title: Physicochemical and toxicological characteristics of urban aerosols during a recent Indonesian biomass burning episode.
abstract: Air particulate matter (PM) samples were collected in Singapore from 21 to 29 October 2010. During this time period, a severe regional smoke haze episode lasted for a few days (21-23 October). Physicochemical and toxicological characteristics of both haze and non-haze aerosols were evaluated. The average mass concentration of PM2.5 (PM with aerodynamic diameter of ≤2.5 μm) increased by a factor of 4 during the smoke haze period (107.2 μg/m(3)) as compared to that during the non-smoke haze period (27.0 μg/m(3)). The PM2.5 samples were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency and 10 transition metals. Out of the seven PAHs known as potential or suspected carcinogens, five were found in significantly higher levels in smoke haze aerosols as compared to those in the background air. Metal concentrations were also found to be higher in haze aerosols. Additionally, the toxicological profile of the PM2.5 samples was evaluated using a human epithelial lung cell line (A549). Cell viability and death counts were measured after a direct exposure of PM2.5 samples to A459 cells for a period of 48 h. The percentage of metabolically active cells decreased significantly following a direct exposure to PM samples collected during the haze period. To provide further insights into the toxicological characteristics of the aerosol particles, glutathione levels, as an indirect measure of oxidative stress and caspase-3/7 levels as a measure of apoptotic death, were also evaluated.
authors.affiliation: Singapore Delft Water Alliance, National University of Singapore, Singapore 117576, Singapore.
authors.forename: Shruti
authors.initials: S
authors.lastname: Pavagadhi
authors.forename: Raghu
authors.initials: R
authors.lastname: Betha
authors.forename: Shriram
authors.initials: S
authors.lastname: Venkatesan
authors.forename: Rajasekhar
authors.initials: R
authors.lastname: Balasubramanian
authors.forename: Manoor Prakash
authors.initials: MP
authors.lastname: Hande
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry / Q000633:toxicity; D000397:Air Pollution / Q000009:adverse effects / Q000032:analysis; D018533:Biomass; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004784:Environmental Monitoring; D004847:Epithelial Cells / Q000187:drug effects* / Q000502:physiology; D005390:Fires; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007214:Indonesia; D008168:Lung / Q000166:cytology; D008670:Metals / Q000032:analysis / Q000633:toxicity; D018384:Oxidative Stress; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis / Q000737:chemistry / Q000633:toxicity; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000633:toxicity; D012906:Smoke / Q000009:adverse effects / Q000032:analysis; D023382:Toxicity Tests, Acute
chemical_list: D000393:Air Pollutants; D008670:Metals; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons; D012906:Smoke