the challenge of cairo, egypt

As air pollution professionals, one of the greatest challenges we face is how

to maintain air quality while allowing for growth and development. This is

especially true in the case of megacities in the developing world, where rapid

increases in population coupled with limited infrastructure, increased traffic,

and major industrial facilities within city limits can lead to significant health

risks. To develop a better understanding of the issues involved and how to

improve air quality in megacities, this article uses Cairo, Egypt as an example

of the challenges we face when trying to improve air quality in developing

urban areas.

Air Quality Issues in Megacities:The Challenge of Cairo, Egypt

The Challenge of Cairo, Egypt by Alan Gertler, Mounir Labib, and Douglas Lowenthal

em • The Magazine for Environmental Managers • A&WMA • April 2017



Cairo is the largest city in Africa and the 17 largest city in the world. Approximately one-third of the population ofEgypt is located in the Greater Cairo area (>20 million people), along with 60 percent of the country’s industry. Onaverage, the population density in Cairo proper is approxi-mately 19,000/km2; however, in the older parts of the city,the density can approach 100,000/km2. This high degree of urbanization has led to significant emissions from mobilesources, industrial sources, waste burning, and resuspendedgeological material. These emissions, coupled with poor dispersion and a dry climate, have resulted in a high frequency of air pollution episodes.

The air quality is degraded by high mass concentrations offine and coarse particulate matter (PM2.5 and PM10; particleswith aerodynamic diameters smaller than 2.5 and 10 µm, respectively), carbon monoxide, oxides of nitrogen, sulfurdioxide, hydrocarbons (VOCs), lead (Pb), and ozone.1-7 Inorder to develop and implement a pollution-control strategyand to reduce the health impacts of air pollution in Cairo, the U.S. Agency for International Development (USAID)sponsored the Cairo Air Improvement Project (CAIP).8 A keycomponent of CAIP was the implementation of a monitoringprogram for PM10, PM2.5, and Pb at sites throughout thegreater Cairo area. This effort provided the first long-termspatial and temporal data for these pollutants and highlightedthe critical need for implementing pollutant abatement

strategies. For example, initial CAIP results reported byHowes et al.9 for the baseline year monitoring found only 37 of the 1,783 PM10 measurements recorded during thatperiod were below the Egyptian 24-hr limit of 70 µg/m3. Further, annual average PM10 Pb levels in the Shobra areawere 26 µg/m3—almost 200 times the current quarterly U.S. standard of 0.15 µg/m3.

Pollutant Levels and SourcesIn order to determine the sources contributing to the elevatedlevels of PM10, PM2.5, Pb, and VOCs, a series of source attribution studies were conducted as part of the CAIP.1-3 Aspart of these efforts, samples were collected during intensivemeasurement periods conducted in winter 1999 (February21 to March 3), fall 1999 (October 29 to November 27),and summer 2002 (June 8 to June 26). Following the CAIPstudy, the World Bank supported another round of measure-ments of PM10, PM2.5, and Pb conducted during summer2010 (May 28 to June 21) and fall 2010 (October 10 to30).10 All samples were shipped to the Desert Research Institute (Reno, NV) for chemical analysis and source appor-tionment modeling. This extended series of studies has enabled us to establish long-term trends in both Cairo airquality and the sources contributing to elevated pollutant levels, along with allowing for an evaluation of efforts to improve air quality in a highly polluted urban area.

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Table 1 presents the PM10 and PM2.5 mass and Pb resultsfor the five monitoring locations where measurements wereconducted during all of the intensive monitoring periods (fall and winter 1999, summer 2002, and summer and fall2010): Kaha (background, agricultural, located upwind in the Nile Delta); Shobra (industrial and residential location); El-Qualaly (middle of the city, heavy mobile source impact);Zamalek (located on an island in the Nile, residential); andHelwan (southern part of the city, residential). Results for1999 and 2002 were taken from Abu-Allaban et al.,2 whilethose for 2010 were reported by Lowenthal et al.10 If we look at the change in mass concentrations, we see that bothPM2.5 and PM10 mass concentrations were lower during fall 2010 compared with fall 1999 at all sites. Summer PM2.5concentrations were also lower (generally within 20 percent)in 2010 compared with 2002, with the difference beinggreatest for Shobra (37 percent). There was no significantchange in PM10 between summer 2002 and summer 2010.PM10 and PM2.5 mass concentrations were highest duringfall 1999, and decreased and remained relatively constantthereafter. Given the influence of meteorology on observedconcentrations, coupled with changes in emissions, it is difficultto determine if pollutant reduction strategies had much of an impact over the eleven-year period.

By contrast, PM2.5 and PM10 Pb concentrations decreaseddramatically from 1999 to 2010. The largest change was atShobra, where PM10 Pb decreased from 34 µg/m3 duringwinter 1999 to 0.3 µg/m3 during summer 2010. PM10 Pbat Shobra also decreased significantly from 34 µg/m3 to 12.7 µg/m3 between winter and fall 1999. A similar decreasein PM10 Pb by a factor of 2.7 over this period occurred atEl-Qualaly. Large decreases in PM10 Pb between the sum-

mers of 2002 and 2010 were seen at Shobra and El-Qualaly.Similar trends are seen for PM2.5 Pb. Why did such a significantchange occur? Based on the CAIP results obtained in 1999,the Egyptian Government relocated the largest Pb smelter outof the Shobra area, leading to the large decrease observed in the following years.

Figures 1 and 2 present the source contributions to PM2.5and PM10, respectively. The values represent seasonal averagesover the five sampling sites. Rather than looking at all sources,it is instructive to consider contributions from a number ofimportant source categories: geological, mobile sources, leadsmelters, open burning, and secondary species (ammoniumsulfate, nitrate, and chloride). Geological material is the domi-nant source of PM10 mass. The geological contribution toPM10 peaked during summer 2002 due to high contributions

Table 1. Trends in seasonal average concentrations (µg/m3) for PM10 and PM2.5 mass and Pb in Cairo from1999 to 2010 (from Lowenthal, et al., 2014).10



at El-Qualaly, Zamalek, and Helwan and during summer 2010due to high contributions at Kaha and Shobra. However, aswith the observed mass concentrations, there is no long-termtrend, suggesting that meteorological factors determine thegeological dust contribution.

The contribution due to lead smelting is important to consider due to the high levels coupled with the health effects of lead exposure. This contribution was a small fractionof PM at all sites except Shobra. The source apportionmentresults are consistent with the previously mentioned observa-tions attributing the decrease in the lead smelter contributiondue to the implemented control strategy following the 1999measurements. Further, not only did this implemented control have a major impact at Shobra, it also led to decreases at the other sites.

Over the 1999 to 2010 period, there was no statistically significant trend in the contribution of motor vehicles to theobserved PM concentrations; although as a percent contribu-tion, there appears to have been a small increase. In general,open (vegetative/trash) burning was the largest contributor toPM2.5. The largest contributions were found during the fallseason, although the relative contributions do not appear to

have changed significantly from fall 1999 to fall 2010. Muchof this is due to agricultural waste burning, especially at Kaha, coupled with the burning of trash. With respect to thesecondary species, the primary change was the decrease inthe contribution from ammonium chloride. The 1999 resultshighlighted this contribution. Following those measurements,a bleaching plant that had significant chloride emissions wascontrolled, leading to the observed decrease.

What Did We Learn?Long-term trends were examined by comparing the resultsof a number of intensive source attribution monitoring studiesconducted over an 11-year period in the Greater Cairo area.The major contributors to PM10 included resuspended geological dust, mobile source emissions, and open (vegeta-tive/trash) burning, while for PM2.5 they were open burning,motor vehicles, secondary PM, and soil. During the fall periods, the open burning contribution exceeded that fromsoil and motor vehicles. This is likely due to agricultural wasteburning following the fall harvest. Based on these studies, anumber of control strategies were implemented and we wereable to assess their effect on observed PM2.5, PM10, and Pb concentrations. The relocation of a major smelter in theShobra area had a significant impact on ambient Pb levels.

Figure 1. Average PM2.5 source contributions (µg/m3) at five sampling locations for intensive measurement studiesconducted in 1999, 2002, and 2010.



Similarly, controlling emissions from a bleaching plant in theNile Delta led to an observable decrease in the contributionof ammonium chloride to ambient PM.

In spite of these positive outcomes, without a significant reduction of geological dust, motor vehicle, and open burning

emissions, ambient PM concentrations will remain at levelsharmful to human health. Developing and implementing effective control strategies for these sources is a challenge not only in Cairo, but also in other megacities around the world. em

Figure 2. Average PM10 source contributions (µg/m3) at five sampling locations for intensive measurement studiesconducted in 1999, 2002, and 2010.

Alan W. Gertler, Ph.D., and Douglas H. Lowenthal, Ph.D., are both with Desert Research Institute, Reno, NV. Mounir Labib,Ph.D., is with the National Academy of Science, Cairo, Egypt. E-mail: [email protected].

References1. Abu-Allaban, M.; Gertler, A.W.; Lowenthal, D.H. A preliminary apportionment of the sources of ambient PM10, PM2.5, and VOCs in Cairo; Atmos. Environ.

2002, 36, 5549-5557.2. Abu-Allaban, M.; Lowenthal, D.H.; Gertler, A.W.; Labib, M. Sources of PM10 and PM2.5 in Cairo’sambient air; Environ. Monitor. Assess. 2007, 133, 417-425.3. Abu-Allaban, M.; Lowenthal, D.H.; Gertler, A.W.; Labib, M. Sources of Volatile Organic Compounds in Cairo’s Ambient Air; Environ. Monitor. Assess. 2009,157, 179-189.

4. Boman, J.; Shaltout, A.A.; Abozied, A.M.; Hassan, S.K. On the elemental composition of PM2.5 in central Cairo, Egypt; X-Ray Spectrometry 2012, 42, 276-283.5. Khoder, M.I. Ambient levels of volatile organic compounds in the atmosphere of Greater Cairo; Atmos. Environ. 2007, 41, 554-566. 6. Rodes, C.E.; Nasralla, M.M.; Lawless, P.A. An assessment and source apportionment of airborne particulate matter in Cairo, Egypt; Activity report No. 22, prepared

for the USAID Mission to Egypt under EHP activity No. 133-RCm delivery order No. 7, 1996.7. Safar, Z.; Labib, M.W. Assessment of particulate matter and lead levels in the Greater Cairo Area for the period 1998–2007; J. Adv. Res. 2010, 1, 53-63.8. Howes, J.E.; Samaha, N.; Labib, M.; Sabry, M.; El Araby, H. Ambient PM2.5, PM10, and lead measurements in Cairo, Egypt. Presented at the A&WMA Annual Conference & Exhibition, St. Louis, MO, 1999.9. Howes, J.E.; Serre, M.L.; Labib, M.; Samaha, N.; Sabra, M.; Araby, H. Ambient PM and lead levels in Cairo, Egypt: baseline year monitoring results. Presented at

the A&WMA Annual Conference & Exhibition, Salt Lake City, UT, 2000.10. Lowenthal, D.H.; Gertler, A.W.; Labib, M.W. Particulate matter source apportionment in Cairo: Recent measurements and comparison with previous studies; Int.J. Environ. Sci. Technol. 2014, 11, 657-670.

the challenge of cairo, egypt

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