When research bites the dust

The populations of West Africa are among the most exposed in the world to desert dust. Yet interest in scientific research into this particular form of pollution is virtually nil. A team from Benin and Europe is now appealing for international institutions to pay more attention to the problem.

There is a high probability that the health of African populations is very seriously affected by Saharan dust that, in certain seasons, rises to an altitude of several thousand metres before falling back to the ground in Europe, America and most of the West African countries in particular. That is the hypothesis of a team of researchers from Parakou University (Benin) and two Belgian universities, who have just published an article  [1] based on a systematic review of international literature of the past decade devoted to the subject.

Carried by the Harmattan

Their concern is focused on the huge dust clouds capable of travelling thousands of kilometres that regularly form in various areas of the globe first and foremost in the Sahara, where between 50% and 58% of these clouds are believed to originate. In West Africa, these so-called “PM 10” particles (their diameter is less than 10 microns) enter the air mainly in Mali, Mauritania and around Lake Chad. They are then carried by the Harmattan[2] , a dry wind that blows from late November through to March, in the direction of the Gulf of Guinea by way of, inter alia, Benin, Nigeria, Togo, Ghana and Ivory Coast .

Intrigued by the possible health impact of this desert dust, the university team studied 231 scientific articles devoted to the impact of PM 10 particles on air quality. Affecting the upper respiratory channels, these particles made up largely of quartz play a major role in a number of respiratory diseases, including asthma, pneumonia and chronic obstructions. They could well play a part in respiratory infections that are responsible for up to 20% of infant mortality in certain regions.

Surprisingly, just three studies – 1.3% of the total – were found to be concerned with air pollution in Africa! After a second review of the literature, this time targeting key words with greater “health” connotations (for example, mortality, morbidity and asthma), the researchers arrived at an even more startling conclusion: of the 41 studies identified, not a single one was devoted to Africa.  

“The international scientific interest accorded to this subject shows a clear regional imbalance,” concludes Florence De Longueville, a post-doc specialised in the management of natural risks at the Department of Geography of the Faculté Universitaire Notre-Dame de la Paix (FUNDP) in Namur (Belgium). Whereas North Africa is the region that produces the most desert dust by far, the literature remains largely silent on the subject, whereas Asia, the big dust producer in the region of the Gobi Desert (China/Mongolia), is much better studied.” Another pertinent finding is that while only between 5% and 10% of Saharan dust enters the European atmosphere, the effects of the PM 10 particles on the population in Spain is better documented than the effects on populations in West Africa. In 2008 a study showed, for example, that desert dust particles present in the air in Barcelona were associated with an 8.4% increase in the death rate.

 Scientific shortcomings

There are a number of explanations for this scientific under-investment in West Africa: the lack of meteorological and synoptic stations, shortcomings in training and promoting awareness of the phenomenon among medical and nursing staff, weakness of a hospital network to record data in the field and lack of integration between the scientific disciplines concerned. “These failings are all the more worrying as the population concerned is particularly vulnerable and malnutrition rates - already among the highest in the world - are rising all the time,” says Pierre Ozer, a geographer at the Department of Science and Environmental Management at ULg in Belgium. “The unanswered questions are many: does chronic exposure to low doses have a significantly different effect than mass exposure during sand storms? How do smaller particles, with the ability to penetrate the pulmonary alveoli, perform when found in combination with the PM 2.5 pollution found in cities?”

Looking in particular to the World Meteorological Organization (WMO) and the World Health Organization (WHO), the Beninese and Belgian scientists hope that more attention will soon be paid to these phenomena due to growing concerns about climate change and its effects on public health. But, without health data collected on a regular basis in the field, our knowledge – and thus the protection of populations – will be unable to progress significantly in this part of Africa.

Philippe Lamotte

[1]“What do we know about the effects of desert dust on air quality and human health in West Africa compared with other regions?” Science of the Total Environment, 2010, by Yvon-Carmen Hountondji (Parakou, Benin), Florence de Longueville and Sabine Henry (FUNDP, Belgium), Pierre Ozer (ULG, Belgium)

[2]The Harmattan can cloud the atmosphere for days at a time, leaving aircraft grounded and favouring meningitis epidemics, the suspended particles rendering the mucous membranes fragile and making it easier for the meningococii to enter the bloodstream.