Greater Cairo, the largest megacity of the Middle East North Africa (MENA) region, is currently suffering from major aerosol pollution, posing a significant threat to public health. However, the main sources of pollution remain insufficiently characterized due to limited atmospheric observations. To bridge this knowledge gap, we conducted a continuous 2-month field study during the winter of 2019–2020 at an urban background site, documenting for the first time the chemical and physical properties of submicron (PM1) aerosols. Crustal material from both desert dust and road traffic dust resuspension contributed as much as 24 % of the total PM1 mass (rising to 66 % during desert dust events), a figure not commonly observed in urban environments. Our observations showed significant decreases in black carbon concentrations and ammonium sulfate compared to data from 15 years ago, indicating an important reduction in both local and regional emissions as a result of effective mitigation measures. The diurnal variability of carbonaceous aerosols was attributed to emissions emanating from local traffic at rush hours and nighttime open biomass burning. Surprisingly, semi-volatile ammonium chloride (NH4Cl) originating from local open biomass and waste burning was found to be the main chemical species in PM1 over Cairo. Its nighttime formation contributed to aerosol water uptake during morning hours, thereby playing a major role in the build-up of urban haze. While our results confirm the persistence of a significant dust reservoir over Cairo, they also unveil an additional source of highly hygroscopic (semi-volatile) inorganic salts, leading to a unique type of urban haze. This haze, with dominant contributors present in both submicron (primarily as NH4Cl) and supermicron (largely as dust) modes, underscores the potential implications of heterogeneous chemical transformation of air pollutants in urban environments.

This work presents an exhaustive chemical characterization of the organic fraction of fine particulate matter (PM2.5) collected at an urban site in the Greater Cairo Area, Egypt, one of the most polluted megacities in the world. An intensive 2-month sampling campaign was conducted at an urban site in Giza (Dokki), from November 26, 2019, to January 28, 2020. Daily (24-h integrated) PM2.5 filter samples were then analyzed for their carbonaceous (OC, EC) and organic fractions including primary (n-alkanes, phthalates, fatty acids, polycyclic aromatic hydrocarbons, hopanes, sugars, and sugar alcohols) and secondary (isoprene and β-caryophyllene oxidation products, and dicarboxylic acids) compounds. Average organic (OC) and elemental carbon (EC) concentrations were 17.8 ± 6.6 μg/m3 and 4.4 ± 1.5 μg/m3, respectively. Biomass burning was confirmed by high daily concentration levels of levoglucosan, mannosan, and galactosan (sum equals to 288 ng/m3). Road traffic was also highlighted by the relative abundance of tetracosane and a carbon preference index close to unity as well as by the concentration ratios of PAHs and hopanes. Moreover, phthalates were identified for the first time in Cairo with high concentrations (654 ng/m3) that might be attributable to open waste burning activities. Fatty acids and sugars were also investigated and assigned to cooking activities and primary biogenic sources, respectively. The average concentration of isoprene and β-caryophyllene oxidation products were 0.89 ± 0.83 ng/m3, and 0.01 ± 0.02 ng/m3, respectively. These low values are expected since no pine trees or even forests exist in Egypt. The macrotracer approach was employed alongside Monte Carlo simulation to identify sources of primary OC and evaluate the uncertainties associated with source attribution and OC reconstruction. The findings revealed a strong contribution from cooking (31% of observed OC) and biomass burning (18%), with median reconstructed OC levels showing significant uncertainty (64%) as expected.

Many studies have detected a relationship between diarrhea morbidity rates with the changes in precipitation, temperature, floods, droughts, water shortage, etc. But, most of the authors were cautious in their studies, because of the lack of empirical climate-health data and there were large uncertainties in the future projections. The study aimed to refine the link between the morbidity rates of diarrhea in some Egyptian governorates representative of the three Egyptian geographical divisions with the meteorological changes that occurred in the 2006–2016 period for which the medical data are available, as a case study. Medical raw data was collected from the Information Centre Department of the Egyptian Ministry of Health and Population. The meteorological data of temperature and precipitation extremes were defined as data outside the 10th–90th percentile range of values of the period of study, and their analysis was done using a methodology similar to the one recommended by the WMO and integrated in the CLIMDEX software. Relationships between the morbidity rates of diarrhea in seven Egyptian governorates and the meteorological changes that occurred in the period 2006 to 2016 were analyzed using multiple linear regression analysis to identify the most effective meteorological factor that affects the trend of morbidity rate of diarrhea in each governorate. Statistical analysis revealed that some meteorological parameters can be used as predictors for morbidity rates of diarrhea in Cairo, Alexandria, and Gharbia, but not in Aswan, Behaira, and Dakahlia where the temporal evolution cannot be related with meteorology. In Red Sea, there was no temporal trend and no significant relationships between the diarrhea morbidity rate and meteorological parameters. The predictor meteorological parameters for morbidity rates of diarrhea were found to be depending on the geographic locations and infrastructures in these governorates. It was concluded that the meteorological data that can be used as predictors for the morbidity rate of diarrhea is depending on the geographical location and infrastructures of the target location. The socioeconomic levels as well as the infrastructures in the governorate must be considered confounders in future studies.

The data of 17 air quality monitoring stations of Greater Cairo are used to perform a statistical analysis aiming to detect any heterogeneous surface effects of mineral dust on the distribution of reactive trace gases (SO 2 NO 2 , and ozone) in. After a thorough quality check, the methodology consisted of i) selecting representative stations by agglomerative hierarchical clustering, ii) identifying dust events based on PM 10 measurements, remote sensing observations, and meteorology, and iii) applying the non-parametric Kruskal Wallis (KW) hypothesis test to compare (at the 95% confidence level) trace gas concentrations during dust and non-dust events. The representative stations display either a background-like or a bimodal variability with concentrations (even that of the secondary product NO 2 ) peaking at traffic rush hours but during dust storms all stations capture the signal of mineral dust advection. Eight wintertime and springtime dust cases are retained for the study. After the role of the confounding factors (i.e., ventilation index, relative humidity, and photolysis) has been carefully discussed and taken into account, the KW test shows that there is no significant reduction of the SO 2 , NO 2 and ozone concentrations attributable to dust during 7 of the 8 events. The drop of the concentrations coinciding with the advection of dry dust-laden Saharan air masses is rather an effect of the dilution resulting from the combination of large wind speed and mixing layer height than of the heterogeneous uptake of these gases on the mineral dust surface.

Land use/ land cover mapping and characterization is required for resource management and planning.In this aspect, remote sensing methods can be employed to classify the land use/ land cover classes over selected areas in an effective and economical manner compared to traditional surveys.In this research an improved supervised classification scheme for Sentinel-2 images classification of a selected area in El-Beheira governorate was developed.Field survey was carried out to collect ground truth data for from December 2020 to March 2021.The supervised classification was preformed after applying various principle component analyses (PCAs) on the used sequential Sentinel-2 images within the winter season.The results revealed that utilizing the proposed image classification technique, an overall accuracy of 86.8% could be achieved for the produced Land Use/Land cover map.The agricultural area covered about 89% of the studied area and was occupied by seven crops.Wheat and Egyptian clover were the major crops and covered about 67% of the studied area while green beans, potato and citrus covered about 21%.

Egypt, located in the Middle East and North Africa region, is considered to be a potential hot-spot of climate change where the warming and increase of the frequency of extreme temperatures could occur faster than at global scale. Precipitation is also expected to decrease in the region. In this work, our aim is to quantify the past and future temperature and precipitation trends at 8 locations selected for being representative of the variety of Egyptian climates. For the past period (1950-2017), we show that the decadal temperature trends derived from the analysis of the assimilated ERA-Interim (ERA-Int) and downscaled CORDEX (Historical and Evaluation) data are consistent. Relative to 1960, the daily maximal and minimal temperatures have increased by 1.3 +/- 0.1 and 1.3 +/- 0.3 degrees C, respectively, at the 8 selected locations. However, at the shorter yearly time scale, sub-regional differences of climate variability can be evidenced: this variability is less at the coastal and Nile Delta sites than at the drier inland locations. For the future, we use an ensemble of 6 CORDEX Africa models. Under the RCP45 scenario, the temperatures are predicted to increase at a rate ranging from 0.28 +/- 0.04 degrees C/decade (Alexandria) to 0.38 +/- 0.09 degrees C/decade (Hurghada and Aswan) between 2010 and 2040, and to abate afterwards (0.12 +/- 0.08 degrees C/decade). Under the RCP85 scenario, the rates of temperature increase before 2040 are similar to those under RCP45 (from 0.24 +/- 0.14 to 0.40 +/- 0.12 degrees C/decade) but considerably larger afterwards (from 0.48 +/- 0.18 degrees C to 0.72 +/- 0.11 degrees C/decade between 2050 and 2100). As compared to the 2006-2015 reference period, the extreme temperatures analysis performed with the CLIMDEX software shows that the hot days and nights will become more frequent at all sites, but that the increase will occur at larger rates at the Red Sea (Hurghada) and upper Egypt (Aswan) sites than at the other ones. These inter-site differences are more pronounced with RCP45 than with RCP85. Considering the latter scenario, in the last decade of this century about 80% of the days in a year would be hotter than the 90th percentile of the 2006-2015 reference period. Regarding the annual precipitation, the analysis of ERA-Interim data of the 1980-2017 period does not reveal any significant trend, but in both RCP45 and RCP85 a significant decrease (from -0.48 to -0.9 mm/y, and from -0.95 to -1.40 mm/y, respectively) is predicted to occur from 2010 to 2100 in the north of Egypt where rain is currently the most abundant.

OBJECTIVE:The poor outdoor air quality in megacities of the developing world and its impact on health is a matter of concern for both the local populations and the decision-makers. The objective of this work is to quantify the mortality attributable to long-term exposure to PM2.5, NO2, and O3 in Greater Cairo (Egypt). METHODS:We analyze the temporal and spatial variability of the three pollutants concentrations measured at 18 stations of the area. Then, we apply the method recommended by the WHO to estimate the excess mortality. In this assessment, three different shapes (log-linear, linear, and log-log) of the concentration-response functions (CRF) are used. RESULTS:With PM2.5 concentrations varying from 50 to more than 100µg/m3 in the different sectors of the megacity, the spatial variability of this pollutant is found to be one important cause of uncertainty on the excess mortality associated with it. Also important is the choice of the CRF. With the average (75µg/m3) PM2.5 concentration and the most favorable log-log shape of the CRF, 11% (CI, 9-14%) of the non-accidental mortality in the population older than 30 years can still be attributed to PM2.5, which corresponds to 12520 (CI, 10240-15930) yearly premature deaths. Should the Egyptian legal 70µg/m3 PM10 limit (corresponding to approximately 37.5µg/m3 for PM2.5) be met, this number would be reduced to 7970, meaning that 4550 premature deaths could be avoided each year. Except around some industrial or traffic hot spots, NO2 concentration is found to be below the 40µg/m3 air quality guideline of the WHO. However, the average concentration (34µg/m3) of this gas exceeds the stricter 10µg/m3 recommendation of the HRAPIE project and it is thus estimated that from 7850 to 10470 yearly deaths can be attributed to NO2. Finally, with the ozone concentration measured at one station only, it is found that, depending on the choice of the CRF, between 2.4% and 8.8% of the mortality due to respiratory diseases can be attributed to this gas. CONCLUSION:In Greater Cairo, PM2.5 and NO2 constitute major health risks. The best estimate is that in the population older than 30 years, 11% and 8% of the non-accidental mortality can be attributed to these two pollutants, respectively.