Large areas of the Americas have recently been enveloped with dust from the Sahara Desert. For them, this is a rare event, the largest in 50 years. However, for tens of millions of people in West Africa, such storms happen frequently and are major killers, particularly of small children. A new study not only measures the cost, but proposes an improbable-sounding solution.
"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," said Professor Marshall Burke of Stanford University in a statement. Air pollution is a big part of that. In most places that means particulates from burning wood, dung, and fossil fuels, but in much of Africa a major component is seasonal dust from the Sahara. Combining the natural dust and the human-made emissions an average of 4-5 years are taken off life expectancy.
In Nature Sustainability, Burke and coauthors studied data on almost a million births over 15 years in 30 countries. They found that years when the dust was worse had more infant mortality. An extra 10 micrograms per cubic meter caused 24 percent more deaths, meaning hundreds of thousands of babies and children die each year as a result.
Cutting human-produced air pollution faces fierce resistance from vested interests, but we have a clear route to do it. Knowing what to do about natural dust isn't so easy. We don't even know if climate change will make it better or worse.
Preventing dust getting into houses would help, but is an enormous task in places where even glass windows are a luxury. Masks are only really an option for those who have survived the most vulnerable age.
However, Burke noted that while the Sahara is vast, most of the dust comes from one modest-sized portion of it, the Bodélé Depression, which in winter produces 700,000 tonnes of dust a day. In years when the depression gets good rainfall, much less dust rises to plague other nations.
Mad as it may seem to try to suppress dust that affects half a continent, the authors argue solar pumps across the Depression could draw up groundwater and spray it to suppress the dust, encouraging plant growth in the process. They calculate it would cost about $30 million per year to reduce the dust load enough to save 37,000 children's lives a year. If these children live an average of 30 years each the cost comes out to $24 a healthy life-year saved, that's competitive with many aid programs in Africa, such as the distribution of bed nets against malaria or vaccine distribution.