GAW Report No. 205 - IGAC Project

CHAPTER 2 - AFRICAratios in Bamako suggest higher organic carbon content, in agreement with more incompletecombustions in Bamako. This feature is confirmed with PAH concentrations being much higher inDakar (diesel sources) than in Bamako. Finally, water-soluble organic carbon (WSOC)concentrations are found much higher in Bamako than in Dakar.2.2.4 Atmospheric Pollution and HealthExposure/Epidemiological studiesIn West Africa, air pollution exposure is expected to be responsible for most respiratorydiseases [WHO, 2006], with lung affections and respiratory irritations respectively due to CO, NO X ,PM 1 , benzene and toluene. However, potential exposures vary with populations, depending ontheir daily activities. As shown by Linden et al. [2012] for Ouagadougou, careful consideration ofboth location and time resolution of measurements is required for accurate exposure assessments.There is an urgent need for exposure scenarios, through displaying for example individual datamonitoring measurements. Heavy exposures are expected for workers near traffic sources and forfemales and young children near domestic fuel combustion. In Nigeria, occupational exposureintensive measurements are available, linking air pollution at workplaces to adverse implications forthe health of workers [Baumbach et al., 1995; Adejumo et al., 1994; Ogunsola et al., 1994; Oyedele etal., 1995].During the POLCA programme, groups of people have been identified for health studieslinked to pollution. In Bamako for example, O. Koita [personal communication] has shown that theselected group is mainly affected by traffic and domestic fuel sources prevailing at the site (only15% of this group is exposed to waste burning, 18% to cigarette smoke, 7% to industries). InDakar, the concept of bio-indicators for air quality was examined: several cytokines such asInterleukin 1 β (IL-1β), interleukin 5 (IL-5) interleukin 8 (IL-8) and proteins (Clara Cells, CC16) havebeen evaluated for subjects exposed to air pollutants prevailing at the POLCA traffic site [Gueye,PhD Thesis 2008]. About 67 subjects are enrolled, including 33 merchants (traders) with collectionof their blood for pro-inflammatory cytokine study. This study has shown a glutathione statusalteration implying a defense system alteration due to atmospheric pollution [Gueye, PhD Thesis2008 ; Gning, PhD 2011].Finally, only few results are presently available for epidemiological studies linked to air pollutionin West Africa using long-term observations. An example is given in Table 4 with a follow up realizedin Kossodo (Burkina Faso) and carried out by the Laboratoire de Physique et de Chimie del'Environnmement of the University of Ouagadougou over 3 years (1999, 2001 and 2002), detectedan increase of upper and lower respiratory track infections (Table 5). Such results are encouragingand need to be largely extended to other cities in West Africa and linked to atmospheric pollution.Indeed, up to now, all estimates for asthma, morbidity or mortality in West Africa are based on doseresponsefunctions only established for northern developed countries. As shown earlier, and due toAfrican pollution specificities, such functions urgently need to be specifically determined for WestAfrica, using in parallel both long-term pollution measurements and health registrations: this is quite aimportant point to be stressed.Table 5 - Prevalence of respiratory infections in the Health District of Kossodo (Ouagadougou). Source: LPCE/UO. Thenumber of cases of respiratory infections was 3 times greater in 2002 than observed in 1999 (35 405 cases versus 11 466)Kossodo Health District/Year 1999 2001 2002Upper respiratory track infections 4 819 9 428 15 072Lower respiratory track infections 6 647 11 847 20 331Total 11 466 21 275 35 40338