The protective effect of green space on heat-related respiratory hospitalization among children under 5 years of age in Hanoi, Vietnam.

Combined effects of global warming and rapid urbanization replace green spaces with urban facilities. Children in urban areas are at a higher risk of heat-related adverse health effects. Our study aimed to examine the protective effect of urban green space on heat-related respiratory hospitalization among children under 5 years of age in Hanoi, the capital city of Vietnam. We estimated district-specific meteorological conditions from 2010 to 2014 by using a dynamic downscaling approach with a fine-resolution numerical climate model. The green space in each district was calculated using satellite data. The attributable fraction of heat-related respiratory hospitalization was estimated using a two-stage model, including a distributed lag non-linear model (DLNM) coupled with multivariate meta-analysis. The association between heat-related respiratory hospitalization and green spaces at the district level was explored using a linear regression model. The central districts were more crowded and hotter, with less green spaces than the outer districts. At temperatures > 34 °C (extreme heat threshold), the hospitalizations in the central districts increased significantly; however, in the outer districts, the hospitalization rate was insignificant. On average, extreme heat attributed 0.33% to citywide hospitalization, 0.35% in the center, and 0.32% in the outer region. Every 1% increase in the green space fraction will reduce heat-related respiratory hospitalization risk by 3.8%. Heat significantly increased the risk of respiratory hospitalization among children under 5 years in Hanoi, Vietnam. These findings are valuable for authorities to consider strategies to protect children's health against the effects of heat, including increasing green space.

Assessment of total concentrations of heavy metals in industrial sludges from the North of Vietnam and their potential impact on the ecosystem.

Industrial sludges from wastewater treatment plants of industrial parks and a drinking water treatment plant in northern Vietnam were investigated in this study. The total concentrations of heavy metals (As, Cd, Cu, Cr, Ni, Hg, Pb, Zn) and other elements (Mn, Pd, Sb, V) in the sludges were measured using the ICP-MS method. In addition, the surface characteristics of the samples were analyzed using SEM-EDS and FTIR techniques. According to Vietnam's current waste management regulation, the investigated industrial sludges belonged to the hazardous waste category (with Pb concentration > 300 µg/g). In contrast, the sludge from the drinking water treatment plant had a low content of heavy metals and toxic elements. The sequential extraction method revealed that the heavy metals in the industrial sludges exhibited higher mobilization forms (exchangeable and reduceable fractions) than those in the drinking water sludges. The mobilization ability of heavy metals is probably related to the surface function groups of the sludges, which were dominated by (-COOH) and (-OH) groups. The potential ecological risk assessment calculations indicated that the industrial sludges had high potential risk (with the RI values ranging from 229.7 to 605.4), mainly due to the content of Cd in the sludge samples. Further studies about the fate and transport of Cd and other toxic metals in the sludges are highly recommended to better understand their risk to the surrounding environment, such as groundwater and agricultural soil.

Particulate air pollution in Ho Chi Minh city and risk of hospital admission for acute lower respiratory infection (ALRI) among young children.

High levels of air pollutants in Vietnam, especially particulate matters including PM2.5, can be important risk factors for respiratory diseases among children of the country. However, few studies on the effects of ambient air pollution on human health have been conducted in Vietnam so far. The aim of this study is to examine the association between PM2.5 and hospital admission due to acute lower respiratory infection (ALRI) among children aged < 5 years old in Ho Chi Minh city, the largest city of Vietnam. Data relating PM2.5 and hospital admission were collected from February 2016-December 2017 and a time series regression analysis was performed to examine the relationship between PM2.5 and hospital admission including the delayed effect up to three days prior to the admission. We found that each 10 µg/m3 increase in PM2.5 was associated with an increase of 3.51 (95%CI: 0.96-6.12) risk of ALRI admission among children. According to the analysis, male children are more sensitive to exposure to PM2.5 than females, while children exposed to PM2.5 are more likely to be infected with acute bronchiolitis than with pneumonia. The study demonstrated that young children in HCMC are at increased risk of ALRI admissions due to the high level of PM2.5 concentration in the city's ambient air.