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 PM 2.5 components as well as to identify PM 2.5 sources under non-hazy weather conditions in a tropical urban city, Petaling Jaya, Malaysia. The non-hazy weather conditions were characterized by copious rainfall throughout the year and ephemeral dry periods, with no significant haze events. The PM 2.5 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 PM 2.5 was determined for source apportionment using the Positive Matrix Factorization (PMF) model. Daily PM 2.5 concentrations were in the range 9.80–59.9 μgm⁻³. Dry weather conditions, rainfall and atmospheric stability in different seasons influenced the daily PM 2.5 variations. The maximum PM 2.5 concentration (33.1 μgm⁻³) was measured during the inter monsoon (INT I) season. The major constituents of PM 2.5 were OC (6.80 μgm⁻³, 24.4%), EC (0.700 μgm⁻³, 2.5%) and inorganic matter (IM) (6.6 μgm⁻³, 23.7%). The PMF identified eight factor profiles of PM 2.5 sources and the major source contributors were secondary inorganic aerosol (SIA), traffic and oil combustion (28.5%). We note that source characteristics of PM 2.5 were significantly modulated by seasonal factors during non-hazy weather conditions. • PM 2.5 and its potential sources under non-hazy tropical conditions were determined • The daily PM 2.5 concentration was in the range of 9.80 to 59.9 μgm⁻³ • Positive Matrix Factorization identified eight factor profiles of PM 2.5 sources • PM 2.5 sources ensued with more traceable pollutant groups from local activities [ABSTRACT FROM AUTHOR]