CHARACTERIZATION OF URBAN AEROSOLS AND THEIR SOURCES IN LEBANON

Abstract:

During the last decades, air pollution has become an increasing concern, especially in urban areas, due to its adverse effect on human health. Respiratory and cardiovascular illnesses related to particulate matter (PM) exposure have been well established in the literature.

Therefore, there is a dire need for studies focusing on characterizing the chemical composition of PM and identifying its major sources. So far, such studies have been conducted in Europe and the USA, while there is currently a paucity of data in the Middle East region where emissions are projected to exceed those of Europe and the US worsening the regional air quality.

The aim of this work is to measure the concentration of fine particles in two nearby sampling sites in Beirut, Lebanon, and investigate the sources of aerosols. The average PM_2.5 concentration during our study exceeded, in both sites, the WHO guidelines of 10 μg/m³ by a factor of three. The present study showed how sources affected in different way two sites having similar PM_2.5 concentration levels. A comprehensive composition and source apportionment of PM_2.5 in Lebanon has been established for the first time. The chemical compositions of particulate matter, including major components, OC, EC, ionic species, elements, and organic compounds, were analyzed to identify the sources of atmospheric aerosols using PMF as a source apportionment model. The PMF model using organic markers was able to provide more detailed information about the source of organic aerosols such as biomass burning, secondary organic aerosol and vegetative detritus, which are usually not identified by PMF analysis using only inorganics. Thus, using organic molecular markers for source apportionment provides a more comprehensive assessment of the source of fine particulate in Lebanon. This study gives a better understanding of the pollution level and main pollution sources in two sites in Lebanon. The results can be useful for policy decision makers in formulating effective PM_2.5 control strategies. This work pointed how the challenges that this country is facing, such as an unsustainable transport sector, an unregulated power generation sector, and high urban densities, amplify negatively the air-quality.