Carbon Monoxide Concentrations Research Articles

Quasi-open Cu(I) sites for efficient CO separation with high O2/H2O tolerance.

Carbon monoxide (CO) separation relies on chemical adsorption but suffers from the difficulty of desorption and instability of open metal sites against O2, H2O and so on. Here we demonstrate quasi-open metal sites with hidden or shielded coordination sites as a promising solution. Possessing the trigonal coordination geometry (sp2), Cu(I) ions in porous frameworks show weak physical adsorption for non-target guests. Rational regulation of framework flexibility enables geometry transformation to tetrahedral geometry (sp3), generating a fourth coordination site for the chemical adsorption of CO. Quantitative breakthrough experiments at ambient conditions show CO uptakes up to 4.1 mmol g-1 and CO selectivity up to 347 against CO2, CH4, O2, N2 and H2. The adsorbents can be completely regenerated at 333-373 K to recover CO with a purity of >99.99%, and the separation performances are stable in high-concentration O2 and H2O. Although CO leakage concentration generally follows the structural transition pressure, large amounts (>3 mmol g-1) of ultrahigh-purity (99.9999999%, 9N; CO concentration < 1 part per billion) gases can be produced in a single adsorption process, demonstrating the usefulness of this approach for separation applications.

Study on the Influence of Ventilation Speed on Smoke and Temperature Characteristics of Complex Underground Spaces

This study explores the intricate behaviors of smoke flow, temperature distribution, carbon monoxide (CO) levels, and visibility dynamics within complex underground spaces during fire incidents. A key revelation is the profound impact of ventilation speed, with the identification of a critical range between 2 and 3 m/s that consistently proves to be instrumental in curbing smoke-related hazards and ensuring the safe evacuation of personnel. Furthermore, this paper underscores the influence of accelerated longitudinal winds on temperature profiles, particularly under high HRR conditions, underscoring the importance of accounting for wind effects in comprehensive fire response strategies. Regarding CO concentration, which is a critical safety concern, this study demonstrates that higher ventilation speeds effectively reduce hazardous gas levels, thereby fortifying overall safety measures. The visibility is analyzed, with the findings indicating that elevated ventilation speeds enhance visibility, albeit with considerations about potential drawbacks on personnel evacuation due to excessive wind speed. In conclusion, this paper offers a comprehensive understanding of the pivotal role played by ventilation speed in underground space safety by encompassing smoke control and temperature management.

Fuel-flexible biomass off-gassing: The impact of antioxidant spent coffee grains on emissions of CO2, CO, CH4, and VOCs, physical deposits, and combustion in wood pellets

The surging global demand for sustainable energy has propelled the solid biofuel industry, particularly wood pellets. However, the industry grapples with persistent challenges involving off-gassing during storage and transportation. This study introduces an alternative: harnessing a biogenic extract from spent coffee grains (SCG) to manage emissions of carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and volatile organic compounds (VOCs). Our approach involves applying SCG extract to pinewood sawdust pellets in controlled volumes (0.1 L) and concentrations (0.05 %, 0.1 %, 0.2 %, and 0.4 employing an airbrush compressor for even distribution. To assess emissions, triplicate 0.1 kg samples were placed in gastight chambers at regulated temperatures (25, 35, and 50 °C) and humidity levels (30 %, 60 %, and 90 %). They were measured at five-day intervals over six months. Pellets with the antioxidant additive at 0.05 % exhibited approximately 18,269 ppm of gases (CO2, CO, CH4, and VOCs), compared to 21,039 ppm in untreated pellets, indicating a consistent 13.2 % reduction in total off-gassing. Specifically, CO concentrations in treated and untreated pellets were 3795 ppm and 5012 ppm, respectively, translating into a 24.3 % reduction. Significant reductions were also observed in CO2 (12.95 %), CH4 (19.35 %), and VOCs (5.45 %). Environmental factors, particularly humidity levels above 60% and elevated temperatures within the range of 35–50 °C, were identified as influencing factors in these emissions. This insight was elucidated through a conditional inference tree (CIT) analysis. Stakeholders can leverage these findings to optimize pellet storage and transportation practices, aligning with the global commitment to advancing sustainable energy solutions.

The capabilities of the adjoint of GEOS-Chem model to support HEMCO emission inventories and MERRA-2 meteorological data

Abstract. The adjoint of the GEOS-Chem (Goddard Earth Observing System with Chemistry) model has been widely used to constrain the sources of atmospheric compositions. Here, we designed a new framework to facilitate emission inventory updates in the adjoint of the GEOS-Chem model. The major advantage of this new framework is good readability and extensibility, which allows us to support Harmonized Emissions Component (HEMCO) emission inventories conveniently and to easily add more emission inventories following future updates in GEOS-Chem forward simulations. Furthermore, we developed new modules to support MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications, version 2) meteorological data, which allows us to perform long-term analyses with consistent meteorological data for the period 1979–present. The performances of the developed capabilities were evaluated with the following steps: (1) diagnostic outputs of carbon monoxide (CO) sources and sinks to ensure the correct reading and use of emission inventories, (2) forward simulations to compare the modeled surface and column CO concentrations among various model versions, (3) backward simulations to compare adjoint gradients of global CO concentrations to CO emissions with finite-difference gradients, and (4) observing system simulation experiments (OSSEs) to evaluate the model performance in 4D variational (4D-Var) assimilations. Finally, an example application of 4D-Var assimilation was presented to constrain anthropogenic CO emissions in 2015 by assimilating Measurement of Pollution in the Troposphere (MOPITT) CO observations. The capabilities developed in this work are important for better applications of the adjoint of the GEOS-Chem model in the future. These capabilities will be submitted to the standard GEOS-Chem adjoint code base for better development of the community of the adjoint of the GEOS-Chem model.

Long-term exposure to air pollution and risk of Sarcopenia in adult residents of Taiwan: a nationwide retrospective cohort study

BackgroundSarcopenia is an age-related, multifactorial syndrome. Previous studies have shown that air pollutants are associated with inflammation and oxidative stress. However, the association between long-term exposure to air pollution and sarcopenia is not completely understood.MethodsThe Taiwan National Health Research Database (NHIRD) contains medical records of almost all Taiwanese residents. Daily air pollution data collected by the Taiwan Environmental Protection Agency was used to analyze concentrations of sulfur oxide (SO2), carbon monoxide (CO), nitrogen monoxide (NO), nitrogen dioxide (NO2), and particulate matter (PM2.5, PM10). The databases were merged according to the insurants’ living area and the location of the air quality monitoring station. We categorized the pollutants into quartiles (Q1, Q2, Q3, and Q4).ResultsOur study population consisted of 286,044 patients, among whom 54.9% were female and 45.1% were male. Compared to Q1 levels of pollutants, Q4 levels of SO2 (adjusted hazard ratio [aHR] = 8.43; 95% confidence interval [CI] = 7.84, 9.07); CO (aHR = 3.03; 95%CI = 2.83, 3.25); NO (aHR = 3.47; 95%CI = 3.23, 3.73); NO2 (aHR = 3.72; 95%CI = 3.48, 3.98); PM2.5 (aHR = 21.9; 95% CI = 19.7, 24.5) and PM10 (aHR = 15.6; 95%CI = 14.1, 17.4) increased risk of sarcopenia.ConclusionsOur findings indicated a significantly increased risk of sarcopenia in both male and female residents exposed to high levels of air pollutants.

Estimating Daily Concentrations of Near-Surface CO, NO2, and O3 Simultaneously Over China Based on Spatiotemporal Multi-Task Transformer Model

Accurate and efficient estimation of near-surface air pollutant concentrations holds significant practical importance. Current models for estimating near-surface concentrations (NSC) primarily rely on shallow methods and focus on estimating a single pollutant. However, these models face challenges in capturing the complex spatiotemporal patterns of NSC and demonstrate inefficiency. To overcome these limitations, we propose a spatiotemporal multi-task Transformer model (stmtTransformer) to simultaneously estimate the NSC of carbon monoxide (CO), nitrogen dioxide (NO2), and ozone (O3). Estimation experiments conducted in China from 2021 to 2022 demonstrate that stmtTransformer achieves optimal performance by effectively capturing the spatiotemporal variations of NSC. Based on sample-based validation, the R2 values are 0.643 (CO), 0.781 (NO2), and 0.902 (O3), and the RMSE values are 0.194 mg/m3 (CO), 5.613 µg/m3 (NO2), and 13.330 µg/m3 (O3), respectively. In terms of efficiency, stmtTransformer significantly improved the training efficiency by 185.21 % and the estimation efficiency by 129.44 % compared to the single-task model. Finally, when plotting the daily and seasonal maps of NSC for 2022, it is evident that the estimates exhibit a consistent spatial distribution.

Clearing the air: unraveling past and guiding future research in atmospheric chemosynthesis.

Atmospheric chemosynthesis is a recently proposed form of chemoautotrophic microbial primary production. The proposed process relies on the oxidation of trace concentrations of hydrogen (≤530 ppbv), carbon monoxide (≤90 ppbv), and methane (≤1,870 ppbv) gases using high-affinity enzymes. Atmospheric hydrogen and carbon monoxide oxidation have been primarily linked to microbial growth in desert surface soils scarce in liquid water and organic nutrients, and low in photosynthetic communities. It is well established that the oxidation of trace hydrogen and carbon monoxide gases widely supports the persistence of microbial communities in a diminished metabolic state, with the former potentially providing a reliable source of metabolic water. Microbial atmospheric methane oxidation also occurs in oligotrophic desert soils and is widespread throughout copiotrophic environments, with established links to microbial growth. Despite these findings, the direct link between trace gas oxidation and carbon fixation remains disputable. Here, we review the supporting evidence, outlining major gaps in our understanding of this phenomenon, and propose approaches to validate atmospheric chemosynthesis as a primary production process. We also explore the implications of this minimalistic survival strategy in terms of nutrient cycling, climate change, aerobiology, and astrobiology.

Dynamics of skewness and kurtosis of dangerous environmental parameters in the event of fire

The object of this study is the dynamics of skewness and kurtosis of the selective distribution of dangerous parameters of the gas environment in the current time when materials are ignited. The theoretical substantiation of the methodology for determining the dynamics of skewness and kurtosis based on a sample of an arbitrary size of dangerous parameters of the gas medium moving in the current time of observation has been performed. Thresholds for current skewness and kurtosis are determined depending on sample size and null hypothesis significance levels. The procedure makes it possible to investigate the peculiarities of the dynamics of skewness and kurtosis and to identify moments of time for which alternative hypotheses (stability of parameter dynamics) are valid. Laboratory experiments were conducted to study the dynamics of skewness and kurtosis in terms of carbon monoxide concentration, smoke density, and the temperature of the gas environment during the ignition of alcohol and textiles. The results indicate that the investigated dangerous parameters are generally not Gaussian in the observation interval. It was found that the nature of the dynamics of measures of the current sample distributions of dangerous parameters depends on the type of ignition material and the dangerous parameter. It was established that in the absence of ignition, the dynamics of skewness and kurtosis of dangerous parameters is characterized by different directional skewness and kurtosis. In the event of ignition, the dynamics of skewness and kurtosis are fluctuating (from –4 to 18), which indicates the instability of the development of the dangerous parameter over time. The specified procedure creates an opportunity to detect the instability of the development of a dangerous parameter, which in practice makes it possible to detect the occurrence of fires (with a given reliability) in order to eliminate them and prevent the occurrence of a fire

Passive Smoking And The Health Of Children: A Primary Concern In Pakistan.

Dear Madam, Environmental tobacco smoke (ETS), also referred to as second-hand, involuntary, or passive smoke, is produced from the combustion of tobacco products or puffed out by active smokers. The smoke emitted from the tip of a cigarette contains about two times the concentration of nicotine, five times the concentration of Carbon monoxide, and 50 times the concentration of ammonia than active smoke1. Furthermore, amongst the exposed population, children are far more susceptible to complications associated with ETS due to their manner of exposure and developmental physiology. According to the 2014 Global Adult Tobacco Survey for Pakistan, 43.3% of households were exposed to ETS, with a significant amount of children included in that percentage2. Thus, children's health is more detrimentally impacted by ETS than adults. Exposure of children to ETS in domestic and public settings risks a higher occurrence of respiratory and middle-ear diseases. According to numerous studies, dose-dependent exposure to ETS directs more frequent and severe asthma attacks accompanied by wheezing. Moreover, it is observed that school-aged individuals who live in a smoking household tend to develop a range of lung diseases, including bronchitis, bronchiolitis, and pneumonia. Their lungs become weak, resulting in impaired pulmonary function3. With reference to a population-based cohort study conducted by Lovasi et al. (ref 4), it was evident that childhood ETS exposure from 2 or more smokers compared with none is linked with early emphysema in adulthood4. In addition, constant ETS exposure leads to swelling and obstruction of the eustachian tube, which interferes with pressure equalization leading to pain, fluid accumulation, and infection. Ear infections and middle ear fluid are the most common causes of hearing loss in children. Being the primary reason behind several disease, ETS is also known to cause acute effects on cardiovascular function in children. Compelling evidence demonstrates that childhood ETS exposure risks the accumulation of factors associated with cardiovascular diseases, including obesity, dyslipidemia, and imbalanced systolic and diastolic blood pressure5. [Exposure to hazardous chemicals found in ETS, for instance, benzopyrene, is known to accelerate the development of atherosclerosis]. Moreover, studies show convincing evidence that hypertension is common in children exposed to ETS at home. It is also observed that hypertension is a common risk factor for cardiovascular disease and cardiovascular stress hyperactivity in children with smoking parents. ---Continue

Investigation of the Effect of ZnO Film Thickness over the Gas Sensor Developed for Sensing Carbon Monoxide

Herein, a facile and inexpensive ZnO thin film‐based carbon monoxide gas sensor is fabricated using a solution‐process technique. To vary the thickness of ZnO thin films, the precursor solutions of two different molarities, 3 and 5 m, are spin coated over glass substrates. The 3 m ZnO thin‐film device demonstrates more than two times improvement in sensing response as compared to 5 m ZnO films, for 50 ppm carbon monoxide concentration. Additionally, the 3 m ZnO film is found to perform better for low carbon monoxide concentrations, whereas the 5 m ZnO film shows a linear response over a wider range of carbon monoxide concentrations. The gas sensing mechanism and the impact of film thickness on the performance of the device are thoroughly studied and discussed, which may open the doors for the design and development of facile and high‐sensitivity metal oxide‐based gas sensors.

CATALYST BASED ON PALLADIUM(II), COPPER(II) COMPOUNDS AND THERMALLY-MODIFIED TRIPOLI FOR THE PREPARATION OF RESPIRATORY REMEDIES FROM CARBON MONOXIDE IN EMERGENCY SITUATIONS

Nowadays, the number of emergency situations related to fires is quite high. The high percentage of human deaths is mainly due to poisoning by gaseous toxic substances including carbon monoxide. The most problematic issue is the development or application of existing catalysts in means of individual protection of human respiratory organs – respirators, gas masks, self-rescuers. The compositions based on thermally modified tripoli obtained by the method of impregnation of the carrier by moisture content with compounds of copper(II), palladium(II) and potassium bromide were investigated. According to X-ray phase analysis, it was established that thermally modified tripoli is a polyphase crystalline mineral containing the following main phases: a-quartz, a-tridymite, b-cristobalite, a-cristobalite. The influence of the initial concentration of CO, which does not exceed 15 MPC, on the kinetic and stoichiometric parameters of the reaction varied in the range from 100 to 300 mg/m3. It was noted that the reaction rate in the stationary mode (Wst) is directly proportional to the increase in the initial concentration of carbon monoxide in the gas phase. The values of the constant kI and the degree of CO conversion (ηst) do not depend on CinCO, which also confirms the first order of CO concentration. Particular attention is paid to the aspects of ensuring protection against carbon monoxide when its concentration exceeds 15 MPC. Usually, special equipment, such as filtering self-rescuers, is used to clean the air from carbon monoxide at concentrations from 1000 to 6500 mg/m3. The catalyst developed by us is intended for use in lightweight personal respiratory protective equipment (RPE) at concentrations not exceeding 15 MPC. Therefore, there was an interest in researching the possibilities of using this catalyst in the self-saving filter system. The concentration of carbon monoxide in the gas-air mixture was varied from 400 to 2500 mg/m3 in the presence of the К2PdCl4-Cu(NO3)2-КBr/300-Tr(K) system. It was established that Wst increases in direct proportion with an increase in the gas-air mixture up to 1250 mg/m3, which indicates the first order of the reaction according to carbon monoxide. It was found that at CinCO = 1000 mg/m3 only under the condition τ´ = 1.13 s (mk = 10 g) the К2PdCl4-Cu(NO3)2-KBr/Tr catalyst provides air purification below the breakthrough CO concentration (CfCO = 200 mg/m3). Experiments on the influence of SO2 on the activity of carbon monoxide oxidation catalysts have shown that they lose their activity, so in air purification systems from CO, it is necessary to provide for the stage of capturing sulfur dioxide.

An analysis of waste/biomass gasification producing hydrogen-rich syngas: A review

In the last few decades, the population growth level has increased exponentially so the waste disposal level has increased gradually. Wastes like biodegradable wastes, kitchen wastes, hotel wastes, and other agro wastes can be processed through bio methanation and composting technology but non-biodegradable materials like plastics, rubber, industrial sludge, and other wastes cannot be processed in simple ways or technologies. These wastes are critical to handle and need robust technology. Gasification and incinerators are a technology to utilize these waste materials and convert them into useful energy. However, the incinerator has a drawback of control over emissions generated by waste material combustion. Gasification is the best-suited technology which can convert the waste material into gaseous form and this gas provides heat to the prime movers to generate energy/power. Carbon monoxide, hydrogen, methane, carbon dioxide, oxygen, and nitrogen are the main components of synthetic gas (syngas), which has a low calorific value. Increased hydrogen and carbon monoxide concentrations improve this gas's calorific value. Different gasification methods like gasification using agent as steam, catalytic gasification, and gasification using different combination of fuels (waste-coal/biomass) are used to enrich the hydrogen content of the syngas. This paper reviewed the theory of waste-to-energy technologies, incineration technology, gasification technology, methods for increasing hydrogen in syngas, also different methods. This review discusses waste gasification disposal methods and hydrogen enrichment.

Traffic-related air pollution and Parkinson's disease in central California

BackgroundPrior studies suggested that air pollution exposure may increase the risk of Parkinson's Disease (PD). We investigated the long-term impacts of traffic-related and multiple sources of particulate air pollution on PD in central California. MethodsOur case-control analysis included 761 PD patients and 910 population controls. We assessed exposure at residential and occupational locations from 1981 to 2016, estimating annual average carbon monoxide (CO) concentrations - a traffic pollution marker - based on the California Line Source Dispersion Model, version 4. Additionally, particulate matter (PM2.5) concentrations were based on a nationwide geospatial chemical transport model. Exposures were assessed as 10-year averages with a 5-year lag time prior to a PD diagnosis for cases and an interview date for controls, subsequently categorized into tertiles. Logistic regression models were used, adjusting for various factors. ResultsTraffic-related CO was associated with an increased odds ratio for PD at residences (OR for T3 vs. T1: 1.58; 95% CI: 1.20, 2.10; p-trend = 0.02) and workplaces (OR for T3 vs. T1: 1.91; 95% CI: 1.22, 3.00; p-trend <0.01). PM2.5 was also positively associated with PD at residences (OR for T3 vs. T1: 1.62; 95% CI: 1.22, 2.15; p-trend <0.01) and workplaces (OR for T3 vs. T1: 1.85; 95% CI: 1.21, 2.85; p-trend <0.01). Associations remained robust after additional adjustments for smoking status and pesticide exposure and were consistent across different exposure periods. ConclusionWe found that long-term modeled exposure to local traffic-related air pollution (CO) and fine particulates from multiple sources (PM2.5) at homes and workplaces in central California was associated with an increased risk of PD.

Temporal assessment of air quality in major cities in Nigeria using satellite data

This study evaluated the concentrations of tropospheric nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and Aerosol Index (AI) as well as different meteorological parameters, including atmospheric temperature (AT), relative humidity (RH), and wind speed (WS) in nine Nigerian cities: Aba, Benin, Ibadan, Kaduna, Kano, Lagos, Onitsha, Port Harcourt, and Umuahia. The role of socioeconomic activities on air pollution was also investigated using nighttime light radiance as a surrogate measure. Welch's one-way ANOVA test was performed for the variance study to evaluate the concentration dynamics of the selected tropospheric air pollutants and their association with nighttime light radiance. The mean concentration of CO and AI was highest in Kano, while that of O3 was the lowest. A similar pattern was also observed in the spatiotemporal transition of the selected pollutants and the nighttime light during the study period. Further, the correlation analysis revealed that AT is positively correlated with NO2 except in Aba and Benin cities, while it is positively correlated with CO and AI for all cities. The principal component analysis (PCA) revealed that O3 and RH have strong negative factor loadings, whereas CO, AI, and AT have strong positive factor loadings. This study will guide future researchers by associating the level of pollution with socioeconomic activities, especially during the absence of permanent air quality stations.

Impact of air pollution on healthcare utilization in patients with bronchiectasis.

Air pollutants are increasingly recognized to affect long-term outcomes in patients with bronchiectasis. We aimed to figure out the association between air pollutants and the risk of healthcare utilization in patients with bronchiectasis. Data for 1,029 subjects with bronchiectasis in Seoul were extracted. The air pollutants included particulate matter of 10 μm or less in diameter (PM10), particulate matter of 2.5 μm or less in diameter (PM2.5), sulfur dioxide (SO2), carbon monoxide (CO), ozone (O3), and nitrogen dioxide (NO2). The outcome was all-cause healthcare uses, defined as outpatient visit, emergency department visit, or hospitalization. The concentration-response curves between each air pollutant and relative risks for healthcare utilization were obtained. There were significant correlations between air pollutant concentrations and the risk of healthcare utilization, particularly for PM10, NO2, SO2, and CO. This risk was observed even at concentrations below the recommended safe thresholds for the general population. The slopes for the association between PM10 and NO2 and the risk of healthcare use showed a logarithmic growth pattern, with the steepest increase up to 30 μg/m3 and 0.030 parts per million (ppm), respectively. The curves for SO2 and CO showed an inverted U-shaped pattern, with a peak at 0.0045 ppm and a slow upward curve, respectively. No specific trends were observed for PM2.5 and O3 and the risk of healthcare use. Increased concentrations of PM10, NO2, SO2, and CO were associated with increased healthcare utilization in patients with bronchiectasis. For patients with bronchiectasis, there were no safety thresholds for those air pollutants, and even low levels of air pollutant exposure can negatively impact bronchiectasis outcomes.

Internet of Things-based sustainable environment management for large indoor facilities.

Due to global warming and climate change, the poultry industry is heavily impacted, especially the broiler industry, due to the sensitive immune system of broiler chickens. However, the continuous monitoring and controlling of the farm's environmental parameters can help to curtail the negative impacts of the environment on chickens' health, leading to increased meat production. This article presents smart solutions to such issues, which are practically implemented, and have low production and operational costs. In this article, an Internet of Things (IoT) based environmental parameters monitoring has been demonstrated for the poultry farmhouse. This system enables the collection and visualization of crucially sensed data automatically and reliably, and at a low cost to efficiently manage and operate a poultry farm. The proposed IoT-based remote monitoring system collects and visualizes environmental parameters, such as air temperature, relative humidity (RH), oxygen level (O2), carbon dioxide (CO2), carbon monoxide (CO), and ammonia (NH3) gas concentrations. The wireless sensor nodes have been designed and deployed for efficient data collection of the essential environmental parameters that are key for monitoring and decision-making process. The hardware is implemented and deployed successfully at a site within the control shed of the poultry farmhouse. The results revealed important findings related to the environmental conditions within the poultry farm. The temperature inside the control sheds remained within the desired range throughout the monitoring period, with daily average values ranging from 32 °C to 34 °C. The RH showed slight variations monitoring period, ranging from 65% to 75%, with a daily average of 70%. The O2 concentration exhibited an average value of 17% to 18.5% throughout the monitoring period. The CO2 levels showed occasional increases, reaching a maximum value of 1,100 ppm. However, this value was below the maximum permissible level of 2,500 ppm, indicating that the ventilation system was effective in maintaining acceptable CO2 levels within the control sheds. The NH3 gas concentration remained consistently low throughout the duration, with an average value of 50 parts per million (ppm).

Carbon monoxide formation from total volatile organic compounds from the use of household spray products

Introduction: Air pollutants emitted from household spray products used in our homes and offices have adverse effects on human health. The quantification and identification of emission sources of air pollutants forms a foundation for an effective indoor exposure control. This study presents the results of a fundamental study conducted to evaluate the kinetics and emission trends Total Volatile Organic Compounds (TVOCs) and Carbon Monoxide (CO) from household spray products.&#x0D; Materials and methods: Fortyfive (45) commonly used household spray products were selected for this study. The experiment was conducted in an isolated empty room of dimension (2.72×2.82×2.00) m3 with no known/ significant indoor emission source(s). CO and TVOCs concentrations were measured with Aeroqual® 500 series monitor with CO and TVOCs head at 15 min, 1 h, 3 h, and 24 h, for all 45 samples of household spray products.&#x0D; Results: Spontaneous second – order conversion of TVOCs to CO was observed for most of the spray products in the indoor environment. For the insecticides samples, TVOCs initial concentrations were 7.2–73±19.76 ppm which after one hour the concentrations became 1.8 – 17±7.20 ppm. CO measured initial concentration were 0 – 4±1.08 ppm which the concentration levels reduced to 0–7±2.16 ppm. TVOCs concentration was above the permissible limit set by USEPA and CO concentration for some of the air fresheners, perfume, shoe impregnation spray and hair sprays fall short the limit of 40,081.89 and 25,562.37 µg/m3 set by United States Environmental Protection Agency (USEPA) and World Health Organization (WHO), respectively.&#x0D; Conclusion: As the concentration of TVOCs decreased as the concentration the concentration, CO increased following a second order kinetics. The result obtained will help in the development of safer products and a proper guide on how to use them in a way it will not cause harm to both the user of the product and the environment.

Sensitive carbon monoxide detection based on light induced thermoelastic spectroscopy with a hollow waveguide and 2.3 μm diode laser

In this paper, a sensitive carbon monoxide (CO) detection system based on light induced thermoelastic spectroscopy (LITES) using a hollow waveguide (HWG) and 2.3 μm diode laser is reported. The HWG has an inner diameter of 4 mm, in which light and CO gas can fully react. Its large inner diameter makes optical coupling easier compared to hollow-core anti-resonant fiber (HC-ARF). In addition, it has the advantages of wide transmission band range, simple structure and low loss. An absorption line of CO located at 4288.26 cm−1 was chosen, therefore a diode laser with an emission wavelength of 2.3 μm was selected as the excitation source. In the experiment, the current modulation depth of the CO-HWG-LITES sensor was optimized to 34.6 mA. The results demonstrated a very nice linear relationship between the CO concentration and the corresponding 2f signal peak value, indicating that the CO-HWG-LITES sensor had a superior linear response to the gas concentration. The minimum detection limit (MDL) for CO in this system was determined to be 31.6 ppm. Finally, the Allan deviation analysis was performed and results indicated that the MDL can reach 4.7 ppm when the integration time was 100 s.

An electronic nose for harmful gas early detection based on a hybrid deep learning method H-CRNN

Among harmful gases, carbon monoxide (CO) has posed a significant threat to human safety due to its concealment and harmfulness. Therefore, it’s imperative for the preservation of human safety to implement early detection for CO concentration. However, traditional methods for gas detection are either plagued by the limitations of insufficient accuracy like electronic nose (E-nose) equipped with relatively simple machine learning algorithms such as vanilla SVM or RNN, or limited by the incapacity to make early prediction such as sensory analysis, which requires a large amount of manpower resources and time. To address this issue, a novel technique, namely H-CRNN, is presented for E-nose to perform early prediction of low concentration CO, leveraging the strengths of convolutional and recurrent neural network to efficiently capture long-term dependencies within data. Also, shortcut connection and a novel gated attention mechanism is applied to enhance the capacity to capture crucial features. Furthermore, a linear process unit has been incorporated to handle the scale insensitivity issue. The experimental results show that the proposed H-CRNN outperforms RNN with a notable average reduction of 50.51% in the root relative squared error and 53.8% in the relative absolute error, and exhibits varying degrees of improvement when compared to state-of-the-art algorithms (TCN, TPA-LSTM, STCN, LSTNet, LSTM). Additionally, the H-CRNN achieved an average accuracy rate of 96.42%, surpassing all other algorithms and demonstrating the highest level of performance. Therefore, our work substantiates the proposed H-CRNN as an applicable method for early prediction of CO concentration.

Mutual disposal of municipal solid waste and flue gas on isolated islands

Municipal solid waste (MSW) management in rural and remote areas (e.g., isolated islands) is a noteworthy issue. Transportation of MSW from isolated islands to the mainland requires large-scale energy, so it demands a high amount of diesel fuel in diesel generators. To alleviate environmental pollution and energy consumption during transportation, this paper proposes a mutual disposal strategy for MSW and fuel gas from diesel generators and explores the feasibility and potential benefits based on MSW drying experiment in a self-designed device. The following were the primary conclusions: (1) the flue gas could provide sufficient heat energy for drying MSW, and the effective utilization rate can reach 60.22 ± 2.88%. It would take 60–85 min to dry MSW below 200 °C. (2) Within the permissible limits of environmental standards, the MSW contributes to the reduction of particulate matter and methane in the flue gas, while the carbon monoxide, nitric oxide, and non-methane hydrocarbon contents increase due to thermal decomposition of the MSW. The global warming potential of the carbon in the treated gas can be decreased by 16.94%, and the nitric oxide contributes to carbon emission reduction. (3) The proposed mutual disposal strategy could alleviate issues in landfill leachate and simplify the treatment technology, leading to subsequent environmental, economic, and technical benefits.