The autoxidation of polyether-polyurethane open cell soft foam: An analytical aging method to reproducibly determine VOC emissions caused by thermo-oxidative degradation

Attenuation or enhancement—a one-dimensional analysis on shock transmission in the solid phase of a cellular material

A simple sampling method for quantification of hazardous volatile organic compounds in mainstream cigarette smoke: Method development and prestudy validation

Distribution of VOCs in urban and rural atmospheres of subtropical India: Temporal variation, source attribution, ratios, OFP and risk assessment

Planar cellular materials, or honeycombs, are considered as two-phase materials where the properties of one of it phases (voids) degenerates to zero. They are characterized by a low relative density and herein we assume that the solid phase of the material can be modeled as an assembly of axially loaded rods or general flexural elements in infinite and repetitive truss or frame structures, respectively. For the analysis and evaluation of the effective mechanical properties of a 2D cellular material the repetitive structure representing the material is assumed to be in a repetitive stress state. This allows for the analysis to be performed on a single repetitive cell under appropriate boundary conditions. However, all published results refer to cellular materials with repetitive modules possessing at least two orthogonal axes of symmetry. It seems that no general method of analysis of cellular material construed as infinite repetitive structures under periodic stresses for arbitrary repetitive cells is available, unless, as said, the repetitive cell possesses at least two perpendicular axes of symmetry. This is the subject matter of this study - to present a general exact technique to analyze infinite repetitive structures, with nonsymmetrical repetitive cells, under periodic stresses.

The correct analysis of shocks in a cellular material

Uncertainties in material properties, geometry, manufacturing processes, and operational environments are clearly critical at all scales (nano-, micro-, meso-, and macro-scale). The incorporation of reliability analysis is critical in designing material structures when material properties are uncertain. The concept of mesostructured or cellular materials is motivated by the desire to put material only where it is needed for a specific application. Typically, the cellular materials have superior structural compliant performance per weight than parts with bulk material or foams. This research develops a reliability-based synthesis method to design cellular material structures under random fields. The efficiency of the proposed framework is achieved with the combination of topology optimisation and stochastic local regression by utilising polynomial chaos expansion and Karhunen–Loeve transform. The effectiveness of the proposed framework is demonstrated with two examples including a ground truss structure and an automotive component which is composed of cellular material.

Dynamic stress–strain states for metal foams using a 3D cellular model

Volatile organic compounds (VOCs) emissions from the plywood manufacturing industry in China have received concerns during recent years. A total of 115 VOCs were measured in the adhesive-making, adhesive-coating, and hot-pressing workshops of the plywood manufacturing industry to investigate fugitive emission characteristics of VOCs and assess their health risks to workers. The average concentration of total VOCs in workshops of the plywood manufacturing industry is 467 ± 359 μg/m3, whereas the value for ambient air is 81.4 μg/m3. For specific processes, the adhesive-coating and hot-pressing processes show higher VOCs concentrations (501 μg/m3–519 μg/m3) than the adhesive-making process (340 μg/m3). Formaldehyde, ethyl acetate, and dichloromethane are the three most abundant VOCs in workshops, with relative contributions to total VOCs of 55.9–63.1%, 4.3–11.0%, and 1.7–4.4%, respectively. For ozone formation potential (OFP) of VOCs, formaldehyde is the largest contributor (86.1%), followed by toluene, xylenes, and propanal. The non-cancer toxic risks (HI) and cancer risks of total VOCs (T-LCR) for three processes are calculated as 2.93–3.94 and 2.86–4.17 × 10−4 using the US EPA recommended methods, both significantly higher than threshold values (1.0 for HI and 10−4 for LCR), suggesting the highly toxic and cancer risks to workers. Formaldehyde contributes 68.1–78.2% and 91.4–93.9% of HI and T-LCR, respectively. The designed risk reduction scheme of VOCs based on air ventilation suggests that air ventilation rates of formaldehyde need to reach 4–5 times in 8 h in three processes to reduce T-LCR to 10−5. These results are useful for developing VOCs control measures and evaluating VOCs occupational health risk for workers in the plywood manufacturing industry.

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Predicting the emission characteristics of VOCs in a simulated vehicle cabin environment based on small-scale chamber tests: Parameter determination and validation

Genetic algorithm (GA) - Artificial neural network (ANN) modeling for the emission rates of toxic volatile organic compounds (VOCs) emitted from landfill working surface

Occupational exposures to volatile organic compounds (VOCs) have been associated with numerous health complications including steatohepatitis and liver cancer. However, the potential impact of environmental/residential VOC exposures on liver health and function is largely unknown. To address this knowledge gap, the objective of this cross-sectional study is to investigate associations between VOCs and liver injury biomarkers in community residents. Subjects were recruited from six Louisville neighborhoods, and informed consent was obtained. Exposure biomarkers included 16 creatinine-adjusted urinary metabolites corresponding to 12 parent VOCs. Serological disease biomarkers measured included cytokertain-18 (K18 M65 and M30), liver enzymes, and direct bilirubin. Associations between exposure and disease biomarkers were assessed using generalized linear models. Smoking status was confirmed through urinary cotinine levels. The population comprised of approximately 60% females and 40% males; White persons accounted 78% of the population; with more nonsmokers (n = 413) than smokers (n = 250). When compared with nonsmokers, males (45%) and Black persons (26%) were more likely to be smokers. In the overall population, metabolites of acrolein, acrylonitrile, acrylamide, 1,3-butadiene, crotonaldehyde, styrene, and xylene were positively associated with alkaline phosphatase. These associations persisted in smokers, with the exception of crotonaldehyde, and addition of N,N-dimethylformamide and propylene oxide metabolites. Although no positive associations were observed for K18 M30, the benzene metabolite was positively associated with bilirubin, irrespective of smoking status. Taken together, the results demonstrated that selected VOCs were positively associated with liver injury biomarkers. These findings will enable better risk assessment and identification of populations vulnerable to liver disease.

For surface water samples collected from the Hangzhou section of Qiantang River (before, during, or after the occurrence of a water odor pollution event), 125 kinds of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs)were quantitatively determined via purge&trap-gas chromatography-mass spectrometry and liquid-liquid extraction-gas chromatography-triple quadrupole mass spectrometry. Then, the pollution characteristics of the VOCs and SVOCs were analyzed, and the health risk of these compounds was assessed. The results showed that 17 VOCs and SVOCs in the surface water samples of 4 monitoring sections were detected, in a concentration range of 0.01-1.21 μg·L-1, which is a low pollution level. The concentration of dichloromethane was the highest of 17 VOCs and SVOCs, accounting for 36.3%, and it was thus clear that dichloromethane was the main contributing factor. During the water odor pollution event, the concentrations of VOCs and SVOCs were significantly higher than they were in the three months before or after the occurrence of the event, by 2.1-4.6 times, reflecting the strong external source input. In addition, human health risk assessment of ingestion through drinking water and absorption through skin contact was performed using US EPA recommended methods. It indicated that the total non-carcinogenic and total carcinogenic risks (∑HI and ∑R) caused by VOCs and SVOCs are 2.4×10-3-3.6×10-2 and 1.9×10-7-1.0×10-6, respectively, both of which belong to the acceptable risk level. Therefore, although ∑HI and ∑R during the occurrence of the odor event were significantly higher than those in the three months before or after the event, the VOCs and SVOCs detected will not cause obvious non-carcinogenic nor carcinogenic health effects on humans.

Daycare centers (DCCs) play an instrumental role in early childhood development, making them a significant indoor environment for a large number of children globally. Amidst routine DCC activities, young children are exposed to a myriad of volatile organic compounds (VOCs), potentially impacting their health. Therefore, this study aims to investigate the VOC emissions during typical DCCs activities and evaluate respective health risk assessments. Employing a full-scale experimental setup within a well-controlled climate chamber, research was conducted into VOC emissions during three typical DCC events: arts-and-crafts (painting, gluing, modeling), cleaning, and sleeping activities tied to mattresses. The research identified 96 distinct VOCs, grouped into twelve categories, from 20 different events examined. Each event exhibited a unique VOC fingerprint, pinpointing potential source tracers. Also, significant variations in VOC emissions from different events were demonstrated. For instance, under cool & dry conditions, acrylic painting recorded high total VOC concentrations of 808 μg/m3, whereas poster painting showed only 58 μg/m3. Given these disparities, the study emphasizes the critical need for carefully selecting arts-and-crafts materials and cleaning agents in DCCs to effectively reduce VOC exposure. It suggests ventilating new mattresses before use and regular mattress check-ups to mitigate VOCs exposure during naps. Importantly, it revealed that certain events resulted in VOC levels exceeding the 10−5 cancer risk thresholds for younger children. Specifically, tetrachloroethylene and styrene from used mattresses in cool & dry conditions, ethylene oxide from new mattresses in warm & humid conditions, and styrene, during sand modeling in both conditions, were the key compounds contributing to this risk. These findings highlight the critical need for age-specific health risk assessments in DCCs. This study highlights the significance of understanding the profiles of VOC emissions from indoor events in DCCs, emphasizing potential health implications and laying a solid foundation for future investigations in this field.

This paper presents the extent to which kitchen structures influence household exposure to firewood-induced volatile organic compounds (VOCs). The sample consisted of 69 firewood users who were conveniently sampled from Senwabarwana Villages. An Integrated Environmental Health Risk Assessment framework (IEHRA) was adopted as the research methods of the current study. The VOC samples were collected from selected priority firewood species used in the study area, namely mushu (Umbrella thorn), mohwelere (red bushwillow), moretshe (Sickle bush), motswiri (Leadwood) and mokgwa (Black monkey thorn). Four VOCs, namely benzene, toluene, ethylbenzene and xylene were analysed from each of the selected plant species. Available literature shows that these VOCs are associated with the kind of common firewood used in the study area. The outcomes of this study reveal that mushu emits the highest concentration of the four selected VOCs, followed by moretshe, mohwelere, mokgwa and motswiri, respectively. The influence of kitchen structural factors such as number and positioning of windows, fireplace or stove type, roofing material and designs, among others on the concentration and indoor dispersion of VOCs was also investigated. Behavioural practices of households during fire making such as opening or closing of doors and windows during cooking, water heating and space heating were also found to influence exposure levels. Consequently, low VOCs emitting firewood species and kitchen structural designs have been confirmed as the key drivers of firewood-induced VOC exposure.