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This study investigated atmospheric particulate matter (PM) with an aerodynamic diameter of < 2.5 µm (PM 2.5 ) observed at the Prince of Songkla University (Phuket Campus) in southern Thailand. All samples (n = 75) were collected using MiniVol™ portable air samplers from March 2017 to February 2018. Carbonaceous aerosol compositions, i.e., organic carbon (OC) and elemental carbon (EC), water-soluble ionic species (WSIS), and polycyclic aromatic hydrocarbons (PAHs) in the PM 2.5 samples were identified and quantified. We found that the average PM 2.5 concentration was 42.26 ± 13.45 µg m -3 , while the average concentrations of OC and EC were 3.05 ± 1.70 and 0.63 ± 0.58 µg m -3 , respectively. The OC/EC ratio was in the range of 2.69-16.9 (mean: 6.05 ± 2.70), and the average concentration of 10 selected ions was 6.91 ± 3.54 µg m -3 . The average concentration of SO 4 2was the highest throughout the entire study period (2.33 ± 1.73 µg m -3 ); the average contribution of SO 4 2to the major ionic components was 34%. Surprisingly, the average concentrations of NO 3and NH 4 + were relatively low. The mean ratio of [NO 3 -]/[SO 4 2-] was 0.33 ± 0.24. Strong positive correlation was found between K + and both OC and EC (r = 0.90 and r = 0.93, respectively). It is also precious to highlight that biomass burning (BB) is the major source of OC, EC and K + , which multiple studies have confirmed that the role of K + as a biomass marker. Results showed that BB episodes might play a major role in producing the observed high levels of OC. The relatively high abundance of both B[g,h,i]P and Ind suggests that motor vehicles, petroleum/oil combustion, and industrial waste burning are the primary emission sources of PAHs in the ambient air of Phuket. Interestingly, principal component analysis (PCA) indicated that vehicular exhausts are the main source of carbonaceous aerosol compositions found in the ambient air of Phuket, whereas the contributions of biomass burning, diesel emissions, sea salt aerosols and industrial emissions were also important.

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Along with rapid economic growth and enhanced agricultural productivity, particulate matter emissions in the northern cities of Thailand have been increasing for the past two decades. This trend is expected to continue in the coming decade. Emissions of particulate matter have brought about a series of public health concerns, particularly chronic respiratory diseases. It is well known that lung cancer incidence among northern Thai women is one of the highest in Asia (an annual age-adjusted incidence rate of 37.4 per 100,000). This fact has aroused serious concern among the public and the government and has drawn much attention and interest from the scientific community. To investigate the potential causes of this relatively high lung cancer incidence, this study employed Fourier transform infrared spectroscopy (FTIR) transmission spectroscopy to identify the chemical composition of the PM 2.5 collected using Quartz Fibre Filters (QFFs) coupled with MiniVol™ portable air samplers (Airmetrics). PM 2.5 samples collected in nine administrative provinces in northern Thailand before and after the "Haze Episode" in 2013 were categorised based on three-dimensional plots of a principal component analysis (PCA) with Varimax rotation. In addition, the incremental lifetime exposure to PM 2.5 of both genders was calculated, and the first derivative of the FTIR spectrum of individual samples is here discussed.

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