Impact of dust processes on air quality in Niamey, Niger, and consequences on human health

It is now irrefutable that air pollution caused by large amounts of respiratory particulates (Particulate Matter less than 10 µm in aerodynamic diameter, PM10) has numerous undesired consequences on human health. Although air quality degradation far away from the African continent in the US and in Europe caused by high concentration of African dust is seen as a major health threat although most of these countries are very distant from the Sahara; no estimates of PM10 levels near the Saharan dust source are available. Based on horizontal visibility observations which are reduced by the presence of dust in the atmosphere, PM10 levels are estimated during 2005 at Niamey-Airport, Niger. It appears that excessive concentrations of particles are very important both in magnitude and frequency as the 24-hour PM10 thresholds established by the US EPA National Ambient Air Quality Standards and the EU Limits Values for Air Quality were exceeded 103 and 67 times, respectively. The average yearly concentration is far above air quality standards and estimated to 92 µg m-3 for PM10. These very high particulate levels are likely to represent an important public health threat and should be considered as a major environmental risk.