Saharan Dust Impacts on Air Quality: What Are the Potential Health Risks in West Africa?

ABSTRACT

Despite the proximity of the Sahara, very few studies about dust impact on air quality and human health have been conducted in West Africa. The lack of data is a major constraint on our understanding of the impacts on human health in this area. We analyzed PM₁₀ concentrations and horizontal visibility recorded in four West African stations. The pollution levels often exceed the standards defined by many countries/regulatory authorities and have been associated with serious health risks outside Africa. Over the Sahelian stations, 45.6% of the days between November 2006 and March 2007 were likely to impact human health and the studied Sudanian population was exposed to potential health effects every 5 days.

Key Words:

• dust
• PM₁₀
• air quality
• AQI
• health
• West Africa.

ACKNOWLEDGMENTS

Conor Cahill, a professional medical writer, reviewed and corrected the final version of this article.

Notes

Editor's note: Sahelian refers to the Sahel, which is the ecoclimatic and biogeographic zone of transition between the Sahara desert in the north and the Sudanian savannas in the south. It is the semidesert south fringe of the Sahara desert and stretches from Mauritana to Chad (Wikipedia 2012).

Strictly speaking the dry season lasts longer in these regions of West Africa but analyses focused on these five months of dry season because data collected in Kandi (Benin) are only for these months.

For instance, in Niger, total population exceeded 15.10⁶ inhabitants in 2010. While population density is relatively weak (12 inh.km^–2), spatial repartition is very mixed: more than 75% of the population live in the southern part of the territory (Heinrigs and Perret 2006).

The intensity and type of health impacts depend on the grain-size distribution and the chemical composition of particles (Nel 2005). In the absence of this information, we considered the PM₁₀ concentrations in a comprehensive manner in this study, bearing in mind that differences could exist.

Table 1 USEPA Air Quality Index (AQI), associated 24-h PM₁₀ concentration, and health effects (USEPA 1999).