Saharan dust active at home and abroad

Dust storms heading west across the Atlantic from the Sahara are nothing new, but the latest has been particularly large and impressive.

This image shows a plume moving from Africa’s west coast to the Caribbean Sea and up through the Gulf of Mexico between 15 and 25 June.

It was created by combining Ozone Mapping and Profiling Suite (OMPS) aerosol index data with Visible Infrared Imaging Radiometer Suite (VIIRS) imagery from the NASA/NOAA’s Suomi NPP satellite.

NASA’s Earth Observatory says the plume appeared to stretch about 2500 kilometres on 18 June, but more than three times that distance six days later.

In the Americas, the arriving dust can have a negative effect on air quality but be of value at ground level, fertilising soils in the Amazon and building beaches in the Caribbean.

Closer to the source, however, it has a very damaging impact on the health of children in particular, according to new research.

Researchers from Stanford University, US, analysed 15 years of household surveys from 30 countries across Sub-Saharan Africa covering nearly a million births then combined this with satellite-detected changes in particulate levels driven by the Bodélé Depression in Chad – the largest source of dust emissions in the world.

They found that a roughly 25% increase in local annual mean particulate concentrations in West Africa causes an 18% increase in infant mortality.

The new study, combined with previous findings from other regions, makes clear that air pollution, even from natural sources, is a “critical determining factor for child health around the world”, the researchers write in a paper in the journal Nature Sustainability.

“Africa and other developing regions have made remarkable strides overall in improving child health in recent decades, but key negative outcomes such as infant mortality remain stubbornly high in some places,” says senior author Marshall Burke.

Climate change remains the great unknown here. Burke and colleagues say it’s not clear whether it will mitigate or exacerbate the current problem. They do, however, have what they admit is a “seemingly exotic solution” to the immediate issue: damp the dust down.

They estimate that deploying solar-powered irrigation systems in the desert area could avert 37,000 infant deaths per year in West Africa at a cost of US $24 per life, making it competitive with many leading health interventions currently in use, including a range of vaccines and water and sanitation projects.

“Standard policy instruments can’t be counted on to reduce all forms of air pollution,” says lead author Sam Heft-Neal.

“While our calculation doesn’t consider logistical constraints to project deployment, it highlights the possibility of a solution that targets natural pollution sources and yields enormous benefits at a modest cost.”