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Using climate-optimized flight trajectories is one essential measure to reduce aviation's climate impact. Detailed knowledge of temporal and spatial climate sensitivity for aviation emissions in the atmosphere is required to realize such a climate mitigation measure. The algorithmic Climate Change Functions (aCCFs) represent the basis for such purposes. This paper presents the first version of the Algorithmic Climate Change Function submodel (ACCF 1.0) within the European Centre HAMburg general circulation model (ECHAM) and Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model framework. In the ACCF 1.0, we implement a set of aCCFs (version 1.0) to estimate the average temperature response over 20 years (ATR20) resulting from aviation CO2 emissions and non-CO2 impacts, such as NOx emissions (via ozone production and methane destruction), water vapour emissions, and contrail cirrus. While the aCCF concept has been introduced in previous research, here, we publish a consistent set of aCCF formulas in terms of fuel scenario, metric, and efficacy for the first time. In particular, this paper elaborates on contrail aCCF development, which has not been published before. ACCF 1.0 uses the simulated atmospheric conditions at the emission location as input to calculate the ATR20 per unit of fuel burned, per NOx emitted, or per flown kilometre.In this research, we perform quality checks of the ACCF 1.0 outputs in two aspects. Firstly, we compare climatological values calculated by ACCF 1.0 to previous studies. The comparison confirms that in the Northern Hemisphere between 150–300 hPa altitude (flight corridor), the vertical and latitudinal structure of NOx-induced ozone and H2O effects are well represented by the ACCF model output. The NOx-induced methane effects increase towards lower altitudes and higher latitudes, which behaves differently from the existing literature. For contrail cirrus, the climatological pattern of the ACCF model output corresponds with the literature, except that contrail-cirrus aCCF generates values at low altitudes near polar regions, which is caused by the conditions set up for contrail formation. Secondly, we evaluate the reduction of NOx-induced ozone effects through trajectory optimization, employing the tagging chemistry approach (contribution approach to tag species according to their emission categories and to inherit these tags to other species during the subsequent chemical reactions). The simulation results show that climate-optimized trajectories reduce the radiative forcing contribution from aviation NOx-induced ozone compared to cost-optimized trajectories. Finally, we couple the ACCF 1.0 to the air traffic simulation submodel AirTraf version 2.0 and demonstrate the variability of the flight trajectories when the efficacy of individual effects is considered. Based on the 1 d simulation results of a subset of European flights, the total ATR20 of the climate-optimized flights is significantly lower (roughly 50 % less) than that of the cost-optimized flights, with the most considerable contribution from contrail cirrus. The CO2 contribution observed in this study is low compared with the non-CO2 effects, which requires further diagnosis.
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[...]it is often argued—as by Yifei Li and Judith Shapiro, for example—that China's dictatorship should be an advantage in this context: ‘Given the limited time that remains to mitigate climate change and protect millions of species from extinction, we need to consider whether a green authoritarianism can show us the way' (Li and Shapiro 2020, quoted from the publisher's book description). Since CCP bosses do not have to contend with public hearings, environmental studies, recalcitrant legislatures, labour unions, a critical press, and so on, Xi should be able to force state-owned polluters to stop polluting or else, and ram through his promised transition to renewable energy (see Smith 2017, 2020c). Climate Action Tracker estimates that in 2021 China's emissions increased by 3.4 per cent to 14.1 gigatonnes of carbon dioxide equivalent (GtCO2e)—nearly triple those of the United States (4.9 GtCO2e) with a gross domestic product just three-fourths as large (CAT n.d.;EIA 2022). Since 2019, China's emissions have exceeded those of all developed countries combined and presently account for 33 per cent of total global emissions (Larsen et al. 2021;IEA 2021). In the first half of 2021, rebounding from the first wave of Covid-19, China's carbon dioxide emissions surged past pre-pandemic levels to reach an all-time high 20 per cent increase in the second quarter before dropping back in late 2021 and the first half of 2022 as the real estate collapse, Omicron lockdowns, and drought-induced hydropower reductions slashed economic growth to near zero in the summer (Hancock 2021;Myllyvirta 2022a;Riordan and Hook 2022). China promised to stop building coal-fired power plants abroad, but it is building more than 200 new coal-fired plants at home in a drive to boost economic growth, maintain jobs in coal-dependent regions, and ensure energy self-sufficiency—locking the country into coal reliance for many decades to come, derailing the transition to renewables, and dooming Xi's UN pledge to transition to a green and low-carbon mode of development (Xie 2020).
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Objectives: We sought to evaluate 2-year outcome of V-V ECMO support for COVID-19 related severe respiratory failure in our center. Method(s): Retrospective analysis of 41 consecutive patients (73% male, mean age 51.6+/-14.2 years, mean BMI 35.1+/-12.5 kg/m2) with critical hypoxemic and/or hypercapnic refractory respiratory failure (mean P/F ratio 67.9+/-14.3 mmHg, mean pCO2 77.6.0+/-185.7 mmHg, Murray Score 3.71+/-0.4) on V-V ECMO support from October 2020 to January 2022 Results: With mean support duration of 234.4+/-63.2 hours, 29 patients (70.7%) were successfully weaned off. Finally, 19 of them (46.3%) were discharged home with good neurological outcome (CPC 1,2). During followup, 30-day, 6-, 12-, and 24 -month survival rate was 61.3%, 46.2%, 41.9%, and 41,9% respectively. In survivor group shorter symptoms onset to respiratory failure time (4+/-4.7 vs. 7+/-6.7 days, p=0.04), higher P/F ration (86+/-41.5 vs. 65+/-37.5 mmHg, p=0.04) and norepinephrine support (0.03+/-0.06 vs. 0.09+/-0.12 ug/kg/min, p=0.04), and lower IL-6 level (12.3+/-7.5 vs. 25.9+/-8.8 ng/l, p=0.03) p=0.01) were analysed before cannulation. Mean in-ICU stay and in-hospital stay in survivors;groups reached 32.5+/-27.7 days and 42.6+/-35.8 days, respectively. All long-term survivors (17 patients) complained about slight functional health limitation only with normal 6MWT (542.6+/- 89.2 min), near to normal spirometry parameters (FEV/VC 87+/-7.4%, DLCO 63.1+/-13.7%, KCO 82.,1+/-19.4%) and minimal neurological disability (CPC 1-2) Conclusion(s): 2-year outcome of V-V ECMO support in COVID-19 severe respiratory failure is acceptable even in the scope of low-volume ECMO centre. Reported functional status of long-term survivors was good despite the complicated and prolonged in-hospital stay. (Table Presented).
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BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has created severe medical and economic consequences worldwide since 2019. Tocilizumab is one of the therapies considered capable of improving the condition of patients with COVID-19. However, there is not much information about the best time to give tocilizumab. METHOD(S): This was an analytical study with a retrospective cohort design, using the data of 125 patients infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with signs of acute respiratory distress syndrome in Dr. Moewardi Hospital, Surakarta, from March to August 2020. We analyzed various available clinical data to see which factors into clinical improvement with tocilizumab therapy. RESULT(S): Most patients showed clinical improvement after administration of tocilizumab. During the follow-up period, 21 patients died despite tocilizumab therapy. Significant risk factors associated with the need for intubation were heart rate, neutrophil, lymphocyte, pH, PaCO2, and PO2. The most influential variable on the need for intubation without being associated with other risk factors was PaO2 (p = 0.003, Confidence Intervals 95%). CONCLUSION(S): Tocilizumab has a role in treating patients infected by SARS-CoV-2, preventing the need for intubation when given to patients in good saturation condition with oxygen supplementation without positive pressure (PaO2 >65mmHg;SpO2 >93%).Copyright © 2023 Septian Adi Permana, Adhrie Sugiarto, Sidharta Kusuma Manggala, Muhammad Husni Thamrin, Purwoko Purwoko, Handayu Ganitafuri.
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Objectives: Unfractionated heparin (UFH) remains the anticoagulation of choice at most centres for patients receiving extracorporeal membrane oxygenation (ECMO). One disadvantage of UFH relies on its individual dosing requirement to achieve target values. In this context heparin resistance has been described, defined as doses exceeding 35,000 IU UFH/d. However, the incidence of heparin resistance and its association with thromboembolic complications despite anticoagulation within target ranges remains unknown. Method(s): This retrospective study included adults receiving venovenous (VV) and venoarterial (VA) ECMO, or extracorporeal CO2-removal (ECCO2R) between 2010 and May 2022. The primary outcome was the incidence of heparin resistance (>35,000 IU of UFH/d). Secondary outcomes were heparin failure (thromboembolic complications despite anticoagulation within target ranges) and survival. A multivariable poisson regression model was fitted to analyse the effect of heparin resistance, COVID-19 and ECMO type on the incidence rate of thromboembolic events. Result(s): Of 197 included patients, 33 (16.8%) had heparin resistance. Patients with COVID-19 (n=51) had a higher rate of heparin resistance compared to nonCOVID-19 patients (37% vs. 9.6%, P<0.001). Thromboembolic complications occurred at a rate of 5.89/100 ECMO days. There was a significant effect of COVID-19 (incidence rate ratio (IRR) 2.12, 95% confidence interval (CI) 1.4 to 3.3, P<0.001) and ECMO type (VA ECMO: IRR 2.35;95% CI 1.43 to 3.87, P<0.001;ECCO2R: IRR 2.63, 95% CI 1.37 to 4.9, P=0.003;reference VV ECMO) on incidence rate of thromboembolic events, but not of heparin resistance (IRR 1.11, 95% CI 0.7 to 1.76, P=0.7). ECMO duration was longer (25d (IQR 11-33) vs. 8d (IQR 4-18), P<0.001) in patients with heparin resistance, but hospital survival did not differ (23 (70%) vs. 91 (57%), P=0.2). Conclusion(s): The study revealed a high incidence of heparin failure in ECMO patients, especially in those with COVID-19. Heparin resistance had no effect on the incidence rate of thromboembolic events, whereas our data suggest an increased risk in patients with COVID19, VA ECMO and ECCO2R.
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Telemedicine is a modality which utilizes technology to provide and support health care across large distances. It has redefined the practices of medicine in many specialties and continues to be a boon for clinicians on many frontiers. Its role in the branch of anesthesia remains largely unexplored but has shown to be beneficial in all the three phases: pre-operative, intra-operative, and post-operative. Now time has come that anesthesiologists across the globe reassess their strategies and utilize the telemedicine facilities in the field of anesthesia.Copyright © 2021 EDP Sciences. All rights reserved.
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The COVID‐19 pandemic resulted in a widespread lockdown during the spring of 2020. Measurements collected on a light rail system in the Salt Lake Valley (SLV), combined with observations from the Utah Urban Carbon Dioxide Network observed a notable decrease in urban CO2 concentrations during the spring of 2020 relative to previous years. These decreases coincided with a ∼30% reduction in average traffic volume. CO2 measurements across the SLV were used within a Bayesian inverse model to spatially allocate anthropogenic emission reductions for the first COVID‐19 lockdown. The inverse model was first used to constrain anthropogenic emissions for the previous year (2019) to provide the best possible estimate of emissions for 2020, before accounting for emission reductions observed during the COVID‐19 lockdown. The posterior emissions for 2019 were then used as the prior emission estimate for the 2020 COVID‐19 lockdown analysis. Results from the inverse analysis suggest that the SLV observed a 20% decrease in afternoon CO2 emissions from March to April 2020 (−90.5 tC hr−1). The largest reductions in CO2 emissions were centered over the northern part of the valley (downtown Salt Lake City), near major roadways, and potentially at industrial point sources. These results demonstrate that CO2 monitoring networks can track reductions in CO2 emissions even in medium‐sized cities like Salt Lake City.Alternate :Plain Language SummaryHigh‐density measurements of CO2 were combined with a statistical model to estimate emission reductions across Salt Lake City during the COVID‐19 lockdown. Reduced traffic throughout the COVID‐19 lockdown was likely the primary driver behind lower CO2 emissions in Salt Lake City. There was also evidence that industrial‐based emission sources may of had an observable decrease in CO2 emissions during the lockdown. Finally, this analysis suggests that high‐density CO2 monitoring networks could be used to track progress toward decarbonization in the future.
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The collection and distribution network of ports is the main cause of carbon emissions. The carbon peak is a basic policy in China, and the subsidy policy is one of the common measures used by the government to incentivize carbon reduction. We analyzed the transportation methods and the flow direction of a port and proposed a carbon emission calculation method based on emission factors. Based on the transportation time and the cost, a generalized transportation utility function was constructed, and the logit model was used to analyze the impacts of subsidy policies on transportation, thus calculating the effects of the subsidies on carbon reduction. We used Guangzhou Port as a case study, and calculated the carbon reduction effects in six different subsidy policy scenarios and concluded that the absolute carbon reduction value was proportional to the subsidy intensity. In addition, we constructed a subsidy carbon reduction efficiency index and found that the Guangzhou Port collection and distribution network had higher subsidy carbon reduction efficiency in low-subsidy scenarios. Finally, a sensitivity analysis was conducted on the subsidy parameters, and scenario 8 was found to have the highest subsidy carbon reduction efficiency. This achievement can provide decision support for the carbon emission strategy of the port collection and distribution network.
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When it comes to supplying oxygen, current standard hospitals in Iran have proven inadequate in the face of the COVID-19 pandemic, particularly during infection peaks. Power disruptions drastically reduce the oxygen pressure in hospitals, putting patients' health at risk. The present study is the first to attempt to power an oxygen concentrator with a solar-energy-based system. The HOMER 2.81 package was used for technical–economic–environmental–energy analysis. The most notable aspects of this work include evaluating different available solar trackers, using up-to-date equipment price data and up-to-date inflation rate, considering the temperature effects on solar cell performance, sensitivity analysis for the best scenario, considering pollution penalties, and using a three-time tariff system with price incentives for renewable power. The study has been carried out at Hajar Hospital, Shahrekord, Chaharmahal and Bakhtiari Province, Iran. The study showed that, by supplying 60% of the power demand, the dual-axis solar tracking system offered the highest annual power output (47,478 kWh). Furthermore, generating power at—$0.008/kWh due to selling power to the grid, the vertical-axis tracker was found to be the most economical design. Comparing the configuration with a vertical-axis tracker with the conventional scenario (relying on the power distribution grid), the investment is estimated to be recovered in three years with $234,300 in savings by the end of the 25th year. In the best economic scenario, 6137 kg CO2 is produced, and the analysis revealed the negative impact of a temperature rise on the performance and solar power output.
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Objectives: The effectiveness of prone positioning (PP) under VV-ECMO for severe COVID-19 still be unclear. Until now, PP under VV-ECMO was often performed as the trump card for refractory hypoxemia and weaning off ECMO. On the other hand, PP has the effect of promoting homogenization of Lung aeration and leading to prevention of VILI. Combine use of early prone positioning together VV-ECMO may have synergy effects of ultra-lung protective strategy. In this study, we analyzed early PP cases under VV-ECMO for severe COVID-19 in our hospital and examined their efficacy and feasibility. Method(s): We performed a retrospective study of patients with SARS-CoV-2-induced ARDS submitted to early PP during VV-ECMO. During VVECMO, PP was considered in case of "Type-H transition in imaging findings (CT / LUS) " and cases that the physician deemed necessary. The lung aeration is evaluated by LUS before and after each PP. If there is a finding that the dorsal collapsed lung is improved through PP, it is implemented as effective, and it continued. Result(s): From April 2021 to August 2021, there were a total of 10 early PP cases under ECMO, and the age was (average) 56 years. ECMO was implanted with P/F 98 and Murray score 3.3 points, and PP was started 14 hours after the ECMO implantation. The average PP duration is 17.4 hours and PP performed 5.8 times per patient. Comparing blood gas and respiratory mechanics before and after PP showed a significant difference in PaCO2 (before: 46 +/- 8 vs after: 42 +/- 9, p = 0.02). Finally, there were 10 ECMO successful weaning (100%) and 8 surviving discharges (80%). No major complications were observed. Conclusion(s): Early PP under VV-ECMO for severe COVID-19 can be safely performed, and it is suggested that the synergy effect of ultra-lung protective strategy may be associated with a reduction of hospital mortality.
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Aim: While recent evidence describes atypical outcomes of coronavirus disease 2019 (COVID-19) in elderly patients, the frequency of delirium and associated outcomes in elderly patients with COVID-19 (coronavirus disease 2019) infection undergoing emergency surgery are not well defined. This study aims to determine the effect of COVID-19 on postoperative delirium and postoperative death in elderly patients undergoing emergency surgery. Material(s) and Method(s): This descriptive and cross-sectional study was conducted in general surgery, orthopedics, and cardiovascular surgery clinics of a public hospital, including 30 days of follow-up between April 1 and May 1, 2021. All patients who were admitted to these clinics for emergency surgery intervention on these dates constituted the study population, while a total of 140 patients aged >=65 years, who met the study criteria, formed the sample of the study. Descriptive Characteristics Form and Nursing Delirium Screening Scale (Nu-DESC) were used as data collection tools in the study. SPSS 25.0 statistical program was used for data analysis. Result(s): Thirty (42.85%) of the SARS-CoV-2 positive (n=70) patients developed delirium in the study. 12.9% (n=18) of the patients died within 30 days of follow-up after surgery. There were 30 (69.8) of 70 SARS-CoV-2 positive patients who developed delirium, and 12 patients (25.5) died after testing positive for COVID-19, with a mean of 8.08T1.56 days within 30 days of admission. Discussion(s): These findings may lead to a poor clinical prognosis for COVID-19 infection delirium and postoperative death in patients over 65 years of age undergoing emergency surgery.Copyright © 2023, Derman Medical Publishing. All rights reserved.
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The outbreak of the recent Covid-19 pandemic changed many aspects of our daily life, such as the constant wearing of face masks as protection from virus transmission risks. Furthermore, it exposed the healthcare system's fragilities, showing the urgent need to design a more inclusive model that takes into account possible future emergencies, together with population's aging and new severe pathologies. In this framework, face masks can be both a physical barrier against viruses and, at the same time, a telemedical diagnostic tool. In this paper, we propose a low-cost, 3D-printed face mask able to protect the wearer from virus transmission, thanks to internal FFP2 filters, and to monitor the air quality (temperature, humidity, CO2) inside the mask. Acquired data are automatically transmitted to a web terminal, thanks to sensors and electronics embedded in the mask. Our preliminary results encourage more efforts in these regards, towards rapid, inexpensive and smart ways to integrate more sensors into the mask's breathing zone in order to use the patient's breath as a fingerprint for various diseases. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.
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Background: At our hospital, people with COVID-19 (coronavirus disease 2019) had a high rate of pulmonary barotrauma. Therefore, the current study looked at barotrauma in COVID-19 patients getting invasive and non-invasive positive pressure ventilation to assess its prevalence, clinical results, and features. Methodology: Our retrospective cohort study comprised of adult COVID-19 pneumonia patients who visited our tertiary care hospital between April 2020 and September 2021 and developed barotrauma. Result(s): Sixty-eight patients were included in this study. Subcutaneous emphysema was the most frequent type of barotrauma, reported at 67.6%;pneumomediastinum, reported at 61.8%;pneumothorax, reported at 47.1%. The most frequent device associated with barotrauma was CPAP (51.5%). Among the 68 patients, 27.9% were discharged without supplemental oxygen, while 4.4% were discharged on oxygen. 76.5% of the patients expired because of COVID pneumonia and its complications. In addition, 38.2% of the patients required invasive mechanical breathing, and 77.9% of the patients were admitted to the ICU. Conclusion(s): Barotrauma in COVID-19 can pose a serious risk factor leading to mortality. Also, using CPAP was linked to a higher risk of barotrauma.Copyright © 2021 Muslim OT et al.
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Background: We reviewed patients with COVID-19 ARDS managed with VV-ECMO support at our center from March 2020 until February 2022. Material(s) and Method(s): We extracted data from electronic health records (Metavision and DIPS). We registered premorbid health status, ventilator-settings before initiation of ECMO, the time-course, and hospital mortality. Result(s): Thirty patients were managed at our hospital, with a median age of 57.2 years (28-65) and median BMI 28 (22-40). No patient had any serious comorbidity. Twenty-two patients received non-invasive ventilation prior to intubation (1-10 days). The median time on ventilator were 8.0 days (1-19) prior to ECMO and median tidal volume was 5.8 mL/kg PBW (3.1-7.5). Hypoxemia (median PaO2-FiO2 ratio 8 kPa, range 6-12 kPa) and hypercapnia (median PaCO2 11.9 kPa, range 4.2-18.5) [SEP1] despite lung protective ventilation were the main indications for VV-ECMO. Two patients had severe respiratory acidosis without hypoxemia. 18 patients developed serious complications while managed with ECMO (acute renal failure, clinically significant bleeding, sepsis, right ventricular heart failure, dislocation of cannulae). Seven patients received renal replacement therapy. Sixteen patients (53%) died. Thirteen patients (43%) died on ECMO, three (10%) after weaning, Twelve (40%) were discharged from hospital, two are currently in ICU (7%). The median duration of ECMO and ventilator treatment, was 27 (6-50) and 37 (9-78) days, respectively. Conclusion(s): Management of patients with COVID-19 ARDS with VV-ECMO is very resource-intensive, and accompanied by serious complications and high mortality. In-hospital mortality in our cohort was 53%, which is comparable with reports from other centers. However, the duration of ECMO, and pre-ECMO mechanical ventilation, were longer than typically reported.
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This exploratory study evaluated the risk of contagion from airborne diseases, such as coronaviruses, in schools. For three days, the concentration of carbon dioxide in two university classrooms was monitored for 90 minutes, while the students took their math classes. We use these values to validate a first-order model for carbon dioxide concentration and calculate the air exchange rate indirectly (avoiding the need for expensive measurement equipment). The air exchange rate obtained allowed us to assess whether the usual ventilation systems (both natural and mechanical) are sufficient to guarantee a low risk of contagion of aerosols due to respiration. The results show that the risk of contagion is low if three factors are considered: the level of conversation within the classroom, the usage of a moisture extraction system, and the lecture duration. The risk is low if the lecture time is less than 50 minutes, the level of conversation is moderate, and a moisture extraction system is available. If these conditions are not met the risk is considerably higher even if mechanical ventilation is employed.
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Introduction: Since the advent of Covid, oxygen has been the centre of discussion despite being the most important entity for the survival of human life. As various modes of its delivery has been in practice for a long time, using the non-rebreather mask has been a part of most guidelines for emergencies and hypoxia. This requires a higher flowrate of up to 15 l/min. Most flowmeters can deliver upto 75 l/min over the maximum calibrated mark.1 What may appear as a small rise from the maximum labelled mark can deliver more oxygen than required and result in wastage of oxygen or hide the severity of the patient's condition. Using this audit/ QIP we are trying to determine if the flowrates delivered are as per the prescription/protocol. Aim(s): To find out if the oxygen administration when it is prescribed at 15L/min is at the prescribed value and therefore quantify the amount of oxygen that is being wasted. Method(s): Data was collected randomly, observing the flow rates that the patients were receiving as prescribed or over the prescribed rate for those on non rebreather mask. Result(s): 54 observations were recorded from ED, ITU, AMU and theatre recovery across two hospitals. It was found that 57.4% of the patients were on flowrates more than the prescribed value. Conclusion & Discussion: More than half the patients requiring high flow rate of oxygen were on rates more than prescribed. This is potentially due to the lack of understanding of the calibration of the flowmeter. This results in the wastage of oxygen causing significant financial loss and an increase in the carbon dioxide emission impacting the environmental pollution. We plan to run an educational intervention for staff in these departments to emphasise the importance of administering drugs (including oxygen) as they are prescribed, and how easy it is to over administer oxygen.
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Developing a sustainable and reliable photovoltaic (PV) energy system requires a comprehensive analysis of solar profiles and an accurate prediction of solar energy performance at the study site. Installing the PV modules with optimal tilt and azimuth angles has a significant impact on the total irradiance delivered to the PV modules. This paper proposes a comprehensive optimization model to integrate total irradiance models with the PV temperature model to find the optimal year-round installation parameters of PV modules. A novel integration between installation parameters and the annual average solar energy is presented, to produce the maximum energy output. The results suggest an increase in energy yields of 4% compared to the conventional scheme, where tilt angle is equal to the latitude and the PV modules are facing south. This paper uses a real-time dataset for the NEOM region in Saudi Arabia to validate the superiority of the proposed model compared to the conventional scheme, but it can be implemented as a scheme wherever real-time data are available.
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The COVID-19 pandemic prompted several nations, including China, to enact unprecedented lockdown measures, leading to significant alterations in environmental conditions. Previous studies have solely analysed the impact of lockdown measures on air pollutants or carbon dioxide (CO2) emissions during the COVID-19 pandemic in China, but few have focused on the spatio-temporal change characteristics and synergistic effects between the two. In this study, we constructed a methodological framework to examine the spatiotemporal characteristics and co-effects of air quality (PM2.5, SO2, and NO2) and CO2 changes in 324 prefecture-level cities in China due to the COVID-19 blockade measures from January 24 to April 30, 2020, using the regression discontinuity in time method and co-effect control coordinate system. The results show that a significant improvement in air quality and CO2 emissions during the lockdown period, with notable northâsouth heterogeneity. During the major lockdown period (January 24 to February 29), the measures resulted in respective reductions of 5.6%, 16.6%, and 25.1% in the concentrations of SO2, NO2, and CO2 nationwide. The proportions of cities with negative treatment effects on PM2.5, SO2, NO2, and CO2 were 39.20%, 70.99%, 84.6%, and 99.38%, respectively. Provinces where concentrations of CO2 and NO2 declined by over 30% were primarily concentrated in southern areas of the 'Yangtze River Defense Line'. Starting from March, the improvement effect of air quality and CO2 has weakened, and the concentration of air pollutants has rebounded. This study offers crucial insights into the causal effects of lockdown measures on air quality changes, and reveals the synergy between air quality and CO2, thereby providing a reference for devising effective air quality improvement and energy-saving emission reduction strategies.
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Ventilation performance plays a significant role in distributing contaminants and airborne infections indoors. Thus, poorly ventilated public spaces may be at high risk due to the presence of both infectious and susceptible people. Adapting HVAC ventilation systems to mitigate virus transmission requires considering ventilation rate, airflow patterns, air balancing, occupancy, and feature placement. The study aims to identify poorly ventilated spaces where airborne transmission of pathogens such as SARS-CoV-2 could be critical. This study is focused on evaluating the ventilation performance of the building stock and the safety of using the facilities based on measured indoor CO2. The results revealed the spaces with the potential risk of indoor airborne transmission of COVID-19. The study proposes recommendations for utilising air ventilation systems in different use cases. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.
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The ongoing COVID-19 pandemic has caused millions of deaths worldwide along with detrimental socioeconomic consequences. Existing evidence suggests that the rate of indoor transmission is directly linked with the Indoor Air Quality (IAQ) conditions. Most of the existing methodologies for virus transmissibility risk estimation are based on the well-known Wells-Riley equation and assume well-mixed, uniform conditions;so spatiotemporal variations within the indoor space are not captured. In this work, a novel fine-grained methodology for real-time virus transmission risk estimation is developed using a 3D model of a real office room with 31 occupants. CONTAM-CFD0 software is used to compute the airflow vectors and the resulting 3D CO2 concentration map (attributed to the exhalations from the occupants). Simulation results are also provided that demonstrate the efficacy of using CO2 sensors for estimating the infection risk in real-time in the 3D office environment. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.