Temporal variations of fine and coarse particulate matter sources in Jeddah, Saudi Arabia.

UNLABELLED

This study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (aerodynamic diameter <2.5 μm; PM) and coarse (aerodynamic diameter 2.5-10 μm; PM) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over 1 yr, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM (21.9 μg/m) and PM (107.8 μg/m) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM (10 μg/m) and PM (20 μg/m), respectively. Similar to other Middle Eastern locales, PM is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM and PM: (1) soil/road dust, (2) incineration, and (3) traffic; and for PM only, (4) residual oil burning. Soil/road dust accounted for a major portion of both the PM (27%) and PM (77%) mass, and the largest source contributor for PM was from residual oil burning (63%). Temporal variations of PM and PM were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency) and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM and PM masses in this city may have implications regarding the toxicity of these particles versus those in the Western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting.

IMPLICATIONS

Temporal variations of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia, for the first time. The main source of PM is natural windblown soil and road dust, whereas the predominant source of PM is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effect studies to be conducted in this region, so as to directly assess the applicability of the existing guidelines to the Middle East air pollution.