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The increasing prevalence of atopic dermatitis (AD) is associated with variations in indoor environments. In Korea, many inner walls of homes are covered with wallpaper: such walls emit indoor air pollutants, including volatile organic compounds (VOCs) and formaldehyde. This randomized, double-blind study investigated the effects of wallpaper on indoor air quality and AD. Thirty-one children (aged three to eight years) with moderate AD were assigned to environmentally-friendly (EF) and polyvinyl chloride (PVC) wallpaper groups. Indoor air concentrations of VOCs, natural VOCs (NVOCs), formaldehyde, and total suspended bacteria were measured before and two (W2) and eight weeks (W8) after wallpapering. Scoring Atopic Dermatitis (SCORAD) evaluations and blood tests were performed during the same period. The EF wallpaper and PVC wallpaper groups showed similar trends in the changes in total VOCs (TVOC) and formaldehyde content in the indoor air. However, the EF wallpaper group showed more improvement on the SCORAD at W2 and W8 than the PVC wallpaper group. The SCORAD index was positively correlated with several indoor air pollutants. Further, the SCORAD index and NVOC % were negatively correlated. Improved SCORAD index and effects of wallpapering on indoor air quality improvements occurred within a short period of time in both groups. We believe that NVOCs in indoor air after EF wallpapering have a beneficial effect on health.

Humanity has become a dominant force in shaping the face of Earth 1 – 9 . An emerging question is how the overall material output of human activities compares to the overall natural biomass. Here we quantify the human-made mass, referred to as ‘anthropogenic mass’, and compare it to the overall living biomass on Earth, which currently equals approximately 1.1 teratonnes 10 , 11 . We find that Earth is exactly at the crossover point; in the year 2020 (± 6), the anthropogenic mass, which has recently doubled roughly every 20 years, will surpass all global living biomass. On average, for each person on the globe, anthropogenic mass equal to more than his or her bodyweight is produced every week. This quantification of the human enterprise gives a mass-based quantitative and symbolic characterization of the human-induced epoch of the Anthropocene. Estimates of global total biomass (the mass of all living things) and anthopogenic mass (the mass embedded in inanimate objects made by humans) over time show that we are roughly at the timepoint when anthropogenic mass exceeds total biomass.

Humans are undoubtedly altering many geological processes on Earth—and have been for some time. But what is the stratigraphic evidence for officially distinguishing this new human-dominated time period, termed the “Anthropocene,” from the preceding Holocene epoch? Waters et al. review climatic, biological, and geochemical signatures of human activity in sediments and ice cores. Combined with deposits of new materials and radionuclides, as well as human-caused modification of sedimentary processes, the Anthropocene stands alone stratigraphically as a new epoch beginning sometime in the mid–20th century. Science , this issue p. 10.1126/science.aad2622 Human activity is leaving a pervasive and persistent signature on Earth. Vigorous debate continues about whether this warrants recognition as a new geologic time unit known as the Anthropocene. We review anthropogenic markers of functional changes in the Earth system through the stratigraphic record. The appearance of manufactured materials in sediments, including aluminum, plastics, and concrete, coincides with global spikes in fallout radionuclides and particulates from fossil fuel combustion. Carbon, nitrogen, and phosphorus cycles have been substantially modified over the past century. Rates of sea-level rise and the extent of human perturbation of the climate system exceed Late Holocene changes. Biotic changes include species invasions worldwide and accelerating rates of extinction. These combined signals render the Anthropocene stratigraphically distinct from the Holocene and earlier epochs.

To mitigate global warming, replacing concrete and steel with timber as the primary construction material for construction projects, such as check dams, is being promoted in Japan and other countries. Timber check dams have more limited installation sites than concrete or steel dams because of installation conditions such as locations less susceptible to debris flows and locations where there is constant running water. However, even when the installation conditions are met, engineers and contractors are reluctant to select timber as a construction material because of its high construction cost. In this study, an input-output table was used to compare the greenhouse gas (GHG) emissions associated with the construction of a timber check dam at the design stage with those associated with the construction of concrete and steel check dams to quantitatively evaluate the added value of timber utilization (in addition to its construction cost). The results revealed that replacing concrete and steel check dams with timber check dams could reduce GHG emissions by 61% and 34%, respectively. This study demonstrated the possibility of evaluating the GHG emissions associated with a construction project at the design stage. Moreover, it highlights the importance of considering the GHG emissions associated with construction materials when selecting the most appropriate materials for public works projects.

To promote the sustainable utilization of industrial solid wastes in concrete applications, this study systematically investigates the combined use of lithium slag (LS) as a cement replacement and recycled fine aggregates (RFA) as a substitute for river sand (RS). Through experimental analysis with a fixed water-cement ratio (0.46), we evaluated the effects of varying LS content (0–40%) and RFA replacement rates (0–30%) on concrete performance. The results indicate that the optimal LS incorporation (20%) enhances compressive strength, splitting tensile strength, and flexural strength by 12.7%, 11.9%, and 9.16%, respectively, while maintaining adequate workability. In contrast, RFA addition caused a linear reduction in mechanical properties, with 30% RFA leading to a 19.07% decrease in compressive strength. However, the addition of LS effectively mitigated the performance losses induced by RFA, providing a compensatory effect. The conversion formulas established between cubic compressive strength and other mechanical parameters demonstrated high correlation coefficients, offering practical guidelines for lithium slag-recycled fine aggregate concrete (LSRFAC) applications. This dual-waste utilization strategy presents an environmentally responsible solution for construction material innovation, addressing both the recycling of industrial byproducts and the conservation of natural resources. Overall, this study provides a sustainable approach to concrete production by reducing environmental burdens and supporting the circular use of industrial and construction waste in structural engineering.

A variety of ashes used as the binder in geopolymer concrete such as fly ash (FA), ground granulated blast furnace slag (GGBS), rice husk ash (RHA), metakaolin (MK), palm oil fuel ash (POFA), and so on, among of them the FA was commonly used to produce geopolymer concrete. However, one of the drawbacks of using FA as a main binder in geopolymer concrete is that it needs heat curing to cure the concrete specimens, which lead to restriction of using geopolymer concrete in site projects; therefore, GGBS was used as a replacement for FA with different percentages to tackle this problem. In this study, Artificial Neural Network (ANN), M5P-Tree (M5P), Linear Regression (LR), and Multi-logistic regression (MLR) models were used to develop the predictive models for predicting the compressive strength of blended ground granulated blast furnace slag and fly ash based-geopolymer concrete (GGBS/FA-GPC). A comprehensive dataset consists of 220 samples collected in several academic research studies and analyzed to develop the models. In the modeling process, for the first time, eleven effective variable parameters on the compressive strength of the GGBS/FA-GPC, including the Activated alkaline solution to binder ratio (l/b), FA content, SiO 2 /Al 2 O 3 ( Si/Al ) of FA, GGBS content, SiO 2 /CaO ( Si/Ca ) of GGBS, fine ( F ) and coarse ( C ) aggregate content, sodium hydroxide ( SH ) content, sodium silicate ( SS ) content, ( SS/SH ) and molarity ( M ) were considered as the modeling input parameters. Various statistical assessments such as Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the Coefficient of determination (R 2 ) were used to evaluate the efficiency of the developed models. The results indicated that the ANN model better predicted the compressive strength of GGBS/FA-GPC mixtures compared to the other models. Moreover, the sensitivity analysis demonstrated that the alkaline liquid to binder ratio, fly ash content, molarity, and sodium silicate content are the most affecting parameter for estimating the compressive strength of the GGBS/FA-GPC.

Construction materials are significantly exposed to ecological hazards due to the presence of hazardous chemical constituents found in industrial and agricultural solid wastes. This study aims to investigate the use of sawdust particles (SDPs) and sawdust wastewater (SDW) in alkali-activated composites (AACs) made from a mixture of different silicon-aluminum-based solid wastes (slag powder-SP, red mud-RM, fly ash-FA, and carbide slag-CS). The study examines the impact of SDP content, treated duration of SDPs, and SDW content on both fresh and hardened properties of the AACs, including electrical conductivity, fluidity, density, flexural and compressive strengths, and drying shrinkage. The study also analyzes the microstructures and product compositions of the AACs influenced by SDW through a comprehensive analysis of microstructures and product compositions by using XRD, SEM-EDS, and FTIR. The results show that treating SDPs with a 2.5 mol/L NaOH solution for 12 hours decreases the fluidity and electrical conductivity of the AACs but improves their flexural and compressive strengths. Additionally, in the synthesis of a composite material incorporating binder materials SP, RM, and FA in a mass ratio of 10:3:18, a 2.0 mol/L NaOH solution is employed. The liquid-to-solid ratio is maintained at 20:31, and the sand-to-binder ratio is set at 3:1. The substitution of 12.28% SDW to NaOH solution improves the resistance to drying shrinkage and long-term mechanical strength development of the AACs. Interestingly, the addition of SDW does not affect the product compositions due to the generation and decomposition of organic acid salts from organic impurities in the acidic SDW during long-term curing at room temperature. These findings provide valuable insights for the sustainable recycling of bioresources and solid wastes containing silicon-aluminum in construction materials.

The concentrations of primordial radionuclides (226Ra, 232Th and 40K) in commonly used building materials (brick, cement and sand), the raw materials of cement and the by-products of coal-fired power plants (fly ash) collected from various manufacturers and suppliers in Bangladesh were determined via gamma-ray spectrometry using an HPGe detector. The results showed that the mean concentrations of 226Ra, 232Th and 40K in all studied samples slightly exceeded the typical world average values of 50 Bq kg(-1), 50 Bq kg(-1) and 500 Bq kg(-1), respectively. The activity concentrations (especially 226Ra) of fly-ash-containing cement in this study were found to be higher than those of fly-ash-free cement. To evaluate the potential radiological risk to individuals associated with these building materials, various radiological hazard indicators were calculated. The radium equivalent activity values for all samples were found to be lower than the recommended limit for building materials of 370 Bq kg(-1), with the exception of the fly ash. For most samples, the values of the alpha index and the radiological hazard (external and internal) indices were found to be within the safe limit of 1. The mean indoor absorbed dose rate was observed to be higher than the population-weighted world average of 84 nGy h(-1), and the corresponding annual effective dose for most samples fell below the recommended upper dose limit of 1 mSv y(-1). For all investigated materials, the values of the gamma index were found to be greater than 0.5 but less than 1, indicating that the gamma dose contribution from the studied building materials exceeds the exemption dose criterion of 0.3 mSv y(-1) but complies with the upper dose principle of 1 mSv y(-1).

The extensive waste produced in construction and demolition activities affects the ecological environment, impeding green development in countries worldwide, including China. China has paid increasing attention to managing construction and demolition waste (CDW). However, most of the existing research only qualitatively studies the factors affecting the recycling of CDW and does not reveal the critical factors. Therefore, based on stakeholder theory and the grey-DEMATEL method, this paper aims to identify and quantitatively analyze the critical factors in CDW recycling from the perspective of China. This paper drew the following conclusions: (1) Stakeholders in China’s CDW recycling mainly include the government, CDW production units, and CDW recycling units. (2) Public policy, government subsidies, media promotion, human resources, cost, environmental awareness, technological innovation, and supply chain management are the eight dimensions with 13 factors that constitute CDW recycling in China. (3) For the total relations between factors affecting the recycling of CDW in China, the most influential factor is specific legislation and regulations. The factor with the highest degree of prominence is environmental awareness. The factor with the largest net cause value is the rationality of disposal and landfill charges. The factor with the largest net effect value is experienced construction workers. (4) The critical factors in China’s CDW recycling include specific legislation and regulations, mandatory degree of normative standards, environmental awareness, the supply of raw materials for CDW recycling units, and the sale of remanufactured products. Finally, this paper identifies the following management implications: (1) the government should prioritize the task of improving specific legislation and regulations, with a focus on a mandatory degree of normative standards. (2) CDW production units should put the task of improving environmental awareness high on their agenda, with a focus on the supply of raw materials for recycling units. (3) CDW recycling units should prioritize the issue of the sale of remanufactured products. This paper also provides a theoretical basis for revealing the critical factors of CDW recycling in other countries or regions.