Room Ventilation Research Articles

Resolving the Loss of Intermediate-Size Speech Aerosols in Funnel-Guided Particle Counting Measurements

Modeling of airborne virus transmission and protection against it requires knowledge of the amount of biofluid emitted into the atmosphere and its viral load. Whereas viral concentrations in biofluids are readily measured by quantitative PCR, the total volume of fluids aerosolized during speaking, as measured by different researchers using various technologies, differs by several orders of magnitude. We compared collection methods in which the aerosols first enter into a low-humidity chamber either by direct injection or via commonly used funnel and tubing arrangements, followed by standard optical particle sizer measurement. This “collect first, measure later” approach sacrifices the recording of the temporal correlation between aerosol generation and sound types such as plosives and vowels. However, the direct-injection mode prevents inertia deposition associated with the funnel arrangements and reveals far more intermediate-size (5–20 μm in diameter) particles that can dominate the total mass of ejected respiratory aerosol. The larger aerosol mass observed with our method partially reconciles the large discrepancy between the SARS-CoV-2 infectious dose estimated from superspreader event analyses and that from human challenge data. Our results also impact measures to combat airborne virus transmission because they indicate that aerosols that settle faster than good room ventilation rates can dominate this process.

Humidity regime of building envelope structures of the drying compartment tula brewery

The article presents the results of a study of the humidity regime of building enclosing structures of the drying department of the brewery located in Tula. The assessment of the humidity regime was carried out in order to identify the causes of damage to external, internal walls and attic floors, and the task was also set to develop technical solutions for steam and waterproofing of the above-mentioned enclosing structures. To solve the tasks set, thermophysical calculations of building enclosing structures were performed, as well as an assessment of their moisture accumulation during the operation of the building. The position of the plane of possible condensation was determined using the author’s methodology. The results of thermophysical calculations showed the presence of moisture accumulation in the above-mentioned structures, which is associated with the use of PVC polyethylene film as wind protection. It was also revealed that there was a discrepancy with the regulatory requirements for thermal protection of the external wall of the electrical panel. In order to eliminate these problems, recommendations were made, which consisted in using an Isospan A type film as a vapor barrier, increasing the thickness of the insulation, organizing natural supply and exhaust ventilation of the attic room, as well as waterproofing the structures of the outer wall made of monolithic reinforced concrete.

Conversion of a regular patient room to negative pressure at Ancona university hospital (Italy). A combined experimental and numerical investigation

Negative pressure isolation rooms are employed to prevent the spread of infectious diseases to surrounding spaces. This study reports a combined experimental and numerical analysis aimed at reliably assessing the performance of hospital ventilation systems and effectively reducing the risk of airborne infections. The study appraises the enhancement of the safety conditions by retrofitting an existing, positive pressure room ventilation system with a negative pressure and recirculation one. The assessment consisted in experimental measurements of airborne particle concentration and Computational Fluid Dynamics (CFD) simulations with Lagrangian particle tracking of respiratory droplets. The ventilation performance improvement was quantified in terms of recovery rate, contaminant removal effectiveness, particle transfer toward adjacent spaces and probability of infection.Two experimental campaigns were carried out: an ISO standard recovery assessment and a test in real operational conditions. The negative pressure configuration significantly improved the safety inside the patient ward: the recovery rate for droplets with diameter larger than 5 μm increased by a factor three, and the contaminant removal effectiveness after 15 min increased from 45% to 81%. The numerical model for Computational Fluid Dynamics simulation was successfully validated, confirming the ability of the approach to reproduce the undergoing Physics. The negative pressure design eliminated the particle transmission to surrounding spaces, while 2.5% of the emitted respiratory droplets escaped the room in the original existing scenario. The probability of infection after 15 min exposure was reduced by a factor three and peak values reaching 15% were limited to the immediate vicinity of the patients.

Occurence and risk factors of tuberculosis infection in orphanage children in Bali

Background Tuberculosis (TB) is an infectious disease that is still a common threat worldwide, especially in pediatric populations. TB transmission occurs particularly when the transmitter has no obvious manifestation of the disease. There is a higher incidence of TB infection in children than in the general population, especially in high risk populations such as children in orphanages. However, the incidence of TB infection in orphaned children in Indonesia, including Bali, is unknown. Objective To describe the incidence and risk factors for TB infection in children in orphanages in Bali. Methods This case-control study was conducted in 12 orphanages in Bali. Subjects were divided into a case group comprised of children with TB infection, and a control group comprised of those without TB infection. TB infection was diagnosed by positive tuberculin test without clinically confirmed TB. Results A total of 175 children were recruited as subjects. There were 49 (28.0%) children with TB infection. Bivariate analysis revealed significant associations between density, humidity, ventilation/room area ratio, and area of ??origin with TB infection. Multivariate analysis showed that ventilation/room area ratio and room humidity of ?73% were independently positive correlated with TB infection. Natural lighting and BCG scar were not significantly different between groups. Conclusion The occurence of TB infection in children residing in orphanages in Bali is high (28%). The risk factors identified independently are lower ventilation and higher room humidity.

Identification of primary input parameters affecting evacuation in ventilated main control room through CFAST simulations and application of a machine learning algorithm to replace CFAST model

Accurately predicting evacuation time in a ventilated main control room (MCR) during fire emergencies is crucial for ensuring the safety of personnel at nuclear power plants. This study proposes to use neural networks alongside consolidated fire and smoke transport (CFAST) simulations to serve as a surrogate model for physics-based simulation tools. Our neural networks can promptly predict the evacuation time in MCRs, proving to be a valuable asset in fire emergencies and eliminating the need for time-consuming rollouts of the CFAST simulations. The CFAST model simulates fire and evacuation scenarios in a ventilated MCR with variations in input parameters such as door conditions, ventilation flow rate, leakage area, and fire propagation time. Target output parameters, such as hot gas layer temperature (HGLT), heat flux (HF), and optical density (OD), are used alongside standardized evacuation variables to train a machine learning model for predicting evacuation time. The findings suggest that high ventilation flow rates help to dilute smoke and discharge hot gas, leading to lower target output parameters and quicker evacuation. Standardized evacuation variables exceed the required abandonment criteria for all door conditions, indicating the importance of proper evacuation procedures. The results show that neural networks can generate evacuation times close to those obtained from CFAST simulations.

The Impact of Electrocautery Smoke on Surgical Staff and the Efficacy of Normal Surgical Masks Versus N95 Masks.

Electrocautery is a commonly used technique in surgical procedures, generating smoke that poses health risks to surgical staff. This study investigates the comparative efficacy of normal surgical masks versus N95 masks in mitigating the harmful effects of electrocautery smoke. Through a systematic review of literature spanning two decades, we explore the causes and effects of electrocautery smoke exposure, including potential long-term inhalation effects. Our findings highlight significant disparities in the protection offered by different masks and underscore the importance of adequate respiratory protection in surgical settings. In addition, we examine the factors influencing the generation and composition of electrocautery smoke, such as the power settings used, the type of tissue being cauterized, and the duration of the procedure. Furthermore, we discuss the potential health risks associated with long-term exposure to electrocautery smoke, including the possibility of respiratory conditions, cardiovascular effects, and carcinogenicity. Our analysis also addresses the importance of implementing appropriate smoke evacuation systems and optimizing operating room ventilation to minimize the concentration of smoke particles in the surgical environment. Overall, this comprehensive analysis provides valuable insights into the impact of electrocautery smoke in surgical settings and the varying levels of protection offered by different masks.

Experimental study of the hydrogen leakage and ignition in a ventilated room

Experimental study of the hydrogen leakage and ignition in a ventilated room

Numerical simulation of a hydrogen leakage in a ventilated room

Numerical simulation of a hydrogen leakage in a ventilated room

Predictors of SARS-CoV-2 transmission in congregate living settings: a multicenter prospective study.

Older adults residing in congregate living settings (CLS) such as nursing homes and independent living facilities remain at increased risk of morbidity and mortality from coronavirus disease 2019. We performed a prospective multicenter study of consecutive severe acute respiratory coronavirus virus 2 (SARS-CoV-2) exposures to identify predictors of transmission in this setting. Consecutive resident SARS-CoV-2 exposures across 17 CLS were prospectively characterized from 1 September 2022 to 1 March 2023, including factors related to environment, source, and exposed resident. Room size, humidity, and ventilation were measured in locations where exposures occurred. Predictors were incorporated in a generalized estimating equation model adjusting for the correlation within CLS. Among 670 consecutive exposures to SARS-CoV-2 across 17 CLS, transmission occurred among 328 (49.0%). Increased risk was associated with nursing homes (odds ratio (OR) = 90.8; 95% CI, 7.8-1047.4), Jack and Jill rooms (OR = 2.2; 95% CI, 1.3-3.6), from source who was pre-symptomatic (OR = 11.2; 95% CI, 4.1-30.9), symptomatic (OR = 6.5; 95% CI, 1.4-29.9), or rapid antigen test positive (OR = 35.6; 95% CI, 5.6-225.6), and in the presence of secondary exposure (OR = 6.3; 95% CI, 1.6-24.0). Exposure in dining room was associated with reduced risk (OR = 0.02; 95% CI, 0.005-0.08) as was medium room size (OR = 0.3; 95% CI, 0.2-0.6). Recent vaccination of exposed resident (OR = 0.5; 95% CI, 0.3-1.0) and increased ventilation of room (OR = 0.9; 95% CI, 0.8-1.0) were marginally associated with reduced risk. Prospective assessment of SARS-CoV-2 exposures in CLS suggests that source characteristics and location of exposure are most predictive of resident transmission. These findings can inform risk assessment and further opportunities to prevent transmission in CLS.

Investigation of combined parallel and triple-pass v-corrugated solar air heater: A numerical and experimental study

Renewable and safe energy sources have been used more in recent years because of rising energy needs and finite fossil fuel resources. A solar air heater (SAH) is a device that utilizes solar energy to warm air for diverse applications, including room heating, drying procedures, or ventilation. The major aim of the current study is investigating the performance of the combined utilization of grooved absorber and triple-flow air channel modification in a SAH using numerical modeling. Accordingly, CFD method has been used to model the heat and flow characteristics inside a parallel-flow v-grooved SAH (PFVSAH), a triple-flow v-grooved SAH (TFVSAH), and a combined-SAH. The experimental and numerical evaluation of PFVSAH was conducted under different climatic conditions and mass flow rates of 0.019 kg/s, 0.015 kg/s, and 0.012 kg/s. Additionally, a numerical comparison was made between PFVSAH, TFVSAH and combined-SAH. According to the numerical results, the calculated temperature differences in a TFVSAH are greater than those in a PFVSAH and less than in a combined-SAH. According to the experimental results, when the mass flow rate is 0.012 kg/s, the PFVSAH shows average thermal and exergy efficiencies of 59.51% and 29.09%, respectively. In PFVSAH, the highest temperature difference between the outlet and the inlet was 28 °C. The recorded values for the top heat loss coefficient (THLC) of the PFVSAH varied between 4.3 and 8.93 W/m2.

Simulation model of a flat plate air solar collector

Simulation model of a flat plate air solar collector

COVID-19 outbreak among employees of a German hospital: risk factor analysis based on a follow-up questionnaire and seroprevalence

BackgroundThe Co-FriSero study describes a COVID-19 outbreak at the Friedrichroda hospital in Thuringia, Germany, with 185 beds and 404 employees, at the onset of the pandemic between March 30th, 2020, and April 13th, 2020. This study aimed to analyze potential sources of SARS-CoV-2 transmission amongst hospital employees.MethodsAfter the outbreak, a comprehensive follow-up was conducted through a questionnaire and a seroprevalence study using two different immunoassays for IgG detection and a third for discordant results.ResultsPCR screenings confirmed SARS-CoV-2 infection in 25 of 229 employees, with an additional 7 detected through serology. Statistical analysis indicated that direct patient contact, exposure to high flow ventilation in non-isolated rooms, direct contact with colleagues, shared use of recreational rooms, and carpooling were associated with an increased infection risk. Conversely, contact with family and friends, public transportation, public events, and use of locker rooms were not associated with infection. Male gender showed a lower infection likelihood, independent of age and other risk factors.ConclusionThis study highlights the role of direct patient care and internal staff interactions in the spread of SARS-CoV-2 in the hospital setting. It suggests that non-traditional transmission routes like carpooling require consideration in pandemic preparedness.

ИССЛЕДОВАНИЕ ХИМИЧЕСКОГО СОСТАВА НЕКОТОРЫХ ПРЕДСТАВИТЕЛЕЙ РОДА TANACETUM L.

The purpose of the study is to study the biochemical parameters of three species of the genus Tanacetum: T. balsamita L. (balsamite), T. balsamitoides Sch.Bip. (P. balsamonosa) and T. vulgare L. (P. vulgare). For the study, we used the raw materials of tansy produced by OJSC Krasnogorskleksredstva, a wild-growing type of tansy harvested in the Ufa District of Bashkiria, and we also used the raw materials of balsam tansy and balsam-like tansy, grown in the botanical garden-institute (Ufa). For chemical analysis, plants were harvested at the beginning of flowering, cutting off shoots at a level of 10–15 cm from the ground. The raw materials were dried using the air-shade method under canopies in ventilated rooms, laid out in a thin layer and stirred periodically. The raw materials were packaged and stored in accordance with the requirements of regulatory documentation (OFS.1.1.0019.15) at room temperature in a dry room, not infested with pests, with good ventilation, without direct sunlight. Commodity analysis of raw materials was carried out by generally accepted pharmacopoeial methods according to the following indicators: moisture, total ash and ash insoluble in hydrochloric acid. Qualitative detection of biological active substances was carried out using qualitative reactions and chromatographic research methods. Quantitative determination of ascorbic acid (FS.2.5.01.06.18), tannins (OFS 1.5.3.0008.18) and organic acids (FS.38) in tansy flowers was carried out by titrimetric methods, determination of essential oil content by steam distillation (OFS.1.5.3.0010.15). The commodity indicators of the raw materials of the studied tansy samples: moisture, total ash and ash insoluble in a 10 % hydrochloric acid solution do not exceed the content standards specified in the pharmacopoeial monograph. The chemical composition of the studied tansy species contains valuable biologically active substances, among them essential oils, tannins, ascorbic acid, and organic acids, which may allow the use in scientific medicine not only of T. vulgare, but also of T species used so far only in folk medicine balsamita and T. balsamitoides, which successfully passed the introduction test at the South Ural Botanical Garden-Institute of the Federal Research Center of the Russian Academy of Sciences.

Effects of operating room ventilation on particle exposure and removal during general endotracheal anesthesia

The operating room (OR) ventilation system is a primary method for reducing particle exposure in the OR. However, most ventilation studies in operating rooms were conducted using computational fluid dynamics (CFD) models, which may not be able to predict the complexity of real operating conditions. In this study, we recruited 40 patients undergoing general endotracheal anesthesia in a total of 13 operating rooms. We tested the effectiveness of OR ventilation on mitigating patient and nebulizer-generated particles during the preoxygenation, induction, and intubation phases of care. Sampling locations were selected close to the patient's face (reference), physician's head area, and medical assistant's standing location. A total of six sampling sessions characterizing patient and healthcare worker activities were included. We observed a significantly higher number of particles during endotracheal intubation compared to preoxygenation with deep breathing and coughing, suggesting potential disruptive effect of surgical activities (i.e., intubation) on airflow, which affected particle concentration. Particle decay rates measured at all three locations (reference 50 ± 20 h-1; physician 46 ± 22 h-1; medical assistant 33 ± 21 h-1) were considerably higher than the regulated operating room air exchange rate of 20 h-1, indicating highly effective overall ventilation function. Nevertheless, healthcare workers should still be cautious about particle exposure risks in operations that generate large number of particles. Results from this study reflect the effectiveness of OR ventilation on particle mitigation in real-world scenario and may facilitate the validation of future CFD studies as well as the establishment of effective OR regulation guidelines to protect healthcare workers from particle exposures.

Air flow prediction and evaluation of ventilation effectiveness with different zonal configurations

This paper proposes a numerical method for the study of ventilation efficiency in buildings. The developed model is validated with the experimental results of Nielsen [5] who tested the isothermal flow in a scaled model of a ventilated room. A zonal method is used to predict airflow patterns in the same ventilated room. The different equations governing the flow in the room were coded in Matlab for different operating conditions, different zonal configurations of the room and different number of cells (control volumes). The efficiency of the ventilation was determined by calculating the number of air changes per hour (ACH) for each cell. The present results show the importance of the inlet air flow rate, the space resolution and the jet inlet dimensions on the determination of air quality.

Quality control analysis of chiffon cake pandan in Holland Bakery

The advancement of business development affects economic competition. Companies with strong competitive advantages must compete with other companies in the same field. One way to compete with the same competitors is to favor the quality of the products produced. Holland Bakery is one of the cake and bread manufacturers. Holland Bakery continues to strive to produce quality products, but there is still damage that exceeds the standard limit by 2.13% in 2022 with the standard limit set, which is 2%. One way to do quality control is to use the Statistical Quality Control (SQC) method. This study aims to analyze the quality of one of Holland Bakery's products, namely Chiffon Cake Pandan Sponge Cake, which is still within the tolerance limit or not, and what types of damage occur most often. This research was conducted from September 21 - October 20, 2023, with the results obtained that the level of damage is still within the tolerance limit. However, there is still damage exceeding the UCL line on the 10th day of production by 10% due to burning, the 19th day by 6.67% due to non-standard shape, the 23rd day by 11.11% due to burning, and the 29th day by 10% due to burning. The most dominant damage is due to burning as many as 16 pieces. Then, the cause-and-effect diagram shows that damage factors occur due to humans (man), environment (environment), and methods (method). Improvements from various aspects such as humans, environment, and methods can be made to minimize damage so that quality is always maintained. It is expected that Holland Bakery can review the production method of Chiffon Cake Pandan, monitor the condition of workers, and add air ventilation in the production room.

Study on the infection control performance under interactive cascade ventilation: A focus on a conference room environment

With the rise of respiratory infectious diseases, many scholars focus on finding an appropriate ventilation method to effectively improve the indoor environmental protection effect, especially for crowded spaces, which can cause a widespread spread of the epidemic. Interactive cascade ventilation (ICV), as a recently proposed ventilation method, has presented advantages in thermal comfort, infection control and energy consumption. This study discusses the effect of the outlet/inlet locations on infection control performance under interactive cascade ventilation in a conference room with an experimentally verified model. Ninety-five simulations are carried out by considering changes in the location of the outlet/inlet opening and infection source. Particle removal efficiency (ε), predicted infection risk (Pi) and contaminant dispersion index (CDI) are introduced to evaluate the infection control performance comprehensively. The simulation results show that double-side supply air outlets coupled with double-side return air inlets can reduce Pi by 51.1 % compared with other ventilation strategies investigated in this paper. It indicates that ventilation zoning design is more effective for reducing cross-infection in dense spaces. The findings in this study can efficiently provide new insights for the actual application of ventilation strategies in conference rooms under epidemic normalization.

Surgical smoke: a matter of hygiene, toxicology, and occupational health.

The use of devices for tissue dissection and hemostasis during surgery is almost unavoidable. Electrically powered devices such as electrocautery, ultrasonic and laser units produce surgical smoke containing more than a thousand different products of combustion. These include large amounts of carcinogenic, mutagenic and potentially teratogenic noxae. The smoke contains particles that range widely in size, even as small as 0.007 µm. Most of the particles (90%) in electrocautery smoke are ≤6.27 µm in size, but surgical masks cannot filter particles smaller than 5 µm. In this situation, 95% of the smoke particles which pass through the mask reach deep into the respiratory tract and frequently cause various symptoms, such as headache, dizziness, nausea, eye and respiratory tract irritation, weakness, and abdominal pain in the acute period. The smoke can transport bacteria and viruses that are mostly between 0.02 µm and 3 µm in size and there is a risk of contamination. Among these viruses, SARS-CoV-2, influenza virus, HIV, HPV, HBV must be considered. The smoke may also carry malignant cells. The long-term effects of the surgical smoke are always ignored, because causality can hardly be clarified in individual cases. The quantity of the smoke changes with the technique of the surgeon, the room ventilation system, the characteristics of the power device used, the energy level at which it is set, and the characteristics of the tissue processed. The surgical team is highly exposed to the smoke, with the surgeon experiencing the highest exposure. However, the severity of exposure differs according to certain factors, e.g., ventilation by laminar or turbulent mixed airflow or smoke evacuation system. In any case, the surgical smoke must be removed from the operation area. The most effective method is to collect the smoke from the source through an aspiration system and to evacuate it outside. Awareness and legal regulations in terms of hygiene, toxicology, as well as occupational health and safety should increase.

Field Survey Analysis of CO2 Concentration and Its Impact on Sleep Efficiency in University Dormitory

This study aims to investigate the impact of carbon dioxide (CO2) levels on sleep efficiency in university dormitories. The quality of the indoor environment, including CO2 concentrations, can significantly influence the health and comfort of dormitory occupants. Poor sleep efficiency can lead to long-term cognitive disturbances and health problems. Therefore, understanding the relationship between CO2 levels and sleep efficiency in the university dormitory environment is crucial to improving the living conditions of students. The study was carried out through field surveys at Diponegoro University Dormitory. The real-time CO2 data in the rooms was measured using a logger monitoring device. In addition, the sleep efficiency of the students was evaluated using sleep tracking devices and sleep journals filled out by the participants. Other data, such as ventilation rates and room temperature, were also collected as determinants of environmental quality. The results of the analysis revealed a significant association between CO2 levels (665.33 ± 207,20 ppm) and sleep efficiency (86,71 ± 3,11 %). High levels of CO2 were found to be associated with lower sleep efficiency, leading to sleep disturbances and irregular sleep patterns. Other environmental factors, such as ventilation rates, were also relevant to sleep efficiency.

The effect of location and method of tooth preparation on aerosol and splatter mitigation

Abstract Objectives: This study investigated the influence of tooth position within the quadrant and method of tooth preparation on aerosol and splatter reduction by suction techniques. Materials and methods: Using four suction techniques, tooth preparation was done using fast handpiece and combined air and water spray on tooth #28, #29 and #30. Splatter, aerosol and total sound generated were recorded. Two-way analysis of variance and posthoc pairwise comparisons compared amount of aerosol, spatter and total sound among suction techniques, tooth location and method of preparation. Results: There were statistically significant more splatter (P < 0.000) for tooth preparation with air and water spray compared with high-speed handpiece for all suction techniques, but no significant difference in aerosol and total sound (P > 0.05) was recorded. A significant reduction in environmental splatter during tooth preparation of the distal tooth #30 by all suction methods was observed compared with tooth #28. However, there was no significant difference in the amount of face shield, chest, right arm and left arm splatter, aerosol and total sound based on tooth location. Overall, the prototype suction device had statistically significant less environmental splatter (P < 0.001) and aerosol (P = 0.004) than the conventional HVE device. Conclusions: The method of tooth preparation affected splatter mitigation by suction techniques but had no influence on aerosol mitigation. Mitigation of environmental splatter by suction techniques was affected by tooth position within the arch. The prototype suction device reduced environmental spatter and aerosol more than the conventional HVE device. Clinical Significance: The variations observed in aerosol and splatter mitigation based on tooth preparation methods and tooth location provides evidence for adjunctive means of reducing risk of direct transmission of infection in the dental practice such as combining strategies of protective equipment, improved room ventilation and use of air filtration system.