Measurements Of Carbon Dioxide Concentrations Research Articles

Periodic open and closed resonators as a biosensor using two computational methods

The volatile particles and molecules in our dry exhaled breath can reveal enormous information about the health of any person, such as the person’s respiratory and metabolic functioning. Beyond the carbon dioxide level is an indicator of life, it provides important health-related data like people’s metabolic rate. This study considers periodic open and closed resonators for measuring carbon dioxide concentration in dry exhaled breath. Transfer matrix and green methods are used to simulate the interaction between acoustic waves and the proposed sensor. The band gaps using the green method coincide with the transmittance spectra by the transfer matrix. The suggested sensor recorded a sensitivity of 5.3Hz.m-1.s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$5.3 Hz.{m}^{-1}.s$$\\end{document}, a figure of merit of 10,254 m-1.s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${m}^{-1}.s$$\\end{document}, a detection limit of 5×10-6m.s-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$5\ imes {10}^{-6} m.{s}^{-1}$$\\end{document}, and a quality factor of 3×106\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$3\ imes {10}^{6}$$\\end{document}. Furthermore, the efficiency shows that the proposed design is appropriate as a diagnostic sensor for different diseases such as chronic obstructive pulmonary. Besides, cylindrical-adapted sensors are urgently needed in medicine, industry, and biology because they can simultaneously be used for fluid transport and detection.

The influence of displacement ventilation on indoor carbon dioxide exposure and ventilation efficiency in a living laboratory open-plan office

Good indoor air quality in office environments is essential for occupant health and productivity. In open-plan offices, displacement ventilation has been recognized for its higher efficiency compared to mixing ventilation. This study evaluates the performance of displacement ventilation in an open-plan office under cooling and heating conditions, considering various supply ventilation rates, supply air temperatures, and occupancy levels. Field measurements were conducted over three months in a living laboratory office in a high-performance building. The indoor environment was controlled by an independent variable air volume (VAV) air conditioning system. The supply ventilation rate ranged from 6 to 12 h−1. Real-time measurements of carbon dioxide (CO2) concentrations in the supply air, return air, and breathing zone of the office were conducted to assess occupants’ exposure to CO2 and ventilation efficiency. The results show that the supply ventilation rate plays an important role in shaping the air distribution and overall effectiveness of the mechanical ventilation system. Higher supply ventilation rates can enhance air distribution robustness, improving ventilation efficiency and reducing CO2 exposure under both cooling and heating conditions. These findings also suggest the need for an optimized control logic that differs from the conventional control logic used in VAV systems. Specifically, during the heating condition of displacement ventilation, it is recommended to maintain the supply ventilation rate at a higher level to effectively mitigate the impact of occupant behavior on air quality, minimize CO2 exposure risks, and ensure a more robust and reliable indoor air distribution.

Inferring ventilation rates with quantified uncertainty in operational rooms using point measurements of carbon dioxide: Classrooms as a case study

We present a robust integral method to estimate the daily mean per-person ventilation rate Q¯pp based on carbon dioxide (CO2) concentration measurements in operational spaces, and limited other data. The method makes no assumptions regarding the ventilation provision throughout the day, nor requires the room to be in a steady state, nor the air within to be well-mixed. We demonstrate that several integral parameters remain reliably close to a value of unity, despite large variations in room conditions. Evaluating the likely distributions of integral parameters provides a method to quantify the uncertainty bounds and therefore assess the reliability of these ventilation estimates. Taking school classrooms as a case study, estimates of Q¯pp based on measured CO2 are shown to exhibit uncertainty bounds (of 95% confidence intervals) of approximately ±24% if no other data than the classroom timetable is available. Deploying four CO2 sensors within a classroom is expected to halve the uncertainty bounds to around ±12%. Moreover, the framework presented herein evidences that when the same classroom experiences similar usage on two different days, the relative per-person ventilation rate achieved during these two days can be simply determined by the ratio of their integral excess CO2 concentrations. These significant findings offer great scope to facilitate more reliable ventilation estimates, particularly from large-scale data sets of CO2 measured in operational spaces, to better inform assessments of indoor air quality.

Robustness of point measurements of carbon dioxide concentration for the inference of ventilation rates in a wintertime classroom

Indoor air quality in schools and classrooms is paramount for the health and well-being of pupils and staff. Carbon dioxide sensors offer a cost-effective way to assess and manage ventilation provision. However, often only a single point measurement is available which might not be representative of the CO₂ distribution within the room. A relatively generic UK classroom in wintertime is simulated using Computational Fluid Dynamics. The natural ventilation provision is driven by buoyancy through high- and low-level openings in both an opposite-ended or single-ended configuration, in which only the horizontal location of the high-level vent is modified. CO₂ is modelled as a passive scalar and is shown not to be ‘well-mixed’ within the space. Perhaps surprisingly, the single-ended configuration leads to a ‘more efficient’ ventilation, with lower average CO₂ concentration. Measurements taken near the walls, often the location of CO₂ sensors, are compared with those made throughout the classroom and found to be more representative of the ventilation rate if made above the breathing zone. These findings are robust with respect to ventilation flow rates and to the flow patterns observed, which were tested by varying the effective vent areas and the ratio of the vent areas.

Hydrothermal fluid circulation within the restless structural frame of Hasandağ volcanic system (Central Anatolia, Türkiye) inferred from Self-potential, CO2, and temperature measurements

Hasandağ is an active composite volcanic system located in the Central Anatolian Volcanic Province (CAVP). A comprehensive field survey was conducted to reveal the hydrothermal activity within the Hasandağ volcanic system, with particular emphasis on Self-Potential (SP) mapping. The Hasandağ system is characterised by the presence of twin stratovolcanoes that arise from pre-existing partially buried calderas. In conjunction with the SP measurements, carbon dioxide concentration (CO2) and surface temperature (ST) measurements were taken. The temperature measurements were elaborated with thermal infrared remote (TIR) sensing methods. The SP results, with a peak-to-peak magnitude of 3.8 Volts, revealed the presence of a significant hydrothermal input in both of the twin cones, characterised by a typical W-shaped anomaly commonly observed in active volcanoes. The highest SP signal coincides with the active fumarole zone at the western flank of G. Hasandağ summit, where we measured ∼70 °C vapour temperatures and relatively high CO2 output (>100,000 ppm). The SP/elevation (Ce) gradient assisted in revealing the hydrothermal and hydrogeological zonation, providing substantial evidence of the relationship between hydrothermal circulation and the structural frame of the volcano. Integrated evaluation of SP, CO2, and temperature data revealed the structural control on the hydrothermal and hydrogeological circulation, with the contribution of Hasandağ, Karacaören, and Karkın Faults as major structural components. The partially buried rim of the Hasandağ caldera was revealed through the detection of a ‘double Ce-low’ signal, providing valuable insights on the dimensions of the structure and its role in the hydrogeological cycle of the system. The extent and magnitude of the hydrothermal activity observed, the Holocene eruptive history of the volcano, and its proximity to populated areas denote the requirement of further geophysical and geochronological research and the necessity of hazard assessment and instrumental monitoring.

Углекислый газ: проблемы нормирования, контроля и профилактики неблагоприятного воздействия в образовательных организациях

This article is a review of data published in Russian and foreign studies that reflect current problems concerning content of carbon dioxide in spaces of residential and public buildings, including children's educational organizations. We consider: mechanisms of action of high concentrations of carbon dioxide on the human body, which manifests as acute and delayed disruptions of metabolic processes in circulatory, central and respiratory systems; existing carbon dioxide content measurement methods used for indoor spaces; principles of setting microclimate and air quality standards for temporarily and constantly occupied indoor spaces and the respective parameter control principles. This analytical review revealed the need for standard-setting efforts, development and approval of a methodology enabling measurement of the actual carbon dioxide concentration in children's educational institutions, since routine measures adopted for the purpose lack in effectiveness or realization, which prevents normalization and stabilization of all qualitative and quantitative air parameters at the levels making the environment of a classroom safe and optimal for education-related activities given high occupancy of the space.

A Model for the Determination of Potato Tuber Mass by the Measurement of Carbon Dioxide Concentration.

The implementation of advanced precision farming systems, which are becoming relevant due to rapid technological development, requires the invention of new approaches to the diagnostics and control of the growing process of cultivated crops. This is especially relevant for potato, as it is one of the most demanded crops in the world. In the present work, an analytic model of the dependence of potato tubers mass on carbon dioxide concentration under cultivation in a closed vegetation system is presented. The model is based on the quantitative description of starch molecule synthesis from carbon dioxide under photosynthesis. In the frame of this work, a comprehensive description of the proposed model is presented, and the verification of this model was conducted on the basis of experimental data from a closed urban vertical farm with automated climate control. The described model can serve as a basis for the non-contact non-invasive real-time measurement of potato tuber mass under growth in closed vegetation systems, such as vertical farms and greenhouses, as well as orbital and space crop production systems.

Determination of the Interzonal Airflows in Naturally Ventilated Dwellings Based on Concentration Measurements of the Metabolic Carbon Dioxide

The role of interzonal airflows is especially pronounced in naturally ventilated buildings. In such buildings, reversed airflows in the ventilation stacks might occur as well. This affects the air exchange rate and contaminant distribution in buildings. A significant increase in carbon dioxide concentration is a characteristic phenomenon for poorly ventilated rooms. This paper demonstrates the application of metabolic carbon dioxide concentration measurements for interzonal airflow estimation in naturally ventilated buildings. The presented method is based on the continuous measurements of CO2 concentration at one point in each zone. These measurements are used to estimate airflow pattern in a multizone building by applying an inverse analysis. The developed methodology employs an iterative Levenberg-Marquardt procedure to maximise the nonlinear likelihood function. The validity of the method was verified against measurements carried out in a single naturally ventilated room. Further, the method was applied to calculate the airflow pattern in two apartments in Poland, containing 4 and 6 zones. The obtained results revealed very poor ventilation in both investigated apartments and reversed airflow in exhaust ducts. The amount of fresh air entering the rooms was insufficient to ensure good indoor air quality. The developed methodology can be effectively used as a diagnostic tool to identify the potential problems with ventilation systems.

Assessment of a Low-Cost Portable Device for Gas Concentration Monitoring in Livestock Housing

The increasing regulatory pressure to monitor and reduce GHG emissions and air pollutants requires cost-effective methods for their surveillance. The most common techniques used for scientific investigations into gas concentration monitoring in barns are accurate but expensive and require complex maintenance. This research study analyzed the potential use of low-cost portable measurement devices for the measurement of ammonia (NH3) and carbon dioxide (CO2) concentrations in an open dairy barn. A comparison between the gas concentrations acquired at different heights from the floor by using portable devices and those acquired by a photoacoustic infrared multigas spectroscope (i.e., reference measurement) in the same sampling locations was carried out to determine the precision of the low-cost portable devices. The performances of the low-cost portable devices were statistically analyzed by application of the one-way analysis of variance, correlation analysis, and regression analysis. The results showed a significant difference between the gas concentration values at various heights from the floor for both NH3 and CO2. The correlations between the concentrations acquired by the low-cost portable devices and the INNOVA were statistically significant (r = 0.83; p < 0.001) for gas concentrations monitored at 0.4 m from the floor. Compared with the reference measurement device, the low-cost devices were effective at the monitoring of NH3 concentrations at 0.40 m from the floor; however, they underestimated the concentrations in the barn at increasing heights from the floor, and the device was not adequate for CO2 concentrations. In detail, the relative measurement error of the low-cost devices compared to the INNOVA was reduced close to the floor during NH3 concentration measurements. Within these limitations, this device may be useful for monitoring the NH3 concentration in the barn and assessing variations in the NH3 concentrations mainly related to the animal occupied zone. Further efforts are needed in this field of research to identify a low-cost device that can simplify emission estimation from open dairy barns.

The Role of Portable Air Purifiers and Effective Ventilation in Improving Indoor Air Quality in University Classrooms.

In this study we investigated the effectiveness of air purifiers and in-line filters in ventilation systems working simultaneously inside various classrooms at the University of Southern California (USC) main campus. We conducted real-time measurements of particle mass (PM), particle number (PN), and carbon dioxide (CO2) concentrations in nine classrooms from September 2021 to January 2022. The measurement campaign was carried out with different configurations of the purifier (i.e., different flow rates) while the ventilation system was continuously working. Our results showed that the ventilation systems in the classrooms were adequate in providing sufficient outdoor air to dilute indoor CO2 concentrations due to the high air exchange rates (2.63-8.63 h-1). The particle penetration coefficients (P) of the investigated classrooms were very low for PM (<0.2) and PN (<0.1), with the exception of one classroom, corroborating the effectiveness of in-line filters in the ventilation systems. Additionally, the results showed that the efficiency of the air purifier exceeded 95% in capturing ultrafine and coarse particles and ranged between 82-88% for particles in the accumulation range (0.3-2 µm). The findings of this study underline the effectiveness of air purifiers and ventilation systems equipped with efficient in-line filters in substantially reducing indoor air pollution.

Experimental studies of carbon dioxide concentration in the space under the face mask protecting against Covid-19 - Pilot studies.

Masks are the primary tool used to prevent the spread of COVID-19 in the current pandemic. The use of masks may result in some discomfort, which may be caused by the accumulation of carbon dioxide in the inner space of the mask. This paper presents tests of carbon dioxide concentration in the inner space of the mask during work at a computer, for various flat and convex masks. Five different masks were used in the tests. Convex masks showed a greater accumulation of carbon dioxide than flat masks. The concentration of carbon dioxide was also higher for masks made of more layers. The dependence of the average values of carbon dioxide concentrations under the masks for selected people depending on the BMI and the type of mask was determined, as well as the measurements of carbon dioxide concentrations without the mask. An increase in carbon dioxide concentration was observed with increasing BMI.The development of effective self-defense tools against the virus, including masks, is essential to contain the spread of COVID-19.

AIR QUALITY MONITORING IN A SELECTED CLASSROOM

As part of the research entitled "Experimental determination of the optimal amount of air in a selected room in Ukraine based on measurements of carbon dioxide concentration", an experimental measurement was performed in a selected school room in Ukraine. The aim of the experimental measurement was to determine the course of air temperature, relative humidity and carbon dioxide concentration during the teaching process. From the carbon dioxide concentration curves, it is possible to calculate the required ventilation intensity in the room. This article documents the results of measuring the air temperature and the carbon dioxide concentration in the room, as well as the reactions of people in the room to the air quality.

Testbed for Studying the Efficiency of Plants Photosynthetic Irradiation Based on Measuring Carbon Dioxide Concentration in the Air

The work is devoted to the description of a testbed that allows studying the efficiency of photosynthetic irradiation of plants by measuring the level of carbon dioxide concentration in the air, which in turn determines the intensity of photosynthetic processes in plants. This method makes it possible to significantly increase the speed of comparative research of the effect of irradiation modes on crop yields. The developed testbed is based on the ESP8266 microcontroller with sensors for measuring carbon dioxide concentration, temperature, air humidity, and a microcontroller implementing the control of plant irradiation modes. Measurement of carbon dioxide concentration was carried out using the MH-Z16 sensor, the principle of which is based on the measurement of non-dispersive infrared radiation (NDIR). In the testbed LED irradiators with a continuous emission spectrum and LED irradiators with a combined emission spectrum (white light + “red” radiation) were used. The testbed allowed us to study the dependence of the efficiency of photosynthesis on the conditions of irradiation by varying the spectral composition of radiation, irradiance intensity. The measurement of carbon dioxide concentration in the phytotron showed its significant dependence on the irradiation conditions. Since the rate of change in the concentration of carbon dioxide occurs over a sufficiently long period of time, research into the irradiation efficiency was carried out on the basis of an assessment of the dynamics of carbon dioxide concentration. Another variant of the research was the consistent comparison of changes in the concentration of carbon dioxide under different irradiation conditions.

Effect of time and sample size on serum bicarbonate testing

A number of preanalytical factors have been described as affecting the measurement of plasma total carbon dioxide concentration. Here we present the effect of using varying blood volumes on bicarbonate concentration.

Seasonal patterns and semi-empirical modeling of in-vehicle exposure to carbon dioxide and airborne particulates in Dalian, China

Field measurements of in-vehicle carbon dioxide (CO2), PM0.3, PM1.0, PM2.5, and PM10 mass concentrations were conducted along three main roadways in Dalian, China, during spring, summer, and winter. The temperature, relative humidity, and air pressure both inside and outside the vehicle were recorded simultaneously. A correlation analysis was used to evaluate the dominant factors influencing the CO2 and particle mass concentrations. Two semi-empirical pollutant models describing the in-vehicle CO2 and particle mass concentrations were established and validated using field data. The in-vehicle CO2 concentration exceeded the 1000 ppm limit during the majority of the period. Among the different cases, the averaged in-vehicle CO2 concentration under international air conditioning (AC) conditions was highest at 2977.9 ± 914.1–3866.7 ± 1035.9 ppm. In contrast, the in-vehicle PM2.5 mass concentration did not reveal significant variation among the different cases. These results, especially those of semi-empirical pollutant dispersion models, could predict in-vehicle pollutant exposure levels, providing useful guidance for optimized ventilation control in vehicles.

Measurement of indoor carbon dioxide concentrations when using a carbon dioxide fire extinguisher in a room

Measurement of indoor carbon dioxide concentrations when using a carbon dioxide fire extinguisher in a room

Modeling cycles and interdependence in irregularly sampled geophysical time series

AbstractWe show how an autoregressive Gaussian process model incorporating a time scale coefficient can be used to represent irregularly sampled geophysical time series. Selection of this coefficient, together with the order of autoregression, provides flexibility of the model appropriate to the structure of the data. This leads to a valuable improvement in the identification of the periodicities within and dependence between such series, which arise frequently and are often acquired at some cost in time and effort. We carefully explain the modeling procedure and demonstrate its efficacy for identifying periodic behavior in the context of an application to dust flux measurements from lake sediments in a region of subtropical eastern Australia. The model is further applied to the measurements of atmospheric carbon dioxide concentrations and temperature obtained from Antarctic ice cores. The model identifies periods in the glacial‐interglacial cycles of these series that are associated with astronomical forcing, determines that they are causally related, and, by application to current measurements, confirms the prediction of climate warming.

Genetic Variability of Methane Production and Concentration Measured in the Breath of Polish Holstein-Friesian Cattle.

Simple SummaryMethane is one of the main contributors to climate change. A potential to reduce emissions by genetic selection exists; however, the genetic architecture of methane production remains largely unknown. We aimed to estimate its heritability and to perform genome-wide association studies for the identification of candidate genes associated with daily methane production and concentration. Methane was measured in the air exhaled by dairy cows during milking in an automated milking system and was analyzed using genomic information that was available for some of the cows. We showed that methane production and concentration are partly controlled by genes; however, no major genes were found. The estimated heritabilities indicate that selection for lower methane emission could be successful.The genetic architecture of methane (CH4) production remains largely unknown. We aimed to estimate its heritability and to perform genome-wide association studies (GWAS) for the identification of candidate genes associated with two phenotypes: CH4 in parts per million/day (CH4 ppm/d) and CH4 in grams/day (CH4 g/d). We studied 483 Polish Holstein-Friesian cows kept on two commercial farms in Poland. Measurements of CH4 and carbon dioxide (CO2) concentrations exhaled by cows during milking were obtained using gas analyzers installed in the automated milking system on the farms. Genomic analyses were performed using a single-step BLUP approach. The percentage of genetic variance explained by SNPs was calculated for each SNP separately and then for the windows of neighbouring SNPs. The heritability of CH4 ppm/d ranged from 0 to 0.14, with an average of 0.085. The heritability of CH4 g/d ranged from 0.13 to 0.26, with an average of 0.22. The GWAS detected potential candidate SNPs on BTA 14 which explained ~0.9% of genetic variance for CH4 ppm/d and ~1% of genetic variance for CH4 g/d. All identified SNPs were located in the TRPS1 gene. We showed that methane traits are partially controlled by genes; however, the detected SNPs explained only a small part of genetic variation—implying that both CH4 ppm/d and CH4 g/d are highly polygenic traits.

Recent Insights into the Measurement of Carbon Dioxide Concentrations for Clinical Practice in Respiratory Medicine.

In the field of respiratory clinical practice, the importance of measuring carbon dioxide (CO2) concentrations cannot be overemphasized. Within the body, assessment of the arterial partial pressure of CO2 (PaCO2) has been the gold standard for many decades. Non-invasive assessments are usually predicated on the measurement of CO2 concentrations in the air, usually using an infrared analyzer, and these data are clearly important regarding climate changes as well as regulations of air quality in buildings to ascertain adequate ventilation. Measurements of CO2 production with oxygen consumption yield important indices such as the respiratory quotient and estimates of energy expenditure, which may be used for further investigation in the various fields of metabolism, obesity, sleep disorders, and lifestyle-related issues. Measures of PaCO2 are nowadays performed using the Severinghaus electrode in arterial blood or in arterialized capillary blood, while the same electrode system has been modified to enable relatively accurate non-invasive monitoring of the transcutaneous partial pressure of CO2 (PtcCO2). PtcCO2 monitoring during sleep can be helpful for evaluating sleep apnea syndrome, particularly in children. End-tidal PCO2 is inferior to PtcCO2 as far as accuracy, but it provides breath-by-breath estimates of respiratory gas exchange, while PtcCO2 reflects temporal trends in alveolar ventilation. The frequency of monitoring end-tidal PCO2 has markedly increased in light of its multiple applications (e.g., verify endotracheal intubation, anesthesia or mechanical ventilation, exercise testing, respiratory patterning during sleep, etc.).

THE VENTILATION OF BLIND WORKINGS OF WATER—SUPPLY TUNNEL OF HYDRO POWER IN CASE OF GENERATION OF A CARBON DIOXIDE IN THE MASSIF

A question of local sources of carbon dioxide have considered in this work that were detected during of tunneling of water-supply tunnel of Lukhuni hydго power. This event led to the termination of tunnel works, since formed an unfavorable environment for breathing and have had poisoned staff. As a result of various measurements of carbon dioxide concentration was varied in the range of 4.5-5.5%.