| Summary: | This study developed analytical methods to quantify particulate-bound polycyclic aromatic hydrocarbons (pPAHs). The methods were used to characterise PAHs in house dust and particulate matter (PM10) samples, respectively, in two case studies. Dust samples were collected from rural households in Malawi to represent indoor particles from biomass fuel combustion. PM10 samples were collected from three sites in the Bangkok Metropolitan Administration (BMA), Thailand to represent air pollutants in roadside, industrial and urban background environments. PAHs were quantified using a gas chromatograph-mass spectrometer (GC-MS). Comprehensive two-dimensional gas chromatograph coupled with time-of-flight mass spectrometer(GCxGC TOFMS) was used for the screening of unknown air pollutants in PM10. Low molecular weight 2-ring and 3-ring PAHs were more abundant in dust samples collected in Malawi, while high molecular weight 4-ring to 6-ring PAHs were more abundant in PM10 samples collected in Thailand. Spatial and temporal variations in PM10 and pPAH concentrations were examined between and within the three sampling sites in Thailand. Annual average benzo[a]pyrene (BaP) concentrations were 0.47 ± 0.39 ng m-3, 0.35 ± 0.27 ng m-3 and 0.24 ± 0.19 ng m-3 at the roadside, industrial and urban background sites, respectively. Cancer risks associated with pPAHs were estimated using BaP and BaP toxic equivalency (BaP-TEQ) concentrations. The highest incremental lifetime cancer risk was found in the residential adult group at 4.2 x 10-7 at the industrial site. Although the highest PM10 and total PAHs concentrations were found at the roadside site, the highest carcinogenic potential of total PAH (in terms of BaP toxic equivalency concentration) was found at the industrial site. Thus, the cancer risk estimation relies more on the composition of pPAHs than its concentration. Estimated lifetime lung cancer risks associated with pPAHs in all three sites were in the ‘acceptable’ range of less than 1 x 10-6 defined by the United States Environmental Protection Agency.
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