Indoor air最新文献

Researchers and transnational public health organizations have recognized aerosol transmission as an essential route of COVID-19 transmission. Therefore, improving ventilation systems is now adopted as a core preventive measure. As young children aged 2–6 in kindergartens generally lack vaccine protection and multiple infection clusters have been identified during the pandemic, we aimed to quantify the risk of aerosol transmission in kindergartens in Taipei, Taiwan. From August to November 2021, we conducted on-site visits and continuously monitored indoor air quality indicators including carbon dioxide (CO₂) in a kindergarten located in northern Taiwan. We utilized the Wells–Riley model to estimate the basic reproduction number (R₀) of each classroom and staff office, with input parameters including the number of occupants, duration of their stay, and indoor/outdoor CO₂ concentration. Contagious settings were defined as those where the R₀ estimate exceeded 1. We conducted a scenario/sensitivity analysis to assess the effect of simulated improvement measures. During school hours, the average concentration of CO₂ in each classroom and the staff office was often more than 400 ppm higher than the outdoor levels. The R₀ estimates gradually increased from Monday to Friday and throughout school hours, corresponding to the hourly and daily distribution of the CO₂ concentration, which could not dissipate completely during off-duty time. The R₀ estimates during school hours ranged from 3.01 to 3.12 in classrooms with a maximum of 30 occupants. To lower the R₀ estimate, it is imperative to substantially reduce the number of occupants, the duration of their stay, and indoor CO₂ concentration. The risk of outbreaks of cluster infections in kindergartens should not be underestimated. Feasible strategies to mitigate this risk should include improving ventilation systems through engineering control and limiting the number of indoor occupants and their time staying indoor through administrative control.

The COVID-19 pandemic has prompted renewed interest in indoor air quality (IAQ). Poor ventilation habits, energy obsolescence, and the lack of cooling equipment in schools, combined with increasing temperatures due to climate change, are leading to situations of thermal stress in classrooms. Changes in school operation, following the COVID pandemic, have made it necessary to establish an accurate understanding of the current situation. This research work presents an assessment of winter and summer IAQ and thermal comfort (TC) for a sample of 7 archetypal secondary schools in 5 Mediterranean climate variants in southern Spain in a postpandemic situation. IAQ was assessed through CO₂, PM2.5, PM10, and CH₂O, while static and adaptive models were used in the case of TC. Surveys were also used to assess both of these. The main novelty is the use of IAPI (indoor air pollution index) and IDI (indoor dissatisfaction index) objective global dimensionless indices to optimize the joint assessment of both variables. Poor objective IAQ results, especially for CO₂ and PM2.5, were obtained for both seasons and all climate variants. Global IAPI is between 6.2 and 8.1, with an index of 10 considered unacceptable, while time percentages exceeding established limits are more variable in winter, ranging from 7% to 31.9%, than in summer, ranging from 14.3% to 20.9%. TC objective results varied, and the summer percentage of hours outside the comfort bands reached 40%–47% due to excess heat in the hottest regions. This discomfort was reported by 58.3% of users.

We introduce the holographic air-quality monitor (HAM) system, uniquely tailored for monitoring large particulate matter (PM) over 10 μm in diameter—particles critical for disease transmission and public health but overlooked by most commercial PM sensors. The HAM system utilizes a lensless digital inline holography (DIH) sensor combined with a deep learning model, enabling real-time detection of PMs with greater than 97% true positive rate at less than 0.6% false positive rate and analysis of PMs by size and morphology at a sampling rate of 26 L/min for a wide range of particle concentrations up to 4000 particles/L. Such throughput not only significantly outperforms traditional imaging-based sensors but also rivals some lower-fidelity, nonimaging sensors. Additionally, the HAM system is equipped with additional sensors for smaller PMs and various air quality conditions, ensuring a comprehensive assessment of indoor air quality. The performance of the DIH sensor within the HAM system was evaluated through comparison with brightfield microscopy, showing high concordance in size and morphology measurements. The efficacy of the DIH sensor was also demonstrated in two 2-h experiments under different environments simulating practical conditions, with one involving distinct PM-generating events. These tests highlighted the HAM system’s advanced capability to differentiate PM events from background noise and its exceptional sensitivity to irregular, large-sized PMs of low concentration.

This study investigates the adoption of indoor air quality (IAQ) management technologies in Germany and Portugal, focusing on the common and differentiating factors influencing individuals’ motivations and the perceived health impacts of these technologies. Utilizing a model based on the protection motivation theory, we surveyed 800 participants (400 from each country) to understand how their perceptions of the risks associated with poor IAQ and their evaluations of the effectiveness and costs of technologies like air purifiers and sensors drive the adoption intention of these technologies and well-being of individuals. To estimate the complex relationships in our model, we employed partial least squares structural equation modeling (PLS-SEM). Our model explains nearly 50% of the variance in well-being for both countries. The results revealed significant differences in the factors driving technology adoption: Germans are primarily motivated by individual efficacy and personal responsibility with the people close to them. Regarding the similarities, participants from both countries value the technology’s effectiveness in improving IAQ and do not see being vulnerable to health issues derived from poor IAQ as a motivator. These insights highlight the need for strategies that are tailored to specific cultural and national contexts to promote the adoption of IAQ management technologies, aiming to enhance IAQ and public health outcomes.

Air exchange rate is a key determinant of indoor air quality which is highly variable within the rooms of a naturally ventilated terraced house (townhouse). Window opening can increase the air exchange rate, but internal door opening between rooms inside decreases the rate. Inert perfluorocarbon gas-phase tracers demonstrated flow within the house, and the penetration of tracers released outside into the house showed a strong dependence on wind speed and wind direction. Between experiments, it was found that the tracer could be detected within certain parts of the house weeks after the initial release, with implications for pollutants and their impact on the indoor environment. A limited number of reactive tracer experiments suggested an upper limit for indoor [OH]~1 × 10⁵ molecule cm^-3 with up to 0.5 ppt of [NO₃] estimated, leading to an estimated indoor lifetime for d5 isoprene of many hours. Ultrafine particulate matter generated in the kitchen travels throughout the house, and the persistence of elevated aerosol concentrations is seen even in well-ventilated rooms, with implications for particle exposure in the evening and during the night.

Detailed investigation of pathogen transmission by respiratory droplets requires extensive experimental datasets with high spatial–temporal resolution in a wide range of ambient conditions. Respiratory simulators are attractive tools for those measurements, because they improve repeatability, endurance, and control of experimental conditions with respect to studies on human subjects. They also enable the use of powerful experimental techniques, which may raise health concerns if employed on humans. In this paper, we design and present a respiratory simulator, which is capable of accurately reproducing physiological flow rate profiles and allows the investigation of the spatial and temporal features of the exhaust flow by background-oriented schlieren (BOS) and particle image velocimetry (PIV). We use laser interferometry and high-magnification shadowgraphy to verify the size distributions of the emitted droplets, and we quantify the evolution of the droplet concentration during cough events by Mie scattering analysis. The experiments demonstrate the ability of the respiratory simulator to generate highly reproducible cough events with precise and controllable droplet size distributions over a wide range of flow rates.

Background: The COVID-19 pandemic has triggered a renewed interest in indoor air sampling for infectious disease surveillance. However, scalability is currently limited, as samples are usually collected in a single indoor space. An alternative is to place the device within a heating, ventilation, and air conditioning system (HVAC), but this approach has not been tested against room air sampling.

Methods: In this observational study, we sampled the air in an indoor fitness centre for 2 or 6 h, simultaneously in three locations of the main exercise hall and in the return plenum of the HVAC system. Samples were collected twice weekly for 11 weeks. All samples were tested for 29 respiratory pathogens using PCR. We compared the ventilation system and exercise hall air with regard to the presence and quantity of pathogens.

Findings: Samples collected in two locations in the exercise hall had a similar overall sensitivity to the HVAC sampler for detecting pathogens, while a third sampling location was associated with significantly lower sensitivity. Overall, the pathogen concentration was similar in the ventilation system and the exercise hall air (ratio: 1.0; 95% CI: 0.8–1.3).

Interpretation: Our results show that air sampling within a ventilation system can have equal sensitivity for detecting respiratory pathogens, compared to room-based sampling. Thus, placing samplers within central ventilation systems could increase the scalability of air sampling for infectious disease surveillance.

The quality of the internal microclimate is a very important issue nowadays, considering that people in developed societies spend a good part of their day inside buildings and means of transport. But the poor quality of indoor air has a double effect; on the one hand, it can harm human health, and on the other hand, it can cause the degradation of materials. Thus, the current study considers the potential influence of a number of 20 pollutants on the exhibits, visitors, and employees of a synagogue that is over 140 years old in the Municipality of Oradea (Romania), which today is included in the list of historical monuments and is open to be visited. The monitoring period consisted of 9 months, during which parameters such as temperature, relative humidity, CO concentration, light intensity, concentration of particulate matter, and other pollutants were monitored. All the obtained values were then reported to the international standards in force for each indicator, both regarding the potential for human health and the integrity of the exhibits. The results indicate that the values of most pollutants respect the allowed thresholds, with more or less permitted exceptions. The most problematic are the values of temperature, relative humidity, HCHO, and VOC, which substantially exceed the allowed limits and vary a considerable difference. This can induce additional stress on the exhibits, leading over time to damage and premature aging; in terms of human health, the indoor microclimate can, in rare cases, cause discomfort associated with headaches, dizziness, and irritation, but the potential to cause persistent ailments is quite low. To maintain a clean internal microclimate, preventive conservation through the continuous monitoring of internal parameters as well as the establishment of long-term strategies to stabilize the values of pollutants are necessary actions.

Household cleaning products (HCPs) are widely used; however, their airborne emissions and hazards have not been thoroughly studied. This study is aimed at evaluating the concentrations of volatile organic compounds (VOCs) and metals present in HCPs and the hazards associated with them. A total of 23 VOCs and 19 metals from 75 HCPs (four spray types and 14 intended usage categories) were analyzed using gas chromatography–mass spectrometry and inductively coupled plasma-mass spectrometry/optical emission spectroscopy. The largest number of VOCs (21 of 23 ingredients) were detected in spray-type and had the highest frequency (176). d-Limonene was found in almost all products (69 of 75) and had the highest concentration. Benzene, a carcinogen, was detected in six spray-type products. Only three of the 23 VOCs—d-limonene, ethyl acetate, and heptane—appeared in three, one, and one product labels, respectively. Eight of 19 metals were primarily detected in spray-type and spray foam-type products, with sodium, magnesium, and calcium as the main components. Nickel, another carcinogen, was detected in both spray-type and trigger-type products. Caution is required when using spray-type products, especially sticker/glue/tar/oil removers containing benzene and nickel. The study discovered that the VOCs and metals varied by their spray type and lacked sufficient harmful information.

Since most people spend more time at work in recent times, this has led to more workplace issues and health problems. The well-being of occupants and their overall health are strongly impacted by factors that determine the standard of indoor environments. These factors include the air quality, the level of thermal comfort, the inclusion of indoor plants, the admission of daylighting, and a variety of other factors. The absence of any of these may result in sick building syndrome (SBS). Therefore, well-planned indoor workspaces are vital for occupants’ health and productivity at work. The aim of this article is to investigate proactive measures for mitigating SBS in office buildings located within universities in the United Kingdom. The study administered a questionnaire to gather perceptions of office occupants, followed by a comparative case study analysis of two office buildings at the University of Greenwich located on different campuses to highlight the correlation among the physical parameters of indoor office spaces and the occurrence of SBS. The results showed that a notable percentage of participants reported experiencing at least two symptoms of SBS. This study provided clear evidence that symptoms of SBS are primarily associated with the physical characteristics of the building, and these elements significantly influence the occupants’ experiences. The mitigation of potential adverse effects on the well-being of inhabitants during the operating phase of a building resulting from physical variables can be achieved by the implementation of conscious design considerations during the initial planning stages of future buildings. One of the practical implications of this study is that it raises the urgency for built environment professionals to be fully aware of how their design decisions could either contribute to or prevent SBS symptoms.