airborne desert dust is mixed with pollutants emitted by the oil refining industry, fertiliser production and mining activity in Morocco, Algeria and Tunisia. The dust also carries sulphate, nitrate, ammonium and various heavy metals such as chromium, nickel and zinc. The scientific community is monitoring the haze to establish how it affects climate change.
