Publications by authors named "To Thi Hien"

The aim of this study is to assess the spatiotemporal variation, sources, and health impacts of the carbonyl compounds (carbonyls) in Ho Chi Minh City (HCMC), the third-most populous city in Southeast Asia. Sampling was conducted according to the US.EPA Method TO-11A, from 2012 to 2016 in both the dry and the rainy seasons at twelve sites.

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  • Microplastics are a growing environmental issue affecting marine ecosystems, particularly in Vietnam, which has a long coastline and significant human activities that contribute to pollution.
  • A study conducted in April 2019 sampled coastal surface seawater from Southern Vietnam, finding microplastics at all sites, with higher concentrations near estuaries, ranging from 0.074 to 0.56 pieces/m.
  • The microplastics were mostly small fragments under 2.8 mm, mainly in white or transparent colors, with polypropylene, polyethylene, and ethylene-vinyl acetate being the most common materials, highlighting the need for more research on environmental factors influencing microplastic distribution.
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The quantitative measurement of urinary biomarkers in wastewater has emerged as a robust tool for estimating alcohol and tobacco consumption in populations. In this study, we applied the wastewater-based epidemiology (WBE) approach to compare alcohol and tobacco use between university students and urban inhabitants in Ho Chi Minh City, Vietnam. Ethyl sulfate and cotinine serve as markers for alcohol and tobacco use, respectively.

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  • - The COVID-19 pandemic allowed researchers to examine how lockdowns affected air quality in the Asian Monsoon region, finding significant decreases in air pollutants like particulate matter and nitrogen dioxide during strict lockdowns.
  • - Satellite data showed a notable reduction in nitrogen dioxide across major cities, alongside reductions in other pollutants, while surface ozone levels increased due to changes in chemical reactions from lower nitrogen oxides.
  • - Some Asian countries showed positive economic growth during the pandemic despite lockdowns, indicating a possible link between reduced industrial activity and improved air quality, suggesting that emission reductions from traffic can enhance air quality in the region.
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Aerosolized microorganisms have become an important factor in assessing air quality. To determine the characteristics of bacterial bioaerosols in air and rainwater, as well as calculate the recovery rate of bacteria after rains in Ho Chi Minh City, our study was performed using the SKC Biostage sampler for airborne bacteria and Plate Count Agar (PCA) medium for bacterial concentration. Subsequently, the study determined the bacterial community composition at the phylum and order levels using the 16S rRNA (16S metabarcoding) method.

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Exports of atmospheric mercury (Hg) from continental East Asia, a major Hg emitter in the globe, have been reported by several studies in neighboring countries such as Japan and Korea. Nonetheless, studies concerning this topic in Southeast Asia (SEA) countries are still limited. Accordingly, gaseous elemental mercury (GEM) has been measured from Can Thanh High School (CTHS), a suburban coastal site in southern Vietnam to study its characterization and discover the evidence of Hg trans-boundary transport from regional sources (e.

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Background: Traffic-related air pollution (TRAP) problems are unlikely to be solved in the short term, making it imperative to educate children on protective measures to mitigate the negative impact on their health. Children and their caregivers may hold differing views on wearing a face mask as a safeguard against air pollution. While many studies have focused on predicting children's health-protective behaviours against air pollution, few have explored the differences in perceptions between children and their caregivers.

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Volatile organic compounds (VOCs) play an important role in urban air pollution, both as primary pollutants and through their contribution to the formation of secondary pollutants, such as tropospheric ozone and secondary organic aerosols. In this study, more than 30 VOC species were continuously monitored in the two most populous cities in Vietnam, namely Ho Chi Minh City (HCMC, September-October 2018 and March 2019) and Hanoi (March 2019). In parallel with ambient VOC sampling, grab sampling was used to target the most prevalent regional-specific emission sources and estimate their emission factors (EFs).

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  • Particulate-bound mercury (PBM) is a significant global environmental issue due to its impact on both terrestrial and marine ecosystems, particularly in urban areas like Ho Chi Minh City (HCMC), Vietnam, where the first PBM concentration study was conducted.
  • In 2018, 222 samples were collected in HCMC, revealing an average PBM concentration of 67.3 ± 45.9 pg/m³ and a mercury (Hg) mass fraction of 1.18 ± 1.12 μg/g, showing that while PBM levels were lower than in some Chinese cities, the Hg mass fraction was similar, emphasizing the enrichment from local anthropogenic sources.
  • The study indicated that traffic
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Microplastic pollution has become a worldwide concern. However, studies on the distribution of microplastics (MPs) from inland water to the ocean and their affiliated polycyclic aromatic hydrocarbons (PAHs) are still limited in Vietnam. In this study, we investigated the distribution of MPs and PAHs associated with MPs in canals, Saigon River, and Can Gio Sea.

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Objective: Lack of recognition of asthma in childhood results in unmet asthma treatment needs and leads to the risk of sub-optimal respiratory health. The present study assessed the prevalence of asthmatic under-recognition in middle school children in Vietnam.

Methods: We conducted a school-based survey among 15,112 Vietnamese children.

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  • * It identifies key research priorities based on a series of workshops, aiming to support authorities in tackling PM pollution and its health impacts through evidence-based strategies.
  • * The study outlines five specific PM research gaps that can be addressed using these sensors, emphasizing the importance of collaboration, affordability, and stakeholder engagement for successful implementation.
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This is the first investigation on overall characteristics of 25 polycyclic aromatic hydrocarbons (PAHs) (15 PAHs regulated by US-EPA (excluding naphthalene) and 16 PAHs recommended by the European Union) in ambient air of Ho Chi Minh City, Vietnam. Their levels, congener profiles, gas/particle partitioning, potential sources of atmospheric PAHs (gas and particulate phases), and lung cancer risks in the dry and rainy seasons were examined. The ∑25 PAH concentration in the dry and rainy seasons ranged from 8.

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In recent years, with rapid economic development, air pollution has become extremely serious, causing many negative effects on health, environment and medical costs. PM is one of the main components of air pollution. Therefore, it is necessary to know the PM air quality in advance for health.

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Recently, air quality has significantly improved in developed country, but that issue is of concern in emerging megacity in developing country. In this study, aerosols and their precursor gas were collected by NILU filter pack at two distinct urban sites during the winter and summer in Osaka, Japan and dry and rainy seasons in Ho Chi Minh City (HCMC), Vietnam. The aims are to investigate the contribution of water-soluble inorganic ions (WSIIs) to PM, thermodynamic characterization and possible formation pathway of secondary inorganic aerosol (SIA).

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Atmospheric PCDD/Fs and dl-PCBs samples were collected in Hochiminh city, Vietnam to address the effect of meteorological parameters, especially rainfall, on the occurrence and gas/particle partitioning of these persistent organic pollutants. The results indicate that PCDD/Fs and dl-PCBs concentrations in industrial site are higher than those measured in commercial and rural sites during both rainy and dry seasons. In terms of mass concentration, ambient PCDD/F levels measured in dry season are significantly higher than those measured in rainy season while dl-PCB levels do not vary significantly between rainy and dry seasons.

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Vietnam has a double burden of dioxin from both industrial sources and historical sources. To evaluate the concentration of PCDD/Fs in ambient air in different areas of Vietnam and their possible sources, atmospheric samples were collected from three areas namely Son La (rural area) and Da Nang (harbor - Agent Orange hotspot area), and Ho Chi Minh City (metropolitan - industrial city). Vapor and solid phases of PCDD/Fs were collected and analyzed following the TO-9A sampling method.

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  • Continuous measurements of ammonia gas (NH) and fine particulate ammonium (PMNH) were conducted in urban areas of Osaka, Japan, and Ho Chi Minh City (HCMC), Vietnam, using a new online instrument during different seasons in 2015.
  • The average NH concentrations were found to be much higher in HCMC compared to Osaka, attributed to different emission sources, with traffic emission being a significant contributor in Osaka but negligible in HCMC, where high NH levels stemmed from human activities and poor waste management.
  • Conversely, PMNH levels peaked during the cold period in Osaka, mainly influenced by atmospheric conditions, while in HCMC, PM levels were primarily generated from road traffic, especially motorcycles.
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Metal contamination is one of the major issues to the environment worldwide, yet it is poorly known how exposure to metals affects tropical species. We assessed the sensitivity of a tropical micro-crustacean Daphnia lumholtzi to three trace metals: copper (Cu), zinc (Zn) and nickel (Ni). Both, acute and chronic toxicity tests were conducted with metals dissolved in in situ water collected from two sites in the lower part of the Mekong River.

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Air pollution has become an alarming issue in Vietnam recently; however, there was only one study so far on the effects of ambient air pollution on population health. Our study aimed to investigate the short-term effects of air pollutants including PM10, NO2, SO2, and O3 on respiratory and cardiovascular hospitalizations in Ho Chi Minh City (HCMC), the largest city in Vietnam. Data on hospitalization from the two largest hospitals in HCMC and daily records of PM10, NO2, SO2, O3 and meteorological data were collected from February 2004 to December 2007.

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A comparative study of polycyclic aromatic hydrocarbons (PAHs) associated with particulate matter (TSP) in the ambient air in an urban area in Ho Chi Minh City, Vietnam and in Osaka, Japan was carried out from 2005 to 2006. The objective of this study was to investigate the environmental levels, emission sources, seasonal variations and health risk of eleven PAHs in the two cities, especially Ho Chi Minh City where air pollution is becoming a serious concern. The results showed that the concentrations of TSP and total PAHs were significantly higher in Ho Chi Minh City than levels in Osaka.

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