Spatial and temporal variation in fine particulate matter mass and chemical composition: The middle east consortium for aerosol research study

Ambient fine particulate matter (PM_2.5) samples were collected from January to December 2007 to investigate the sources and chemical speciation in Palestine, Jordan, and Israel. The 24-h PM_2.5samples were collected on 6-day intervals at eleven urban and rural sites simultaneously. Major chemical components including metals, ions, and organic and elemental carbon were analyzed. The mass concentrations of PM_2.5across the 11 sites varied from 20.6 to 40.3 g/m³, with an average of 28.7 g/m ³. Seasonal variation of PM_2.5concentrations was substantial, with higher average concentrations (37.3 g/m³) in the summer (April-June) months compared to winter (October-December) months (26.0 g/m³) due mainly to high contributions of sulfate and crustal components. PM_2.5 concentrations in the spring were greatly impacted by regional dust storms. Carbonaceous mass was the most abundant component, contributing 40% to the total PM_2.5mass averaged across the eleven sites. Crustal components averaged 19.1% of the PM_2.5mass and sulfate, ammonium, and nitrate accounted for 16.2%, 6.4%, and 3.7%, respectively, of the total PM_2.5 mass. The results of this study demonstrate the need to better protect the health and welfare of the residents on both sides of the Jordan River in the Middle East.