Estimation of air quality degradation due to Saharan dust at Nouakchott, Mauritania, from horizontal visibility data

Ozer, P.; Laghdaf, M.B.O.M.; Lemine, S.O.M.; Gassani, J.

Estimation of air quality degradation due to Saharan dust at Nouakchott, Mauritania, from horizontal visibility data

2007

Ozer, P. | Laghdaf, M.B.O.M. | Lemine, S.O.M. | Gassani, J.

It is now irrefutable that air pollution caused by large amounts of Total Suspended Particulates (TSP) and respiratory particulates or Particulate Matter less than 10 μm in aerodynamic diameter (PM₁₀) has numerous undesired consequences on human health. Air quality degradation far from the African continent, in the US and in Europe, caused by high concentrations of African dust, is seen as a major threat even though most of these countries are very distant from the Sahara. Surprisingly, no estimates of TSP or 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, TSP and PM₁₀ levels are estimated throughout the year 2000 at Nouakchott-Airport, Mauritania, using relations found in the literature. It appears that concentrations of particles are significant both in terms 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 86 and 137 times, respectively. The average annual concentration is far above air quality standards and estimated at 159 μg m-³ for TSP and 108 μg m-³ for PM₁₀. These very high particulate levels are likely to represent an important public health hazard and should be considered as a major environmental risk.

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