Harmattan dust deposition and particle size in Ghana

Breuning‐Madsen, Henrik; Awadzi, Theodore W.

doi:10.1016/j.catena.2005.04.001

Cited by 65 publications

(39 citation statements)

References 19 publications

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“…According to D'Almeida (1986), overall 60% of the total particles from the Sahara Desert are transported to the Gulf of Guinea. The number of particles, mass distribution, dust flows, the deposition rate and the mean size of the particles have been estimated in several countries, especially in Ghana (Afeti and Resch, 2000;Breuning-Madsen and Awadzi, 2005;Resch et al, 2007;Sunnu et al, 2008), Mali (McTainsh et al, 1997) and Nigeria (Anuforom, 2007). These studies show that the dust quantity (which varies from year to year) is greater in the northern parts of these countries and that the dust particles become finer in size as they move further south.…”

Section: Origin and Movement Of Desert Dustmentioning

confidence: 99%

What do we know about effects of desert dust on air quality and human health in West Africa compared to other regions?

Longueville¹,

Hountondji²,

Henry³

et al. 2010

Science of The Total Environment

166

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This study aims to compare, on the one hand, the geographical distribution of the desert dust source areas, their contribution to quantities emitted into the atmosphere, the trajectories and the quantities deposited, with on the other hand the areas of research interest focused on the desert dust impacts on air quality and/or human health. Based on a systematic review of the literature using the ISI Web of Knowledge database, we found 231 articles published over the last decade on the desert dust impacts on air quality. Of these, 48% concerned Asian dust and 39% Saharan dust, with the remaining 13% divided between the other dust source areas. However, only one of these studies addressed the worsening air pollution in West Africa, even though it is very close to the Sahara, the greatest contributor to the global dust budget. Moreover, there have been very few studies (41) looking at the direct links between desert dust and human health; in this context too, no interest has been shown in West Africa. Yet this region is also among the areas in which morbidity rates have been noted to be far higher than those found in other regions of the world, and where respiratory infections alone account for more than 20% of the causes of infant mortality. This survey highlights a clear imbalance between those areas most exposed to dust and the most studied areas in terms of dust impacts. Given these findings and the often alarming results published about other regions of the world, we advocate a revival of interest in research on West Africa in order to achieve a better understanding of the desert dust impacts on air quality and health among the populations of this region.

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Section: Origin and Movement Of Desert Dustmentioning

confidence: 99%

What do we know about effects of desert dust on air quality and human health in West Africa compared to other regions?

Longueville¹,

Hountondji²,

Henry³

et al. 2010

Science of The Total Environment

166

View full text Add to dashboard Cite

show abstract

“…The above trajectories can be seen during specific times of the year, with the intensity varying annually [50]. Overall, 60% of total Saharan dust particles are blown southwards across the West African states [51][52][53] into the Gulf of Guinea [54] and across the Atlantic [55] to the Central Americas [56], where their health implications have been explored in such countries as Trinidad, Barbados, Grenada, and Puerto Rico. The Sahara is also a major source of dust deposition into the Mediterranean Sea and neighboring countries [57,58].…”

Section: Geographical Distribution Of Studies Addressing Health Effecmentioning

confidence: 99%

A Systematic Review of Global Desert Dust and Associated Human Health Effects

et al. 2016

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Dust storms and sandy dust events originating in arid and semi-arid areas can transport particulate material, pollutants, and potential transport long distances from their sources. Exposure to desert dust particles is generally acknowledged to endanger human health. However, most studies have examined anthropogenic particulate sources, with few studies considering contributions from natural desert dust. A systematic literature review was undertaken using the ISI Web of Knowledge and PubMed databases with the objective of identifying all studies presenting results on the potential health impact from desert dust particles across the world. This review reveals an imbalance between the areas most exposed to dust and the areas most studied in terms of health effects. Among the human health effects of dust storms are mortality and morbidity, arising from respiratory system, circulatory system, and other diseases. We summarize the quantitative results of current scientific health research and possible pathological mechanisms, and describe some of the many challenges related to understanding health effects from exposures to desert dust particles. Overall, for respiratory and circulatory mortality, both positive and negative associations have been reported for PM 10 of desert dust, but only a positive relationship was reported between PM 2.5-10 and mortality, and a positive relationship was also reported between PM 2.5 and human mortality. Future pathological studies should continue to focus on those mechanisms causing the most harmful effect of desert dust on respiratory and cardiovascular diseases. More attention should also be paid to the association between desert dust and the morbidity of other diseases, such as those affecting the reproductive system and nervous system.

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“…Despite these efforts the direct quantification of dust deposition remains difficult. Experimental studies usually show a wide range in deposition values, depending on which technique is used [Goossens and Offer, 1994;Vallack, 1995;Breuning-Madsen and Awadzi, 2005;Goossens, 2005].…”

Section: Introductionmentioning

confidence: 99%

Relationships between horizontal transport flux and vertical deposition flux during dry deposition of atmospheric dust particles

Goossens

2008

J. Geophys. Res.

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[1] Wind tunnel experiments were conducted to investigate the relationships between vertically settling dust and the horizontal dust flow from which the particles originate. The study primarily focused on the grain size characteristics and on the horizontal and vertical sediment fluxes. Simultaneous samplings of vertical deposition flux and horizontal transport flux were carried out at an almost identical altimetric level (a very narrow layer immediately above a water surface generating no resuspension). This made it possible to relate deposition flux to the horizontal transport flux and to study how deposition alters the sedimentological characteristics of horizontally moving dust. The use of water as a deposition surface implied that the dust was subjected to some degree of dispersion after the settling. This restricted the analysis to grains >10 mm, but the trends for grains <10 mm were easy to reconstruct. The experiments show that deposited dust is generally coarser than the parent dust from which it originates but only for friction velocities below 0.34 m s À1 . For higher wind speeds the median grain diameter of settling dust does not differ from that of the parent dust. Similar observations were made for the horizontal and vertical dust fluxes. At a constant horizontal transport flux (Fh) vertical deposition flux (Fs) drops with wind speed; however, from the same critical friction velocity of 0.34 m s À1 the ratio Fs/Fh remains constant. It was also found that the relationships between Fh and Fs depend on the grain size of the particles but only for sufficiently fine particles. Particles >50 mm no longer affect these relationships. Vertical mixing created by the turbulent nature of the flow strongly affects deposition of atmospheric dust. Mixing significantly hampers deposition of the grains, especially the small ones. The wind tunnel experiments allowed the magnitude of the effect mixing exerts on deposition to be calculated. For coarse grains the effect is small, but for fine grains mixing may hamper deposition by several dozen per cent. Theoretical dust deposition models should thus consider vertical mixing or otherwise include it in the numerical value of the velocity of deposition v d . Citation: Goossens, D. (2008), Relationships between horizontal transport flux and vertical deposition flux during dry deposition of atmospheric dust particles,

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Harmattan dust deposition and particle size in Ghana

Cited by 65 publications

References 19 publications

What do we know about effects of desert dust on air quality and human health in West Africa compared to other regions?

What do we know about effects of desert dust on air quality and human health in West Africa compared to other regions?

A Systematic Review of Global Desert Dust and Associated Human Health Effects

Relationships between horizontal transport flux and vertical deposition flux during dry deposition of atmospheric dust particles

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