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Uncertainty analysis of facemasks in mitigating SARS-CoV-2 transmission
2022
Liu, Fan | Qian, Hua
In the context of global spread of coronavirus disease 2019 (COVID-19) caused by a novel coronavirus (SARS-CoV-2), there is a controversial issue on whether the use of facemasks is promising to control or mitigate the COVID-19 transmission. This study modeled the SARS-CoV-2 transmission process and analyzed the ability of surgical mask and N95 in reducing the infection risk with Sobol's analysis. Two documented outbreaks of COVID-19 with no involvers wearing face masks were reviewed in a restaurant in Guangzhou (China) and a choir rehearsal in Mount Vernon (USA), suggesting that the proposed model can be well validated when airborne transmission is assumed to dominate the virus transmission indoors. Subsequently, the uncertainty analysis of the protection efficiency of N95 and surgical mask were conducted with Monte Carlo simulations, with three main findings: (1) the uncertainty in infection risk is primarily apportioned by respiratory activities, virus dynamics, environment factors and individual exposures; (2) wearing masks can effectively reduce the SARS-CoV-2 infection risk to an acceptable level (< 10⁻³) by at least two orders of magnitude; (3) faceseal leakage can reduce protection efficiency by approximately 4% when the infector is speaking or coughing, and by approximately 28% when the infector is sneezing. This work indicates the effectiveness of non-pharmaceutical interventions during the pandemic, and implies the importance of the synergistic studies of medicine, environment, social policies and strategies, etc., on reducing hazards and risks of the pandemic.
Show more [+] Less [-]A hybrid kriging/land-use regression model with Asian culture-specific sources to assess NO2 spatial-temporal variations
2020
Chen, Tsun-Hsuan | Xu, Yanjing | Zeng, Yu-Ting | Candice Lung, Shih-Chun | Su, Huey-Jen | Chao, Hsing Jasmine | Wu, Chih-Da
Kriging interpolation and land use regression (LUR) have characterized the spatial variability of long-term nitrogen dioxide (NO₂), but there has been little research on combining these two methods to capture small-scale spatial variation. Furthermore, studies predicting NO₂ exposure are almost exclusively based on traffic-related variables, which may not be transferable to Taiwan, a typical Asian country with diverse local emission sources, where densely distributed temples and restaurants may be important for NO₂ levels. To advance the exposure estimates in Taiwan, a hybrid kriging/LUR model incorporates culture-specific sources as potential predictors. Based on 14-year NO₂ observations from 73 monitoring stations across Taiwan, a set of interpolated NO₂ values were generated through a leave-one-out ordinary kriging algorithm, and this was included as an explanatory variable in the stepwise LUR procedures. Kriging interpolated NO₂ and culture-specific predictors were entered in the final models, which captured 90% and 87% of NO₂ variation in annual and monthly resolution, respectively. Results from 10-fold cross-validation and external data verification demonstrate robust performance of the developed models. This study demonstrates the value of incorporating the kriging-interpolated estimates and culture-specific emission sources into the traditional LUR model structure for predicting NO₂, which can be particularly useful for Asian countries.
Show more [+] Less [-]Land-use regression with long-term satellite-based greenness index and culture-specific sources to model PM2.5 spatial-temporal variability
2017
Wu, Chih-Da | Chen, Yu-Cheng | Pan, Wen-Chi | Zeng, Yu-Ting | Chen, Mu-Jean | Guo, Yue Leon | Lung, Shih-Chun Candice
This study utilized a long-term satellite-based vegetation index, and considered culture-specific emission sources (temples and Chinese restaurants) with Land-use Regression (LUR) modelling to estimate the spatial-temporal variability of PM2.5 using data from Taipei metropolis, which exhibits typical Asian city characteristics. Annual average PM2.5 concentrations from 2006 to 2012 of 17 air quality monitoring stations established by Environmental Protection Administration of Taiwan were used for model development. PM2.5 measurements from 2013 were used for external data verification. Monthly Normalized Difference Vegetation Index (NDVI) images coupled with buffer analysis were used to assess the spatial-temporal variations of greenness surrounding the monitoring sites. The distribution of temples and Chinese restaurants were included to represent the emission contributions from incense and joss money burning, and gas cooking, respectively. Spearman correlation coefficient and stepwise regression were used for LUR model development, and 10-fold cross-validation and external data verification were applied to verify the model reliability. The results showed a strongly negative correlation (r: −0.71 to −0.77) between NDVI and PM2.5 while temples (r: 0.52 to 0.66) and Chinese restaurants (r: 0.31 to 0.44) were positively correlated to PM2.5 concentrations. With the adjusted model R² of 0.89, a cross-validated adj-R² of 0.90, and external validated R² of 0.83, the high explanatory power of the resultant model was confirmed. Moreover, the averaged NDVI within a 1750 m circular buffer (p < 0.01), the number of Chinese restaurants within a 1750 m buffer (p < 0.01), and the number of temples within a 750 m buffer (p = 0.06) were selected as important predictors during the stepwise selection procedures. According to the partial R², NDVI explained 66% of PM2.5 variation and was the dominant variable in the developed model. We suggest future studies consider these three factors when establishing LUR models for estimating PM2.5 in other Asian cities.
Show more [+] Less [-]Workplace personal exposure to respirable PM fraction: a study in sixteen indoor environments
2014
Saraga, Dikaia E. | Volanis, Lefteris | Maggos, Thomas | Vasilakos, Christos | Bairachtari, Kyriaki | Helmis, Costas G.
The present paper focuses on respirable particulate matter (RPM) measurements conducted at the breathing zone of adult volunteers in sixteen different working environments: two offices, a house, a chemical laboratory, a non–smoking shop, a pharmacy store, a car garage, a hairdresser's store, a photocopy store, a taxi, a gym, a mall, a restaurant, a bar, a kiosk and a school. The sixteen different cases were categorized according to the location, the type of the activities taking place indoors, the number of occupants, the proximity to heavy traffic roads, the ventilation pattern etc. According to the results, the maximum particle concentration (in average 285μg m−3) was recorded at the hairdresser store while the minimum concentration was measured in the cases of the housewife and the employee in the non–smoking shop (in average 30μg m−3). The results indicated smoking as a factor which strongly influences the exposure levels of both smokers and passive smokers. Furthermore, it was found that the building ventilation pattern comprises an important factor influencing the exposure levels especially in cases of buildings with great number of visitors (resuspension) and smoking.
Show more [+] Less [-]Microplastic pollution in Rawa Jombor Reservoir, Klaten, Central Java, Indonesia: accumulation in aquatic fauna, heavy metal interactions, and health risk assessment
2022
Adji, Basith Kuncoro | Octodhiyanto, Indradi | Rahmayanti, Rita | Nugroho, Andhika Puspito
The sustainability of the Rawa Jombor Reservoir (RJR) in Indonesia is threatened by microplastic (MP) pollution. This issue requires critical investigation owing to possible detrimental consequences in humans, especially due to the growing concern regarding the adsorption of hazardous compounds by MPs. This study investigated the accumulation and characteristics of MPs in aquatic fauna (zooplankton, benthos, and fish), water samples, and sediments of the RJR, determined their interactions with heavy metals (HMs) (Cd, Cu, Zn, and Pb), and assessed their potential risk. The MPs extracted from aquatic fauna were characterized by stereomicroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope energy-dispersive X-ray spectroscopy (SEM–EDS), and flame atomic absorption spectroscopy (FAAS). Their potential risk was assessed from the polymer hazard index (PHI), pollution load index (PLI), potential ecological risk index (PERI), estimated daily intake (EDI), target hazard quotient (THQ), total target hazard quotient (TTHQ), and target cancer risk (TR). MP concentrations were highest in the water near the main inlet (S1) and floating restaurant (S5), and the sediments near the densely populated water hyacinth area (S2). The pattern of MP accumulation in aquatic fauna, except the benthos, was similar to that of the MP concentrations in water. The MPs adsorbed high concentrations of HMs on their surface. MP concentrations in aquatic fauna increased through the food chains, indicating possible biomagnification. The fishes were safe for consumption, but their long-term consumption may induce cancer, primarily due to Cd. Therefore, the management of plastic waste by involving all stakeholders is crucial for mitigating this issue.
Show more [+] Less [-]Using textile industrial sludge, sewage wastewater, and sewage sludge as inoculum to degrade recalcitrant textile dyes in a co-composting process: an assessment of biodegradation efficiency and compost phytotoxicity
2021
Testolin, Renan C. | Feuzer-Matos, Ana Júlia | Cotelle, Sylvie | Adani, Fabrizio | Janke, Leandro | Poyer-Radetski, Gabriel | Pereira, Antonio C. | Ariente-Neto, Rafael | Somensi, Cleder A. | Radetski, Claudemir M.
Recalcitrant dyes found in textile wastewater represent a threat for sustainable textile production due to their resistance to conventional treatments. This study assessed an alternative co-composting system for the treatment of recalcitrant textile dyes where textile industrial sludge, sewage wastewater, or sewage sludge were used as microbial compost inocula. The biodegradation efficiency of bioreactor trials and compost quality of the co-composting system were assessed by visible spectrophotometry and by a phytotoxicity test. The co-composting system (dry weight (dw) basis) consisted of 200 g of restaurant organic residues + 200 g sewage sludge (or 100 mL sewage wastewater, or 200 g textile sludge) + 100 mL of a 10% dye solution (Reactive Red 195, or Synolon Brown, or Orange Remazol, or Yellow Synozol, or Reactive Orange 122, or Reactive Black 5). After 60 days of composting, all dyes were biodegraded according to spectrophotometric data, with efficiency varying from 97.2 to 99.9%. Inoculum efficiency ranking was textile sludge > sewage sludge > sewage wastewater. Regarding compost quality, a phytotoxicity study with lettuce showed no toxicity effect. Thus, co-composting can be a low-cost and efficient method for recalcitrant textile dye biodegradation and for managing textile sludge in terms of waste recycling, contributing to environmental sustainability.
Show more [+] Less [-]Mechanical pretreatment of municipal biowaste to produce an aqueous slurry dedicated to anaerobic digestion
2021
Moretti, Paul | de Oliveira, Mariana Moreira | Bayard, Rémy | Buffiere, Pierre | de Araujo, Joacio Morais | de Castilhos, Armando Borges Jr | Gourdon, Rémy
The present study investigated a wet mechanical pretreatment to improve methane production by anaerobic digestion from biowaste material by separating a biodegradable aqueous slurry fraction (ASF) from a more recalcitrant particulate fraction (PF). Four source-sorted municipal biowastes were studied, namely household (HBW), supermarket (SBW), restaurant (RBW), and green biowaste (GBW). The treatment consisted in soaking the waste in water and then pressing the slurry through a grid with 3-mm openings to separate the two fractions. Methane production of ASF and PF obtained from the four biowastes were measured using the BMP protocol and compared to the potential of the respective untreated biowaste. Results were very different for GBW as compared to the other three BWs. With GBW, which was the most lignocellulosic of the BW studied, only 17% of the initial methane potential was recovered in the ASF. The extraction was much better on the other biowastes and increased in the following order: HBW (58%) ≃ RBW (57%) < SBW (67%). The ASF from these biowastes exhibited low total solid contents and high BMPs (416, 408, and 423 NLCH₄.g⁻¹ᵥₛ for HBW, RBW, and SBW respectively). The experimental results obtained in this study therefore showed that wet pressing separation was an efficient pretreatment to improve and facilitate methane production by anaerobic digestion of biowaste such as HBW, RBW, and SBW.
Show more [+] Less [-]SME financing role in developing business environment and economic growth: empirical evidences from technical SMEs in Vietnam
2022
Van Song, Nguyen | Mai, Tran Thi Hoang | Thuan, Tran Duc | Van Tien, Dinh | Phuong, Nguyen Thi Minh | Van Ha, Thai | Que, Nguyen Dang | Uan, Tran Ba
Distinguishing the significance of business environments for technical small and medium-sized enterprises (SMEs), this study examines the connection between business environments, GDP growth, and SMEs’ financing choices in Vietnam. The study considered the agency theory as a theoretical base to explain how information asymmetry between SMEs and lenders influences SMEs’ financing choices and encompasses the effects on business environment and GDP growth of Vietnam. For this binary logistic regression, text is applied. Global Entrepreneurship Monitor and World Bank data were analyzed. The findings of the study are robust and showed that SME financing (e.g., formal and informal) under the financial infrastructure and tax regulation may enhance formal credit choice and reduce informal credit choice. This enhances the depth in the business environment of technical SMEs and found significant effects on GDP growth. For the first time, this research examines the impact of information asymmetry and agency theory on restaurant financing choices. The research has significance for industry practitioners and governments interested in SMEs’ financial viability. On the recent topicality, study also presents policy implications for key stakeholders.
Show more [+] Less [-]Value addition in the services sector and its heterogeneous impacts on CO2 emissions: revisiting the EKC hypothesis for the OPEC using panel spatial estimation techniques
2020
This study examines the Environmental Kuznets Curve (EKC) hypothesis in the context of 12 members of the OPEC by utilizing data on both the aggregate gross value added and the services’ sectoral value-added between 1992 and 2015. This empirical work contributes to the literature by applying the panel spatial techniques which resulted in the findings as follows. Firstly, the results verify the authenticity of the EKC hypothesis for the aggregate level of gross value added as perceived from its inverted-U shaped association with CO2 emissions. Secondly, the disaggregated analysis affirms the heterogeneity of the validity of the EKC hypothesis across the subsectors within the services sector; this justifies the importance of analyzing the EKC hypothesis from a comprehensive (disaggregated) perspective for unearthing key sector-specific policy implications. The results reveal that the EKC hypothesis holds only in the context of construction services only but not for the cases of restaurant services, tourism and transportation services. These key findings call for effective measures to be undertaken to address the adverse environmental impacts that can be attributed to thse three sub-sectors for which the EKC did not hold. In line with the overall findings from the empirical exercises, it is recommended that the concerned OPEC members reduce their monotonic dependency on the consumption of fossil fuels, oil in particular, and gradually incorporate renewable energy resources into the energy-mix particularly within their respective services sector.
Show more [+] Less [-]Restaurant oil and grease management in Hong Kong
2021
Yau, Yiu-Hung | Rudolph, Victor | Lo, Cat Chui-man | Wu, Kam-Chau
Oil and grease (O&G) in wastewater can be considered as two parts or proportion contained in emulsion which exceeded O&G standard. Most of oil becomes emulsified with water when they pass through grease trap and discharged in the effluents. Thus, it may indicate that either treatment of grease traps or standards for O&G content stipulated in technical memorandum of Water Pollution Control Ordinance (WPCO) do not reflect the actual situation. Existing grease traps should be upgraded to meet the requirements of WPCO. Alternative technologies need to be developed to tackle this unsolved problem. Good management and practices are also important to ensure proper collection and waste recycling rather than just disposing effluent into drains. Collected O&G content can be recycled as valuable products such as biofuel, flotation agent, or other derivatives. This approach not only protects the environment by improving water quality, it also encourages large flow restaurant operators to recycle oil and grease content towards cleaner production.
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