Air pollution and risks of premature mortality in Africa: A large uncertainty
The World Health Organization (WHO) released for 2014 an alarming report on the risk of premature mortality; nearly 7 million people died prematurely in 2012 - one in eight worldwide - due to exposure to air pollution. These figures are more than double previous estimates and confirm that air pollution has become a major environmental risk to health worldwide. Millions of lives can be saved by fighting against air pollution [1].
The WHO report indicates that the scientific studies clearly showed the relation between the indoor and outdoor air pollution and cardiovascular diseases (cerebrovascular accident, and ischemic heart disease), and between air pollution and cancer.
Dr.Flavia Bustreo, Deputy Director General of WHO for Health Family, Women and Children said: “a better air can prevent non-communicable diseases and to reduce risks for women and the vulnerable groups, including children and old persons ". She also said: “ poor women and children pay heavily the consequences of the indoor air pollution, because they spend more time at the house to inhale smokes and soot from furnaces with wood or with coal badly ventilated.". The report reveals that the most part of deaths caused by atmospheric pollution are due to cardiovascular diseases as it’s shown in the figure 1.
Number of deaths (%) by cardiovascular diseases related to air pollution
The main pollutants of the air in the global scale in terms of concentration and turned out toxicity are the ozone and the atmospheric particles (PM, particulate matter), called also sprayers by the scientific community. The present ozone in the lower layer of the atmosphere ( the tropospheric), is a toxic gas formed from the photochemical reactions between the organic compounds (COVS among which some are highly toxic as the benzene) and the dioxides of nitrogen ( NOx). We indicate by the way that we are speaking about a toxic gas in the nearness of the ground, not to confuse with the stratospheric ozone covering the protective layer against the toxic ultraviolet radiations.
The atmospheric particles deserving of interest for the study of the toxicity of the air pollution, are those whose diameter is lower than 2.5 micrometers (PM2.5). Once inhaled by man, these microparticles can reach lung cells and provoke an irritation of the walls of these last ones. More serious, these particles can contain toxic chemical substances which can possibly cross the blood barrier. The organic fraction constituting about 70 % of the sprayer is the part the least known because of its complexity and of the number of substances which it conceals. The study on the characterization of the chemical composition of the sprayer which we led on six sizes of particle showed that pollutants the most toxic as aromatic polycyclics hydrocarbons ( HAPs) and more exactly the benzo ( a ) pyrene, classified by the International Centre of the Cancer as highly carcinogenic, are present mainly in the finest particles [ 2 ].
The major source at the world level carcinogenic HAPs lives the motor traffic and more particularly the emissions(emissions,issues) of vehicles diesel. But other sources as the combustion contribute to the release of these toxic contaminants towards the atmosphere.
Under our reserach works, we developed a tool that allows us to determine the carcinogenic power of particles [3]. it’s about a ration measuring the carcinogenic power regarding to the benzo (a) pyrene as a reference.
The estimation report of mortality caused by air polution published this year by the WHO put into evidence the impact of diesel motors emissions on the growth of mortality.
In another part, the natural emissions of particles or desert dusts, globaly important, could induce healthy risks if they trosport toxic pollutants. The preliminary study that we led in Algeria shows that desert particles countain very low concentrations in dangerous substances for health [4].
At a local level, the countries of Southeast Asia and the Western Pacific are those who have experienced the heaviest linked to air pollution load in 2012, with 3,3 million premature deaths due to indoor pollution and 2,6 million premature deaths due to outdoor pollution.
In this context, the team of Prof. Jos Lelieveld, Director of the Institute of Chemistry Max Planck, Germany and Director of the Centre for Research on Energy, Environment and Water of Cyprus have developed a model to monitor the global distribution and growth of premature mortality related to air pollution [5]. The study is based on the rate of premature death in 2005, and considers the air pollution caused by ozone and PM2.5. It is estimated that 69% of the world population exposed to annual average PM2.5 concentration greater than 10 micrograms per cubic of air breathed (WHO limit value) meter anthropogenic. Natural desert dust were not included in this estimation. The results of this study indicate that PM2.5 and ozone anthropogenic sources cause higher mortality in the most populous regions of Asia with a strong predominance in China and India. The premature mortality rates are higher in urban regions such as the Pearl River area, Delhi, Kolkata, Jakarta, Shanghai, Dhaka, Beijing, Mumbai, the area of Szechuan Tokyo, Seoul and other regions in the south and eastern Asia.
The highest level of premature mortality caused by the ozone is in China, India, USA, Japan, and Bengladesh where the mortality per person is more important in Algeria, Macao and Taiwan [5].
This latest report, enaugh surprising for us, encourage us to instal- or to authorize the existing network-a network measuring of the air quality allowing to follow closely the concentrations of the ozone and the other atmospheric pollutants and their spatial and temporal evolutions.
Epidemiological and social studies must be led in a close collaboration with scientifics working on air pollution to examine better the amplitude of the air pollution in our country and estimate its impact on the health of the population.
Because of absence of network of measures in the majority of the African countries where the emissions of pollutants of the air are submitted to no control or in an effective regulation, all the estimations of the risks of the atmospheric pollution on the mortality suffer enormous uncertainties.
Furthermore, the future energy strategies in these countries are not clear and do not integrate the human life as being the center of any development plan. The African continent establishes a " hot spot" for numerous scientists.
According to the various estimations made by European and American laboratories [ 6 ], the air emissions of gas and particles derived of the combustion of fossil fuels and biofuels in Africa would increase substantially in a near future because of the urbanization. Africa risks to be pointed for its contribution to the climate change , according to the same estimations. Certainly the African countries have other major challenges; eradication of the poverty, the eradication of the epidemics (Ebola for example), the health, the access to the education, to the water and to the energy but all this has to join the context of the sustainable development. An international support is necessary by setting up relevant strategies and allowing mechanisms the support for the technological development, he innovation, the transfer and the distribution of technology and for the building of human capacities.
The future projections are optimistic in certain regions of the world (in Europe and in the USA) where the regulations of emissions are very strict and pessimistic (in Africa and in Asia) as for the growth of the risks of premature mortality bound to the air pollution. With the current rhythm of industrialization and urbanization (a big part of the population of the world will live in urban areas; about 55 % in 2025 and 57 % in 2050), the inhalation of an air healthy risks of being threatened. Strategies and actions concrete and arranged to reduce emissions as the use of the renewable energies, the efficiency and the energy saving, the change of the populations behavior by inculcating the culture of moderate consumption, the environment-friendly industry, the public transport, the agriculture rational and the promotion of the concept of the intelligent city, where nothing gets lost everything is transformed, are able to protect the quality of the air which we inhale as long as we live, for us and for the future generation. These measures have certain co-profits both from the point of view of the protection of the human life, the environmental protection and the fight against the climatic change and from the point of view of savings in health expenses and fight against the wasting of resources.
Professor Noureddine Yassaa, Director of the CDER
References
[1]http://www.who.int/mediacentre/news...
[2] R. Ladji, N. Yassaa, C. Balducci, A. Cecinato, Particle size distribution of n-alkanes and poycyclic aromatic hydrocarbons (PAHs) in urban and industrial aerosols of Algiers, Algeria, Atmospheric Pollution and Research 21, 2014, 1819-1832.
[3] N. Yassaa, B.Y. Meklati and A. Cecinato, "Particulate n-alkanes, n-alkanoic acids and polycyclic aromatic hydrocarbons in the atmosphere of Algiers City Area", Atmospheric Environment 35, 2001, 1843-1851.
[4] R. Ladji, N. Yassaa, C. Balducci, A. Cecinato, “Organic components of Algerian desert dust”, Chemosphere 81, , 2010, 925-931.
[5] J. Lelieveld, C. Barlas, D. Giannadaki, and A. Pozzer, “Model calculated global, regional and megacity premature mortality due to air pollution”, Atmospheric Chemistry and Physics 13, 7023–7037, 2013.
[6] C. Liousse, E Assamoi, P Criqui, C. Granier and R. Rosset, “Explosive growth in African combustion emissions from 2005 to 2030”, Environmental Research Letter. 9 (2014) 035003.
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