GAW Report No. 205 - IGAC Project

CHAPTER 2 - AFRICADuring autumn, biomass burning aerosols originating from rice straw burning in the NileDelta, known as the ‘‘Black Cloud’’ event, have shown to account for 12%, 35% and 50% of CairoEC, water insoluble organic carbon (WIOC) and water soluble organic carbon (WSOC) massconcentrations, respectively. Overall, non-dust aerosols were equally distributed betweencarbonaceous aerosols and ions, and their concentrations were of the order of 100 µg m -3 inautumn and winter, and of 60 µg m -3 in spring and summer. Remarkably, relatively low WSOC/OCratios (about 1/3) were obtained all the year-long [Favez et al., 2008a]. Favez et al. [2008b] furtherinvestigated the carbonaceous content in the sub micron fraction of aerosols by at an urban site inCairo in spring 2005. They found well-marked diurnal patterns for the WSOC/EC and WIOC/ECratios, with minima during the traffic-influenced morning period and maxima during the intensephotochemical period, suggesting significant formation of both water-soluble and water insolublesecondary organic aerosols during the afternoon. Applying the EC-tracer method, freshly formedsecondary organic carbon was found to possibly account for more than 50% of OC concentrationsmeasured during the early afternoon period, and this fresh SOC was calculated to be mainly(~60%) composed of water-insoluble species. The latter (unexpected) result has been suggestedto be due to low ambient relative humidity as well as to the importance of anthropogenic volatileorganic compounds in Cairo [Favez et al., 2008b].RegulationsIn 1995, the first environmental acts were introduced and the situation has seen someimprovement with 36 air monitoring stations and emissions tests on cars. Twenty thousand buseshave also been commissioned to the city to improve congestion levels, which are very high. In2003, Egypt initiated an enforced vehicle emission-testing programme in Greater Cairo. The limitsof CO, hydrocarbons and opacity for the vehicles before and after 1995 have the values of (7, 4.5percent) (1000, 900 ppm) and (65, 50 percent), respectively. The publicized information indicatedan overall failure rate of about 10 percent [El Mowafi and Atalla, 2005].2.4.4 HealthLead smelters have been found to be major sources of lead in Cairo’s ambient atmosphere[Abu-Allaban et al., 2007]. Melting down of old circuit boards and other electronic components fortheir metal content has been shown to expose communities to extremely high levels of dioxins andmetals such as lead, cadmium and mercury [Carroll and Essik, 2008]. About 40% of the totalpopulation in Egypt is below 25 years old while only 3% exceeds the age of 65. In 2006 the birthrate was significantly higher than the death rate with 25.3 ‰ births compared to 6.2‰ deaths.As reported by El Mowafi and Atalla [2005] health risks studies due to air pollution in Cairoconducted by Smith [1999] indicated that approximately 3% of the population is chronicallyexposed to PM 10 levels above 100µg/m 3 , compared to 48 % exposed to 50-100 µg/m 3 and 49 %exposed to 5-50 µg/m 3 PM 10 . Thus, it was suggested that Cairo air pollution causes about 3,400premature deaths, 28 million restricted activity days and other additional cases of air pollutionrelateddiseases, e.g. asthma attacks and chronic bronchitis. Based on ambient atmosphericconcentrations of criteria pollutants, notably total suspended particles (TSP; 593 µg.m -3 ), SO 2 (37µg.m -3 ), and nitrogen dioxide (NO 2 ; 59 µg.m -3 ), Gurjar et al. [2008] have classified Cairo asextremely poor air quality megacity where measures for air pollution reduction need to be takenurgently. It is estimated that 10,000 to 25,000 people a year in Cairo die due to air pollution-relateddiseases. The World Bank [2002] evaluated that environmental degradation in Egypt at 0.7-2.3 ofGDP per year, accounting that air pollution causes about 20,000 premature deaths every year, inthe two metropolitan areas and 450,000 disability adjusted life year with about 92 % of them beingin the Greater Cairo because of the higher air pollution and larger population. These findingsindicate the significant benefits that could be achieved by implementing the proper abatementmeasures to improve air quality in Cairo.2.5 GENERAL CONCLUSIONSThis chapter strongly stresses the need to seriously considering air pollution andassociated health risks in African megacities as a subject of its own. Air pollution levels are53