3D multi-robot olfaction in naturally ventilated indoor environments: Locating a time-varying source at unknown heights.

Source localization is significant for mitigating indoor air pollution and safeguarding the well-being and safety of occupants. While most study focuses on mechanical ventilation and static sources, this study explores the less-explored domain of locating time-varying sources in naturally ventilated spaces. We have developed an innovative 3D localization system that adjusts to varying heights, significantly enhancing capabilities beyond traditional fixed-height 2D systems. To ensure consistency in experimental conditions, we conducted comparative analyses of 2D and 3D methods, using a swinging fan to simulate natural ventilation. Our findings reveal a substantial disparity in performance: the 2D method had a success rate below 46.7% in cases of height mismatches, while our 3D methods consistently achieved success rates above 66.7%, demonstrating their superior effectiveness in complex environments. Furthermore, we validated the 3D strategies in real naturally ventilated settings, confirming their wider applicability. This research extends the scope of indoor source localization and offers valuable insights and strategies for more effective pollution control.

Numerical performance of CO2 accumulation and droplet dispersion from a cough inside a hospital lift under different ventilation strategies.

The impact of mechanical ventilation on airborne diseases is not completely known. The recent pandemic of COVID-19 clearly showed that additional investigations are necessary. The use of computational tools is an advantage that needs to be included in the study of designing safe places. The current study focused on a hospital lift where two subjects were included: a healthy passenger and an infected one. The elevator was modelled with a fan placed on the middle of the ceiling and racks for supplying air at the bottom of the lateral wall. Three ventilation strategies were evaluated: a without ventilation case, an upwards-blowing exhausting fan case and a downwards-blowing fan case. Five seconds after the elevator journey began, the infected person coughed. For the risk assessment, the CO2 concentration, droplet removal performance and dispersion were examined and compared among the three cases. The results revealed some discrepancies in the selection of an optimal ventilation strategy. Depending on the evaluated parameter, downward-ventilation fan or no ventilation strategy could be the most appropriate approach.

Working with cattle slurry on farms: emission and dispersion of hydrogen sulfide gas during stirring.

Over the past 15 years, there have been numerous fatalities related to working with animal slurry. Working with cattle slurry releases toxic gases, in particular, hydrogen sulphide (H2S), which can cause acute central nervous system toxicity, breathing difficulties, and death if exposed to high concentrations. Real-time measurements of H2S gas were taken over distance and time, during the stirring of cattle slurry on farms. Gas was measured at eight slurry stores with differing typical configurations of indoor or outdoor stores and with or without slatted flooring. Highest H2S gas levels were measured from indoor stores under slatted floors, and generally at positions closest to the stirrer or the point of maximum stirring, with levels decreasing with distance from source. Most of the data indicate H2S gas levels increase very rapidly after stirring starts, and mostly decline to baseline levels within 30 min post start of stirring. There were, however, circumstances where gas levels remained high and only started to decline once the stirrer had stopped. H2S gas levels at all farms, at all positions measured were consistently below 10 ppm within 30 min of the stirrer being stopped. The current data highlight areas of the farm and ways of working that have the potential for workers and others to be at risk of exposure to toxic slurry gases. The area should be left to ventilate naturally for at least 30 min after the stirrer has been stopped before re-entering buildings. Influencing the design of stirring equipment and future slurry stores would likely reduce the risk of worker exposure to slurry gases.

Influence of Ventilation on Formation and Growth of 1-20 nm Particles via Ozone-Human Chemistry.

Ozone reaction with human surfaces is an important source of ultrafine particles indoors. However, 1-20 nm particles generated from ozone-human chemistry, which mark the first step of particle formation and growth, remain understudied. Ventilation and indoor air movement could have important implications for these processes. Therefore, in a controlled-climate chamber, we measured ultrafine particles initiated from ozone-human chemistry and their dependence on the air change rate (ACR, 0.5, 1.5, and 3 h-1) and operation of mixing fans (on and off). Concurrently, we measured volatile organic compounds (VOCs) and explored the correlation between particles and gas-phase products. At 25-30 ppb ozone levels, humans generated 0.2-7.7 × 1012 of 1-3 nm, 0-7.2 × 1012 of 3-10 nm, and 0-1.3 × 1012 of 10-20 nm particles per person per hour depending on the ACR and mixing fan operation. Size-dependent particle growth and formation rates increased with higher ACR. The operation of mixing fans suppressed the particle formation and growth, owing to enhanced surface deposition of the newly formed particles and their precursors. Correlation analyses revealed complex interactions between the particles and VOCs initiated by ozone-human chemistry. The results imply that ventilation and indoor air movement may have a more significant influence on particle dynamics and fate relative to indoor chemistry.

Study on infection risk in a negative pressure ward under different fresh airflow patterns based on a radiation air conditioning system.

COVID-19 and other respiratory infectious viruses are highly contagious, and patients need to be treated in negative pressure wards. At present, many negative pressure wards use independent air conditioning equipment, but independent air conditioning equipment has problems such as indoor air circulation flow, condensate water accumulation, and improper filter maintenance, which increase the risk of infection for healthcare workers and patients. The radiation air conditioning system relies on the radiation ceiling to control the indoor temperature and uses new air to control the indoor humidity and air quality. The problems caused by the use of independent air conditioning equipment should be avoided. This paper studies the thermal comfort, contaminant distribution characteristics, contaminant removal efficiency, and accessibility of supply air in a negative pressure ward with a radiation air conditioning system under three airflow patterns. In addition, the negative pressure ward was divided into 12 areas, and the infection probability of healthcare workers in different areas was analyzed. The results show that the application of radiation air conditioning systems in negative pressure wards can ensure the thermal comfort of patients. Stratum ventilation and ceiling-attached jets have similar effects in protecting healthcare workers; both can effectively reduce the contaminant concentrations and the risk of infection of healthcare workers. Ceiling-attached jets decreases the contaminant concentrations by 10.73%, increases the contaminant removal efficiency by 12.50%, and decreases the infection probability of healthcare workers staying indoors for 10 min by 23.18%, compared with downward ventilation.

Heating, ventilation, and air-conditioning systems in healthcare: a scoping review.

Guidelines for heating, ventilation, and air-conditioning systems have been developed for different settings. However, there is a lack of up-to-date evidence providing concrete recommendations for the heating, ventilation, and air-conditioning systems of an isolation room, which is essential to appropriately guide infection control policies. To highlight the guidelines for heating, ventilation, and air-conditioning systems in isolation rooms to inform relevant stakeholders and policymakers. A systematic search was performed based on Joanna Briggs Methodology using five databases (CINAHL, Embase, Joanna Briggs Institute, Medline, and Web of Science) and websites. Eight articles published by government departments were included in this review. Most studies recommended controlled airflow without recirculation, 12 air changes per hour, high-efficiency particulate air filtrate to exhaust contaminated air from the airborne isolation room, humidity ≤60%, and temperature in the range of 18-30 °C. This review provides further evidence that there is a need for interdisciplinary collaborative research to quantify the optimum range for heating, ventilation, and air conditioning system parameters, considering door types, anterooms, and bed management, to effectively reduce the transmission of infection in isolation rooms.

Parametric modeling study for blown-dust secondary pollution and optimal ventilation velocity during tunnel construction.

Tunnel construction often relies on drilling and blasting. High dust pollution is one of the primary problems of drilling and blasting construction. The level of secondary blown dust pollution caused by ventilation matches that of dust pollution caused by drilling construction. In this study, a critical flow model and blown dust rate model for deposited dust were established via force analysis, which was validated against the test data. The research results showed that the characteristic airflow velocity for blowing dust particles with a 100 µm diameter reached approximately 0.42 m/s for tunnel diameter is 10 m, and the ventilation Re values under smooth and rough conditions were 2.3 × 105 and 1.4 × 105, respectively. Furthermore, when ventilation Re reached 4 × 105, the blown dust pollution rate caused by ventilation under smooth conditions was approximately 1.8 × 10-2 kg/s. If dust particle size is more or less the critical dust particle size, the characteristic airflow velocity was increased. Moreover, the optimal velocity at which the deposited dust does not flow or move during tunnel construction was related to the tunnel size and roughness. For the smooth tunnel with a diameter of 10 m, the optimal ventilation velocity was 3.5 m/s. When the tunnel roughness was increased from 0.005 to 0.5 m, the optimal ventilation velocity decreased from 3.3 to 1.6 m/s. The deposited dust critical flow model and blown dust pollution rate model established in this study provide a sound theoretical basis for selecting the optimal velocity of tunnel ventilation and recognizing the risks of secondary blown dust pollution due to ventilation.

Effect of ventilation strategy on performance of upper-room ultraviolet germicidal irradiation (UVGI) system in a learning environment.

Upper-room ultraviolet germicidal irradiation (UVGI) system is recently in the limelight as a potentially effective method to mitigate the risk of airborne virus infection in indoor environments. However, few studies quantitatively evaluated the relationship between ventilation effectiveness and virus disinfection performance of a UVGI system. The objective of this study is to investigate the effects of ventilation strategy on detailed airflow distributions and UVGI disinfection performance in an occupied classroom. Three-dimensional computational fluid dynamics (CFD) simulations were performed for representative cooling, heating, and ventilation scenarios. The results show that when the ventilation rate is 1.1 h-1 (the minimum ventilation rate based on ASHRAE 62.1), enhancing indoor air circulation with the mixing fan notably improves the UVGI disinfection performance, especially for cooling with displacement ventilation and all-air-heating conditions. However, increasing indoor air mixing yields negligible effect on the disinfection performance for forced-convection cooling condition. The results also reveal that regardless of indoor thermal condition, disinfection effectiveness of a UVGI system increases as ventilation effectiveness is close to unity. Moreover, when the room average air speed is >0.1 m/s, upper-room UVGI system could yield about 90% disinfection effect for the aerosol size of 1 µm-10 µm. The findings of this study imply that upper-room UVGI systems in indoor environments (i.e., classrooms, hospitals) should be designed considering ventilation strategy and occupancy conditions, especially for occupied buildings with insufficient air mixing throughout the space.

Refined design of ventilation systems to mitigate infection risk in hospital wards: Perspective from ventilation openings setting.

To prevent respiratory infections between patients and medical workers, the transmission risk of airborne pollutants in hospital wards must be mitigated. The ventilation modes, which are regarded as an important strategy to minimize the infection risk, are challenging to be systematically designed. Studies have considered the effect of ventilation openings (inlets/outlets) or infected source locations on the airflow distribution, pollutant removal, and infection risk mitigation. However, the relationship (such as relative distance) between ventilation openings and infected sources is critical because it affects the direct exhaust of exhaled pollutants, which has not been thoroughly studied. To explore pollutant removal and infection prevention in wards, different ventilation modes (with varying ventilation openings) and infected patient locations must be jointly considered. This study investigated displacement ventilation (DV), downward ventilation (DWV), and stratum ventilation (SV) with 4, 6, and 10 scenarios of ventilation openings, respectively. The optimal ventilation mode and relative distance between outlets and infected patients were analyzed based on the simulated pollutant concentration fields and the evaluated infection risk. The pollutant removal effect and infection risk mitigation of SV in the ward were largely improved by 75% and 59% compared with DV and DWV, respectively. The average infection risk was reduced below 7% when a non-dimensional relative distance (a ratio of the actual distance to the cubic root of the ward volume) was less than 0.25 between outlets and infected patient. This study can serve as a guide for the systematic ventilation system design in hospitals during the epidemic.

A single-blind field intervention study of whether increased bedroom ventilation improves sleep quality.

A four-week-long field intervention experiment was conducted in twenty-nine bedrooms with extract ventilation systems and air inlet vents. During the first week no interventions took place. In the three weeks that followed, each participant slept for one week under a low, moderate, and high ventilation rate condition in a balanced order. These conditions were established by covertly altering the fan speed of the exhaust ventilation system without changing other settings. Participants were not informed when or even whether the changes to bedroom ventilation would be executed. The bedroom environmental quality was monitored continuously and sleep quality was monitored using wrist-worn trackers. Tests of cognitive performance were conducted in the evening and morning. In twelve bedrooms where clear differences between the three ventilation conditions occurred, as indicated by the measured CO2 concentrations, participants had significantly less deep sleep, more light sleep and more awakenings at lower ventilation rate conditions. In twenty-three bedrooms where a clear difference in ventilation rate between the high and low ventilation conditions was observed, as confirmed by the measured CO2 concentrations, the deep sleep was significantly shorter in the low ventilation rate condition. No differences in cognitive performance between conditions were observed. At lower ventilation rate conditions, the concentrations of CO2 increased, as did the relative humidity, while bedroom temperatures remained unchanged. The present results, which were obtained in actual bedrooms, confirm the findings in previous studies of a positive effect of increased ventilation on sleep quality. Further studies with larger populations and better control of bedroom conditions, particularly ventilation, are required.

Associations between illness-related absences and ventilation and indoor PM2.5 in elementary schools of the Midwestern United States.

This study monitored indoor environmental data in 144 classrooms in 31 schools in the Midwestern United States for two consecutive days every fall, winter, and spring during a two-year period; 3,105 pupils attended classrooms where the measurements were conducted. All classrooms were ventilated with mechanical systems that had recirculation; there were no operable exterior windows or doors. The daily absence rate at the student level and demographic data at the classroom level were collected. The overall mean ventilation rate, using outdoor air, was 5.5 L/s per person (the corresponding mean carbon dioxide concentrations were < 2,000 ppm), and the mean indoor PM2.5 was 3.6 µg/m3. The annual illness-related absence rate at the classroom level was extracted from the student-level absence data and regressed on measured indoor environmental parameters. Significant associations were found. Every 1 L/s per person increase in ventilation rate was associated with a 5.59 decrease in days with absences per year. This corresponds to a 0.15% increase in the annual daily attendance rate. Every additional 1 µg/m3 of indoor PM2.5 was associated with a 7.37 increase in days with absences per year. This corresponds to a 0.19% decrease in the annual daily attendance rate. No other relationships were significant. Present results agree with the previously demonstrated benefits of reduced absence rates when classroom ventilation is improved and provide additional evidence on the potential benefits of reducing indoor inhalable particles. Overall, reduced absence rates are expected to provide socioeconomic benefits and benefits for academic achievements, while higher ventilation rates and reduced particle levels will also contribute to reduced health risks, including those related to airborne respiratory pathogens.

Meta-Analysis of the Effect of Ventilation on Intellectual Productivity.

Indoor air quality (IAQ) influences the health and intellectual productivity of occupants. This paper summarizes studies investigating the relationship between intellectual productivity and IAQ with varying ventilation rates. We conducted a meta-analysis of five studies, with a total of 3679 participants, and performed subgroup analyses (arithmetic, verbal comprehension, and cognitive ability) based on the type of academic performance. The task performance speed and error rate were evaluated to measure intellectual productivity. The effect size of each study was evaluated using the standardized mean difference (SMD). In addition, we calculated a dose-response relationship between ventilation rate and intellectual productivity. The results show that the task performance speed improved, SMD: 0.18 (95% CI: 0.10-0.26), and the error rate decreased, SMD: -0.05 (95% CI: -0.11-0.00), with an increase in ventilation rate. Converting the intervention effect size on the SMD into the natural units of the outcome measure, our analyses show significant improvements in the task performance speed: 13.7% (95% CI: 6.2-20.5%) and 3.5% (95% CI: 0.9-6.1%) in terms of arithmetic tasks and cognitive ability, respectively. The error rate decreased by -16.1% (95% CI: -30.8-0%) in arithmetic tasks. These results suggest that adequate ventilation is necessary for good performance.

Comparison of number of airborne bacteria in operating rooms with turbulent mixing ventilation and unidirectional airflow when using reusable scrub suits and single-use scrub suits.

INTRODUCTION: A low count of airborne bacteria in the operating room is a means to prevent surgical site infection. AIM: To investigate levels of airborne bacteria during surgical procedures in two operating rooms with turbulent mixing ventilation (TMV) and unidirectional airflow (UDAF), both with an air supply of 2600 L/s, when staff used either reusable scrub suits made from a mixed material (dry penetration ≤300 cfu) or single-use scrub suits made from polypropylene (dry penetration ≤100 cfu). MATERIAL AND METHODS: In the TMV-room cfu/m3 air was measured during eight procedures with staff wearing reusable scrub suits and seven procedures with single-use scrub. In the UDAF-room cfu/m3 air was measured during seven procedures with staff wearing reusable scrub suits. FINDINGS: Mean values of cfu/m3 air were 1.3-10.8 in the TMV-room with staff dressed in reusable scrub suits and 0.8-4.0 with staff dressed in single-use scrub suits (P<0.01). Mean values of cfu/m3 air were 0.2-4.5 in the UDAF-room with staff dressed in reusable scrub suits. The difference obtained with reusable scrub suits in the two rooms was significant (P<0.01). CONCLUSIONS: The mode of ventilation affects the cfu levels when staff are dressed in less occlusive scrub suits despite a high air supply. It is possible to decrease the cfu levels in a TMV-room by using scrub suits made from a tight material, thus reaching the same levels that are achieved by less protective scrub suits in a UDAF-room.

Indoor air surveillance and factors associated with respiratory pathogen detection in community settings in Belgium.

Currently, the real-life impact of indoor climate, human behaviour, ventilation and air filtration on respiratory pathogen detection and concentration are poorly understood. This hinders the interpretability of bioaerosol quantification in indoor air to surveil respiratory pathogens and transmission risk. We tested 341 indoor air samples from 21 community settings in Belgium for 29 respiratory pathogens using qPCR. On average, 3.9 pathogens were positive per sample and 85.3% of samples tested positive for at least one. Pathogen detection and concentration varied significantly by pathogen, month, and age group in generalised linear (mixed) models and generalised estimating equations. High CO2 and low natural ventilation were independent risk factors for detection. The odds ratio for detection was 1.09 (95% CI 1.03-1.15) per 100 parts per million (ppm) increase in CO2, and 0.88 (95% CI 0.80-0.97) per stepwise increase in natural ventilation (on a Likert scale). CO2 concentration and portable air filtration were independently associated with pathogen concentration. Each 100ppm increase in CO2 was associated with a qPCR Ct value decrease of 0.08 (95% CI -0.12 to -0.04), and portable air filtration with a 0.58 (95% CI 0.25-0.91) increase. The effects of occupancy, sampling duration, mask wearing, vocalisation, temperature, humidity and mechanical ventilation were not significant. Our results support the importance of ventilation and air filtration to reduce transmission.

The Influence of Ventilation Measures on the Airborne Risk of Infection in Schools: A Scoping Review.

OBJECTIVES: To review the risk of airborne infections in schools and evaluate the effect of intervention measures reported in field studies. BACKGROUND: Schools are part of a country's critical infrastructure. Good infection prevention measures are essential for reducing the risk of infection in schools as much as possible, since these are places where many individuals spend a great deal of time together every weekday in a small area where airborne pathogens can spread quickly. Appropriate ventilation can reduce the indoor concentration of airborne pathogens and reduce the risk of infection. METHODS: A systematic search of the literature was conducted in the databases Embase, MEDLINE, and ScienceDirect using keywords such as school, classroom, ventilation, carbon dioxide (CO2) concentration, SARS-CoV-2, and airborne transmission. The primary endpoint of the studies selected was the risk of airborne infection or CO2 concentration as a surrogate parameter. Studies were grouped according to the study type. RESULTS: We identified 30 studies that met the inclusion criteria, six of them intervention studies. When specific ventilation strategies were lacking in schools being investigated, CO2 concentrations were often above the recommended maximum values. Improving ventilation lowered the CO2 concentration, resulting in a lower risk of airborne infections. CONCLUSIONS: The ventilation in many schools is not adequate to guarantee good indoor air quality. Ventilation is an important measure for reducing the risk of airborne infections in schools. The most important effect is to reduce the time of residence of pathogens in the classrooms.

Effect of ventilation mode and airflow rate on the flow field and particle mass concentration distribution of a high-speed rail carriage in the putty polishing workshop.

Objectives. The putty polishing procedure usually produces a large number of micron-sized particles, which can lead to serious respiratory diseases as well as skin conditions. The diagonal ventilation system is widely used to decrease the particle concentration in different environments. However, it becomes less effective for a large empty factory workshop, such as the polishing workshop for high-speed rail carriages, in which the diagonal ventilation mode usually results in turbulence in the airflow. In this article we report that the situation can be improved by optimizing the number and locations of the air inlets and outlets in the carriage-polishing workshop. Three modified ventilation modes are proposed, whose efficiencies are evaluated by numerical simulations and compared to the diagonal mode. Results. The results show that the mode with two inlets close to the ceiling and two outlets close to the floor yields the best performance. Besides, the optimum airflow rate under this mode is further determined by both simulations and in-situ measurements. The results reported can serve as a reference for the design of the ventilation systems in the polishing workshops of similar sizes.

Observational study of sterile field bioburden levels during orthopedic arthroplasty surgery in operating rooms complying with current United States ventilation specifications.

BACKGROUND: Airborne contamination from microbe carrying particles (MCPs) is a risk factor for devastating early onset periprosthetic joint infection(PJIs). There are no published guidelines to quantify this risk factor for PJI events. This observational cohort project addresses this gap and utilizes a simple passive system to produce quantitative data from 80 total joint replacement cases performed in operating rooms built to current USA standards. METHODS: A petri dish-based system inspired by industrial cleanroom technology was deployed. Surgical helmet systems (SHSs) and strict protocols were used in all cases. 450 MCPs/m2 was used as a cutoff for bioburden. This benchmark corresponds to the ultraclean air standard of 10 MCPs/m3. RESULTS: 75/80 cases (94%) achieved desired benchmark levels of bioburden at the wound zone compared to only 52/80 (65%) of back table zones. No surgical site infections (SSI) or PJI events (0/80; 95% CI, 0.00-3.68%) at minimum 18-month (average 25.8 months) follow-up were detected. DISCUSSION: The current USA ventilation design uses low velocity airflow and appears to achieve ultraclean air conditions at the surgical site but requires SHSs and strict protocols. Higher contamination levels seen in back tables are consistent with this design. CONCLUSIONS: This settle plate system may be useful for early onset PJI event investigations and thus lower the incidence of these complications.

Heating Control Strategy Based on Dynamic Programming for Building Energy Saving and Emission Reduction.

Finding the optimal balance between end-user's comfort, lifestyle preferences and the cost of the heating, ventilation and air conditioning (HVAC) system, which requires intelligent decision making and control. This paper proposes a heating control method for HVAC based on dynamic programming. The method first selects the most suitable modeling approach for the controlled building among three machine learning modeling techniques by means of statistical performance metrics, after which the control of the HVAC system is described as a constrained optimization problem, and the action of the controller is given by solving the optimization problem through dynamic programming. In this paper, the variable 'thermal energy storage in building' is introduced to solve the problem that dynamic programming is difficult to obtain the historical state of the building due to the requirement of no aftereffect, while the room temperature and the remaining start hours of the Primary Air Unit are selected to describe the system state through theoretical analysis and trial and error. The results of the TRNSYS/Python co-simulation show that the proposed method can maintain better indoor thermal environment with less energy consumption compared to carefully reviewed expert rules. Compared with expert rule set 'baseline-20 °C', which keeps the room temperature at the minimum comfort level, the proposed control algorithm can save energy and reduce emissions by 35.1% with acceptable comfort violation.

Response to the COVID-19 Pandemic in Classrooms at the University of the Basque Country through a User-Informed Natural Ventilation Demonstrator.

The COVID-19 pandemic has generated a renewed interest in indoor air quality to limit viral spread. In the case of educational spaces, due to the high concentration of people and the fact that most of the existing buildings do not have any mechanical ventilation system, the different administrations have established natural ventilation protocols to guarantee an air quality that reduces risk of contagion by the SARS-CoV-2 virus after the return to the classrooms. Many of the initial protocols established a ventilation pattern that opted for continuous or intermittent ventilation to varying degrees of intensity. This study, carried out on a university campus in Spain, analyses the performance of natural ventilation activated through the information provided by monitoring and visualisation of real-time data. In order to carry out this analysis, a experiment was set up where a preliminary study of ventilation without providing information to the users was carried out, which was then compared with the result of providing live feedback to the occupants of two classrooms and an administration office in different periods of 2020, 2021 and 2022. In the administration office, a CO2-concentration-based method was applied retrospectively to assess the risk of airborne infection. This experience has served as a basis to establish a route for user-informed improvement of air quality in educational spaces in general through low-cost systems that allow a rational use of natural ventilation while helping maintain an adequate compromise between IAQ, comfort and energy consumption, without having to resort to mechanical ventilation systems.

Airplane cabin mixing ventilation with time-periodic supply: Contaminant mass fluxes and ventilation efficiency.

Airplane cabin ventilation is essential to ensure passengers' well-being. The conventional ventilation method is mixing ventilation with a statistically steady supply, which, according to former studies, has reached its limits regarding, for example, the ventilation efficiency. However, the effect of a statistically unsteady (time-periodic) supply on the mixing ventilation efficiency has remained largely unexplored. This research uses computational fluid dynamics (CFD) with the large eddy simulation (LES) approach to study isothermal time-periodic mixing ventilation in a section of a single-aisle airplane cabin model, in which the air exhaled by the passengers functions as (passive) contaminants. Two time-periodic supply strategies are evaluated. The induced time-periodic airflow patterns promote an efficient delivery of fresh air to the passenger zone and affect the passengers' expiratory plumes. This results in increased mean contaminant mass fluxes, causing a strong reduction of the mean contaminant concentrations in the passenger zone (up to 23%) and an increased contaminant extraction from the cabin. Mean velocities increase with up to 55% but remain within the comfortable range. It is shown that the ventilation efficiency improves; that is, the contaminant removal effectiveness and air change efficiency (in the full cabin volume) increase with up to 20% and 7%, respectively.