Residential building materials: An important source of ambient formaldehyde in mainland China

Health risk assessment of indoor formaldehyde exposure across Chinese residences: Effects of building material grades

Prolonged exposure to elevated indoor formaldehyde levels poses significant health risk. This study investigates the emission characteristics of building materials, indoor environmental parameters, and their impacts on Chinese residents. Eleven representative cities across five climate zones in China were analyzed to predict indoor formaldehyde concentrations, assess population exposure doses, and evaluate cancer risks for three grades of building materials (E1, E0, and ENF). Results indicate that the average indoor formaldehyde concentrations ranged from 0.008 to 0.028 mg/m3 for ENF, 0.014-0.057 mg/m3 for E0, and 0.027-0.109 mg/m3 for E1. Formaldehyde pollution was more severe in summer than winter and higher in bedrooms than in living rooms. Due to heating policies, indoor formaldehyde concentrations in severe cold (Zone I) and cold zones (Zone II) during winter were significantly higher than those in other climate zones, with a maximum difference of 2.34 times. The lifetime cancer risk for populations exposed to E1 grade building materials ranged from 3.0 × 10-4 to 8.6 × 10-4, exceeding acceptable risk thresholds. Infants exhibited daily exposure dose over 2.8 times higher than adults. Replacing E1 grade materials with ENF grade materials across various climate zones could reduce cancer risk by 62.2-78.2 %. Adopting higher-grade building materials is a feasible and effective strategy for mitigating health risks associated with indoor formaldehyde exposure.

Association between Volatile Organic Compound Exposure and Sex Hormones in Adolescents: The Mediating Role of Serum Albumin

The associations between VOCs and sex hormones in adolescents remain unclear, and the role of serum albumin in these associations deserves to be explored. We conducted cross-sectional analyses using generalized linear models (GLMs), weighted quantile sum (WQS) regression, and mediation analysis, based on data from 584 adolescents from the National Health and Nutrition Examination Survey (NHANES). The GLM analyses revealed that seven kinds of mVOCs potentially affected sex hormone levels. According to the WQS regression results, 2-aminothiazoline-4-carboxylic acid (ATCA) was the major contributor to the significant associations of mixed mVOC exposure with testosterone, estradiol, and free androgen index in males; N-acetyl-S-(N-methylcarbamoyl)-L-cysteine (AMCC) was the major contributor to the significant associations of mixed mVOC exposure with sex hormone-binding globulin in males; and N-acetyl-S-(benzyl)-L-cysteine (BMA) was the major contributor to the significant associations of mixed mVOC exposure with the ratio of testosterone to estradiol in females. Moreover, serum albumin could mediate up to 9.2% of the associations between mixed exposure to mVOCs and sex hormones. Our findings could provide a reference for studies on the mechanisms underlying the effects of VOCs on sex hormones in adolescents and emphasize the necessity of reducing exposure to ATCA, AMCC, BMA, and their parent compounds.

Household air pollution and attributable burden of disease in rural China: A literature review and a modelling study

Household air pollution prevails in rural residences across China, yet a comprehensive nationwide comprehending of pollution levels and the attributable disease burdens remains lacking. This study conducted a systematic review focusing on elucidating the indoor concentrations of prevalent household air pollutants-specifically, PM2.5, PAHs, CO, SO2, and formaldehyde-in rural Chinese households. Subsequently, the premature deaths and economic losses attributable to household air pollution among the rural population of China were quantified through dose-response relationships and the value of statistical life. The findings reveal that rural indoor air pollution levels frequently exceed China's national standards, exhibiting notable spatial disparities. The estimated annual premature mortality attributable to household air pollution in rural China amounts to 966 thousand (95% CI: 714-1226) deaths between 2000 and 2022, representing approximately 22.2% (95% CI: 16.4%-28.1%) of total mortality among rural Chinese residents. Furthermore, the economic toll associated with these premature deaths is estimated at 486 billion CNY (95% CI: 358-616) per annum, constituting 0.92% (95% CI: 0.68%-1.16%) of China's GDP. The findings quantitatively demonstrate the substantial disease burden attributable to household air pollution in rural China, which highlights the pressing imperative for targeted, region-specific interventions to ameliorate this pressing public health concern.

What can be done to protect toddlers from air pollution: Current evidence

PROBLEM

Toddlers are more prone to exposure to widely distributed air pollution and to health damage from it. However, systematic summaries of evidence on protective behaviors against air pollution for toddlers are lacking.

OBJECTIVE

To identify currently available evidence on protective behaviors against air pollution for toddlers.

METHODS

The literature retrieval was performed in selected databases, limited from 2002 to 2022. Studies meeting the following criteria were included and praised: 1) clinical practice guideline, systematic review, expert consensus, recommended practice, randomized control test (RCT) or cohort study published in Chinese or English; 2) studies reporting effects of protective behaviors against air pollution on toddlers' health outcomes or providing recommendation on these behaviors. The evidence in the included studies was extracted, synthesized and graded for evidence summary.

RESULTS

Studies (N = 19) were used for evidence summary development and 35 pieces of best evidence were synthesized, which were divided into three categories, including "avoiding or reducing air pollution generation", "removing existing air pollution", and "avoiding or reducing exposure to existing air pollution".

CONCLUSIONS

More evidence is needed to identify protective measures against outdoor air pollution and tobacco smoke. Research in the future should focus on the safety, effectiveness and feasibility of universal measures implemented in toddlers, and try to develop protective measures specific to toddlers which highlight their special nature.

IMPLICATIONS

The results of this study can help pediatric nurses provide individualized advice and assistance for toddlers and their families, and conduct research on the effectiveness of toddler-targeting protective behaviors more efficiently.

Patterns of Resident Activity and Their Impact on Environmental Parameters in Residential Apartments: Case Study and Implications for Design and Management

In the quest to optimize residential environments for health and sustainability, understanding the interaction between pedestrian dynamics and environmental parameters is crucial. This study delves into this intersection by conducting a detailed spatial‐temporal analysis within an apartment building. The research reveals pivotal insights about the relationship between pedestrian flow and environmental quality. Key findings reveal distinct patterns in pedestrian traffic, with two main peaks in early morning and late evening, accounting for approximately 24% of daily movement. The study identifies a pronounced preference for upward elevator use, reflecting residents’ lifestyle and floor‐level choices. Importantly, we observed variable correlations between pedestrian flow and environmental pollutants. Pollutants like PM2.5 and carbon monoxide exhibited weak correlations, while noise, TVOC, formaldehyde, and ozone showed stronger associations with human movement. The research uncovered significant spatial differences in pollutant levels across the building, with higher particulate matter and ozone levels in the seventh‐floor elevator room. The data suggest a need for tailored pollution management strategies, especially for noise and hazardous compounds like formaldehyde and ozone, which exceed safety limits in certain areas. Our findings offer critical insights for the design and management of residential environments, emphasizing the importance of considering both pedestrian flow and environmental factors in optimizing living spaces for health and efficiency.

Development of an Innovative Lightweight Composite Material with Thermal Insulation Properties Based on Cardoon and Polyurethane

The search for innovative and sustainable solutions to improve the energy efficiency of the construction industry has been a hot topic for researchers due to the tremendous impact of insulator materials in the thermal comfort of buildings. In the present work, an innovative lightweight composite material with thermal insulation properties was developed, for the first time, by using cardoon particles and polyurethane. The formulation of the composite material was optimized in terms of cardoon fraction and the polyol/isocyanate ratio, to achieve the best compromise between internal bond (IB) strength and thickness swelling (TS). The best performing composite was PU75-CP45, with 45 wt% of cardoon particles and 75% of isocyanate, achieving an IB of 0.41 MPa and a TS of 5.3%. Regarding insulation properties, the PU75-CP45 composite material exhibits a promising performance when compared to conventional construction industry materials by tuning its thickness. Additionally, the composite material presented very low emissions of volatile organic compounds and formaldehyde (bellow to legislation levels) and high resistance to biological degradation.

Development of High Strength Particleboards from Hemp Shives and Corn Starch

In the current study, high-strength boards for the construction industry were developed from renewable natural resources, fibrous hemp shives, and corn starch. During the research, the influence of the composition of the mixture, the processing of raw materials, and technological parameters on the operational properties of the board were evaluated. The influence of the binding material and the water content on the properties of the molded boards was evaluated. It was established that the rational amount of starch is 15% of the mass of the shives, and the amount of water is 10%. It has been established that with the proper selection of the forming parameters of the board, it is possible to avoid internal disintegration of the structure due to the water vapor pressure, increase the bending strength, and ensure uniform sintering of the board throughout the entire volume. It was found that additional processing of hemp shives can increase bending strength by more than 40%. Furthermore, during the processing of shives by chemical means, soluble substances are washed out, which reduces the density and thermal conductivity of the shives. Selection of a rational level of compression allowed us to increase the bending strength of the boards by 40%. The assessment of all factors made it possible to obtain boards with a bending strength of 40 MPa. The additives used made it possible to reduce the water absorption of the boards up to 16 times and obtain non-flammable boards. The thermal conductivity of the resulting boards varied from 0.07 to 0.095 W/(m·K). The analysis of macrostructure and microstructure allowed us to evaluate the process of the formation of bonds between hemp shives.

Non-negligible health risks caused by inhalation exposure to aldehydes and ketones during food waste treatments in megacity Shanghai

Aldehydes and ketones in urban air continue to receive regulatory and scientific attention for their environmental prevalence and potential health hazard. However, current knowledge of the health risks and losses caused by these pollutants in food waste (FW) treatment processes is still limited, especially under long-term exposure. Here, we presented the first comprehensive assessment of chronic exposure to 21 aldehydes and ketones in urban FW-air environments (e.g., storage site, mechanical dewatering, and composting) by coupling substantial measured data (383 samples) with Monte Carlo-based probabilistic health risk and impact assessment models. The results showed that acetaldehyde, acetone, 2-butanone and cyclohexanone were consistently the predominant pollutants, although the significant differences in pollution profiles across treatment sites and seasons (Adonis test, P < 0.001). According to the risk assessment results, the estimated cancer risk (CR; mean range: 1.6 × 10^-5-1.12 × 10^-4) and non-cancer risk (NCR; mean range: 2.98-22.7) triggered by aldehydes and ketones were both unacceptable in most cases (CR: 37.8%-99.3%; NCR: 54.2%-99.8%), and even reached the limit of concern to CR (1 × 10^-4) in some exposure scenarios (6.18%-16.9%). Application of DALYs (disability adjusted life years) as a metric for predicting the damage suggested that exposure of workers to aldehydes and ketones over 20 years of working in FW-air environments could result in 0.02-0.14 DALYs per person. Acetaldehyde was the most harmful constituent of all targeted pollutants, which contributed to the vast majority of health risks (>88%) and losses (>90%). This study highlights aldehydes and ketones in FW treatments may be the critical pollutants to pose inhalation risks.

Sapropel as a Binding Material for Wood Processing Waste in the Development of Thermal Insulation Biocomposite

When developing new innovative building materials, their performance characteristics as well as their environmental friendliness are important. It is difficult to produce a fully ecological material for building envelopes, because there is a lack of ecological binding materials on the market, good binding materials are very expensive, and cheaper ones have poorer adhesive properties and performance characteristics. In this work, natural organic sapropel was used as an ecological binder. Before use, an organic sapropel was additionally mechanically activated. Its activation efficiency was evaluated on the basis of consistency and tensile strength. Sapropel activation increased its consistency from 112 to 168 mm and its tensile strength from 466 to 958 kPa. Wood processing waste was used as a filler for the thermal insulation biocomposite. Additionally, the wood waste was chopped to regulate the density and main performance properties of the biocomposite. The density of the biocomposite was also regulated using different amounts of sapropel and the degree of compaction of the composite mixture. In this work, the influence of the amount of sapropel, the level of compression of the biocomposite mixture, and the size of the wood waste particles on the thermal conductivity and compressive stress of the biocomposite was analyzed. It was found that the compression level had the greatest influence on both the compressive stress and thermal conductivity, up to 12 times and 43.3%, respectively.

Promotion of formaldehyde degradation by electro-Fenton: Controlling the distribution of ·OH and formaldehyde near cathode to increase the reaction probability

The mismatch of pollutant concentration and ·OH concentration is the key reason for the inefficient degradation of formaldehyde in the electro-Fenton system. Therefore, formaldehyde and ·OH are adsorbed near the cathode, and the high concentration reaction region is constructed to increase the reaction probability, which is called control of the reaction region. Through nitrogen doping modification of the activated carbon cathode, the adsorption capacity of the modified cathode for formaldehyde and active species, and the selectivity of the two-electron oxygen reduction reaction were deeply analyzed. The results show that the suitable nitrogen doping form of the modified cathode significantly promotes the adsorption capacity of formaldehyde and H₂O₂, which is beneficial to realizing the promotion of formaldehyde degradation by nitrogen doped cathodes in the electro-Fenton system through control of the reaction region. Graphite nitrogen and pyrrolic nitrogen improve formaldehyde adsorption by enhancing the van der Waals force (8.897 mg g^-1), and pyridinic nitrogen improve H₂O₂ adsorption (1.841 mg g^-1) by enhancing the effect of hydrogen bonding interaction. Nitrogen doping enhances Fe²⁺ regeneration, which contributes to the generation of ·OH at the cathode, and promotes formaldehyde degradation. The control of the reaction region through modification of the electro-Fenton cathode achieved formaldehyde degradation of 35.1 mg L^-1 (48.51% higher than that of the unmodified cathode), which provides a promising process for formaldehyde treatment.

Phytoremediation of indoor formaldehyde by plants and plant material

Formaldehyde evolves from various household items and is of environmental and public health concern. Removal of this contaminant from the indoor air is of utmost importance and currently, various practices are in the field. Among these practices, indoor plants are of particular importance because they help in controlling indoor temperature, moisture, and oxygen concentration. Plants and plant materials studied for the purpose have been reviewed hereunder. The main topics of the review are, mechanism of phytoremediation, plants and their benefits, plant material in formaldehyde remediation, and airtight environmental and health issues. Future research in the field is also highlighted which will help new researches to plan for the remediation of formaldehyde in indoor air. The remediation capacity of several plants has been tabulated and compared, which gives easy access to assess various plants for remediation of the target pollutant. Challenges and issues in the phytoremediation of formaldehyde are also discussed.Novelty statement: Phytoremediation is a well-known technique to mitigate various organic and inorganic pollutants. The technique has been used by various researchers for maintaining indoor air quality but its efficiency under real-world conditions and human activities is still a question and is vastly affected relative to laboratory conditions. Several modifications in the field are in progress, here in this review article we have summarized and highlighted new directions in the field which could be a better solution to the problem in the future.

Gradient Porous Structured MnO2-Nonwoven Composite: A Binder-Free Polymeric Air Filter for Effective Room-Temperature Formaldehyde Removal

Recently, MnO₂-coated polymeric filters have shown promising performance in room-temperature formaldehyde abatement. However, a commonly known concern of MnO₂/polymer composites is either MnO₂ crystal encapsulation or weak adhesion. This work reports a low-cost high-throughput and green strategy to produce binder-free MnO₂-nonwoven composite air filters. The production approach is energy saving and environmentally friendly, which combines MnO₂ crystal coating on bicomponent polyolefin spunbond nonwovens and subsequent heat immobilizing of crystals, followed by the removal of weakly bonded MnO₂. The binder-free MnO₂-nonwoven composites show firm catalyst-fiber adhesion, a gradient porous structure, and excellent formaldehyde removal capability (94.5% ± 0.4%) at room temperature, and the reaction rate constant is 0.040 min⁻¹. In contrast to the MnO₂-nonwoven composites containing organic binders, the HCHO removal of binder-free filters increased by over 4%. This study proposes an alternative solution in producing catalyst/fabric composite filters for formaldehyde removal.

A comprehensive study of the COVID-19 impact on PM2.5 levels over the contiguous United States: A deep learning approach

We investigate the impact of the COVID-19 outbreak on PM_2.5 levels in eleven urban environments across the United States: Washington DC, New York, Boston, Chicago, Los Angeles, Houston, Dallas, Philadelphia, Detroit, Phoenix, and Seattle. We estimate daily PM_2.5 levels over the contiguous U.S. in March-May 2019 and 2020, and leveraging a deep convolutional neural network, we find a correlation coefficient, an index of agreement, a mean absolute bias, and a root mean square error of 0.90 (0.90), 0.95 (0.95), 1.34 (1.24) μg/m³, and 2.04 (1.87) μg/m³, respectively. Results from Google Community Mobility Reports and estimated PM_2.5 concentrations show a greater reduction of PM_2.5 in regions with larger decreases in human mobility and those in which individuals remain in their residential areas longer. The relationship between vehicular PM_2.5 (i.e., the ratio of vehicular PM_2.5 to other sources of PM_2.5) emissions and PM_2.5 reductions (R = 0.77) in various regions indicates that regions with higher emissions of vehicular PM_2.5 generally experience greater decreases in PM_2.5. While most of the urban environments ⸺ Washington DC, New York, Boston, Chicago, Los Angeles, Houston, Dallas, Philadelphia, Detroit, and Seattle ⸺ show a decrease in PM_2.5 levels by 21.1%, 20.7%, 18.5%, 8.05%, 3.29%, 3.63%, 6.71%, 4.82%, 13.5%, and 7.73%, respectively, between March-May of 2020 and 2019, Phoenix shows a 5.5% increase during the same period. Similar to their PM_2.5 reductions, Washington DC, New York, and Boston, compared to other cities, exhibit the highest reductions in human mobility and the highest vehicular PM_2.5 emissions, highlighting the great impact of human activity on PM_2.5 changes in eleven regions. Moreover, compared to changes in meteorological factors, changes in pollutant concentrations, including those of black carbon, organic carbon, SO₂, SO₄, and especially NO₂, appear to have had a significantly greater impact on PM_2.5 changes during the study period.