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In response to the global impact of the COVID-19 pandemic, international and national authorities, including those in Catalonia (Spain), recognized the crucial need to ensure proper ventilation in classrooms, emphasizing the importance of safe and healthy indoor environments for face-to-face learning. The present work, conducted within the COVID-19 Sentinel Schools Network of Catalonia (CSSNC) framework, aimed to monitor carbon dioxide (CO 2 ) and nitrogen dioxide (NO 2 ) concentrations in 23 schools, ensuring a comprehensive sample regarding educational levels, daily scholar schedules, and classroom typologies distributed across the four provinces of Catalonia. The research spanned three study periods: March and April 2021, October 2021 to January 2022, and March to June 2022. Briefly, 28%, 25%, and 37% of classrooms surpassed the 700 parts per million (ppm) CO 2 limit in each study period, respectively. Generally, CO 2 averages were lower in preschool classrooms (mean ± SD = 486 ± 106 ppm), while high school classrooms displayed the highest CO 2 concentrations (mean ± SD = 710 ± 253 ppm). Moreover, classrooms in towns (<30000 inhabitants) exhibited higher CO 2 levels as compared to classrooms from schools located in cities. As for NO 2 , the highest averages were obtained in urban areas, particularly in the Barcelona metropolitan area (e.g. mean indoor levels of 24.56 μg m -3 as compared to 11.05 μg m -3 in towns). In addition, the Indoor/Outdoor ratio (I/O ratio) in towns was the lowest (0.60). These results, together with the higher concentration of CO 2 indoors, could indicate poorer ventilation in town schools. The results of this study are anticipated to contribute to implementing evidence-based measures to improve indoor air quality (IAQ) in educational settings., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jordi Casabona reports financial support was provided by Government of Catalonia. Mireia Gascon reports financial support was provided by Miguel Servet Fellowship. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Health and safety considerations of indoor occupants in enclosed spaces are crucial for building management which involves the strict control and monitoring of carbon dioxide levels to maintain acceptable air quality standards. For this study, we developed a wireless, noninvasive, and portable platform for the continuous monitoring of carbon dioxide concentration in enclosed environments, i.e., academic rooms. The system aimed to monitor and detect carbon dioxide using novel low-cost metal oxide-based chemoresistive sensors, achieving sensing performance comparable to those of commercially available detectors based on optical working principle, e.g., nondispersive infrared sensors. In particular, a predictive study of carbon dioxide levels was performed by exploiting random forest and curve fitting algorithms on chemoresistive sensor data collected in an academic room, then comparing the results with lab-based measurements. The performance of the models was evaluated with real environment conditions during 7 weeks. The field measurements were conducted to validate and support the development of the system for real-time monitoring and alerting in the presence of relevant concentrations (above 1,000 ppm). Therefore, the study highlighted that the curve fitting model obtained was able to recognize with an F -score of 0.77 the presence of poor air quality, defined as concentration above 1,000 ppm of carbon dioxide as reported by the Occupational Safety and Health Administration.1 -score of 0.77 the presence of poor air quality, defined as concentration above 1,000 ppm of carbon dioxide as reported by the Occupational Safety and Health Administration.

High-quality indoor air is essential in open-kitchen restaurants for ensuring a healthy workplace and comfortable conditions for visitors. In this study, indoor air quality interdependence between the kitchen and the dining zones in open-kitchen restaurants was analyzed. The method was based on measurements of selected air parameters using a sensor technique and mutual information (MI) analysis. A long-term approach (based on a several-hour time series) and a short-term approach (based on a several-minute time series) were applied. This study involved four open-kitchen restaurants. The indoor conditions were represented by the temperature, relative humidity, CO 2 concentration, and content of the total volatile organic compounds (TVOC) in the air. The MI analyses showed that the long-term co-dependence of the indoor conditions between the kitchen and the dining zones was smaller during business hours (MI = 0.12 ÷ 0.40) compared to night hours (MI = 0.24 ÷ 0.58). The ranking of the long-term MI values for the individual air parameters was MI CO2 (0.34) ≅ MI T (0.34) > MI RH (0.28) > MI TVOC (0.23) . The short-term interdependencies were smaller during night hours (median MI = 0.01 ÷ 0.56) compared to business hours (MI = 0.23 ÷ 0.61). Additionally, the short-term MI was subject to high temporal variability. The ranking of the short-term MI values for the individual air parameters was MI CO2 (0.48) > MI T (0.46) > MI RH (0.37) > MI TVOC (0.26). Due to the weak and highly variable co-dependence of the air parameters between the kitchen and dining areas, multi-zone monitoring of air parameters with an emphasis on TVOC measurements is recommended to ensure proper indoor conditions in open-kitchen restaurants. The presented approach may be applied to design indoor air quality monitoring and ventilation systems not only in open-kitchen restaurants but also in other interiors with functionally different zones.

Phytoremediation technology is an effective method to remove formaldehyde indoors, but the purification capacity and physiological response of plants to formaldehyde under the simultaneous influence of light and CO 2 have not been examined in previous studies. In this study, formaldehyde fumigation experiments were conducted on the C 3 plants Epipremnum aureum A. and Chlorophytum comosum L., and the crassulacean acid metabolism (CAM) plant Dieffenbachia maculate A. The phytoremediation performance and physiological response of plants were studied. The initial concentration of formaldehyde was established at 11.950 ± 1.442 [Formula: see text]; the light intensities were 448 ± 7 [Formula: see text], 1628 ± 22 [Formula: see text], and 3259 ± 22 [Formula: see text], respectively; and the concentrations of CO 2 were 455 ± 29 [Formula: see text], 978 ± 50 [Formula: see text], 2020 ± 66 [Formula: see text], and 3006 ± 95 [Formula: see text], respectively. The results indicated that the highest purification rates of formaldehyde by E. aureum, D. maculata, and C. comosum were 55.8%, 43.7%, and 53.2%, respectively. The light intensity had a positive effect on the formaldehyde purification rates of all three plants and positively stimulated peroxidase (POD) activity, while the CO 2 concentration had no significant impact on the formaldehyde purification capacity and plants' physiological characteristics. Exposure to formaldehyde inhibited formaldehyde dehydrogenase (FADH) activity and positively stimulated catalase (CAT) activity. The superoxide dismutase (SOD) activity positively correlated with the formaldehyde purification capacity of plants., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

It is important for dental care professionals to reliably assess carbon dioxide (CO 2 ) levels and ventilation rates in their offices in the era of frequent infectious disease pandemics. This study was to evaluate CO 2 levels in dental operatories and determine the accuracy of using CO 2 levels to assess ventilation rate in dental clinics. Mechanical ventilation rate in air change per hour (ACH VENT ) was measured with an air velocity sensor and airflow balancing hood. CO 2 levels were measured in these rooms to analyze factors that contributed to CO 2 accumulation. Ventilation rates were estimated using natural steady-state CO 2 levels during dental treatments and experimental CO 2 concentration decays by dry ice or mixing baking soda and vinegar. We compared the differences and assessed the correlations between ACH VENT and ventilation rates estimated by the steady-state CO 2 model with low (0.3 L/min, ACH SS30 ) or high (0.46 L/min, ACH SS46 ) CO 2 generation rates, by CO 2 decay constants using dry ice (ACH DI ) or baking soda (ACH BV ), and by time needed to remove 63% of excess CO 2 generated by dry ice (ACH DI63% ) or baking soda (ACH BV63% ). We found that ACH VENT varied from 3.9 to 35.0 in dental operatories. CO 2 accumulation occurred in rooms with low ventilation (ACH VENT ≤6) and overcrowding but not in those with higher ventilation. ACH SS30 and ACH SS46 correlated well with ACH VENT ( r = 0.83, P = 0.003), but ACH SS30 was more accurate for rooms with low ACH VENT . Ventilation rates could be reliably estimated using CO 2 released from dry ice or baking soda. ACH VENT was highly correlated with ACH DI ( r = 0.99), ACH BV ( r = 0.98), ACH DI63% ( r = 0.98), and ACH BV63% ( r = 0.98). There were no statistically significant differences between ACH VENT and ACH DI63% or ACH BV63% . We conclude that ventilation rates could be conveniently and accurately assessed by observing the changes in CO 2 levels after a simple mixing of household baking soda and vinegar in dental settings.

This study evaluates indoor air concentrations of CO 2 , NO 2 , and O 3 and their relationship to other indoor environmental factors in facilities with occupants susceptible to air contaminants, such as hospitals, senior specialized hospitals, elderly care facilities, and postnatal care centers. Indoor air samples were collected from 82 indoor facilities in South Korea and organized by region. Spearman's correlation and Kruskal-Wallis analyses were employed to examine the relationship among and differences between contaminants in the indoor facilities and indoor/outdoor differences of NO 2 and O 3 concentrations. Significant correlations were found between CO 2 and NO 2 concentrations (r 2  = 0.176, p < 0.01), as well as NO 2 and O 3 concentrations (r 2  = - 0.289, p < 0.0001). The indoor/outdoor concentration ratios in the indoor facilities were 0.73 for NO 2 and 0.25 for O 3 . CO 2 and NO 2 displayed the highest mean concentrations during spring, while O 3 displayed the highest and lowest mean concentrations during fall and summer, respectively. The calculated hazard quotient (HQ) for NO 2 was higher than the acceptable level of 1 in postnatal care centers, thus posing a health risk for children. Study results indicate that efficient ventilation is required to reduce indoor contaminants in multiple healthcare facilities. This study provides a novel approach toward health risk assessment for indoor facilities with susceptible occupants on a large geographical scale.

Aware that exposure to stuffy indoor air with high levels of carbon dioxide (CO2) is associated with higher absenteeism and reduced academic performance in school pupils, the World Health Organization (WHO) Regional Office for Europe initiated indoor air quality surveys in schools, including CO2 monitoring, to assess ventilation and exposure to stuffy air. Here we report the findings of the first such survey in Croatia. It was conducted in 60 classrooms of 20 urban and rural elementary schools throughout the country during the heating season. Measurements of CO2 levels showed that all 60 classrooms exceeded the international guidelines of 1938 mg/m3. Mean CO2 concentrations ranged from 2771 to 7763 mg/m3. The highest concentration measured in urban schools was 7763 mg/m3 and in rural schools 4771 mg/m3. Average CO2 levels were higher in continental schools (3683 mg/m3) than the coastal ones (3134 mg/m3), but all demonstrate poor ventilation during the heating season all over Croatia.

This study enabled the assessment of indoor CO 2 levels and evaluated the relationship between occupancy numbers with CO 2 levels in a Taiwan hospital. The measurements were conducted over four seasons for five working days (Monday to Friday), with sampling conducted simultaneously from 09:00 am to 5:00 pm and across six locations (for spatial variability): hall (H), registration and cashier (RC), waiting area (WA), occupational therapy room (OT), physical therapy room (PT), and outdoors (O). Based on the analysis, three of the five indoor sampling sites showed significant differences in seasonal CO 2 concentrations (p < 0.0001). Based on our result, the physical therapy room had the highest level of CO 2 concentration that exceeded the IAQ standard in Taiwan Environmental Protection Agency (EPA) in all seasons, in that the number of occupants contributing to nearly 40% of the variation in CO 2 measured. Our results also showed that the indoor/outdoor (I/O) ratios of CO 2 concentration for all locations and seasons exceeded 1 in ~ 100% of those locations. The median I/O ratio at sites WA and OT was 2.37 and 2.08 during four seasons, respectively. The highest median I/O ratio was found at site PT, with a calculated range of 2.69 in spring to 3.90 in fall. The highest correlation of occupancy number and CO 2 concentration also occurred in PT which correlation coefficients were estimated at 0.47, 0.65, 0.63, and 0.40 in spring, summer, fall, and winter. The findings of the present study can be used to understand occupancy number and its effect on CO 2 levels in a hospital environment, as well as the effect of time of day (Monday to Friday) on the number of patients admitted.

The objective of this study was to investigate the concentration distribution of indoor air pollutants in taxis and ships (passengers) which are frequently used for public transportation and recreational activities in South Korea. In addition, it aimed to assess air quality factors to establish and evaluate the health risks of exposure to polluted indoor air. Particulate matter (PM 10 ) concentrations were not affected by the number of passengers, time of day, and driving characteristics because there were only a few passengers (2 to 4 people) and the space was confined. In the ships, indoor air pollutants responded more sensitively to the operation characteristics depending on the time of sailing (i.e., anchoring and departure, movement of vehicles on the ship, movement of passengers, combustion in the shop, and ventilation) than to the number of people boarding and alighting. The carbon dioxide concentrations in different ship rooms did not vary according to season and degree of congestion; however, there were differences between different ships. These differences may result from the size, type, and operating characteristics of the ships. Volatile organic compounds (VOCs) and aldehydes in new taxis exceeded the standard levels during summer. VOC concentrations in ships were particularly high during summer when the outdoor temperature was high. Similar observations were made for other means of transportation. The risk assessment depended on the means of transportation and demonstrated that mortality risks due to PM 10 and excess carcinogenic and non-carcinogenic risks from VOCs and aldehydes were within safety levels.

In this study, we evaluated solid sorbents for their ability to passively control indoor CO 2 concentration in buildings or rooms with cyclic occupancy (eg, offices, bedrooms). Silica supported amines were identified as suitable candidates and systematically evaluated in the removal of CO 2 from indoor air by equilibrium and dynamic techniques. In particular, sorbents with various amine loadings were synthesized using tetraethylenepentamine (TEPA), poly(ethyleneimine) (PEI) and a silane coupling agent 3-aminopropyltriethoxysilane (APS). TGA analysis indicates that TEPA impregnated silica not only displays a relatively high adsorption capacity when exposed to ppm level CO 2 concentrations, but also is capable of desorbing the majority of CO 2 by air flow (eg, by concentration gradient). In 10 L flow-through chamber experiments, TEPA-based sorbents reduced outlet CO 2 by up to 5% at 50% RH and up to 93% of CO 2 adsorbed over 8 hours was desorbed within 16 hours. In 8 m 3 flow-through chamber experiments, 18 g of the sorbent powder spread over a 2 m 2 area removed approximately 8% of CO 2 injected. By extrapolating these results to real buildings, we estimate that meaningful reductions in the CO 2 can be achieved, which may help reduce energy requirements for ventilation and/or improve air quality., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Indoor carbon dioxide (CO 2 ) concentrations have been used for decades to characterize building ventilation and indoor air quality. Many of these applications require rates of CO 2 generation from the building occupants, which are currently based on approaches and data that are several decades old. However, CO 2 generation rates can be derived from well-established concepts within the fields of human metabolism and exercise physiology, which relate these rates to body size and composition, diet, and level of physical activity. This paper reviews how CO 2 generation rates have been estimated in the past and discusses how they can be characterized more accurately. Based on this information, a new approach to estimating CO 2 generation rates is presented, which is based on the described concepts from the fields of human metabolism and exercise physiology. Using this approach and more recent data on body mass and physical activity, values of CO 2 generation rates from building occupants are presented along with the variability that may occur based on body mass and activity data., (© 2017 The Authors. Indoor Air published by John Wiley & Sons Ltd.)

Health risks are described from elevated indoor air carbon dioxide (CO 2 ), which often ranges from 1,000 to 4,000 ppm, but the mechanisms are unknown. Here, we demonstrate that mice exposed for 2 h to 2,000 or 4,000 ppm CO 2 exhibit, respectively, 3.4 ± 0.9-fold (SE, n = 6) and 4.1 ± 0.7-fold ( n = 10) elevations in circulating microparticles (MPs); neutrophil and platelet activation, and vascular leak in brain, muscle, and distal colon. Interleukin (IL)-1β content of MPs also increases after 2,000 ppm by 3.8 ± 0.6-fold ( n = 6) and after 4,000 ppm CO 2 by 9.3 ± 1.1-fold ( n = 10) greater than control. CO 2 -induced vascular damage is abrogated by treating mice with an antibody to IL-1β or an IL-1β receptor inhibitor. Injecting naïve mice with CO 2 -induced MPs expressing a protein found on mature neutrophils recapitulates vascular damage as seen with elevated CO 2 , and destruction of MPs in CO 2 -exposed mice abrogates vascular injuries without altering neutrophil or platelet activation. We conclude that environmentally relevant elevations of CO 2 trigger neutrophils to generate MPs containing high concentrations of IL-1β that cause diffuse inflammatory vascular injury. NEW & NOTEWORTHY Elevated levels of CO 2 are often found in indoor air and cause adverse health effects, but the mechanisms have not been identified. In a murine model, environmentally relevant levels of CO 2 were found to cause diffuse vascular damage because neutrophils are stimulated to produce microparticles that contain high concentrations of interleukin-1β., (Copyright © 2017 the American Physiological Society.)

The ventilation rate (VR) is a key parameter affecting indoor environmental quality (IEQ) and the energy consumption of buildings. This paper reviews the use of CO₂ as a "natural" tracer gas for estimating VRs, focusing on applications in school classrooms. It provides details and guidance for the steady-state, build-up, decay and transient mass balance methods. An extension to the build-up method and an analysis of the post-exercise recovery period that can increase CO₂ generation rates are presented. Measurements in four mechanically-ventilated school buildings demonstrate the methods and highlight issues affecting their applicability. VRs during the school day fell below recommended minimum levels, and VRs during evening and early morning were on the order of 0.1 h -1 , reflecting shutdown of the ventilation systems. The transient mass balance method was the most flexible and advantageous method given the low air change rates and dynamic occupancy patterns observed in the classrooms. While the extension to the build-up method improved stability and consistency, the accuracy of this and the steady-state method may be limited. Decay-based methods did not reflect the VR during the school day due to heating, ventilation and air conditioning (HVAC) system shutdown. Since the number of occupants in classrooms changes over the day, the VR expressed on a per person basis (e.g., L·s -1 ·person -1 ) depends on the occupancy metric. If occupancy measurements can be obtained, then the transient mass balance method likely will provide the most consistent and accurate results among the CO₂-based methods. Improved VR measurements can benefit many applications, including research examining the linkage between ventilation and health.

Three urban environments, office, apartment and restaurant, were selected to investigate the indoor and outdoor air quality as an inter-comparison in which CO2, particulate matter (PM) concentration and particle size ranging were concerned. In this investigation, CO2 level in the apartment (623 ppm) was the highest among the indoor environments and indoor levels were always higher than outdoor levels. The PM10 (333 µg/m(3)), PM2.5 (213 µg/m(3)), PM1 (148 µg/m(3)) concentrations in the office were 10-50% higher than in the restaurant and apartment, and the three indoor PM10 levels all exceeded the China standard of 150 µg/m(3). Particles ranging from 0.3 to 0.4 µm, 0.4 to 0.5 µm and 0.5 to 0.65 µm make largest contribution to particle mass in indoor air, and fine particles number concentrations were much higher than outdoor levels. Outdoor air pollution is mainly affected by heavy traffic, while indoor air pollution has various sources. Particularly, office environment was mainly affected by outdoor sources like soil dust and traffic emission; apartment particles were mainly caused by human activities; restaurant indoor air quality was affected by multiple sources among which cooking-generated fine particles and the human steam are main factors.

Indoor air quality (IAQ) in preschools is an important public health challenge. Particular attention should be paid to younger children, because they are more vulnerable to air pollution than higher grade children and because they spend more time indoors. Among air pollutants, particulate matter (PM) is of the greatest interest mainly due to its acute and chronic effects on children's health. In addition, carbon dioxide (CO2) levels indicate ventilation conditions. In this paper, we present the concentrations of PM (PM1, PM2.5, PM10 and total-TSP) and CO2 monitored in four naturally ventilated nursery schools located in the area of Gliwice, Poland. The nursery schools were selected to characterize areas with different degrees of urbanization and traffic densities during the winter season. The results indicate the problem of elevated concentrations of PM inside the examined classrooms, as well as that of high levels of CO2 exceeding 1000 ppm in relation to outdoor air. The characteristics of IAQ were significantly different, both in terms of classroom occupation (younger or older children) and of localization (urban or rural). To evaluate the children's exposure to poor IAQ, indicators based on air quality guidelines were proposed to rank classrooms according to their hazard on the health of children.

This study investigated whether sick building syndrome (SBS) complaints among office workers were associated with the indoor air quality. With informed consent, 417 employees in 87 office rooms of eight high-rise buildings completed a self-reported questionnaire for symptoms experienced at work during the past month. Carbon dioxide (CO2), temperature, humidity and total volatile organic compounds (TVOCs) in each office were simultaneously measured for eight office hours using portable monitors. Time-averaged workday difference between the indoor and the outdoor CO2 concentrations (dCO2) was calculated as a surrogate measure of ventilation efficiency for each office unit. The prevalence rates of SBS were 22.5% for eye syndrome, 15.3% for upper respiratory and 25.4% for non-specific syndromes. Tiredness (20.9%), difficulty in concentrating (14.6%), eye dryness (18.7%) were also common complaints. The generalized estimating equations multivariate logistic regression analyses showed that adjusted odds ratios (aORs) and 95% confidence interval (CI) per 100 ppm increase in dCO2 were significantly associated with dry throat (1.10, 95% CI=(1.00-1.22)), tiredness (1.16, 95% CI=(1.04-1.29)) and dizziness (1.22, 95% CI=(1.08-1.37)). The ORs for per 100 ppb increases in TVOCs were also associated with upper respiratory symptoms (1.06, 95% CI=(1.04-1.07)), dry throat (1.06, 95% CI=(1.03-1.09)) and irritability (1.02, 95% CI=(1.01-1.04)). In conclusion, the association between some SBS symptoms and the exposure to CO2 and total VOCs are moderate but may be independently significant.

Carbon dioxide (CO2 ) sensors that provide a visual indication were installed in classrooms during normal school operation. During 2-week periods, teachers and students were instructed to open the windows in response to the visual CO2 feedback in 1 week and open them, as they would normally do, without visual feedback, in the other week. In the heating season, two pairs of classrooms were monitored, one pair naturally and the other pair mechanically ventilated. In the cooling season, two pairs of naturally ventilated classrooms were monitored, one pair with split cooling in operation and the other pair with no cooling. Classrooms were matched by grade. Providing visual CO2 feedback reduced CO2 levels, as more windows were opened in this condition. This increased energy use for heating and reduced the cooling requirement in summertime. Split cooling reduced the frequency of window opening only when no visual CO2 feedback was present., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: We tested the hypothesis that classroom carbon dioxide (CO2 ) concentration is inversely related to child school attendance and educational attainment., Methods: Concentrations of CO2 were measured over a 3-5 day period in 60 naturally ventilated classrooms of primary school children in Scotland. Concentrations of CO2 were related to the class average annual attendance and proportions attaining a national standard for reading, writing, and numeracy, adjusted for socioeconomic status and class size., Results: The median (interquartile range, IQR) CO2 concentration averaged over the school day was 1086 ppm (922, 1310). In the model, Time Weighted Average CO2 concentrations were inversely associated with school attendance but not academic attainments. An increase of 100 ppm CO2 was associated with a reduced annual attendance of 0.2% (0.04, 0.4) roughly equivalent to 1 half day of school per annum, assuming schools are open on 190 days per year. Indoor temperature and relative humidity were not related to attendance or academic attainment., Conclusions: Inadequate classroom ventilation, as evidenced by CO2 concentration exceeding 1000 ppm, is not uncommon and may be associated with reduced school attendance. A relationship between inadequate classroom ventilation and adverse health outcomes in children may be present and this needs to be explored., (© 2014, American School Health Association.)

The aim of this study is to develop internal ventilation by transferred air to achieve a good indoor climate with low energy consumption in educational buildings with constant air volume (CAV) ventilation. Both measurements of CO2 concentration and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor air quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 concentration was studied in different classrooms. The air temperatures and CO2 concentrations were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 concentration in the rooms, which was then compared with the measured ones. Using transferred air between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 concentration., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Sick Building Syndrome (SBS) refers to the health-related symptoms of exposure to an unhealthy microenvironment, especially poor indoor air quality This study investigated the associations of indoor air quality including particulate matter (PM10 and PM2 5), Carbon Dioxide (CO2), Carbon Monoxide (CO), Total Volatile Organic Compounds (TVOCs), and childcare center environment with SBS symptoms among caretakers. SBS was assessed using a self-reported questionnaire The prevalence of SBS was 77 78% among caretakers PM10 negatively correlated with CO2 (r=0-558; p<0 01) PM10 levels were associated with any reported symptoms of SBS (OR=7 38; 95%CI 1 98-27 53), and upper respiratory symptoms (OR= 12 00; 95%CI 1 46-98 08) PM2 5 showed no association with SBS Using air refresher was associated with upper respiratory symptoms (OR=5 10; 95%CI 1 46-13 59), lower respiratory symptoms (OR=3 64; ; 95%CI 1.22-10.82). [ABSTRACT FROM AUTHOR]

Featured Application: The introduction of effective natural ventilation controls can provide acceptable indoor air quality and thermal comfort for school buildings in a subtropical climate. The need for energy-efficient buildings must be based on strong effective passive-design techniques, which coordinate indoor air quality and thermal comfort. This research describes the principles, simulation, implementation, and monitoring of two different natural cross-ventilation algorithm scenarios applied to a school-building case study affected by a subtropical climate during the winter season. These ventilation protocols, the steady and dynamic versions, can control the carbon dioxide concentration and actuate the window openings according to pre-defined window-to-wall ratios. The implementation of the monitoring process during three non-consecutive days in the winter of 2021 validates the opening strategy to maintain carbon dioxide below 800 ppm, described by the protocol Hygiene Measures Against COVID-19, and the temperature within the comfort ranges suggested by the adaptive UNE-EN 16798. The study shows that a steady opening of 2.16% window-to-wall equivalent ratio can be enough to maintain the requested comfort and carbon dioxide conditions. The use of the dynamic window ratios, from 0.23% to 2.16%, modified according to the measured carbon dioxide concentration, can partially maintain the carbon dioxide below the required limits for ASHRAE 62.1, Hygiene Measures Against COVID-19 and UNE-EN 16798 between 48.28% to 74.14% of the time. However, the carbon dioxide limit proposed by RITE, 500 ppm, is only achieved for 15.52% of the time, which demonstrates the inadequacy of the natural ventilation to fulfil the standard. Further improvements in the dynamic control of the openings in these buildings could lead to lower carbon dioxide concentrations while maintaining the thermal comfort in mild winter climates. [ABSTRACT FROM AUTHOR]

As concerns about indoor air quality increase, air purifiers and fresh air systems are increasingly being used in conjunction with air conditioners in office buildings. To study the synergistic effects of multisystem joint operation on indoor air quality, this study used a combination of experimental and simulation methods to study the indoor particulate matter with a diameter of less than 2.5 µm (PM2.5) and carbon dioxide (CO2) concentrations under different operation conditions. The purification time and the PM2.5 concentration distribution under different conditions were compared with the condition in which the purifier was used alone. The results showed that the purification time required for the condition that the air conditioner runs together with the purifier was shortened by 15.2%. When the fresh air system is running together with the purifier, the purification time can be reduced by 30.4%. It was reduced by 32.6% when the three systems were operating at the same time. The PM2.5 concentration distribution under the joint operating condition was much more even than that under the condition in which the purifier was running alone. To analyze the impact on the CO2 distribution, the CO2 distributions under different joint operations were compared. The results show that the fresh air system can effectively dilute CO2 below 1000 ppm in 30 min. The air conditioner and purifier could help to mix the indoor air to provide a much more uniform indoor CO2 distribution. [ABSTRACT FROM AUTHOR]

Waste-Sorting Plant (WSP) workers are exposed to bioaerosols containing a large variety of bacterial and fungal species, posing a critical health risk that needs to be assessed and mitigated. The present study aimed to evaluate the indoor air quality in a Portuguese WSP and the air decontamination efficiency with UV-C. The concentrations of bacteria and fungi and particulate matter (PM2.5 and PM10), CO2, relative humidity, and temperature were determined at different hours in manual sorting areas (cabin and ramp) in autumn and winter in 2022 and in administrative offices and canteen in the autumn of 2023. The PM2.5 and PM10 concentrations in the air increased with the daily waste-sorting activities, especially inside the cabin, averaging 22 and 42 μg/m3, respectively, while the CO2 concentration was in the range of 343–578 ppm in both sampling sites. The bacterial species were mainly environmental (mesophilic bacteria) rather than human sources. In the waste-sorting areas, the concentration of bacteria was often found to exceed outdoor values by more than 1000 CFU/m3 on average. Additionally, the concentration of fungi indoors was consistently higher than outdoor values, in many cases exceeding 500 CFU/m3. These findings suggest that workers in these areas are frequently exposed to high levels of microbes. The indoor-to-outdoor (I/O) contamination ratios revealed that the air quality inside the administrative offices and the canteen had high pollutant concentrations during some time periods. The worst scenarios were observed in the canteen and offices with high occupancy in the afternoon. UV-C lamps at 253.7 nm and with 5.0 W irradiation power were used in the sorting cabin to test the indoor air and surface decontamination, and the results showed a high bacterial removal efficacy of over 87.6% after one hour of exposure to UV-C. The present study raises the question of whether 37 °C is the optimal incubation temperature for WSP samples since the microorganisms' habitat before the sampling had a much lower temperature. As the waste-sorting industry expands, these findings show that the air quality of WSPs remains concerning and requires a holistic approach, integrating the working conditions of all personnel and the implementation and monitoring of mitigation measures. [ABSTRACT FROM AUTHOR]

Indoor air quality is an important aspect of buildings, including libraries where various activities take place. This study aimed to investigate indoor air quality in different microenvironments in a library in Thailand. The indoor air monitoring was conducted in a library for 4 microenvironments: reading, librarian, cafe shop, and photocopy shop zone. Respiratory dust and bioaerosols were analyzed using NIOSH methods 0600, and 0800, respectively. Air movements were determined using an anemometer. Particulate matters (PM) were measured using DustTrak; carbon dioxide and comfort parameters were measured using Q-TRAK with 30-minute average for 8 hours. The results showed that the means of respiratory dust, PM10, PM4, PM2.5 in all zones met the standard, however, temporary variation revealed that PM4 and PM2.5 exceeded the standard in the afternoon. Fungal concentration was above 500 cfu/m3 in the photocopy shop zone where the highest %RH and the lowest air movement were found. Carbon dioxide concentrations in the cafe shop zone exceeded 1,000 ppm. The real-time measurements showed significant strong correlations between the different PM sizes, moderate correlations between %RH and temperature, and CO2 and PM10. The findings suggest that preventive and corrective measures should be implemented to improve indoor air quality in the library. [ABSTRACT FROM AUTHOR]

Carbon dioxide concentration in enclosed spaces is an air quality indicator that affects occupants' well-being. To maintain healthy carbon dioxide levels indoors, enclosed space settings must be adjusted to maximize air quality while minimizing energy consumption. Studying the effect of these settings on carbon dioxide concentration levels is not feasible through physical experimentation and data collection. This problem can be solved by using validated simulation models, generating indoor settings scenarios, simulating those scenarios, and studying results. In previous work, we presented a formal Cellular Discrete Event System Specifications simulation model for studying carbon dioxide dispersion in rooms with various settings. However, designers may need to predict the results of altering large combinations of settings on air quality. Generating and simulating multiple scenarios with different combinations of space settings to test their effect on indoor air quality is time-consuming. In this research, we solve the two problems of the lack of ground truth data and the inefficiency of producing and studying simulation results for many combinations of settings by proposing a novel framework. The framework utilizes a Cellular Discrete Event System Specifications model, simulates different scenarios of enclosed spaces with various settings, and collects simulation results to form a data set to train a deep neural network. Without needing to generate all possible scenarios, the trained deep neural network is used to predict unknown settings of the closed space when other settings are altered. The framework facilitates configuring enclosed spaces to enhance air quality. We illustrate the framework uses through a case study. [ABSTRACT FROM AUTHOR]

Accelerated concrete carbonation is an expanding option for decarbonizing construction. Factors such as concrete mixture design and carbonation environment can influence the maximum CO2 utilization that can be achieved during such a process. A carbonation process designed to utilize a water‐saturated dilute CO2 source wherein 2 < CO2 concentration (v/v%) < 16, was modeled in AspenPlus©. A regression model was developed to correlate CO2 uptake, relative humidity (11%–100%), CO2 concentration ([CO2] = 2—16 v/v%), and temperature (T = 11–74°C) conditions within a carbonation reactor. It was determined that [CO2] was the most significant variable as higher concentrations enhanced CO2 transport through the concrete. The energy use intensity per mass of CO2 utilized (kWh/kgCO2) was determined across a range of processing conditions. As a function of the operational conditions, accelerated carbonation provides a net CO2 reduction of up to 28 kgCO2/tonne of concrete; a reduction of up to ~45% compared to typical formulations. [ABSTRACT FROM AUTHOR]

The impact of the COVID-19 pandemic has caused an increase in knowledge in certain fields such as human breathing and respiratory diseases. In the current study, enclosed-space characteristics were assessed due to the great debate generated because of the pandemic. Temperature, relative humidity, carbon dioxide (CO2) concentration, particulate matter (PM) concentration and cumulative particle concentration percentage per size fraction were measured in three buildings under the occurrence of activities with different intensity levels. For the measurements, Arduino UNO, Sensiron SCD30 and APS-3321 devices were used. Natural ventilation was controlled via windows and/or doors, and the influence of air conditioning was studied in one of these rooms, in which medium- to high-intensity activities were conducted. All experiments revealed a decrease in temperature associated with an increase in the relative humidity when CO2 decreased. As a consequence, drastic decreases occurred a few minutes after windows and doors were opened. In no-ventilation intervals, the observed linear increase changed into an asymptotic trend below the 1000 ppm limit recommended by Sinphonie guidelines. Additionally, the opposite behavior was observed between particles above and below a certain size. This experiment is of interest to further investigate critical ventilation rate versus volume of air per individual. [ABSTRACT FROM AUTHOR]

Indoor air quality (IAQ) in confined spaces like bank vaults and basements is influenced by complex factors such as building layout and HVAC systems. This study examines how mechanical ventilation impacts IAQ in a bank building's occupied basement vault, addressing significant challenges posed by pollutant exposure in these air-tight environments. This study advances safe IAQ in confined spaces, crucial for occupant health and safety, using CFD (ANSYS Fluent Workbench 16.0) and CONTAM 3.2 software for multi-zone ventilation and air quality analysis. It analysed three indoor pollutants: Radon (Rn), Carbon dioxide (CO2), and Particulate Matter (PM2.5), enhancing the reliability and applicability of the findings. The findings indicated that the simulated indoor pollutants concentrations did not exceed the indoor air quality guideline levels. The CFD simulations predicted average steady-state values of 27.2 Bq/m3 for Radon, 574.80 ppm for CO2, and 69.36 µg/m3 for PM2.5 in the basement. For different outdoor air floor rates, an optimal ventilation rate of 4.7 ACH and a cooling load of 17 kW were determined to maintain Radon concentrations below 15 Bq/m3. This provides a practical and actionable solution for maintaining safe IAQ in confined spaces, which is a significant step forward compared to similar studies. These results align with other experimental research, validating the use of numerical techniques in indoor air quality studies. By optimizing HVAC systems to maintain IAQ and minimize energy consumption, the study supports SDG 7 (Affordable and Clean Energy) by enhancing energy efficiency, SDG 3 (Good Health and Well-being) by reducing exposure to indoor pollutants, and SDG 11 (Sustainable Cities and Communities) by improving air quality management in confined spaces. The findings are particularly relevant for Africa, offering practical solutions, informing policy direction, and supporting the African Union's Agenda 2063 and SDGs 3, 7, and 11.

Air cleaning technologies are needed to reduce indoor concentrations and exposure to volatile organic compounds (VOCs). Currently, air cleaning technologies lack an accepted test standard to evaluate their VOC removal performance. A protocol to evaluate the VOC removal performance of air cleaning devices was developed and piloted with two devices. This method injects a VOC mixture and carbon dioxide into a test chamber, supplies outdoor air at a standard building ventilation rate, periodically measures the VOC concentrations in the chamber using solid phase microextraction-gas chromatography-mass spectrometry over a 3-h decay period, and compares the decay rate of VOCs to carbon dioxide to measure the VOC removal air cleaning performance. The method was demonstrated with both a hydroxyl radical generator and an activated carbon air cleaner. It was shown that the activated carbon air cleaner device tested had a clean air delivery rate an order of magnitude greater than the hydroxyl radical generator device (72.10 vs 6.32 m3/h).

This study fabricated a low-cost activated carbon (AC) adsorbent from readily available bamboo trees to control indoor CO2 levels and reduce energy costs associated with sustaining clean indoor air. Bamboo is naturally high in potassium content and has narrow fibrous channels that could enhance selective CO2 adsorption. The prepared bamboo-based activated carbon (BAC) exhibits predominantly micropores with an average pore size of 0.17 nm and a specific surface area of 984 m2/g. Upon amination, amine functionalities, such as pyridine, pyrrole, and quaternary N, were formed on its surface, enhancing its CO2 adsorption capacity of 0.98 and 1.80 mmol/g for low-level (3000 ppm) and pure CO2 flows at the ambient condition, respectively. In addition, the 0.3% CO2/N2 selectivity (αs,g) of the prepared sorbents revealed a superior affinity of CO2 by BAC (8.60) over coconut shell-based adsorbents (1.16–1.38). Furthermore, amination enhanced BAC's CO2αs,g to 13.4. These results exhibit this sustainable approach's potential capabilities to ensure the control of indoor CO2 levels, thereby reducing the cost associated with mechanical ventilation systems. Further research should test the new sorbent's adsorption properties (isotherm, kinetics, and thermodynamics) for real-life applicability. [ABSTRACT FROM AUTHOR]

The population of developed nations spends a significant amount of time indoors, and the implications of poor indoor air quality (IAQ) on human health are substantial. Many premature deaths attributed to exposure to indoor air pollutants result from diseases exacerbated by poor indoor air. CO2, one of these pollutants, is the most prevalent and often serves as an indicator of IAQ. Indoor CO2 concentrations can be significantly higher than outdoor levels due to human respiration and activity. The primary objective of this research was to numerically investigate the indoor relative humidity and CO2 in cob buildings through the CobBauge prototype, particularly during the first months following the building delivery. Both in situ experimental studies and numerical predictions using an artificial neural network were conducted for this purpose. The study presented the use of a piecewise autoregressive exogenous model (PWARX) for indoor relative humidity (RH) and CO2 content in a building constructed with a double walling system consisting of cob and light earth. The model was validated using experimental data collected over a 27-day period, during which indoor RH and CO2 levels were measured alongside external conditions. The results indicate that the PWARX model accurately predicted RH levels and categorized them into distinct states based on moisture content within materials and external conditions. However, while the model accurately predicted indoor CO2 levels, it faced challenges in finely classifying them due to the complex interplay of factors influencing CO2 levels in indoor environments. [ABSTRACT FROM AUTHOR]

In the resource-constrained South African education sector, infrastructure considered temporary or a backup in other countries is used as permanent classrooms, primarily but not exclusively in lower-income areas. Children's cognitive performance and comfort are directly impacted by indoor air quality. Temperature, relative humidity, particulate matter and CO2 levels, substantial determinants of air quality and thermal comfort, have not been investigated across different classroom building and infrastructure types. We measure these parameters with 11-min intervals in 24 classrooms at schools in Stellenbosch, South Africa. These classrooms consist of a range of different infrastructure types. Container classrooms with and without insulation, mobile (prefabricated) classrooms, and brick classrooms of different configurations are included. Measurements are concurrently sampled over ten months (249 days, still ongoing) across multiple seasons with relevant metadata, including ambient weather conditions, school days and times, and electricity availability in the (South) African context, which impacts air conditioning usage. This dataset provides valuable insights into true learning conditions in South African classrooms.

The purpose of this study was to determine the amount of particulate and microbial contaminants, i.e. bacteria and fungi found in indoor air in a lecture hall in one of Lublin's universities and their classification. In the research part, the amount of particulate and microbial pollutants was measured. Bioaerosols were investigated using an Andersen cascade impactor, which was located in the central part of the room at a height of 1-1.5 m, and single-level impactors. Identification of the microorganisms present in indoor air was carried out. The air in the room was sampled before the start of class to determine the "background," i.e. the concentration level of microbial contaminants in the classroom without the presence of students. Subsequent measurements were taken during teaching activities in the presence of students and the teacher. The study shows that the air condition in the classroom during its operation met the requirements in terms of PM2.5, PM10 and microorganisms. The highest risk was recorded for carbon dioxide. Moreover, the highest recorded readings of this pollutant coincided with the maximum concentrations of the other monitored quantities. Therefore, it can be unequivocally stated that in the case of the analyzed room, monitoring carbon dioxide and adjusting the size of the ventilation airflow to maintain its concentration within the limit of 1000 ppm would guarantee the maintenance of adequate indoor air quality. The study showed no correlation between CO2 concentration and measured concentrations of microbial contaminants.

Microalgae-based photobioreactors (PBRs) have gained attention as a sustainable solution for indoor air quality (IAQ) control. This study investigates indoor CO2 absorption performance of Spirulina maxima (S. maxima) in NaHCO3-limited cultivation (standard: NaHCO3-free medium = 1:1 v/v%) of a lab-scale PBR system. Cultivation performance of three medium amendments (standard, 50% NaHCO3, and NaHCO3-free) was compared by observing cell growth for 30 days in a controlled environment. Empirical examinations were conducted to evaluate the algal CO2 uptake, and overall system performance in the culture volumes of 2, 4, and 7 L and natural indoor CO2 concentration of ~1100 ppm. We found CO2 was reduced by ~55%, in an air chamber of 0.064 m3, showing the greatest mitigation rate (~20%) on Day 4. Under a high concentration of CO2 (10,000 ppm), the CO2 levels were decreased up to ~90% before saturation. This research provides valuable insights into the development of S. maxima-activated IAQ control systems for airtight buildings. [ABSTRACT FROM AUTHOR]

The measurement of carbon dioxide (CO2) has emerged as a cost-effective and straightforward technique for indirectly managing indoor air quality, aiding in the reduction of the potentially pathogen-laden aerosol concentrations to which we are exposed. Unfortunately, inadequate practices often limit the interpretation of CO2 levels and neglect methodologies that ensure proper air renewal. This study presents a novel methodology for measuring and controlling indoor CO2 levels in shared spaces, comprising four stages: analysis, diagnosis, correction protocols, and monitoring/control/surveillance (MCS). This methodology underwent validation in practical settings, including a cultural center (representing spaces with uniform activities) and 40 commercial spaces (with diverse activities) in Zaragoza, Spain. The results indicate the feasibility of swiftly implementing measures to enhance shared air renewal, with the immediate opening of doors and windows being the most direct solution. The proposed methodology is practical and has the potential to mitigate the risk of the aerosol transmission of respiratory diseases. Consequently, we anticipate that this work will contribute to establishing methodological foundations for CO2 measurement as a valuable, standardized, and reliable tool. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the amount of particulate and microbial contaminants, i.e. bacteria and fungi found in indoor air in a lecture hall in one of Lublin's universities and their classification. In the research part, the amount of particulate and microbial pollutants was measured. Bioaerosols were investigated using an Andersen cascade impactor, which was located in the central part of the room at a height of 1-1.5 m, and single-level impactors. Identification of the microorganisms present in indoor air was carried out. The air in the room was sampled before the start of class to determine the "background," i.e. the concentration level of microbial contaminants in the classroom without the presence of students. Subsequent measurements were taken during teaching activities in the presence of students and the teacher. The study shows that the air condition in the classroom during its operation met the requirements in terms of PM2.5, PM10 and microorganisms. The highest risk was recorded for carbon dioxide. Moreover, the highest recorded readings of this pollutant coincided with the maximum concentrations of the other monitored quantities. Therefore, it can be unequivocally stated that in the case of the analyzed room, monitoring carbon dioxide and adjusting the size of the ventilation airflow to maintain its concentration within the limit of 1000 ppm would guarantee the maintenance of adequate indoor air quality. The study showed no correlation between CO2 concentration and measured concentrations of microbial contaminants. [ABSTRACT FROM AUTHOR]

Visitors have a significant impact on the indoor climate of buildings housing works of art, and the relationship between the number of visitors, the indoor air quality and the protection of exposed works of art is an important factor in the overall study of the indoor climate of heritage buildings without mechanical ventilation and/or air-conditioning systems. In view of these concerns and the lack of studies on natural ventilation in heritage buildings, this study aims to analyse the performance of natural ventilation in the São Cristóvão Church in Lisbon, Portugal. For the preparation of this study, an analysis of the natural ventilation of this church was carried out by creating a model in the CONTAM software, and the indoor air quality was analysed based on different international standards and guidelines for carbon dioxide levels and air flow rates (ACH). Estimating the current ventilation strategy, an average ACH of 0.75 h−1 was estimated during the time the church is open, and an ACH of 0.15 h−1 was estimated during the time the doors were closed. In a yearly analysis, an average ACH of 0.30 h−1 was obtained. These air exchange values guarantee EN 16798-1 category I air quality for 72% of the year and category II air quality for 18% of the year. Different natural ventilation strategies were analysed: (a) three scenarios exploring different cross ventilation scenarios; (b) a scenario assuming that the church is closed all year round; and (c) a scenario estimating an increase in the number of visitors, giving an idea of the variations in human pollutants and possible consequences. Taking into account the air infiltration and the fact that masses, an occasional situation with a high number of visitors, are always held just before the church closes, it is guaranteed that carbon dioxide levels will never exceed the limit of 350 ppm above the outdoor values imposed by EN-13779, registering a maximum of 291 ppm. [ABSTRACT FROM AUTHOR]

The educational and play-related activities of children proceed mainly indoors in a kindergarten. High concentrations of indoor PM2.5 and CO2 have been linked to various harmful effects on children, considerably impacting their educational outcomes in kindergarten. In this study, we explore different scenarios involving the operation of mechanical ventilation systems and air purifiers in kindergartens. Using numerical models to analyze indoor CO2 and PM2.5 concentration, we aim to optimize strategies that effectively reduce these harmful pollutants. We found that the amount of ventilation required to maintain good air quality, per child, was approximately 20.4 m3/h. However, we also found that as the amount of ventilation increased, so did the concentration of indoor PM2.5; we found that this issue can be resolved using a high-grade filter (i.e., a MERV 13 grade filter with a collection efficiency of 75%). This study provides a scientific basis for reducing PM2.5 concentrations in kindergartens, while keeping CO2 levels low. [ABSTRACT FROM AUTHOR]

Knowledge of indoor air quality (IAQ) in cob buildings during the first few months following their delivery is of vital importance in preventing occupants' health problems. The present research focuses on evaluating IAQ in cob buildings through a prototype built in Normandy, France. To achieve this, the prototype was equipped with a set of sensors to monitor various parameters that determine indoor and outdoor air quality. These parameters include relative humidity (RH), carbon dioxide (CO2), nitrogen dioxide (NO2), ozone (O3), particulate matter (PM1 and PM10), and volatile organic compounds (VOCs). The obtained experimental results indicate that, overall, there is good indoor air quality in the prototype building. However, there are some noteworthy findings, including high indoor RH and occasional spikes in CO2, PM1, PM10, and VOCs concentrations. The high RH is believed to be a result of the ongoing drying process of the cob walls, while the peaks in pollutants are likely to be attributed to human presence and the earthen floor deterioration. To ensure consistent good air quality, this study recommends the use of a properly sized Controlled Mechanical Ventilation system. Additionally, this study explored IAQ in the cob building from a numerical perspective. A Long Short-Term Memory (LSTM) model was developed and trained to predict pollutant concentrations inside the building. A validation test was conducted on the CO2 concentration data collected on-site, and the results indicated that the LSTM model has accurately predicted the evolution of CO2 concentration within the prototype building over an extended period. [ABSTRACT FROM AUTHOR]

The use of smart technologies and the Internet of Things (IoT) is becoming more and more popular in order to enhance the overall building performance by monitoring parameters related to occupants' comfort and health in the built environment. A new modular, custom-made and replicable IoT system is proposed based on an Arduino development board (MKR WiFi 1010) connected to the Arduino IoT Cloud. An Application Programming Interface (API) enables the integration of this system with other possible ones, thus making the system modular, custom-made and replicable. A series of parameters were simultaneously monitored over a 7-day period in two office spaces and a photovoltaic (PV)-testing laboratory. While the meteorological and comfort parameters (temperature, relative humidity, CO2) were monitored in all three spaces, the health parameters (total volatile organic compounds—TVOCs; formaldehyde—HCHO; particulate matter—PM; and radon—222Rn) were monitored only in an office setup located right next to a Chemical Analysis and Testing Laboratory. Generally, the registered values of the health parameters fell within the recommended thresholds. However, the thermal comfort parameters were constantly exceeded: over 90% of the working time in the two office spaces and 83.33% in the PV-testing laboratory. Still, the optimal relative humidity values in the monitored spaces contributed to the discomfort reduction in the occupants. Also, CO2 and TVOCs had some exceptions in particular conditions. CO2 values of up to 1500 ppm due to poor ventilation and TVOC levels of up to 1000 ppb related to chemical experiment development were registered. Also, several other peaks were recorded when monitoring HCHO as well as PM. Thus, special attention must be paid to natural ventilation or to the improvement of building characteristics. Also, the time intervals when experiments in the Chemical Analysis and Testing Laboratory are carried out should be communicated to other personnel from the nearest offices. The testing of the monitoring system over a one-week period showed that the proposed solution operated adequately, representing a reliable tool for data acquisition via the Arduino IoT Cloud. [ABSTRACT FROM AUTHOR]

Introduction: Outdoor air pollution has been considered the primary issueby scientists and environmentalists for decades. With the advancement of technology, the activities of human are shifting from outdoor to indoor, urging researchers to investigate the indoor environment. Theerefore, the focus of this study is to examine indoor air quality in the metropolitan of Lahore. Materials and methods: The Temtop M2000C and Temtop H3 Laser monitors were used to collect data on Particulate Matter (PM), Carbon dioxide (CO2) concentration, Total Volatile Organic Compounds (TVOC), and formaldehyde (HCHO). The concentration of air pollutants in nine indoor areas was measured for a specified time interval. The values of particulate matter are measured to find the impact of the outdoor environment on the indoor environment. Results: The maximum average values of the particulate matter PM2.5 and PM10 were 488.6 μg/m³ and 737.2 6 μg/m³, respectively, which reduced drastically after the rain to 219 μg/m³ and 340 μg/m³, respectively. The maximum values of PM2.5 and PM10 during coal burning outside the room were 997.6 μg/m³ and 999.9 μg/m³, respectively, far higher than the values during normal conditions. TVOC and HCHO were found within the prescribed limits. Conclusion: The outcomes of this study established a deep impact of the outdoor environment on the indoor environment and recommend air purifiers to reduce the level of pollutants in the indoor environment.

Abstract In Japan, the number of elderly people in need of nursing care is increasing while the population of young people is decreasing, and the potential for labor shortages in the field of elder care is of great concern. This study aimed to estimate the behavior of the elderly by using sensors to monitor indoor air quality (IAQ), without placing undue burden on the elderly or their caregivers. Odor and carbon dioxide (CO2) concentrations were monitored in a private room of a nursing home in the Kanto Region of Japan, the behaviors of the resident and staff members were recorded, and the relationship between the two was analyzed. Both odor and CO2 concentrations were higher when the resident was present than when absent, indicating that the resident was one of the main sources of indoor odor and CO2. In addition, after the resident entered the room, the CO2 concentration increased and remained stable, whereas the odor concentration tended to vary after the resident entered the room, first increasing and later decreasing. This suggested that the increase or decrease in odor could be used to monitor the behavior of the resident and staff members. The relationship between the slopes of odor and CO2 in typical behavioral events suggest that if only odor increases and CO2 does not change, the likelihood of the event in which feces were observed during diaper changes is high. In addition, based on the behavior near the sensor, the rate of CO2 and odor emissions differed between the elderly resident and the younger staff members, suggesting that the ratio of odor slope to CO2 slope may be greater in the elderly than in younger people. Furthermore, the repeated number of increases and decreases in odor and CO2 suggested that multiple events could be distinguished. These results suggest that IAQ can be utilized to estimate the behavior of residents and staff in nursing care facilities for the elderly.

In order to explore the indoor air quality during different cooking procedures, a very common kitchen in China is selected for experimental research. An indoor air quality meter is used to measure the temperature, relative humidity, and CO and CO2 concentrations of the indoor air above the stove when people cook four different dishes under different ventilation patterns in the kitchen. The results indicate that the heat and gas consumed during cooking are closely related to the temperature and concentrations of CO and CO2. Some cooking procedures such as boiling water are related to the indoor air temperature and relative humidity in the kitchen. In addition, in kitchens without mechanical ventilation, natural ventilation shows a more significant positive effect on controlling temperature, relative humidity, and concentrations of CO and CO2 during cooking procedures. [ABSTRACT FROM AUTHOR]

The La Fossa volcano is near the inhabited zone of the island of Vulcano and is a suitable case for studying gas sources of different geological origins. Since the last eruption, fumarolic-solfataric activity has interested this area with fumarolic emissions, mainly at the top of the volcanic cone and at Vulcano Porto. In recent decades, the anomalous degassing zones on the island have not significantly changed their location. On the contrary, there have been several significant changes in the emission rate due to the addition of volcanic gas. In these zones, CO2 flux from the ground is responsible for a decrease in the indoor air quality. A recent increase in volcanic degassing led to an increase in the gas hazard in the inhabited area of Vulcano Island, and people were temporarily displaced from Vulcano Porto. The results of this study show that a monitoring system can be used for the early detection of transients in soil CO2 flux (φCO2) in the anomalous degassing zone of Vulcano. Synchronous monitoring of φCO2 and outdoor air CO2 concentration has shown variations in volcanic degassing that affect outdoor air CO2 concentration in the populated zone of Faraglione. [ABSTRACT FROM AUTHOR]

The comfort and health of students may be affected by contaminated interior environments. One of the key elements for improving academic performance is ensuring proper ventilation and indoor thermal comfort. This study aimed to assess the effectiveness of ventilation and measure temperature and humidity levels in several primary school classrooms in southern Iraq's Maisan Province. Utilizing a high-precision sensor, the study was conducted in 26 schools (22 public and 4 private) dispersed throughout the province, where thermal conditions and carbon dioxide (CO2) concentrations were tracked for seven months as an alternative to evaluate ventilation efficiency by Smart air monitoring device. According to the results of CO2 concentration were around 516 - 3,477 ppm, most classrooms had high CO2 levels owing to poor ventilation, exceeding the ASHRAE standard of 62.1. During several monthly readings, the temperature was around 15 - 32.3 0C and relative humidity levels were 18.9 - 79.4%, exceeding the ASHRAE standard 55%. This can be ascribed to the considerable number of pupils occupying the space in the room and the effect of classroom and school building characteristics on indoor air quality. As a result, practical, straightforward steps are required to improve ventilation efficiency. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyze the indoor air quality, in particular, the CO2 level, in a real environment, within 16 apartments located in the municipality of Zalău, Romania, in five recently renovated multifamily buildings in which families live under normal conditions. Long-term monitoring was undertaken for 4.5 months, during the heating season of 2022–2023. A representative microclimate perspective was analyzed: the median value of the time fraction, which exceeded the Indoor Environment Quality Category I (IEQcat I) threshold for adults' bedrooms was 82.30%. For children's bedrooms, it was 75.65%, while for living rooms, it was 58.78%. When considering IEQcat IV, it was identified that for the bedrooms, the time fraction for which the threshold values were exceeded was still significant (median value of 45.37% for adults' bedrooms and 50.14% for children's bedrooms). Even if the indoor thermal comfort conditions increased, it was found that for almost half of the time, the bedrooms did not provide a health-safe indoor environment for the occupants due to inadequate ventilation, exceeding the health threshold values. Thus, it was identified that the ventilation of buildings is a key issue within the renovation process and, currently, is not properly undertaken for the mass renovation of existing multifamily residential buildings. [ABSTRACT FROM AUTHOR]

Indoor air quality is a crucial factor for people's health and well-being, since 90% of many people spend time indoors. The objective of this research was to verify the correlation of carbon dioxide with various study variables. To obtain the concentrations, a direct reading measuring equipment was used and monitoring was carried out for two months (September and October 2021). The Kolmogorov-Smirnov test was applied because the data did not follow a normal distribution, and Spearman's correlation was used, the results indicated a (Rho= -0.584; Sig. (bilateral)=0.00< p=0 0.05), which shows that there is a negative moderate inverse significant correlation between CO2 and ventilation, with respect to carbon dioxide and humidity, has a Spearman coefficient (Rho= -0.180; Sig. (bilateral)=0.315< p=0.05), so there is a very weak inverse negative correlation, in the same way a Spearman coefficient is observed (Rho= 0.130; Sig. (bilateral)=0.470< p=0.05, In conclusion, it is showed a moderate negative correlation between carbon dioxide and ventilation, which means that the higher the concentration of carbon dioxide, the lower the ventilation. Therefore, it is important that windows exist in work environments to ensure adequate ventilation. and create a healthy environment that does not harm people's health and reduces the risk of contagion of COVID-19. [ABSTRACT FROM AUTHOR]