EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Sources and atmospheric aging processes of submicron aerosols in Cairo Megacity.

Aliki Christodoulou1,2, Iasonas Stavroulas1, Efstratios Bourtsoukidis1, Michael Pikridas1, Spyros Bezantakos1, Salwa Hassan3, Mostafa El-Nazer4, Ali Wheida4, Magdy Wahab5, Mohamed Boraiy6, Agnes Borbon7, Charbel Afif1,8, Stéphane Sauvage2, and Jean Sciare1
Aliki Christodoulou et al.
  • 1Climate and Atmosphere Research Centre (CARE-C), The Cyprus Institute, Nicosia, Cyprus
  • 2IMT Nord Europe, Institut Mines-Télécom, Univercity of Lille, France
  • 3Air Pollution Research Department, National Research Centre, Egypt
  • 4Theoretical Physics Department, National Research Centre, Egypt
  • 5Astronomy and Meteorology Department, Cairo University
  • 6Physics and Mathematical Engineering Department, Port Said University
  • 7LaMP Clermont-Ferrand, France
  • 8Saint Joseph University, Beirut, Lebanon

Over the last few decades, Greater Cairo Megacity has experienced rapid population growth and expansion of its industrial activity. Hosting more than 20 million people, Cairo is considered one of the most polluted megacities in the world. Concentration levels of fine particulate matter (PM2.5) are several times higher than those recommended by the World Health Organization (WHO). Although actions have been designed recently to improve air quality in the framework of a “Pollution Management and Environmental Health program” (PMEH) supported by the World Bank, observational studies assessing the main sources leading to this PM pollution are missing, making difficult to implement and monitor the efficiency of local mitigation strategies.

The aim of our study is to investigate atmospheric concentrations levels, temporal variability, as well as major sources, and atmospheric aging of PM in Cairo megacity with a focus on the submicron aerosol fraction (PM1) to better assess human-made activities with lower interference from natural (dust) emissions. A comprehensive suite of on-line and off-line instruments has been set-up to monitor PM1 chemical composition and reactive trace gases (i.e. Volatile Organic Compounds) as a part of the POLCAIR campaign that took place during winter 2019-2020, at an urban background site in Greater Cairo. Chemical composition of PM1 and source apportionment analysis via Positive Matrix Factorization (PMF) on both Q-ACSM (Aerosol Chemical Speciation Monitor, Aerodyne, US) organic mass spectra and co-located filter samples, attributed exceptionally high concentrations of compounds to traffic emissions and diverse combustion sources with pronounced diurnal variability. Two severe pollution episodes were recorded, with hourly mean PM1 concentrations reaching values as high as 300 μg/m3 and lasting for 2 consecutive days favored by low dispersion conditions. Pollutant variability is directly associated with the meteorological conditions, including wind patterns and air mass origins. This helps in recognizing emission hot spots of major anthropogenic PM1 sources. Additionally, the effects of the relative humidity and the role of heterogeneous oxidation reaction mechanisms was investigated. Finally, the multi-variable analyses performed, helped us to better investigate the complex urban atmospheric chemistry in Cairo megacity and to highlight the dynamics of Secondary Organic Aerosol formation.

How to cite: Christodoulou, A., Stavroulas, I., Bourtsoukidis, E., Pikridas, M., Bezantakos, S., Hassan, S., El-Nazer, M., Wheida, A., Wahab, M., Boraiy, M., Borbon, A., Afif, C., Sauvage, S., and Sciare, J.: Sources and atmospheric aging processes of submicron aerosols in Cairo Megacity., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12038,, 2022.