Indoor air最新文献

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.

Ultraviolet germicidal irradiation (UVGI) as an engineering control against pathogenic microbes necessitates a clear understanding of operational parameters and environmental effects on inactivation rates. Here, we investigated the variation laws of ultraviolet-C (UV-C) irradiance under the influence of distance, ambient conditions of temperature, and relative humidity (RH) in a dark chamber using 30-W low-pressure mercury lamps, and all data were analyzed with curve fitting methods. UV-C irradiances in each plane were measured as the distance adjusting between 0.5 and 1.2 m, and a threshold of 70 μW/cm² was utilized to calculate the effective irradiation area. For the temperature and RH, UV-C irradiances were measured at 1 m perpendicular from the lamp axis at the lamp midpoint, with the ambient temperature increasing from 15.5°C to 40°C and RH adjusting from 10% to 97%. Results showed that the UV-C irradiance and effective irradiation area exhibited a notable decrease as the distance increased, both corresponded to polynomial 2nd order fits. The UV-C lamps operate at maximum efficiency at 20°C. Temperature above or below the optimum value will decrease UV output, especially when the ambient temperature exceeds 38°C and the irradiance decreases by 16% compared to the observed maximum. However, the impact of RH on radiant power is negligible with the UV-C irradiance maintaining an overall steady state (84–91 μW/cm²) in the 10%–97% RH range. The use of the measurement and modeling techniques demonstrated in this study may help understand various ambient conditions that influence the irradiance of UV-C and improve reliability and working performance of UVGI systems through better design.

Traffic-related air pollutants inside vehicle cabins are often extremely high compared to background pollution concentrations. The study of the determinants of these concentrations is particularly important for professional drivers and commuters who spend long periods in vehicles. This study is aimed at identifying and quantifying the effect of several exposure determinants on carbon monoxide (CO), equivalent black carbon (eBC), two particulate matter (PM) fractions (PM_0.3–1 and PM_1–2.5), and ultrafine particle (UFP) concentrations inside a passenger car cabin. The novelty of this work consists in examining the effects of the emissions of the first vehicle ahead (henceforth called “leading vehicle”) on pollutant concentrations inside the cabin of the following vehicle (i.e., the car that was equipped with the air monitoring devices), with particular emphasis on the role of the leading vehicle characteristics (e.g., emission reduction technologies). The real-time instrumentation was placed inside the cabin of a petrol passenger car, which was driven by the same operator two times per day on the same route in real driving conditions. The in-cabin ventilation settings were set as follows: windows closed, air conditioning and recirculation modes off, and the fanned ventilation system on. The measurements were conducted over a total of 10 weekdays during two different seasons (i.e., summer and autumn). A video camera fixed to the windscreen was used to retrieve information about traffic conditions and leading vehicle characteristics through careful video analysis. The associations among pollutant concentrations and their potential determinants were evaluated using generalized estimating equation univariate and multiple models. The results confirmed the significant impact of several well-known determinants such as seasonality, microclimatic parameters, traffic jam situations, and route characteristics. Moreover, the outcomes shed light on the key role of leading vehicle emissions as determinant factors of the pollutant concentrations inside car cabins. Indeed, in the tested cabin ventilation conditions, it was demonstrated that in-cabin pollutant concentrations were significantly higher with leading vehicles ahead (from +14.6% to +67.5%) compared to empty road conditions, even though the introduction of newer technologies with better emissions reduction helped mitigate their effect. Additionally, diesel-fuelled leading vehicles compared to petrol-fuelled leading vehicles were impactful on in-cabin CO (−7.2%) and eBC (+45.3%) concentrations. An important effect (+30.4%) on in-vehicle PM_1–2.5 concentrations was found with heavy-duty compared to light-duty leading vehicles. Finally, this research pointed out that road-scale factors are more important determinant factors of in-cabin concentrations than local pollution and meteorological conditions.

Aim: Environmental exposure constitutes a significant determinant in the pathogenesis of metabolic syndrome (MetS). Nevertheless, the contribution of environmental factors to MetS remains ambiguous. The present study was aimed at investigating the correlation between serum terpenes and the risk of MetS in the general population.

Methods: A cross-sectional study was conducted among 1266 individuals from the 2013–2014 National Health and Nutrition Examination Survey (NHANES). Serum terpenes and MetS risk were analyzed using a weighted logistic regression model. Weighted quantile sum (WQS) regression was utilized to explore the relationship between the mixture of serum terpenes and MetS. The restricted cubic spline (RCS) method was employed to assess the dose–response relationship between them. All data and analyses were conducted using the “Survey” package in R software (Version 4.3.2).

Results: The study population, with an average age of 46.82 ± 0.46 years and a body mass index (BMI) of 28.97 kg/m², consisted of 48.15% males and 67.99% Whites. Among the participants, 35.78% were diagnosed with MetS. The weighted logistic regression showed that tertiles of serum levels of α-pinene, β-pinene, and limonene were positively correlated with MetS risk with a OR value of 1.90 (1.14, 3.16), 2.02 (1.23, 3.31), and 2.35 (1.33, 4.13) and elevated triglycerides (TGs) with a OR of 2.36 (1.63, 3.43), 3.51 (2.30, 5.38), and 3.96 (2.55, 6.15) (all p_trend < 0.05). The WQS regression indicated a positive association between serum terpene mixture and MetS risk (OR = 1.65, 95% CI: 1.18–2.3), increased TG (OR = 2.69, 95% CI: 1.94–3.71), and reduced high-density lipoprotein cholesterol (HDL-C) (OR = 1.46, 95% CI: 1.03–2.07) (all p_trend < 0.01). The RCS analysis further supported the dose–response relationship.

Conclusion: This study suggested potential adverse effects of terpene exposure on human health, emphasizing the importance of environmental interventions in maintaining health.

Natural ventilation has become a focal point due to its positive impact on indoor air quality, expanding its role in addressing thermal comfort issues in schools. Despite previous studies exploring various approaches to enhance natural ventilation, factors such as classrooms facing non-windward directions and optimal window opening sizes have not been adequately considered. This lack of consideration poses challenges for implementation in school environments. To address this issue, this study employed response surface methodology, back-propagation neural network, and multiple linear regression to investigate the effects of different factors on natural ventilation. Experiments were conducted in classrooms facing nonwindward directions, measuring indoor air changes per hour (ACH) during peak noon temperatures. Thermal comfort was assessed using the predicted mean vote (PMV). The experimental results showed that single window openings provided better thermal comfort compared to cross window openings while maintaining indoor CO2 concentrations below 1000 ppm. Furthermore, subsequent analysis revealed that the opening size (open and open/gap) increases the range of ACH, suggesting avenues for future research to enhance natural ventilation practices. This underscores natural ventilation’s potential in maintaining indoor thermal comfort and CO2 levels under challenging conditions.

Carbon dioxide is an important parameter for indoor air quality (IAQ) monitoring and demand controlled ventilation (DCV). Usually, CO₂ sensors are wall-mounted at 0.9–1.8 m (3–6 ft) height as prescribed by LEED, although ASHRAE standards seemed to relax this requirement. In this work, we investigate whether positioning these sensors in the ceiling is effective and advantageous. We studied CO₂-level measurements for HVAC control in configurations with mixing ventilation and found that CO₂ from human exhalations experiences buoyancy from several factors. We calculated buoyancy from air properties, and we introduced the notion of “stratification temperature” for exhaled air. By simulation, we test the sensitivity to temperature, and we conducted in situ in vivo measurements to acquire more detailed insights in the feasibility of ceiling sensor positions. Buoyancy calculations show that in exhaled air, the positive buoyancy of H₂O approximately compensates for the negative buoyancy of CO₂, so that thermal buoyancy is the most dominant factor. Exhaled air, containing CO₂ to be measured, will rise towards a ceiling that has a temperature below the stratification temperature. Computational fluid dynamics (CFD) simulations of a small office space indicate that this can also be the case in the presence of air flows induced by a mechanical ventilation system. The measurement results support that using “properly mounted” CO₂ sensors in the ceiling gives lower variability in CO₂ measurements and faster response than wall-mounted sensors and yields slightly higher values than wall sensors. Our results highlight the need to update the standards and regulations for sensing CO₂ to include ceiling-mounted sensors.

This study addresses the critical issue of indoor air quality (IAQ) and pathogen transmission within enclosed spaces at high altitudes, focusing on university classrooms in Quito, an Andean city in South America. The aim is to establish safety thresholds for room occupancy and permissible durations of exposure, tailored to this unique environmental context. Through an experimental approach conducted at an elevation of 2900 m above sea level, various natural ventilation strategies were evaluated for their efficacy in mitigating pathogen transmission risks. The study employs the Concentration Decay Test Method to characterize air changes per hour (ACH) and utilizes the Bazant mathematical model to predict occupancy levels based on ventilation, dimensions of the room, respiratory activity, infectiousness rates, and other parameters. Findings highlight the significant impact of ventilation strategies on room occupancy. Notably, higher infectiousness rates and large exposure times drastically reduce permissible occupancy levels, underscoring the importance of effective ventilation in maintaining safety. This research contributes valuable insights for informed decision-making regarding classroom capacity and safety protocols in Andean higher education settings.

In order to explore the effects of constant and altered workload sequences on mental fatigue in a thermoneutral environment, experiments and surveys were carried out in this study. n-back tasks were used to design different workload sequences. Fifteen healthy right-handed males were required to experience three different workload sequences for 30 min, respectively, including a constant workload (2-back task) and 2 altered workload sequences that contained an elevating workload sequence (1-2-3-back tasks) and a reducing workload sequence (3-2-1-back tasks). The PANAS, VAS-F, and NASA-TLX scales were selected to investigate changes in the mood, the perceived fatigue, and the perceived workload. Meanwhile, the skin temperature during these three workload sequences was continuously collected. Results from the NASA-TLX scale indicated that no significant difference in total workload was observed among all three workload sequences. Meanwhile, results from the VAS-F scale showed that no significant changes in self-reported mental fatigue were observed among these three workload sequences, which meant that mental fatigue was only related to the total workload. However, self-reported “energy” from the VAS-F scale did not reduce significantly during the reducing workload sequence, which meant that the reducing workload sequence could conserve more “energy” than that of the elevating and constant workload sequences. Furthermore, both positive and negative moods changed significantly under the constant workload sequence (2-back task), but they did not show much changes under altered workloads, which meant that the altered workload sequence could attenuate the mood deterioration. What is more, the mental demand, physical demand, temporal demand, effort, and the total workload increased significantly after both the constant workload and elevating workload sequence, but no significant changes in all these six items of the NASA-TLX scale were observed under the reducing workload sequence. Finally, the mean skin temperature under the constant workload sequence was lower than that under the altered workload sequences (p > 0.05), but significant changes in skin temperature at the left hand and neck were only observed between the constant and reducing workload sequences. In conclusion, constant and altered workload sequences contributed equally to the mental fatigue in a thermoneutral environment, but the differences in workload sequence produced some differences in mood, energy, and mental demand, which would affect the working performance. Findings of this study provided implications for the proper planning, assignment, and management of tasks in real working settings.