Indoor air最新文献

Human movement across a doorway and associated door opening and closing motions is an important mechanism of containment failure in protective rooms. Detailed information regarding the 3D, time-dependent air flow field and aerosol concentration field induced by the motions is of pivotal importance for the development of effective intervention strategies. This study used boundary-conformal moving mesh techniques to simulate air and aerosol transport from a contaminated room into a pressure-equilibrium clean room. The simulations were conducted with different directions of manikin movement and door swinging in order to analyze their individual and combined effects on aerosol transport. The results showed that the net transport of air was dominated by the door swinging motion. The volume of air exchange caused by an opening door was around 47% of the volume displaced by the door as it swinged open, while the passage of a human-sized manikin across the doorway only added a few small fluctuations (< 10%) in the curve of air exchange rate. The net transport of aerosol was always associated with an outward motion, either an out-swinging door or an out-moving manikin from the contaminated room toward the clean room. An out-swinging door caused 44% of the aerosols in a volume equal to the displaced volume near the door to escape, with a further 28% added by an out-moving manikin. Comparatively, the amount of aerosol escape induced by an in-swinging door or in-moving making was very small. The study revealed that the vortex flows in the wake regions played a key role in aerosol transport, therefore proposing that destroying the wake flow regions of out-moving objects may be an effective method to mitigate containment failure induced by swinging doors and moving human occupants.

Indoor air quality (IAQ) in educational facilities is shaped by a dynamic interplay of microbial, chemical and physical factors, all of which influence health and cognitive performance. This study explored IAQ in university classrooms by combining microbiological, chemical and physical measurements to better understand microbial–chemical interactions in such environments. Samples (N = 33) were collected from 11 rooms of different sizes, including lecture halls, classrooms and computer labs. Bacteria and moulds were quantified using standard microbiological procedures, while CO₂, O₂, CH₄, temperature, relative humidity and pressure were monitored by portable analysers. MALDI-TOF MS was applied to identify airborne bacterial and fungal species, providing insight into microbial diversity and sources. The average CO₂ concentration was 906 ppm (range 509–1462 ppm). Although the overall mean was below the recommended 1000 ppm limit, more than half of the monitored rooms recorded CO₂ levels above this threshold. Mean bacterial and mould loads were 572 CFU/m³ (range 50–1376 CFU/m³) and 130 CFU/m³ (range 56–260 CFU/m³), respectively. Oxygen remained stable at 20.6 vol.%, while methane concentrations were negligible (mean 2.5 ppm). Relative humidity varied between 25% and 55%. Identified microorganisms were dominated by human-associated bacteria (Staphylococcus, Micrococcus) and environmental fungi (Cladosporium, Penicillium), with noticeable differences between occupied and unoccupied rooms. Correlation analysis showed significant positive associations between CO₂ and bacterial load (ρ = 0.56, p < 0.05), as well as relative humidity and bacterial abundance (ρ = 0.67, p < 0.05). Species richness was negatively correlated with occupancy (ρ = –0.77, p < 0.01), indicating microbial homogenisation in crowded conditions. Multiple regression analysis identified CO₂ and relative humidity as significant independent predictors of bacterial load (p < 0.05). These findings highlight the importance of integrating microbial and physico-chemical monitoring in IAQ assessments. CO₂ and relative humidity emerged as key controllable indicators, offering practical targets for improving air quality and limiting microbial contamination in educational environments.

Single-occupant faculty offices remain underexplored in indoor environmental quality research, despite extensive studies on classrooms and open-plan offices. This study provides case-specific exploratory evidence on how spatial orientation and acoustic conditions influence thermal satisfaction in a LEED-Gold academic building. Offices were classified as street-oriented, corridor-oriented, or void-oriented based on their exposure to outdoor streets, internal corridors, or the central atrium. Over a 40-day summer period, temperature, relative humidity, and airspeed were continuously monitored, and daily surveys captured occupants′ thermal and acoustic perceptions. Three offices representing the three orientations were instrumented, and 12 faculty members participated. Corridor-oriented offices showed the warmest and most humid conditions, with mean values of 29°C and 74.6% RH, exceeding ASHRAE 55-2020 thresholds. Void- and street-oriented offices maintained more moderate conditions. A significant association between acoustic satisfaction and thermal comfort (ρ > 0.60, p < 0.05) was observed, suggesting that sensory dimensions may reinforce one another. Because of the small sample size (n = 12), all findings should be interpreted as exploratory. Even so, the results provide empirical evidence that spatial microclimates and acoustic perception shape comfort in high-performance educational offices. Practical implications include refining HVAC zoning, improving acoustic control, and strengthening occupant-centered post-occupancy evaluation strategies.

Despite growing concerns about both indoor air pollution and depression, research on their association remains limited. This study examined the association between exposure to indoor air pollutants and depression, using nationally representative data. We utilized 1685 participants based on the Eighth Korea National Health and Nutrition Examination Survey data (the 2020–2021 cycle). Indoor concentrations of PM_2.5, CO₂, formaldehyde (HCHO), total volatile organic compounds (TVOCs), and their components including benzene, toluene, ethylbenzene, xylene, and styrene were measured. Depression status was defined as self-reported physician-diagnosed depression during the period of residence at the time of the survey. We analyzed using multivariable logistic regression models adjusted for demographic and environmental covariates, seasonal factors, and a time trend. The prevalence of depression was 2.6%. The mean concentrations of indoor air pollutants excluding TVOC were higher in the depression group. Notably, increased exposure to PM_2.5 was significantly associated with depression (OR: 1.20, 95% CI: 1.04–1.37), as was TVOC exposure (OR: 1.08, 95% CI: 1.01–1.16). We also found the association between depression and benzene (OR: 2.32, 95% CI: 1.35–4.00), toluene (OR: 1.17, 95% CI: 1.04–1.30), and ethylbenzene (OR: 1.11, 95% CI: 1.02–1.20). Specifically, males and low-income groups were more susceptible to the association of PM_2.5, while high-income groups were more strongly associated with TVOC. Our study demonstrated differences in the association between indoor air pollutants and depression across exposure groups and types, providing important insights for public health interventions.

Previous studies on the associations between exposure to various indoor air pollutants, as well as coexposure to ambient and indoor air pollutants, and rhinitis are limited. Data from the Korea National Health and Nutrition Examination Survey (2020–2021) were analyzed (n = 1812). Ambient air pollutant concentrations were estimated using the Community Multiscale Air Quality model, while indoor air pollutant concentrations were measured in each household. Associations with the presence of rhinitis symptoms in the past 12 months (PRS) were examined using logistic regression models for individual ambient and indoor air pollutants, as well as for a composite exposure variable that combined ambient fine particulate matter (PM_2.5) and indoor total volatile organic compound (TVOC) concentrations (low–low, low–high, high–low, and high–high). Stratified analyses by household income were conducted using the same models. A doubling of ambient PM_2.5 concentrations over 1 year was associated with higher odds of PRS (odds ratio [OR] = 2.68, 95% confidence interval [CI]: 1.45, 4.78). A doubling of TVOC (OR = 1.08, 95% CI: 1.01, 1.16) and toluene (OR = 1.10, 95% CI: 1.02, 1.20) concentrations was associated with higher odds of PRS. Compared to the low–low group, other composite exposure groups had increased odds of PRS. These associations were more pronounced among individuals with lower income than among those with higher income. Ambient and indoor air pollution exposures were both individually and collectively associated with a higher risk of rhinitis symptoms among adults. Since this study used a cross-sectional design, further longitudinal studies are needed.

This study experimentally investigated the transport dynamics of exhaled aerosols, which may carry infectious pathogens, in a mixing-ventilated test room using three heated dummies as human simulators. Two dummies were seated at desks separated by a partition wall, while the third stood nearby. Each dummy acted as an infector one at a time, releasing test aerosols through a low-momentum horizontal jet simulating continuous mouth exhalation. Aerosol concentrations were monitored using 28 sensors to provide high-resolution data on aerosol spread dynamics. The mixing ventilation air change rates were 1.8 and 3.2 1/h, and additional measurements were conducted with an air cleaner in operation. CFD simulations revealed that particles from the low-momentum exhalation jet were deflected upwards by the dummy′s thermal plume and quickly mixed with supply air from a circular ceiling diffuser. The results showed that the exhaled particles reached the exposed person′s breathing zone within 20–100 s. Particle concentrations were relatively uniform throughout the room, indicating that a well-mixed approximation is suitable for estimating airborne infection transmission risk from indirect exposure in small spaces. Relative transmission risks were analysed under various conditions. While the partition wall delayed initial exposure, it had minimal impact on long-term risk. Air cleaners increased air mixing and reduced the delay between aerosol release and exposure, potentially elevating short-term risk. However, the long-term benefits of enhanced ventilation outweighed the initial increase in risk, reducing overall airborne infection transmission over extended durations.

Maintaining acceptable indoor air quality (IAQ) in kindergartens is essential for children′s health, cognitive development and staff well-being, yet it remains a persistent challenge. This study introduces an innovative dual-indicator framework for IAQ assessment that combines real-time monitoring of carbon dioxide (CO₂) and radon (Rn) with simulation-based modelling to evaluate and optimise ventilation strategies. Unlike CO₂ alone, which only indicates conditions during occupancy, Rn monitoring captures conditions before and at the start of occupancy, providing a more comprehensive assessment. Measurements were conducted for several months in two playrooms: P1, a modular steel unit with natural ventilation, and P2, a concrete structure with hybrid ventilation. During occupancy, CO₂ levels frequently exceeded health-based thresholds (405−2725 ppm, mean 1266 ± 537 ppm in P1; 405−1910 ppm, mean 865 ± 304 ppm in P2). Rn concentrations were highest before occupancy and declined gradually in the morning (2–386 Bq m⁻³, mean 99 ± 62 Bq m⁻³ in P1; 2–304 Bq m⁻³, mean 59 ± 49 Bq m⁻³ in P2), reflecting differences in airtightness and ventilation efficiency. Simulations categorised IAQ into four levels, with Category I representing optimal conditions. P2 achieved Category I or II for 59% of the time, compared to 28% in P1. Two advanced ventilation strategies were then simulated: constant air volume (CAV) and demand-controlled ventilation (DCV). Both reduced CO₂ and Rn below recommended thresholds, while DCV provided greater adaptability and achieved 17% lower ventilation heat losses than CAV. These results demonstrate the value of integrating dual-indicator monitoring with simulation tools to support data-driven, energy-efficient and health-focused ventilation strategies in early childhood environments.

In the context of climate change, the increase in frequency and intensity of heat waves, as well as air pollution, poses a challenge for environmental conditioning in buildings. This fact is of concern in schools given the special vulnerability of their occupants and the frequent energy-environmental gap of these buildings in southern Spain. The objective of this research is the assessment of different energy efficient ventilation and thermal conditioning systems in typical classrooms in warm Mediterranean climate. For this purpose, a predictive model capable of comprehensively assessing energy consumption, thermal comfort, and air quality is proposed. This model has been generated in TRNSYS and validated by analyzing discrepancies with monitoring data. The introduction of mechanical ventilation systems with heat recovery and simple mechanical ventilation supplemented with a novel evaporative cooling system, with limited implementation in schools, has been evaluated and compared. In addition, the reduction of energy consumption through the installation of a photovoltaic energy production system has been evaluated. The results show that the model is effective for the proposed comprehensive assessment including detailed analysis of indoor air quality. They also prove that the novel mechanical ventilation with evaporative cooling system achieves the best balance between thermal comfort, air quality, and energy efficiency, especially in climate change scenarios with less than 28.4% of school time in discomfort. Its integration with a photovoltaic energy installation, with an installed peak power between 0.45 and 1.35 kWp, would allow covering the ventilation and lighting energy demand, proposing itself as a viable, sustainable and replicable solution for schools in hot-dry climates.

Exposure to radon-222 (²²²Rn) and its decay products poses a significant public health risk. ²²²Rn tends to accumulate in poorly ventilated areas, underground spaces, and caves, which justifies the existence of international reference levels for its annual average indoor concentrations. This comparative study synthesizes findings, drawn from the published literature, from over 30 countries and identifies more than 30 environmental and structural factors influencing seasonal variation in ²²²Rn concentrations in both aboveground and underground buildings and environments. Five different methods for estimating annual averages using seasonal correction factors (SCFs) are critically reviewed. Due to the number and complexity of human-induced and environmental influences, seasonal fluctuations in ²²²Rn activity may be unpredictable and nonsinusoidal. The typical pattern observed in the Northern Hemisphere—elevated indoor ²²²Rn concentrations during autumn and winter—does not universally apply. Accordingly, SCFs should be locally derived and interpreted within the regional climatic and hydrogeological context. Correction factors developed for underground spaces should not be applied to aboveground buildings, and vice versa. In underground structures and caves, local air dynamics and geology can override temperature-driven ventilation effects. In aboveground structures, effective ventilation remains the key factor in reducing indoor radon levels. This study highlights the need for context-specific radon assessments and supports improved modeling and dose estimation practices.