Increasing trans-Atlantic intrusion of Sahara dust: a cause of concern?
Authors: Sateesh Sakhamuri, Safiya Cummings
Journal: The Lancet Planetary Health (2019)

Exposure to outdoor fine particulate matter is the fifth most common risk factor for death worldwide, accounting for 4·2 million deaths and 103·1 million disability adjusted life-years in 2015.1Cohen AJ Brauer M Burnett R et al.Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015.Lancet. 2017; 389: 1907-1918Summary Full Text Full Text PDF PubMed Scopus (3299) Google Scholar Air pollution contributes to the development of pulmonary and cardiovascular diseases and has also been linked to adverse effects on fetal development during pregnancy and lung growth restrictions in children.2Kim D Chen Z Zhou LF Huang SX Air pollutants and early origins of respiratory diseases.Chronic Dis Transl Med. 2018; 4: 75-94Crossref PubMed Google Scholar The UN Environment programme (UNEP) reported that sand and dust storms cause losses of US$13 billion every year in the Middle East and north Africa.3More action needed on sand and dust stormsUnited Nations Environment Programme.https://www.unenvironment.org/es/node/331Date: 2016Date accessed: March 27, 2019Google Scholar Sahara dust has been treasured as a natural feeding source of minerals to the western Atlantic coast and nutrients to the rainforests in South America. Nature lovers admire its vibrant effect on colourful sunsets, and environmental physicists appreciate its protective effect from solar radiation and its marine biogeochemical cycling. Nevertheless, its intrusions have been a cause of global concern in recent times, owing to air pollution and its associated health risks. Besides minerals, it also transports hydrocarbons, allergens, and microbial compounds from Africa. Airborne microorganisms can increase ten-fold in the Caribbean atmosphere on days with a lot of Saharan dust.4Griffin DW Garrison VH Herman JR Shinn EA African desert dust in the Caribbean atmosphere: microbiology and public health.Aerobiologia. 2001; 17: 203-213Crossref Scopus (255) Google Scholar The existence and health effects of Sahara dust are well known in nearby European countries. It can contribute to exceedances of the PM10 daily European limit of 50 μg/m3.5Díaz J Tobías A Linares C Saharan dust and association between particulate matter and case-specific mortality: a case-crossover analysis in Madrid (Spain).Environ Health. 2012; 11: 11Crossref PubMed Scopus (45) Google Scholar Studies from a few European countries have found an association between particulate matter (PM2·5 and PM10) and daily mortality, especially cardiovascular-related mortality.6Stafoggia M Zauli-Sajani S Pey J et al.Desert dust outbreaks in southern Europe: contribution to daily PM10 concentrations and short-term associations with mortality and hospital admissions.Environ Health Perspect. 2015; 124: 413-419Crossref PubMed Scopus (124) Google Scholar A study by Diaz and colleagues,5Díaz J Tobías A Linares C Saharan dust and association between particulate matter and case-specific mortality: a case-crossover analysis in Madrid (Spain).Environ Health. 2012; 11: 11Crossref PubMed Scopus (45) Google Scholar done between 2003 and 2005, showed that Sahara dust affected 20% of days in the city of Madrid, mostly during the hot season (28·4%) with cardiovascular effects, and respiratory effects in the cold season. Dust transportation from the Sahara desert is not restricted to adjacent countries. Between 2007 and 2013, NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite collected data showing that wind and weather pick up, on average, 182 million tonnes of dust each year and carry it past the western edge of the Sahara, from where it travels 1600 miles across the Atlantic Ocean,7Gray E NASA satellite reveals how much Saharan dust feeds Amazon's plants.https://www.nasa.gov/content/goddard/nasa-satellite-reveals-how-much-saharan-dust-feeds-amazon-s-plantsDate: Feb 22, 2015Date accessed: March 28, 2019Google Scholar leading to annual PM10 concentrations exceeding the US national ambient air quality standards of 150 μg/m3 near the eastern coast of South America, over the Amazon basin and over the Caribbean Sea.8Ozer P Laghdaf MBOM Lemine SOM et al.Estimation of air quality degradation due to Saharan dust at Nouakchott, Mauritania, from horizontal visibility data.Water Air Soil Pollut. 2007; 178: 79-87Crossref Scopus (62) Google Scholar Such increased trans-Atlantic intrusions were also seen in the 1910s to 1940s and the 1970s to 1980s,9Evan AT Flamant C Gaetani M Guichard F The past, present and future of African dust.Nature. 2016; 531: 493-495Crossref PubMed Scopus (140) Google Scholar especially during warmer months with increased atmospheric temperatures and low humidity levels. Increasing exposure to Saharan dust plumes has been reported in the southern Caribbean region. A meandering polar jet stream transporting Sahara Desert dust from the North African cyclonic events to the Arctic circle has also been noted by researchers. According to UNEP, the increase in the frequency and severity of dust storms is due to climate change, drought, land degradation, and unsustainable management of land and water resources.3More action needed on sand and dust stormsUnited Nations Environment Programme.https://www.unenvironment.org/es/node/331Date: 2016Date accessed: March 27, 2019Google Scholar Professor Kerry Cook from The University of Texas states that the increased surface temperature (two to four times greater than that of the tropical mean temperature for 1979–2012) and decreasing wintertime cold air surge activity of the Sahara desert are the likely causes of the increased Sahara dust intrusion pattern.10Cook KH Vizy EK Detection and analysis of an amplified warming of the Sahara Desert.J Clim. 2015; 28: 6560-6580Crossref Scopus (62) Google Scholar In addition to increased asthma attacks in children in the Caribbean linked to Sahara dust, studies from western Atlantic countries have also claimed associations with increased incidence of meningococcal meningitis and cancer. Evidence on the deleterious effects of Sahara dust on plants and animals, especially birds, and erosive effects on the aviation industry are scarce. Findings on its influence on the climate are imprecise, particularly on tropical cyclone activity. The overall economic impact of long-distance Saharan dust ride is unknown. One thing that remains certain is that Sahara dust diminishes air quality and has been linked to increased mortality and morbidity at higher concentrations. Satellite monitoring, trans-Atlantic air quality surveillance and early warnings, and reforestation can reduce its effect on human health. If efforts are made to reduce the human-made sources of particulate matter concentrations, the adverse effects of natural causes might be diminished, if not eliminated. We declare no competing interests.