Indoor air最新文献

Throughout the COVID-19 pandemic, several cases of infection associated with elevator rides have been reported. To systematically assess the risk of droplet transmission in an elevator, this study employed computational fluid dynamics (CFD) together with a modified stochastic dose–response model to quantify the infection risk for occupants. Simulation is conducted during a 2-min elevator ride for two individuals facing each other, without considering mask-wearing. Various factors such as ventilation outlet position, ventilation rates, air temperature, relative humidity, ventilation techniques, breathing patterns, and body types have been analyzed in order to assess the inhalation risks for occupants. Their infection probabilities for different viral strains are also considered. The findings highlight the effectiveness of the top-to-bottom ventilation approach. Nasal breathing has risk-reducing benefits, and ventilation rates of 30–50 air changes per hour (ACH) play an important role in reducing the risk of infection. Moreover, the study further reveals that air curtain systems outperform side ventilation. Temperature, relative humidity, the infected individual’s breathing behavior, and the body types between infected and exposed individuals are shown to exert various degrees of influence on droplet transmission.

The rapid deployment of emergency tents for airborne disease containment necessitates effective and sustainable approaches. This study introduces an innovative emergency tent prototype, developed within the INITIATE² project by WFP and WHO, that leverages natural ventilation to mitigate airborne transmission risks when humanitarian tents are deployed in response to epidemics. The tent features a two-zone design with a transparent barrier separating the patient area from the healthcare operator zone and exploits a suitable airflow path to reduce cross-contamination. In order to overcome the constraints imposed by the logistic of the on-site measurements, a novel asynchronous single-gas tracer decay methodology combined with a multizone gray box model was developed, enabling both on-site experimental testing of ventilation effectiveness and estimation of airborne pathogen concentrations for infection transmission risk analysis. This approach allowed for the quantification of interzonal exchanges and ventilation rates under various window configurations, simulating different natural ventilation regimes. Multiple ventilation scenarios were evaluated, revealing that partial windows opening (Scenario 2, with Scenario 1 being windows closed) optimized airflow, achieving up to 15 air changes per hour (ACH), a value aligned with CDC and WHO guidelines. Instead, fully open windows (Scenario 3) increased the ACH in the patient area but compromised, to a certain extent, the containment of the pathogens in the healthcare operator zone. Results highlighted, for all the tested scenarios, an unintended air recirculation between the patient and the doctor zones. While the gray box model effectively estimated flow rates across scenarios, it encountered limitations at ACH > 20 due to the photoacoustic equipment’s sampling constraints. The relatively slow acquisition time impacted on the data accuracy during rapid decay phases, where ventilation time constants were on the order of minutes. The design of the transparent barrier reflects a deliberate trade-off between airtightness and operational functionality, with the field methodology enabling an evidence-based assessment of its performance. These findings emphasize the need for refined airflow management and highlight the potential of natural ventilation in emergency healthcare settings. Future research directions include the development of high sampling rate, multigas, and multipoint monitoring tools, as well as enhanced tent designs that improve airtightness of the transparent barrier.

Experienced temperatures significantly affect the health of older adults due to irreversible physiological declines. In heat exposure studies, temperature measurements in specific spaces cannot fully capture individuals’ thermal experience in daily life, as people naturally and actively move between spaces with distinct thermal environments. The dynamic temperature experienced by rural older individuals in complex daily lives remains unclear, which is crucial for understanding its impact on health. This study discusses the concept of individual experienced temperatures (IETs) and investigated the characteristics and patterns of older adults’ IET in rural China during winter. A new method and equipment for longitudinal and noninvasive IET monitoring were developed and collected 157,800 IET data points, which were organized into 362 valid datasets. The data was gathered in China’s cold climate zone and hot summer cold winter (HSCW) climate zone from December 2023 to February 2024. The results revealed that local climate and weather had a significant impact on older adults’ IET. Cold waves reduced IET, while the effects were alleviated by thermal adaptation behavior of older adults. Diurnal IET was categorized into three patterns (stable group, active group, and moderate group) using K-means clustering analysis. The “stable group” was characterized by frequent IET fluctuations within a narrow and low temperature range. The “active group” was characterized by drastic IET fluctuations and high diurnal temperature range. The “moderate group” was characterized by low fluctuation frequency. For each participant, the majority of diurnal IET concentrated in one or two patterns. The IET of older adults exhibited significant individual variation. This research also discussed the significance of IET in comparison to traditional heat exposure studies. It highlights the dynamic and individualized nature of people’s heat exposure, contributing to the body of knowledge in this field. Furthermore, it provides greater accuracy and robustness in the result when assessing the health risks associated with exposure to varying temperatures. Recommendations for IET improvement were proposed from the perspectives of built environment optimization and policy support.

Indoor air quality is a significant aspect of public health, yet it remains less studied than outdoor air pollution. Understudied indoor pollutants include volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). This review focuses on these two groups of compounds known for their health effects, including respiratory issues, neurological disorders, and carcinogenicity. We systematically compiled and analyzed data from studies reporting measured concentrations of VOCs and PAHs in European indoor environments—homes, schools, and offices—published in the past two decades. Concentration levels vary substantially across studies, influenced by regional differences, climate, building type, ventilation systems, and indoor activities. Identified sources include tobacco smoke, cooking, heating (e.g., biomass burning), and off-gassing from construction and furnishing materials. Our analysis reveals clear geographic patterns: lower concentrations of VOCs and PAHs are consistently reported in Northern and Western European countries, likely due to stricter air quality regulations, cleaner outdoor air, greater use of electric heating, and more advanced ventilation systems. Conversely, higher concentrations are more commonly observed in Southern and Eastern Europe, where biomass heating and poorer ventilation remain more prevalent. Seasonal variation also has a significant role, with higher indoor levels typically measured during colder months due to increased heating and reduced air exchange. This highlights the need for improved indoor air quality management practices and regulatory standards to minimize the health risks associated with VOCs and PAHs. This review of 46 scientific publications is aimed at informing future studies and guiding future field measurements and risk assessments in epidemiological studies.

In the contemporary context of lifestyles, where individuals typically spend around 90% of their lifetimes indoors, indoor air quality becomes a crucial concern with implications for human health. This research examines ethylbenzene concentration in residential and educational buildings, evaluating associated risks. Extensive searches of databases such as Science Direct, PubMed, and Springer were conducted, encompassing data from inception to April 13^th, 2023, focusing on English-language sources. Search terms contained “BTEX,” “Indoor,” “Cigarette,” “Waterpipe,” “Shisha,” “Hookah,” “Tobacco,” and “ETS”. Thirty-one studies were deemed eligible for analysis. Time-series analysis does not show significant trends for ethylbenzene in both indoor and outdoor environments over years. However, ethylbenzene concentrations in residential buildings generally exceeded those in schools (7.49 ± 9.86 vs. 4.67 ± 7.81  μg/m³). Moreover, smoking within residential buildings correlated with higher ethylbenzene concentrations compared to nonsmoking environments (17.75 ± 18.96 vs. 7.16 ± 7.79  μg/m³). Additionally, indoor ethylbenzene concentrations surpassed outdoor concentrations. The calculated cancer risk for all studies related to residential buildings, across genders and age groups, and schools in Group 3, exceeded the established permissible limit (i.e., 10⁻⁶). Conversely, the calculated hazard quotient for all studies remained below the permissible limit (i.e., 1).

Wholesale traditional markets (WTMs) have established the most comprehensive and advanced auction systems for fresh seafood, meat, and fruits. Understanding the levels of bioaerosols of different sizes in WTMs can help to develop strategies to reduce the spread of infectious diseases. This study was aimed at analyzing and comparing the size distributions of culturable airborne bacteria (AB) and airborne fungi (AF) in a typical wholesale traditional fish market (WTFM). The AB and AF concentrations in the WTFM were relatively both high during and after the operation. The average AB concentration significantly increased from 4.73 × 10³ during operation to 8.58 × 10³ CFU/m³ after operation. The highest concentration of AB was observed at the fourth stage (2.1–3.3 μm), accounting for 26.22% and 28.15% of the total AB measured during and after operation, respectively. The average AF concentration remained steady from 2.77 × 10³ during operation to 2.53 × 10³ CFU/m³ after operation. The fourth stage also showed the highest AF concentration postoperation, comprising 35.47% of the total AF measured. Particles in this size range can be easily inhaled and deposited in the bronchial tubes, posing significant health risks. This study identified four and two types of possible pathogenicity in dominant AB and dominant AF, respectively. Commonly pathogenic Flavobacterium spp. frequently found in seafood and the highly pathogenic AF species Aspergillus tamarii and Aspergillus ochraceus were also detected. These pathogens and ultrafine biological aerosols (< 1 μm) can induce respiratory conditions such as aspergillosis. Based on these findings, the WTFM management should implement targeted interventions to reduce the concentration of harmful particles.

Initiatives abound for improving energy efficiency in existing dwellings stock, yet the impact in their indoor thermal comfort conditions, postretrofit performance, and comfort levels are insufficiently explored. Studies that evaluate this parameter, enabling the validation or adjustment of current policies of retrofit actions, would be essential. Thus, this paper details the thermal monitoring and behaviour of a sample of 92 dwellings with a homogeneous user profile, with the aim of identifying thermal and comfort patterns. For this purpose, continuous long-term monitoring is proposed for the comparative analysis of time series data for different climatic periods, instead of complex and individual data collection in situ. In order to correlate the envelope’s thermal behaviour, buildings are characterised in terms of building typology and construction period, after which occupant behaviours are examined via questionnaires on self-reported thermal sensations and adaptive actions. Key results point to a lack of relationship between the building typology and construction period and thermal performance, even after the implementation of energy efficiency improvement measures. Additionally, thermal comfort was found to be intermittent, albeit more present in winter than summer, with a marked heterogeneity when it comes to individual habits. These facts indicate that it is necessary to include additional thermal performance driving factors for determining practical comfort implications and characterising its correlation with energy efficiency.

We provide a systematic review of the literature on computational fluid dynamics (CFD) in the cleanroom sector. The objective is to provide simulation engineers with an overview of studies in the field of cleanroom simulation, as well as to identify the most commonly used simulation parameters. Our findings indicate a persistent preference for the k − ε model for turbulent flow situations, although recent studies suggest a shift toward more sophisticated models, such as the RNG k − ε and SST k − ω. This reflects advancements in the available computational power made in the past years. Our analysis of particle tracking models indicates a clear preference for the Euler–Lagrange method over the Euler–Euler method. Moreover, the analysis of inlet models used indicates that geometrically resolved diffusers are preferred over simplified models. As every simulation study requires proper validation, full-scale experiments are clearly preferred in the reviewed studies. A best practice guide is distilled out of previous studies to provide a meaningful starting point for future CFD studies in the cleanroom sector.

Tobacco smoke is a significant contributor to indoor air pollution and poses serious health risks. This study surveyed the levels of polycyclic aromatic hydrocarbons (PAHs) in smoker household dust and the association between PAHs in dust and symptoms of sick building syndrome (SBS). Sixty samples of settled household dust (20 samples from homes with waterpipe smoker, 20 samples from homes with cigarette smoker, and 20 samples from smoke-free home as control group) were collected from Bandar Abbas City. Two residents of each home, who did not smoke, also completed a survey about SBS symptoms. The concentrations of PAHs were determined using gas chromatography–mass spectrometry (GC-MS). The average ΣPAH concentrations were 1039.66 ± 75.37, 917.51 ± 63.15, and 330.08 ± 58.22 ng/g in dust samples from homes with waterpipe smokers, homes with cigarette smokers, and smoke-free homes. In waterpipe and cigarette smoker homes, a significant relationship was observed between the ΣPAHs levels and reports of headache, skin dryness, skin itching, dryness and inflammation, and abnormal fatigue. The cancer risk of exposure to PAHs via household dust in adults and children based on home groups was waterpipe smokers residents > cigarette smokers > nonsmokers. Total cancer risk from PAH exposure in all three home groups was higher than 1.00E − 4. Multidisciplinary cooperation and participation, including tobacco control, environmental science, medicine, and health promotion, are needed for the effectiveness of management strategies to have a sufficient understanding of the routes of exposure, mechanisms of damage, and identification of vulnerable groups and how to control exposure.

To characterize the air and contaminant transport from an attached garage to a living space in a multizone residential building, a novel mathematical regression model is proposed in this paper to estimate the transport rate and time and interpret the measurement results from a single tracer gas decay test. Unlike conventional contaminant/tracer gas experimental methods, which only characterize air/contaminant transport by comparing the average or highest concentrations of contaminant/tracer gas measured in the release zone and the target zone, this proposed model establishes a mathematical relationship directly between the two tracer gas concentrations, with the air transport rate and time factored into the coefficients of the model equations. Thus, the air/contaminant transport rate can be explicitly and empirically estimated from the data of the tracer gas concentrations measured during a simple tracer gas decay test without extra experimental requirements. The effectiveness of the model is verified with a few application examples showing its goodness of fit to the measured data from tracer gas decay tests in several occupied residential buildings. The proposed method can be practically used to estimate the air/contaminant transport rates and overall transport time from a single source zone to each target zone in a multizone building when all the underlying interzonal airflows are relatively constant and have minimal disturbances.