PM 1.0 and PM 2.5 Characteristics in the Roadside Environment of Hong Kong

Author： Lee S.

ISSN： 1521-7388

Source： Aerosol Science and Technology, Vol.40, Iss.3, 2006-03, pp. : 157-165

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Abstract

Daily mass concentrations of PM 1.0 (particles less than 1.0 µm in diameter), PM 2.5 (particles less than 2.5 µm in diameter), organic carbon (OC), and elemental carbon (EC) were measured from January through May 2004 at a heavily trafficked sampling site in Hong Kong (PU). The average concentrations for PM 1.0 and PM 2.5 were 35.9 ± 12.4 µ g cm - 3 and 52.3 ± 18.3 µ g cm - 3 . Carbonaceous aerosols were the dominant species in fine particles, accounting for ~ 45.7% of PM 1.0 and ~ 44.4% of PM 2.5 . During the study period, seven fine-particle episodes occurred, due to the influence of long-range transport of air masses from mainland China. PM 1.0 and PM 2.5 responded in similar ways; i.e., with elevated mass and OC concentrations in those episode days. During the sampling period, PM 1.0 OC and EC generally behaved similarly to the carbonaceous aerosols in PM 2.5 , regardless of seasonal variations and influence by regional pollutions. The low and relatively constant OC/EC ratios in PM 1.0 and PM 2.5 indicated that vehicular emissions were major sources of carbonaceous aerosols. PM 1.0 and PM 2.5 had the same dominant sources of vehicular emissions in winter, while in spring PM 2.5 was more influenced by PM 1 - 2.5 (particles 1–2.5 µ m in diameter) that did not form from vehicle exhausts. Therefore, PM 1.0 was a better indicator for vehicular emissions at the Roadside Station.