Pierre Ozer

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

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.

Desert dust impacts on human health: an alarming worldwide reality and a need for studies in West Africa.

High desert dust concentrations raise concerns about adverse health effects on human populations. Based on a systematic literature review, this paper aims to learn more about the relationship between desert dust and human health in the world and to analyse the place of West Africa as a study area of interest. Papers focussing on the potential relationship between dust and health and showing quantitative analyses, published between January 1999 and September 2011, were identified using the ISI Web of Knowledge database (N = 50). A number of adverse health effects, including respiratory, cardiovascular and cardiopulmonary diseases, are associated with dust. This survey highlights obvious dust impacts on human health independently of the study area, health outcomes and method. Moreover, it reveals an imbalance between the areas most exposed to dust and the areas most studied in terms of health effects. None of these studies has been conducted in West Africa, despite the proximity of the Sahara, which produces about half of the yearly global mineral dust. In view of the alarming results in many parts of the world (Asia, Europe, America), this paper concludes by stressing the importance of carrying out impact studies of Saharan dust in West Africa, where dust events are more frequent and intense than anywhere else.

Analysis of the vegetation trends using low resolution remote sensing data in Burkina Faso (1982¿1999) for the monitoring of desertification

After about two decades of dramatic rainfall deficits that started in the late 1960s, the Sahel of West Africa has experienced increasing precipitation since the early 1990s. The implementation of the United Nations Convention to Combat Desertification (UNCCD) needs the identification of areas that record declining vegetation productivity over long‐time periods. In this scope, we analyse the state of the vegetation productivity using long‐term time series of NOAA AVHRR NDVI data and compare it to rainfall data. For this, 128 rain gauge data (RR) were compared with the integrated NDVI during the growing period (iNDVI) values in Burkina Faso from 1982 to 1999. During the analysed period, most of the studied stations in the country were stable for the iNDVI/RR (57.8%). However, 39.8% showed a weak to strong negative trend in the iNDVI/RR while only 2.4% showed a weak positive trend. These negative trends may reflect ongoing desertification processes in Burkina Faso and could be a starting point for the identification of hot‐spots areas to determine where to take action to combat desertification.

Recent Extreme Precipitation and Temperature Changes in Djibouti City (1966–2011)

A dataset of 23 derived indicators has been compiled to clarify whether the frequency of rainfall and temperature extremes has changed over the last decades in Djibouti City, eastern Africa. Results show that all precipitation indices have declined over the last decades, although only the very wet day frequency and the very wet day proportion present a significant decline. Annual total precipitation has decreased by 17.4% per decade from 1980 to 2011 and recent mean yearly rainfall (44 mm on average from 2007 to 2011) meets a 73% deficit compared to the 30-year (1981–2010) average (164 mm). The average temperature increase is

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.

Containment in Sierra Leone: the inability of a state to confront Ebola?

The present Ebola virus disease outbreak is spreading across west African nations with alarming rapidity. As of Sept 21, the total number of recorded cases has soared to 6263, with 2917 deaths. The situation is very likely to continue to worsen when the aff ected countries witness the exhaustion of their capacities to respond to a threat of this magnitude, and because massive international assistance is still sorely lacking on the ground. With the objective to put newly infected people into quarantine and to limit the virus’ spread, the government authorities of Sierra Leone decided to impose an unprecedented containment, ordering the nation’s 6·2 million inhabitants to stay at home for three full days, from Sept 19 to 21, with a patrol force of 7000 teams making door-to-door visits to detect possible Ebola victims. Although containment would at fi rst appear to be an easily enacted and economical strategy, its implementation has proven to be more complex, for several reasons. First, how can the entire population of a country, the territory of which extends over more than 70 000 km2, be confi ned while many services must be maintained? Decreeing such an obligation within even a smaller area can be diffi cult. Attempts to place the West Point slum in Morovia, Liberia into quarantine, at the end of August, exemplifi ed this diffi culty. Communication has a crucial role among the challenges presented by the size of the country. How could information be conveyed to the entire population, including the most remote rural areas, which haven’t been taken into account since the beginning of the outbreak? In order for the people to accept containment, it is necessary that they understand and accept the reasoning behind such measures. Moreover, containment eff orts are difficult to implement. Homes and shelters are of para mount importance. Consequently, in a country where access to basic infrastructure is far from widespread, can people truly be expected to remain confi ned in their homes for three days without needing to be resupplied with basic necessities such as water? In a country where more than half of the population lives on less than US

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

1·25 per day, how can the government expect to contain all those for whom having food on the table at night depends on that day’s labour? How can containment be imposed on a rural population who are engaged in agricultural activities, in the middle of the crop harvest? Such practical issues transform into numerous preoccupations that make people apathetic to the authorities’ instructions. Mandating containment at such a large scale raises many questions. The purpose of these eff orts could well be to send a political message to reassure the population by creating the illusion that the authorities have the ability to control a major crisis on the scale of the current Ebola outbreak.