Of late, air pollution in Asia has increased, particularly in built-up areas due to rapid industrialization and urbanization. The present study sets out to examine the impact that pollution can have on the health of people living in the inner city of Bangkok, Thailand. Consequently, in 2021, fine particulate matter (PM2.5) and coarse particulate matter (PM10) chemical composition and sources are evaluated at three locations in Bangkok. To identify the possible sources of such particulates, therefore, the principal component analysis (PCA) technique is duly carried out. As determined via PCA, the major sources of air pollution in Bangkok are local emission sources and sea salt. The most significant local sources of PM2.5 and PM10 in Bangkok include primary combustion, such as vehicle emissions, coal combustion, biomass burning, secondary aerosol formation, industrial emissions, and dust sources. Except for the hazard quotient (HQ) of Ni and Mn of PM2.5 for adults, the HQ values of As, Cd, Cr, Mn, and Ni of both PM2.5 and PM10 were below the safe level (HQ = 1) for adults and children. This indicates that exposure to these metals would have non-carcinogenic health effects. Except for the carcinogenic risk (HI) value of Cr of PM2.5 and PM10, which can cause cancer in adults, at Bangna and Din Daeng, the HI values of Cd, Ni, As, and Pb of PM2.5 and PM10 are below the limit set by the U.S. Environmental Protection Agency (U.S. EPA). Ni and Mn pose non-carcinogenic risks, whereas Cr poses carcinogenic risks to adults via inhalation, a serious threat to the residents of Bangkok.

Arsenic can be found in groundwater that is harmful to human beings. In this research, we present the potential uses of ZnO microparticles, ZnO and TiO2 nanoparticles to removal arsenic in groundwater. The experiments of %arsenic removal upon using ZnO microparticles ZnO and TiO2 nanoparticles were conducted in 25 mL of sample volume with 0.05 g of nanoadorpbents at pH 6. We found that the efficiency of arsenic adsorption increased with a reduction of particle size of theadsorbents. Upon using nanoadsorbents to remove arsenic from the solutions with the concentrations of 200-2000 ppb, we found that the %removal of arsenic decreased from 100% to 84% for ZnO nanoparticles and 100% to 97% for TiO2 nanoparticles. Adsorption capacities upon using ZnO and TiO2 nanoparticles were 0.85 and 0.99 mg of arsenic/g of sorbents, respectively. TiO2 nanoparticles exhibited a better adsorption ability to arsenic than that ZnO because TiO2 nanoparticles had a smaller average particle size and larger surface area allowed the adsorption of hydroxyl groups on the surface that could bond with in coming HAsO42- via hydrogen bonding resulting in a better arsenic adsorptive capacity.

Here we demonstrate the controllability of the morphology of hydrothermal ZnO nanorods (ZnO-NRs) grown on heterogenous Ag seed layers. By varying the crystal orientation of silver thin films (Ag), a high density of ZnO-NRs could be obtained. We find that the density of ZnO-NRs strongly relates to the peak intensity ratio between (111) and (200) planes of Ag thin films due to a heteroepitaxy between (0002) ZnO and (111) Ag rather than that of grain boundary nucleation and/or surface nucleation. In addition, the optimized heterostructure of ZnO nanorod/Ag arrays is investigated via a critical concentration for nucleation and used as a fluorescence enhancement substrate (FES). The experimental results have shown that the FES presents an ability to detect a biological sample (PC-3 cell) with a high sensitivity and low detection limit of 1 cell/μL. Our results highlight that understanding an important key to control and design the morphology of heterogeneous hydrothermal ZnO-NR growth is essential to open up the opportunities for fundamental studies and applications in high-performance integrated nanodevices.

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