High Ventilation Rates Research Articles

Silica coated insect proof screens for effective insect control in greenhouses

Insect proof screens were coated with silica (SiO 2 ) nanoparticles using the plasma coating process. The work studied whether a screen coated by SiO 2 nanoparticles could be more effective on insects' control than a non-coated screen. Thus, the insect control properties of 25- and 40-mesh screens were studied. Besides, a series of experiments were performed to investigate the mechanical, optical, and airflow properties of different (25, 40, and 50) mesh screens coated or not with SiO 2 nanoparticles. The air permeability of the screens was affected, while the mechanical and optical properties of the screens were not significantly affected by the SiO 2 coating. Compared to 40- and 50-mesh non-coated screens, a 25-mesh SiO 2 -coated screen had 54% and 66% higher air permeability values, respectively. The mean number of aphids infesting the leaves and stems of the crop grown under a 25- or a 40-mesh SiO 2 -coated screen was up to 93% and 81% lower than those grown under the non-coated screens, respectively. The number of aphids found on plants grown under a 25-mesh SiO 2 -coated screen were significantly lower (about 80%) than those recorded under a 40-mesh non-coated screen. Based on the differences observed on screen's air permeability and on greenhouse ventilation models available in the literature, it was estimated that a greenhouse with a 25-mesh SiO 2 -coated screen will have 11.5% and 23.1% higher ventilation rate than a greenhouse with a 40- or 50-mesh non-coated screen, respectively. • Insect proof screens were coated with SiO 2 nanoparticles using plasma coating process. • SiO 2 coating slightly affected the optical and mechanical properties of screens. • Use of SiO 2 coated screens decreased 80% the population of aphids in the greenhouse. • A 25 mesh SiO 2 coated screen was very effective on insects' control. • A 25 mesh SiO 2 coated screen has higher air permeability than a 40 mesh non-coated.

A critical evaluation of the dynamic nature of indoor-outdoor air quality ratios

Long term, continuous indoor and outdoor pollutant monitoring was evaluated from a case study hospital, school, office and 18 apartments in the UK. Data was examined in order to explore the dynamic behaviour of indoor-outdoor ratios (I/O) for both particulate matter and nitrogen dioxide. Traditionally I/O ratios have been determined as single aggregate values or static parameters, from passive sampling or short periods of continuous monitoring. Whilst widely reported, I/O ratios are seen as too variable to be of wider use. However, this work reveals the dynamic nature of I/O ratios, with strong diurnal and seasonal variation observed for both particulate matter and nitrogen dioxide. Higher I/O ratios tended to be seen during core or occupied hours, associated with increased human activity and higher ventilation rates. This means that static I/O ratios determined by passive sampling techniques, rather than continuous measurements filtered to core hours, may underestimate I/O ratios associated with occupant exposure. Further, the I/O ratio is shown to be strongly influenced by occupant activity and window opening behaviour. As such, it may represent a personal variable as much as one associated with a building. It is argued that traditionally reported static I/O ratios simplify these dynamic behaviour and modes of operation into a single aggregate value, losing key information in the process. Further, without contextual information on the operation and use of a building during measurements a reported I/O ratio may be hard to interpret or compare to wider studies. Finally, it is argued that the I/O ratio, whilst a limited metric, when evaluated dynamically provides a useful building operation parameter, describing the relationship the building has with the outdoor environment. This can help better define ventilation strategies, schedules, the influence of occupant behaviour and significance of indoor sources.

Predicting transient particle transport in periodic ventilation using Markov chain model with pre-stored transition probabilities

Periodic ventilation has been proposed for effectively removal of air contaminants in indoor environments. To facilitate the design of periodic ventilation, it is essential to predict the transient particle transport. Compared with traditional models, the Markov chain model is faster as it does not require iteration in each time step. However, for unsteady airflow, since the transient transition probabilities need to be updated in each time step, the potential of the Markov chain model in terms of computing speed has been significantly limited. This study developed an improved Markov chain model with pre-stored transition probabilities to reduce the computing cost for predicting transient particle transport under periodic ventilation. The proposed model was validated with experimental data from chamber tests. The validated model was then used to investigate the particle removal performance of periodic ventilation under different conditions. The results show that the periodic ventilation removed particles more effectively than steady ventilation, especially under a high ventilation rate and when the particle source was located in the recirculation zone. Furthermore, the supply-air period and mode had little impact on particle removal. Finally, the computing costs for the two Markov chain models were compared. For the case with six supply-air periods investigated in this study, the pre-storage Markov chain model was 4.8 times faster than the existing Markov chain model. Furthermore, the computing cost ratio of the pre-storage model to the existing model decreased with the product of period and source number.

Evaluating the Environmental Performance of 3D Printed Shelters in Jordan

Three-dimensional (3D) printed shelters are an innovative housing solution for those in need of a shelter after a disaster. The Middle East generated a huge number of refugees due to internal conflicts. The technology has been investigated earlier from a cost and time perspectives and has performed better than steel shelters in Jordan. This research article investigates environmental performance of 3D printed shelters in Jordan in terms of energy, fuel, cooling and ventilation. Syrian refugees of Jordanian camps were selected as a case study. The energy simulation of the steel shelter to that of a printed shelter showed that the latter can achieve higher ventilation rates, lower energy consumption, less electricity cost and better thermal insulation than steel shelters.

The nexus between in-car aerosol concentrations, ventilation and the risk of respiratory infection.

We examined the trade-offs between in-car aerosol concentrations, ventilation and respiratory infection transmission under three ventilation settings: windows open (WO); windows closed with air-conditioning on ambient air mode (WC-AA); and windows closed with air-conditioning on recirculation (WC-RC). Forty-five runs, covering a total of 324km distance on a 7.2-km looped route, were carried out three times a day (morning, afternoon, evening) to monitor aerosols (PM2.5; particulate matter<2.5μm and PNC; particle number concentration), CO2 and environmental conditions (temperature and relative humidity). Ideally, higher ventilation rates would give lower in-car pollutant concentrations due to dilution from outdoor air. However, in-car aerosol concentrations increased with ventilation (WO>WC-AA>WC-RC) due to the ingress of polluted outdoor air on urban routes. A clear trade-off, therefore, exists for the in-car air quality (icAQ) versus ventilation; for example, WC-RC showed the least aerosol concentrations (i.e. four-times lower compared with WO), but corresponded to elevated CO2 levels (i.e. five-times higher compared with WO) in 20 mins. We considered COVID-19 as an example of respiratory infection transmission. The probability of its transmission from an infected occupant in a five-seater car was estimated during different quanta generation rates (2-60.5 quanta hr-1) using the Wells-Riley model. In WO, the probability with 50%-efficient and without facemasks under normal speaking (9.4 quanta hr-1) varied only by upto 0.5%. It increased by 2-fold in WC-AA (<1.1%) and 10-fold in WC-RC (<5.2%) during a 20 mins trip. Therefore, a wise selection of ventilation settings is needed to balance in-car exposure in urban areas affected by outdoor air pollution and that by COVID-19 transmission. We also successfully developed and assessed the feasibility of using sensor units in static and dynamic environments to monitor icAQ and potentially infer COVID-19 transmission. Further research is required to develop automatic-alarm systems to help reduce both pollutant exposure and infection from respiratory COVID-19 transmission.

Fighting the pandemic with collaboration at heart: Report from cardiologists in a COVID-19-dedicated Portuguese intensive care unit.

Introduction and objectivesThe coronavirus disease 2019 (COVID-19) spread quickly around the world. Although mainly a respiratory illness, there is growing interest in non-respiratory manifestations, particularly cardiovascular ones. At our center, mobilization of cardiologists with intensive care training was needed. Our aim is to describe patients with severe COVID-19 admitted to a Portuguese intensive care unit (ICU), the cardiovascular impact of the disease and the experience of cardiologists working in a COVID-19 ICU.MethodsData from adult patients with COVID-19 admitted to the ICU of Centro Hospitalar de Vila Nova de Gaia/Espinho between 16 March 2020 and 21 April 2020 were analyzed retrospectively.ResultsThirty-five patients were admitted. Mean age was 62.6±6.0 years and 23 (65.7%) were male. Dyslipidemia was the most common cardiovascular risk factor (65.7%, n=23), followed by hypertension (57.1%, n=20). Mean ICU stay time was 15.9±10.0 days. Patients had high rates of mechanical ventilation (88.6%, n=31) and vasopressor support (88.6%, n=31). Low rates of new onset left systolic dysfunction were detected (8.5%, n=2). One patient required venoarterial extra-corporeal membrane oxygenation. Mortality was 25% (n=9). Acute myocardial injury and N-terminal pro-B-type natriuretic peptide (NT-proBNP) elevation was detected in 62.9% (n=22). Patients that died had higher NT-proBNP compared to those discharged alive (p<0.05). Care by cardiologists frequently changed decision making.ConclusionsThe cardiovascular impact of COVID-19 seems relevant but is still widely unknown. Studies are needed to clarify the role of cardiac markers in COVID-19 prognosis. Multidisciplinary care most likely results in improved patient care.

Use of High-Rate Ventilation Results in Enhanced Recellularization of Bioengineered Lung Scaffolds.

While transplantation is a viable treatment option for end-stage lung diseases, this option is highly constrained by the availability of organs and postoperative complications. A potential solution is the use of bioengineered lungs generated from repopulated acellular scaffolds. Effective recellularization, however, remains a challenge. In this proof-of-concept study, mice lung scaffolds were decellurized and recellurized using human bronchial epithelial cells (BEAS2B). We present a novel liquid ventilation protocol enabling control over tidal volume and high rates of ventilation. The use of a physiological tidal volume (300 μL) for mice and a higher ventilation rate (40 breaths per minute vs. 1 breath per minute) resulted in higher cell numbers and enhanced cell surface coverage in mouse lung scaffolds as determined via histological evaluation, genomic polymerase chain reaction (PCR) analysis, and immunohistochemistry. A biomimetic lung bioreactor system was designed to include the new ventilation protocol and allow for simultaneous vascular perfusion. We compared the lungs cultured in our dual system to lungs cultured with a bioreactor allowing vascular perfusion only and showed that our system significantly enhances cell numbers and surface coverage. In summary, our results demonstrate the importance of the physical environment and forces for lung recellularization. Impact statement New bioreactor systems are required to further enhance the regeneration process of bioengineered lungs. This proof-of-concept study describes a novel ventilation protocol that allows for control over ventilation parameters such as rate and tidal volume. Our data show that a higher rate of ventilation is correlated with higher cell numbers and increased surface coverage. We designed a new biomimetic bioreactor system that allows for ventilation and simultaneous perfusion. Compared to a traditional perfusion only system, recellularization was enhanced in lungs recellularized with our new biomimetic bioreactor.

Abstract 11488: Ventilation Rate and Sustained Return of Spontaneous Circulation in In-Hospital Cardiac Arrest: Is More Better?

Introduction: Current consensus holds that CPR must balance chest compressions and ventilation rate (VR), with a low VR being essential for venous return and cardiac output. AHA guidelines recommend a VR of 10 ventilations per minute (vpm) after advanced airway placement. We sought to examine VR adherence and its impact on end-tidal CO 2 (ETCO 2 ) and ROSC &gt;20 minutes. Methods: This is a retrospective analysis of data from AWARE II, a multicenter prospective observational study of adult in-hospital cardiac arrest (IHCA) outcomes at 14 US and UK sites. Inclusion criteria were: 1) adult patient in CA, 2) advanced airway already in place or placed during the CA, and 3) at least one minute of VR and ETCO 2 data available after removal of the last minute of CPR in subjects achieving ROSC (due to the rise of ETCO 2 just prior to ROSC). Results: A total of 563 subjects were enrolled in the parent study. Of these, 225 had ETCO 2 and VR tracings available, and 201 had sufficient data for inclusion. Mean age was 69.3 (range 18-100), patients were 63.7% male, and 16.4% had a shockable initial rhythm. A total of 116 subjects (57.7%) achieved ROSC, which was sustained in 76 (37.8%), leading to survival to hospital discharge with favorable neurological outcomes in 9 (4.5%). Mean VR was 16.3 vpm, with 171 (85.1%) subjects being ventilated in excess of guidelines; only 16 (8.0%) subjects received 8-10 vpm. Higher VR had a weak but significant association with increased mean ETCO 2 (linear R 2 = 0.11, p &lt; 1x10 -6 ) and sustained ROSC (OR 1.05; 95% CI: 1.01-1.11; p = 0.02). Patients with sustained ROSC had a significantly higher VR at 17.7 vpm than those without sustained ROSC at 15.6 vpm (p = 0.007). Patients receiving a VR close to AHA guidelines (6-12 vpm) had a significantly lower rate of sustained ROSC (26.1%, n = 46) than patients receiving &gt;12 vpm (42.0%, n = 148) (OR 2.30; 95% CI: 1.08-4.89; p = 0.031 using a multivariate model including patient age, shockable initial rhythm, known cardiac disease, witnessed IHCA, and use of mechanical compressions). Conclusions: VR within AHA guidelines is rare during IHCA. However, ventilation in excess of current guidelines may increase rates of sustained ROSC, an essential predicate to survival. AHA guidelines on VR in CPR with an advanced airway may not yet be optimized.

Abstract 13537: Mortality and Social Vulnerability in the COVID 19 Pandemic

Introduction: A disastrous disease, the COVID-19, continues its spread, this, coupled with its severity, led to a initial global lockdown. Early evidence identified Black counties where mortality risk was higher than in white counties, even more evident in Latin America. In Brazil, with multiple forms of social inequalities, where color/race takes high relevance in this debate, it is even more relevant in Rio de Janeiro. We aimed to analyze these socio economic factors and its correlation with COVID 19 mortality. Hypothesis: Patients hospitalized with COVID 19 with a high social vulnerable background would had greater in-hospital mortality Methods: Prospective study of 274 confirmed adult COVID 19 hospitalized patients in the UHCFF. Clinical features/blood chemistry information were obtained from the clinical record. Using the individual address, we correlated it with the Census Code Area (CCA), using a novel methodology, we geoprocessed each home on the Division map. Giving a high relevance to the socio-economic variables for inequity and vulnerability markers, also analyzing the fact to be transferred from another primary care institution, for its delay potential of advanced medical care. We performed a logistic regression, with in-hospital mortality as our primary outcome. Results: Patients living in low adequacy households(p=0.030) with high in-house individual agglomeration markers (p=0.017), and the fact to have been transferred from another primary care institution (p=0.047) presented high in-hospital mortality, with high ICU admission and Mechanical Ventilation rates. Conclusions: In hospital mortality due to COVID 19 was influenced by social individual background characteristics of vulnerability. Among other clinical parameters, these markers should be taken into account to predict the individual likelihood of complications related to the pandemic, prioritizing the attention and vaccination for those at higher risk should be paramount.

Barotrauma, invasive ventilation, and timing of tocilizumab as predictors of mortality along with inflammatory markers and comorbidities in critically ill COVID-19 patients: A retrospective study.

Barotrauma, invasive ventilation, and timing of tocilizumab as predictors of mortality along with inflammatory markers and comorbidities in critically ill COVID-19 patients: A retrospective study.

Reduced-scale experiments of heat transfer from integrated radiant ceiling panel and diffuse ceiling ventilation

• Reduced-scale experiments of perforated radiant ceiling with diffuse ventilation. • Cooling power increases with increased ventilation rates. • Mapping of heat transfer coefficients for different loads and ventilation rates. • Diffuse ventilation air is pre-heated or -cooled in the plenum by radiant ceiling. Thermal ceiling systems for heating and cooling has several solutions and methods. In this study, an integrated solution that combines a radiant ceiling panel with diffuse ventilation was investigated in a reduced-scale experiment. The purpose of the experiment was to map the heat transfer from the perforated radiant ceiling panel at different ventilation rates. The experiment was scaled for similitude in the plenum. The heat transfer coefficients were compared to the literature and a previous numerical study using Computational Fluid Dynamics. The heat transfer coefficients in the plenum were on par with both the compared literature and the CFD study. It was found that the internal heat gain in the room created a high radiative-to-convective ratio, and the results were most valid for the small values (14 W/m 2 ), where the heat transfer coefficient for cooling scenarios had an increase of 20% from no ventilation to high ventilation rate. The heating scenarios did not show a conclusive change. Although the experiments showed potential, the integrated solution should be investigated further in a full-scale experiment, as some of the uncertainties and differences could be caused by the reduced scale test setup.

Associations between acute exposures to PM2.5 and carbon dioxide indoors and cognitive function in office workers: a multicountry longitudinal prospective observational study

Despite evidence of the air pollution effects on cognitive function, little is known about the acute impact of indoor air pollution on cognitive function among the working-age population. We aimed to understand whether cognitive function was associated with real-time indoor concentrations of particulate matter (PM2.5) and carbon dioxide (CO2). We conducted a prospective observational longitudinal study among 302 office workers in urban commercial buildings located in six countries (China, India, Mexico, Thailand, the United States of America, and the United Kingdom). For 12 months, assessed cognitive function using the Stroop color-word test and addition–subtraction test (ADD) via a mobile research app. We found that higher PM2.5 and lower ventilation rates, as assessed by CO2 concentration, were associated with slower response times and reduced accuracy (fewer correct responses per minute) on the Stroop and ADD for eight out ten test metrics. Each interquartile (IQR) increase in PM2.5 (IQR = 8.8 g m−3) was associated with a 0.82% (95% CI: 0.42, 1.21) increase in Stroop response time, a 6.18% (95% CI: 2.08, 10.3) increase in Stroop interference time, a 0.7% (95% CI: −1.38, −0.01) decrease in Stroop throughput, and a 1.51% (95% CI: −2.65, −0.37) decrease in ADD throughput. For CO2, an IQR increase (IQR = 315 ppm) was associated with a 0.85% (95% CI: 0.32, 1.39) increase in Stroop response time, a 7.88% (95% CI: 2.08, 13.86) increase in Stroop interference time, a 1.32% (95% CI: −2.3, −0.38) decrease in Stroop throughput, and a 1.13% (95% CI: 0.18, 2.11) increase in ADD response time. A sensitivity analysis showed significant association between PM2.5 in four out of five cognitive test performance metrics only at levels above 12 g m−3. Enhanced filtration and higher ventilation rates that exceed current minimum targets are essential public health strategies that may improve employee productivity.

Impact of Air Pollution on High-Caliber Athletic Performance

BACKGROUND AND AIM: Athletes who regularly train and compete outdoors experience elevated levels of exposure to air pollutants due to high minute ventilation rates. While many sports committees use the US Environmental Protection Agency’s Air Quality Index (AQI) to monitor the safety of high pollution events, little is known about the effect of repeated exposure to lower levels of air pollution. To quantify the burden, we estimated the association between repeated exposure to particulate matter (PM2.5) and ozone and race performance of collegiate athletes using pollutant concentrations, two-pollutant (PM2.5 and ozone) version of the AQI, and a summed version of the AQI. METHODS: We aggregated data on 334 collegiate male track & field athletes from 46 universities across the United States during the years 2010-2014, comprising a total of 1,104 5-km meter race outcomes. Using distributed lag non-linear models (DLNMs), we analyzed the relationship between race performance and air pollution exposures 21 days prior to the race. We reported cumulative effect estimates for the change in average race time associated with increases in exposure from the 20th to 80th percentile. RESULTS:We observed a 12.8 (95% CI: 1.3, 24.2) second and 11.5 (95% CI: 0.8, 22.1) second increase in 5-km race times from 21 days of exposure to PM2.5 concentration (10.3 μg/m3 versus 4.9μg/m3) and ozone concentration (54.9ppm vs. 36.9ppm), respectively. Exposure measured by the two-pollutant AQI was not significantly associated with race time (95% CI: -5.23, 16.60); however, the association for summed two-pollutant AQI was similar to the associations for the individual pollutants (12.4 seconds, 95% CI: 1.8, 23.0). CONCLUSIONS:Training and competing at consistently higher levels of air pollution were associated with higher race times. This is a first step at identifying the association between pollution and running performance and a foundation for why coaches should consider approaches to reduce air pollution exposure. KEYWORDS: athletic performance, air pollution, particulate matter, ozone

Fighting the pandemic with collaboration at heart: Report from cardiologists in a COVID-19-dedicated Portuguese intensive care unit

Introduction and objectivesThe coronavirus disease 2019 (COVID-19) spread quickly around the world. Although mainly a respiratory illness, there is growing interest in non-respiratory manifestations, particularly cardiovascular ones. At our center, mobilization of cardiologists with intensive care training was needed. Our aim is to describe patients with severe COVID-19 admitted to a Portuguese intensive care unit (ICU), the cardiovascular impact of the disease and the experience of cardiologists working in a COVID-19 ICU. MethodsData from adult patients with COVID-19 admitted to the ICU of Centro Hospitalar de Vila Nova de Gaia/Espinho between 16 March 2020 and 21 April 2020 were analyzed retrospectively. ResultsThirty-five patients were admitted. Mean age was 62.6±6.0 years and 23 (65.7%) were male. Dyslipidemia was the most common cardiovascular risk factor (65.7%, n=23), followed by hypertension (57.1%, n=20). Mean ICU stay time was 15.9±10.0 days. Patients had high rates of mechanical ventilation (88.6%, n=31) and vasopressor support (88.6%, n=31). Low rates of new onset left systolic dysfunction were detected (8.5%, n=2). One patient required venoarterial extra-corporeal membrane oxygenation. Mortality was 25% (n=9). Acute myocardial injury and N-terminal pro-B-type natriuretic peptide (NT-proBNP) elevation was detected in 62.9% (n=22). Patients that died had higher NT-proBNP compared to those discharged alive (p<0.05). Care by cardiologists frequently changed decision making. ConclusionsThe cardiovascular impact of COVID-19 seems relevant but is still widely unknown. Studies are needed to clarify the role of cardiac markers in COVID-19 prognosis. Multidisciplinary care most likely results in improved patient care.

Optimal control of high-rise building mechanical ventilation system for achieving low risk of COVID-19 transmission and ventilative cooling.

As suggested by many guidelines, a high ventilation rate is required to dilute the indoor virus particles and reduce the airborne transmission risk, i.e., dilution ventilation (DV). However, high ventilation rates may result in high energy costs. Ventilative cooling (VC), which requires high ventilation rates like DV, is an option to reduce the cooling energy consumption. By combining DV and VC, this paper investigated the operation of the mechanical ventilation system in high-rise buildings during the COVID-19 pandemic, aiming to minimizing the cooling related energy consumption and reducing COVID-19 transmission. First, a modified Wells-Riley model was proposed to calculate DV rates. The ventilation rate required to achieve VC was also introduced. Then, a new ventilation control strategy was proposed for achieving DV and VC. Finally, a case study was conducted on a real high-rise building, where the required DV rate and the impact of the settings of the mechanical ventilation on the energy savings were evaluated. The results indicate that the required ventilation rates vary from 36 m3/s to 3306 m3/s depending on the protective measures. When the occupants follow the protective measures, the proper settings of the mechanical ventilation system can reduce energy consumption by around 40%.

The airborne contagiousness of respiratory viruses: A comparative analysis and implications for mitigation

The infectious emission rate is a fundamental input parameter for airborne transmission risk assessment, but data are limited due to reliance on estimates from chance superspreading events. This study assesses the strength of a predictive estimation approach developed by the authors for SARS-CoV-2 and uses novel estimates to compare the contagiousness of respiratory pathogens. We applied the approach to SARS-CoV-1, SARS-CoV-2, MERS, measles virus, adenovirus, rhinovirus, coxsackievirus, seasonal influenza virus and Mycobacterium tuberculosis (TB) and compared quanta emission rate (ERq) estimates to literature values. We calculated infection risk in a prototypical classroom and barracks to assess the relative ability of ventilation to mitigate airborne transmission. Our median standing and speaking ERq estimate for SARS-CoV-2 (2.7 quanta h−1) is similar to active, untreated TB (3.1 quanta h−1), higher than seasonal influenza (0.17 quanta h−1), and lower than measles virus (15 quanta h−1). We calculated event reproduction numbers above 1 for SARS-CoV-2, measles virus, and untreated TB in both the classroom and barracks for an activity level of standing and speaking at low, medium and high ventilation rates of 2.3, 6.6 and 14 L per second per person (L s–1 p–1), respectively. Our predictive ERq estimates are consistent with the range of values reported over decades of research. In congregate settings, current ventilation standards are unlikely to control the spread of viruses with upper quartile ERq values above 10 quanta h−1, such as SARS-CoV-2, indicating the need for additional control measures.

Field measurements on indoor air quality of a residential building in Xi'an under different ventilation modes in winter

In recent years, China is facing severe haze pollution in winter. More and more newly built residential buildings are installed with mechanical ventilation systems. In order to explore the system's application effect, this study selected a new typical residential building in Xi'an, China, and conducted a series of field measurements on indoor air quality (IAQ) under different ventilation modes. Several indoor pollutants including CO2, PM2.5, HCHO, TVOC, CO, and O3 were monitored. Four ventilation modes were considered including natural infiltration, window-opening ventilation, and two mechanical ventilation modes with low and high ventilation rates. The ventilation rates and IAQ under different ventilation modes were evaluated and compared. In order to better analyze the causes of some measurement results, numerical simulation was also employed to simulate the air distribution. The results showed that the measured values of the air change per hour of the four ventilation modes were about 0.2 h−1, 1.2 h−1, 2.15 h−1, 2.84 h−1, respectively. The indoor concentrations of HCHO, TVOC, CO, and O3 could all be controlled far below the Chinese limit under all ventilation modes. The indoor CO2 concentration under the natural infiltration mode reached 3300 ppm. The window-opening ventilation could only reduce the indoor CO2 concentrations for a short time, and the indoor PM2.5 concentrations were far above the Chinese limit in haze days. The mechanical ventilation system with filter could effectively avoid the influence of haze weather on indoor PM2.5 concentration. But the control effect of CO2 concentration was not satisfactory. The indoor CO2 concentrations under the two mechanical ventilation modes reached 1900 ppm and 1500 ppm, respectively. The simulation results indicated it was caused by the short circuit of airflow. It is suggested that significantly more attention should be paid to the design of air distribution of residential mechanical ventilation. This study is expected to contribute field data for natural and mechanical ventilation modes and also provides a guidance for the optimization of residential mechanical ventilation.

Clinical characteristics and outcomes of COVID-19 patients with prediabetes

Background and aimsWe aimed to examine the clinical characteristics and outcomes of coronavirus disease 2019 (COVID-19) patients with prediabetes. MethodsThis was a retrospective cohort study of 102 COVID-19 patients admitted to a tertiary care hospital in India between May and October 2020. ResultsMost patients had a poor clinical profile on admission. They had high rates of invasive mechanical ventilation (48%), intensive care unit admission (48%), complications (72.6%), and mortality (32.4%). ConclusionPeople with prediabetes are at high risk for poor outcomes from COVID-19.

Women of reproductive age in a tertiary intensive care unit: indications, outcome and the impact of pregnancy\u2014a retrospective cohort study

BackgroundTo evaluate the indications for admission and mortality rates of women of reproductive age admitted to a tertiary Intensive Care Unit (ICU) and to compare the outcomes of obstetric and non-obstetric admissions.Methods A retrospective cohort study was performed, including all women aged 17–41 years admitted to a level 3 ICU in the Netherlands, between January 1, 2000 and January 1, 2016. Primary outcome was indication for admission and mortality. Mortality, length of stay (LOS), need for mechanical ventilation and APACHE II score were compared between obstetric and non-obstetric admissions. The obstetric group was further analyzed for maternal and perinatal outcomes.Results3461 women (median age 32 years) were included, with an overall mortality rate of 13.3%. The obstetric group consisted of 265 women (7.7%). The non-obstetric group (n = 3196) was admitted most often for cardiovascular disease (19.6%), followed by oncologic disease (15%). Mortality was the highest in women with oncologic disease (23.9%). The obstetric group had lower mortality compared to the non-obstetric group (4.9% vs. 14%, p < 0.001), despite higher APACHE II score (14 vs. 11, p < 0.001) and a higher ventilation rate (47.9% vs. 39%, p = 0.004). Major surgical or endovascular interventions, besides caesarean section, were performed in 46% of the obstetric group. Perinatal death occurred in 17.2% and of the surviving infants, 63.2% were born preterm and 45.1% required Neonatal Intensive Care Unit admission.ConclusionsCardiovascular disease is the most important indication for admission and oncologic disease is associated with highest mortality in women of reproductive age. Obstetric patients constitute a small percentage of all ICU admissions in a tertiary ICU center. They have lower mortality rates than non-obstetric young female patients, despite a more severe initial presentation. Nevertheless lasting maternal morbidity and perinatal mortality and morbidity is frequent.

Estimation of the Inhaled Dose of Pollutants in Different Micro-Environments: A Systematic Review of the Literature.

Recently, the need to assess personal exposure in different micro-environments has been highlighted. Further, estimating the inhaled dose of pollutants is considerably one of the most interesting parameters to be explored to complete the fundamental information obtained through exposure assessment, especially if associated with a dose-response approach. To analyze the main results obtained from the studies related to the estimation of the inhaled dose of pollutants in different micro-environments (environments in which an individual spends a part of his day), and to identify the influence of different parameters on it, a systematic review of the literature was performed. The principal outcomes from the considered studies outlined that (i) exposure concentration and residence time are among the most important parameters to be evaluated in the estimation of the inhaled dose, especially in transport environments. Further, (ii) the pulmonary ventilation rate can be of particular interest during active commuting because of its increase, which increases the inhalation of pollutants. From a methodological point of view, the advent of increasingly miniaturized, portable and low-cost technologies could favor these kinds of studies, both for the measurement of atmospheric pollutants and the real-time evaluation of physiological parameters used for estimation of the inhaled dose. The main results of this review also show some knowledge gaps. In particular, numerous studies have been conducted for the evaluation (in terms of personal exposure and estimation of the inhaled dose) of different PM fractions: other airborne pollutants, although harmful to human health, are less represented in studies of this type: for this reason, future studies should be conducted, also considering other air pollutants, not neglecting the assessment of exposure to PM. Moreover, many studies have been conducted indoors, where the population spends most of their daily time. However, it has been highlighted how particular environments, even if characterized by a shorter residence time, can contribute significantly to the dose of inhaled pollutants. These environments are, therefore, of particular importance and should be better evaluated in future studies, as well as occupational environments, where the work results in a high pulmonary ventilation rate. The attention of future studies should also be focused on these categories of subjects and occupational studies.