Chemical characterization and sources identification of PM2.5 in a tropical urban city during non-hazy conditions

This study aims to evaluate the variation of PM2.5 components as well as to identify PM2.5 sources under non-hazy weather conditions in a tropical urban city, Petaling Jaya, Malaysia. The nonhazy weather conditions were characterized by copious rainfall throughout the year and ephemeral dry periods, with no significant haze events. The PM2.5 concentrations were recorded on the rooftop of an eight-floor building using a High Volume Sampler (HVS). The water-soluble ion (WSI), trace metal (TM) and organic and elemental carbon (OC-EC) content of PM2.5 was determined for source apportionment using the Positive Matrix Factorization (PMF) model. Daily PM2.5 concentrations were in the range 9.80-59.9 mu gm(-3). Dry weather conditions, rainfall and atmospheric stability in different seasons influenced the daily PM2.5 variations. The maximum PM2.5 concentration (33.1 mu gm(-3)) was measured during the inter monsoon (INT I) season. The major constituents of PM2.5 were OC (6.80 mu gm(-3), 24.4%), EC (0.700 mu gm(-3), 2.5%) and inorganic matter (IM) (6.6 mu gm(-3), 23.7%). The PMF identified eight factor profiles of PM2.5 sources and the major source contributors were secondary inorganic aerosol (SIA), traffic and oil combustion (28.5%). We note that source characteristics of PM2.5 were significantly modulated by seasonal factors during non-hazy weather conditions.