Personal exposure to benzene of selected population groups and impact of commuting modes in Ho Chi Minh, Vietnam

Road dust contamination by polycyclic aromatic hydrocarbons and their methylated derivatives in northern Vietnam: Concentrations, profiles, emission sources, and risk assessment

Concentrations of unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) were examined in road dusts from some representative areas with different land-use types in northern Vietnam, providing updated information about the occurrence, sources, and risks of these pollutants in Southeast Asian region. The Vietnamese road dusts were contaminated with low to moderate levels of PAHs and Me-PAHs as compared to those from other countries in the world. Concentrations of PAHs and Me-PAHs (Σ34PAHs) decreased in the order: urban (median 1800; range 1100-5500) ≈ industrial (1300; 550-10,000) > suburban (450; 310-1300) ≈ rural road dust (330; 210-2300 ng g^-1), suggesting an urban-rural declining trend and effects of urbanization-industrialization processes in PAH emission extent in Vietnam. The profiles and diagnostic ratios of PAHs and Me-PAHs in our samples revealed that these compounds were mainly derived from pyrogenic sources rather than petrogenic sources. Traffic emissions (e.g., vehicle exhaust, tire debris, and possible leaks of fuels, oils, and lubricants) were estimated as principal sources of PAHs and Me-PAHs, especially in the urban and industrial areas. Other pyrogenic sources (e.g., coal, wood, and biomass combustion) were also existed in the industrial, suburban, and rural areas, reflecting PAH origins from thermal industrial processes, open burning of agricultural by-products, and domestic energy utilization. Persons working outdoors and children in the urban and industrial areas were estimated to receive higher intake doses of PAHs and Me-PAHs, which were one to two orders of magnitude higher than those estimated for other groups. Except for potential cancer risk estimated for the occupational groups in the industrial area under the worst exposure scenarios, the non-cancer and cancer risk levels were generally acceptable; however, more comprehensive risk assessment considering other exposure pathways (e.g., inhalation and diet) is needed.

Price Determinants and GIS Analysis of the Housing Market in Vietnam: The Cases of Ho Chi Minh City and Hanoi

Since the introduction of the Doi Moi economic reform in 1986, the real estate market in Vietnam has witnessed a sharp increase in foreign investment inflows and a remarkable growth in the housing market, particularly for high-rise apartments in large cities. This study investigates the determinants of apartment prices in Ho Chi Minh City (HCMC) and Hanoi, the two most representative cities in Vietnam. The spatial distribution of apartments and their price determinants were addressed by the spatial analysis of Geographic Information System (GIS) and the hedonic model. The price determinants of both cities were closely associated with downtown-related factors; moreover, the externalities of urbanization affected each city. While HCMC was more related to the locational attributes of urban amenities and community density as well as programs because of unmanaged urbanization, Hanoi was more related to housing attributes, since the majority of apartment projects were developed under urban infrastructure development supported by the central government. Apartment cluster maps of each city clearly show the contrast of housing distribution. Our findings clarify the impact of government policies on housing price determinants and can be a reference for private- and public-sector stakeholders seeking to undertake economically and socially sustainable housing development projects in Vietnam.

Exposure to air pollutants in Vietnam: Assessing potential risk for tourists

Tourism can form an important component of a nation's GDP, and Vietnam is among the most visited countries in Southeast Asia. Most studies on personal exposure focus on the general population, or occupational cohorts with exposure to specific pollutants. However, short-term exposure to air pollutants while visiting regions with high levels of air pollution can lead to acute health effects. A personal exposure study was conducted across three cities in Vietnam to estimate exposure to particulate matter (PM_2.5) and black carbon for tourists. Measurements were conducted during the wet season in 2014 in Ho Chi Minh City, Da Lat and Nha Trang using portable instrumentation. Average 24-hr PM_2.5 and BC exposures were estimated as 18.9±9.24 and 3.41±1.33μg/m³ and among the three cities, Ho Chi Minh was found to have the highest PM_2.5 concentrations. Environmental tobacco smoke, commuting and street food stands were found to contribute to highest levels of exposure to PM_2.5 and BC across all cities.

Determining factors for levels of volatile organic compounds measured in different microenvironments of a heavy traffic urban area

The levels of BTEX (benzene, toluene, ethylbenzene and xylenes) in a congested urban area of Hanoi were characterized in a winter and a transitional period in 2015. Monitoring was conducted at two roads simultaneously with traffic flows and one ambient site together with meteorology. Hourly and bi-hourly BTEX samples collected using charcoal tubes were analyzed by GC-FID. BTEX levels in winter, 131 ± 71 μg/m³ in heavy traffic Truong Chinh (TC) road, 101 ± 29 μg/m³ in small residential Nguyen Ngoc Nai (NN) road, and 30 ± 15 μg/m³ in the ambient air site (AA, about 150 m from each road) were 1.3-2.1 times higher than the respective levels in the transitional period. Hourly benzene levels exceeded the Vietnam national standard more frequently at TC (45%) than at NN (32%) and least at AA (5%) out of 120-180 measurements, respectively. Roadside hourly levels well reflected the diurnal traffic flow pattern and higher BTEX levels were measured at TC than NN. The ambient site exhibited lower BTEX levels and different diurnal patterns, with more pronounced evening peaks than morning rush hour peaks. BTEX pollution rose showed a strong influence of wind to levels measured at AA. Species ratios (T/B and X/E) showed typical ranges for traffic emissions at roadsides. Ratios for AA and NN after midnight with no vehicles operating showed the aging effects with typical low X/E ratios. Multivariate analysis results suggested association of gasoline vehicles with BTEX at roadsides. Backward trajectory analysis indicated potential regional transport of long-lived benzene associated with continental airmass categories. BTEX at TC our study were 2-3 times lower for every species compared to those previously reported, showing results of fuel quality and vehicle technologies improvement. Health risks of people working at the roadside also reduced by about 3 times during the 10 years.

Considering the effects of ambient particulate matter on the lung function of motorcycle taxi drivers in Bangkok, Thailand

The motorcycle taxi drivers of Bangkok have been heavily exposed to high concentrations of PM₁₀ (particulate matter with an aerodynamic diameter ≤10 μm), and the impact of this on their lungs has been neither documented nor studied. This study examines the association between exposure to PM₁₀ and lung function decline among motorcycle taxi drivers. A cross-sectional study was conducted in Bangkok between two groups: a subject group of motorcycle taxi drivers and control group of enclosed vehicle taxi drivers. The findings of the Thailand Pollution Control Department were used to estimate the annual ambient PM₁₀ concentration levels in the metropolis. Pulmonary functions of motorcycle taxi drivers and enclosed vehicle taxi drivers were measured and compared using the Mann-Whitney test. Multiple linear regression analysis was applied to estimate the effects of PM₁₀ exposure on the lung function of motorcycle taxi drivers. A total of 1283 motorcycle taxi drivers and 600 taxi drivers were investigated. The mean forced expiratory volume in 1 sec/forced vital capacity (FEV₁/FVC) of the motorcycle taxi drivers was significantly lower than that of the taxi drivers (P < 0.001). The mean FEV₁/FVC of motorcycle taxi drivers exposed to ≥50 µg/m³ PM₁₀ was statistically lower (-2.82%; 95% confidence interval [CI]: -4.54% to -1.09%) and the mean % vital capacity (%VC) of those exposed to 40-49.9 µg/m³ PM₁₀ was statistically lower than that of motorcycle taxi drivers exposed to <30 µg/m³ PM₁₀ (-3.33%; 95% CI: -5.79% to -0.87%). Motorcycle taxi drivers were directly exposed to air pollution in their working environment. As a result, their lung function might decrease more than that of enclosed vehicle taxi drivers. With the possible exposure to ≥50 µg/m³ PM₁₀, the vehicular emission standards should be vigorously enforced. Further investigation is warranted to clarify the effect of lung dysfunction on the work and lifestyle of motorcycle taxi drivers.

IMPLICATIONS

Motorcycle taxi drivers are directly exposed to air pollution in their work environment; therefore, their lung function might decrease more than that of enclosed vehicle taxi drivers, especially when exposed to ≥50 µg/m³ PM₁₀. World Health Organization (WHO) vehicular emission standards should be recognized and eventually enforced.

VNN3, a potential novel biomarker for benzene toxicity, is involved in 1, 4-benzoquinone induced cell proliferation

Benzene is widely employed in the field of production, and its toxicity on biological systems has received increasing attention. Cell proliferation is a major life characteristic of living organisms. KLF15 and NOTCH1 are mature and classical genes in cell proliferation studies, particularly in the area of tumor investigation. The aim of this study was to investigate the effect and mechanism of VNN3 on cell proliferation induced by 1,4-benzoquinone (1,4-BQ), an important metabolite of benzene, and obtain a sensitive biomarker for the hazard screening and health care of benzene exposure. Normally growing AHH-1 cells were cultured in vitro and were incubated with different concentrations of 1,4-BQ (0, 10, 20, and 40 μM) for 24 h. A CCK-8 assay was used to assess the cell viability, whereas EdU was used to detect the cell proliferation of AHH-1 cells. The expression of VNN3, KLF15 and NOTCH1 was detected by real-time PCR. Moreover, a lentiviral model was constructed in AHH-1 cells to interfere with VNN3 expression. The results showed that 1,4-BQ clearly increased the expression of VNN3. Moreover, 1,4-BQ dose-dependently inhibited cell proliferation and caused increased KLF15 expression; in contrast, the NOTCH1 expression decreased in AHH-1 cells. Furthermore, following interference with the VNN3 expression, the cell proliferation inhibition and the expression of KLF15 and NOTCH1 were rescued. To further investigate the action of VNN3 in benzene hematotoxicity, we assessed it in benzene-exposed workers. The results showed that there was a remarkable correlation between the VNN3 expression and hemogram, which included RBC, NEUT and HGB. In addition, analysis of the KLF15 and NOTCH1 expression showed that the VNN3 expression was related to cell proliferation, which was consistent with the in vitro results. In conclusion, VNN3 influences cell proliferation induced by 1,4-BQ by regulating the expression of KLF15 and NOTCH1. VNN3 may represent a potential biomarker of benzene toxicity.

Street vending and waste picking in developing countries: a long-standing hazardous occupational activity of the urban poor

Uncontrolled urbanization in developing countries has led to widespread urban poverty and increased susceptibility to environmental exposures owing to the hazardous occupational activities of the urban poor. Street vending and waste picking are the dominant works undertaken by the urban poor, and besides the physical hazards, it also exposes them to several pathogens and high levels of air pollutants present in the outdoor environment. The situation has severe consequences for the health of the workers. Eliminating these occupational activities from the urban landscape of developing countries should therefore receive urgent attention from the global health community and governments. In this article, we provide evidence to support this policy recommendation by documenting exposure experiences of the workers, the associated adverse health effects, whilst also outlining measures for addressing the problem sustainably. We conclude that with the adoption of the sustainable development goals (SDG), governments now have a commitment to address poverty and the associated occupational health hazards experienced by the poor through their choices to help achieve the health-related SDG target (3.9) of substantially reducing the number of deaths and illnesses from hazardous chemicals and air, water, and soil pollution and contamination by 2030.