Characteristics Of Indoor Environment Research Articles

Evaluation of passive cooling through natural ventilation strategies in historic residential buildings using CFD simulations

Natural ventilation in hot climates has the potential to save energy by reducing the need to use mechanical systems. Particularly in historic buildings, it should be considered as a passive retrofit strategy before the addition of any mechanical systems to accommodate their unique indoor environmental characteristics and ensure their preservation. This study investigates the efficiency of multiple natural ventilation strategies in cooling a historic residential structure located in San Antonio, Texas, USA, a hot and humid climate area. It also analyzes their potential to provide a thermally comfortable indoor environment during the spring and summer. Onsite data and ASHRAE standards were used to create and validate Computational Fluid Dynamics (CFD) and energy models. Six different natural ventilation approaches were simulated, and the results were analyzed and compared. The analysis revealed that all the considered scenarios can contribute to energy savings in both seasons, especially in spring, with cross ventilation being the most efficient strategy. It also proved that the size of the openings has an impact on thermal comfort. This study demonstrated that historic preservation and thermal comfort goals can be achieved simultaneously, and the results can be replicated in multiple historic structures in similar climate regions around the globe.

Exploring the role of indoor microbiome and environmental characteristics in rhinitis symptoms among university students

IntroductionRhinitis is one of the most prevalent chronic respiratory diseases worldwide. There is emerging evidence suggesting that the indoor microbiome may contribute the onset and exacerbation of rhinitis symptoms, but comprehensive studies on this topic remain scarce.MethodsIn this study, we assessed the microbiome assemblage of settled air dust collected in Petri dishes in 86 dormitory rooms of Shanxi University, China using 16s rRNA sequencing. A self-administered questionnaire, including questions about rhinitis symptoms and personal information, was completed by 357 students residing in these dormitories. Logistic and linear regression model was applied to examine the associations between environmental characteristics, indoor microbiome, and rhinitis.ResultsThe most abundant genera in the dormitories were Ralstonia (15.6%), Pelomonas (11.3%), Anoxybacillus (9.3%) and Ochrobactrum (6.2%). Taxa richness in the class of Actinobacteria and Fusobacteriia was negatively/protectively associated with rhinitis (p<0.05). Six bacterial genera, including those from Actinobacteria (Actinomyces), Fusobacteriia (Fusobacterium), and Bacteroidetes (Prevotella and Capnocytophaga), were negatively/protectively associated with rhinitis. Conversely, seven genera, predominantly from Alphaproteobacteria and Betaproteobacteria (Sphingomonas, Caulobacter, uncharacterized Caulobacteraceae and Comamonadaceae), were positively associated with rhinitis. Living in higher floor level and higher indoor PM2.5 concentrations were associated with a higher abundance of taxa potentially protective against rhinitis and a lower abundance of taxa potentially increasing the risk of rhinitis (P<0.01). However, having curtain indoor and higher indoor CO2 concentrations were associated with a lower abundance of taxa potentially protective against rhinitis and a higher abundance of taxa potentially increasing the risk of rhinitis (P<0.01).DiscussionThis study enhances our understanding of the complex interactions between environmental characteristics, indoor microbiomes, and rhinitis, shedding light on potential strategies to manipulate indoor microbiome for disease prevention and control.

Rethinking building envelope design: Machine learning approaches to evaluate its impact on indoor ozone exposures

Ozone is widely recognized as an ambient air contaminant that causes acute and chronic health effects. However, there is a limited number of studies investigating indoor exposures to ozone in occupied houses and linking design variables to the predictive power of indoor ozone levels. This study focuses on typical envelope airflow paths used in residences in the Philadelphia area in the United States. The model development draws from the field data, including indoor and outdoor ozone concentration, environmental parameters, and building characteristics from four building envelopes. Five machine learning algorithms (i.e., support vector machine, lasso regression, random forest, Bayesian bridge regression, and gradient boosting) are employed, with indoor ozone concentration as the dependent variable, as it indicates how the hot and sunny weather that might lead to the possibility of indoor air quality (IAQ) alerts due to ozone. The results showed that gradient boosting model based on all field measurements had the highest R-squared value of 0.974 and low enough root mean square error (RMSE) and mean absolute error (MAE) which are 1.182 and 0.788, respectively. We conclude that indoor ozone forecasting model based on inputting environmental survey (ES) in addition to either design variables or indoor environment characteristics can effectively predict and can therefore be used at the building design phase to improve healthy living environments.

Analysis of the Influence of Chilled Water Temperature Setpoint on Thermal Comfort and Energy Consumption

This study experimentally analysed the influence of chilled water temperature setpoints on thermal comfort conditions and energy consumption of an office building. Three chilled water temperature setpoints (10 °C, 12.5 °C, and 14 °C) were studied. The indoor environment variables (temperature and relative humidity) which are considered indicators of thermal comfort were recorded with data loggers for three consecutive days for each chilled water temperature setpoint (CWTS). Similarly, energy consumption was used as a metric to determine the system’s efficiency. The predicted percentage of dissatisfied (PPD) and predicted mean vote (PMV) indicators were computed and analysed using the Thermal Comfort/ASHRAE 55-2020 modelling tool from the centre for the built environment (CBE). Additionally, computational fluid dynamics (CFD) modelling and analysis were performed using ANSYS Fluent to study the indoor environment conditions of the office at the different chilled water temperature setpoints. A comparison between the calculated, measured, and predicted satisfaction of occupants was done. The results obtained when varying the chilled water temperature setpoints reveal that increasing the chilled water temperature setpoint (by 12%) reduces energy consumption per hour by 2% without compromising thermal comfort. The study demonstrated that the CWTS could be reset between 14 and 15 °C to reduce energy consumption and maintain thermal comfort. Moreover, the CFD model can be used to compare the indoor environmental characteristics of chiller systems.

Investigating the temperature distribution of non-enclosed atriums with air infiltration in winter

Low-temperature air infiltration and vertical thermal stratification lead to an unsatisfied bottom-occupied environment of the atrium and increase the space heating load in winter. An integrated prediction model was proposed regarding the interaction between thermal stratification and air infiltration. It includes the extended Block model for predicting the vertical temperature distribution in a non-enclosed atrium, the air infiltration model for calculating the buoyancy-driven air infiltration rate, and the Velocity propagating model for describing the airflow pattern within a foyer. By applying this model, we quantitatively analysed the indoor thermal characteristics in different atrium/foyer spatial morphologies. Beyond the indoor net height, the atrium diameter is also a dominant factor affecting the flow rate of air infiltration introduced from the foyer. The lower the section aspect ratio (SAR) and the higher the bottom floor height of the atrium, the warmer the bottom-occupied environment. The foyer's buffer effect mainly promotes occupants' thermal comfort, as lengthening the foyer length increases the heating load of air infiltration into the atrium while helping reduce the horizontal temperature gradient (HTG) when occupants walk across. This study clarified the indoor environmental characteristics in such spaces in winter and explored the interrelated influencing factors. The methodology and conclusions provide insights into practical engineering.

Satisfactions on Self-Perceived Health of Urban Residents in Chengdu, China: Gender, Age and the Built Environment

Self-perceived health is an important factor for assessing urban residents’ satisfaction and quality of life. However, few have comprehensively investigated the impact of demographics, lifestyle and health awareness, indoor environment characteristics, and neighborhood features on self-perceived health. To fill this gap, we designed a framework using multivariable regressions to derive odd rations and to analyze the determinants of self-rated health, stratified into different sub-groups divided by gender, age, and neighborhood types. The study area is Chengdu, one of the most populous cities in western China. The results show that: (1) female respondents reported worse health, with household income level and marital status significantly affecting self-rated health; (2) elderly people reported the worst health, while unique factors affected only younger people (18–29 years old), such as gender, smoking, and indoor environment characteristics; and (3) different types of neighborhoods influence their residents’ perception of health differently due to historical establishment, current population composition, and housing conditions. Our study provides new observations on neighborhood types, while agreeing with previous studies on the influences of gender and age. We contribute to the field by providing a more complex understanding of the mechanism by which people rate their own health, which is important for understanding the satisfaction of urban residents and the built environment in which they live.

Indoor microbiome and allergic diseases: From theoretical advances to prevention strategies

The prevalence of allergic diseases, such as asthma, rhinitis, eczema, and sick-building syndrome (SBS), has increased drastically in the past few decades. Current medications can only relieve the symptoms but not cure these diseases whose development is suggested to be greatly impacted by the indoor microbiome. However, no study comprehensively summarizes the progress and general rules in the field, impeding subsequent translational application. To close knowledge gaps between theoretical research and practical application, we conducted a comprehensive literature review to summarize the epidemiological, environmental, and molecular evidence of indoor microbiome studies. Epidemiological evidence shows that the potential protective indoor microorganisms for asthma are mainly from the phyla Actinobacteria and Proteobacteria, and the risk microorganisms are mainly from Bacilli, Clostridia, and Bacteroidia. Due to extremely high microbial diversity and geographic variation, different health-associated species/genera are detected in different regions. Compared with indoor microbial composition, indoor metabolites show more consistent associations with health, including microbial volatile organic compounds (MVOCs), lipopolysaccharides (LPS), indole derivatives, and flavonoids. Therefore, indoor metabolites could be a better indicator than indoor microbial taxa for environmental assessments and health outcome prediction. The interaction between the indoor microbiome and environmental characteristics (surrounding greenness, relative humidity, building confinement, CO 2 concentration) and immunology effects of indoor microorganisms (inflammatory cytokines, pattern recognition receptors) are briefly reviewed to provide new insights for disease prevention and treatment. Widely used tools in indoor microbiome studies are introduced to facilitate standard practice and the precise identification of health-related targets.

Factors Influencing the Performance of Indoor Environmental Quality of Pharmaceutical Factory Buildings in Southwest Nigeria

Pharmaceutical factory workers spend 37.5% of their daily time in the production hall manufacturing drugs used for human health needs. There is usually little or no time given to spend in the natural environment. This affects their sanity and well-being. The Pharmaceutical factory building (PFB) is classified as a specialized, controlled, or restrictive building; it provides little or no access to natural environmental conditions like ventilation and lighting, thereby increasing the financial implication of energy for the operation of production of drugs. Hence, the survey was conducted to identify the factors that influence the indoor environmental performance (IEP) of PFBs. The factors responsible for influencing the indoor air quality were measured through a survey conducted in Lagos and Ogun States, Nigeria on 14 PFBs to determine the value of these factors identified, using principal component analysis (PCA), Bartlett Test, and Kaiser-Mayer Olkin (KMO): the conditions for PCA were also observed. PCA is a factors or data reduction technique to select a subset of highly predictive factors from the larger group of factors identified from the study. Indoor environmental quality variables satisfied the condition for PCA while thermal performance variables did not meet the condition. PCA was conducted for Indoor environmental quality and the result showed 2 major factors explaining the variation in the original set of variables. Whereby CO2, P.M1.0, P.M2.5, P.M10, HCHO, airflow, AQICN, and AQIUS as component 1 and TVOC as component 2, the data set was also compared with the standards recommended for indoor environmental quality and thermal performance variables. It was found that at an average air velocity of 29°C and RH of 60%, the average CO, TVOC, PM2.5, and PM10 were 0.25ppm, 0.31ppm, 33.92ppm, and 43.48ppm respectively for the PFBs. Because thermal performance includes several dependent variables, greater research on the indoor environment of PFBs in Nigeria is recommended to determine the impact of indoor environmental characteristics on thermal parameters.

Heat, Moisture and Airflow coupled Model for Historical Building

The current building simulation of heat air and moisture (HAM) only regards the indoor air as homogeneous, which cannot accurately predict and evaluate the thermal and humid environment of complex historical buildings. In this study, the heat, moisture, and airflow coupled model (HAM-CFD model) was developed by FORTRAN programming, and then the simulation results of the HAM model and the HAM-CFD model were compared to study the characteristics of indoor environment under the action of airflow. The results show that there is a coupling effect between the indoor airflow and heat and moisture transfer of walls. The HAM-CFD model can reflect the temperature stability of the building center, and has a better correlation with rainfall. The HAM-CFD model can more truly reflect the changes of building temperature and moisture content in complex thermal and humid environment.

Associations between species-level indoor microbiome, environmental characteristics, and asthma in junior high schools of Terengganu, Malaysia

Associations between species-level indoor microbiome, environmental characteristics, and asthma in junior high schools of Terengganu, Malaysia

A review on reducing indoor particulate matter concentrations from personal-level air filtration intervention under real-world exposure situations.

Improving air quality in indoor environments where people live is of importance to protect human health. In this systematic review, we assessed the effectiveness of personal-level use of air filtration units in reducing indoor particulate matters (PM) concentrations under real-world situations following systematic review guidelines. A total of 54 articles were included in the review, in which 20 randomized controlled/crossover trials that reported the changes in indoor fine PM (PM2.5 ) concentrations were quantitatively assessed in meta-analysis. Standardized mean differences (SMDs) were calculated for changes in indoor PM concentrations following air filtration interventions. Moderate-to-large reductions of 11%-82% in indoor PM2.5 concentrations were observed with SMD of -1.19 (95% CI: -1.50, -0.88). The reductions in indoor PM concentrations varied by geographical locations, filtration technology employed, indoor environmental characteristics, and air pollution sources. Most studies were graded with low-to-moderate risk of bias; however, the overall certainty of evidence for indoor PM concentration reductions was graded at very low level. Considering the effectiveness of indoor air filtration under practical uses, socio-economic disparities across study populations, and costs of air filter replacement over time, our results highlight the importance of reducing air pollution exposure at the sources.

Efficacy of coupling heat recovery ventilation and fan coil systems in improving the indoor air quality and thermal comfort condition

Mechanical Ventilation with Heat Recovery (MVHR) systems are gaining increasing interest in buildings with low energy demand, for improvement of the Indoor Air Quality (IAQ) and reduction of the ventilation energy loss. In retrofitted buildings, MVHRs are often integrated with an additional air heater to cover space heating demand. Hence, evaluation of the interactions between MVHR and heat emitter, and their effects on indoor airflow characteristics is of significant importance. The present study aims to investigate effects of a combined MVHR-fan-coil system in heating mode on IAQ and thermal comfort parameters inside a retrofitted room, by means of a computational fluid dynamic (CFD) code. The proposed CFD model is validated by comparing the numerical results with experimental data. The results yielded by numerical simulations allow evaluating the indoor environmental quality characteristics as well as addressing the MVHR and fan coil interactions. The results indicate that the airflow discharged from the fan coil could have a significant impact on the age of the air; while it provides a desirable thermal comfort condition within the room, it may hinder to some extent delivery of the fresh air to the occupied zone due to creation of counterflow fields. Furthermore, it is shown that although increasing the fan speed (ON mode) would slightly enhance the air change efficiency, the OFF mode yields not only a better distribution of the fresh air but also a higher ventilation efficiency than when fan coil operates.

The reliability and validity of a physical activity and sedentary behaviour home audit tool for children aged 2–5 years

ObjectivesTo test the reliability and validity of a physical activity and sedentary behaviour home environment audit tool for young children (2–5 years old). DesignCross-sectional. MethodsParents of children aged 2–5 years were recruited through online methods (i.e., social media and blogs). Reliability of the SPACES home audit tool was assessed using self-reported surveys (n = 55) completed on two separate occasions, approximately 12 days apart. Validity of the home audit tool was assessed in a separate sample via home observations by researchers conducted after parents completed the self-report survey (n = 21). The audit tool measured indoor and outdoor home environment characteristics hypothesised to influence young children's physical activity and sedentary behaviour. Data were analysed using intraclass correlations (ICCs) and Kappas. ResultsThe majority of items demonstrated acceptable reliability and validity (80.4% and 53.4%, respectively). Size of the child's bedroom showed substantial agreement for reliability (ICC = 0.85), and slight agreement for validity (ICC = 0.23). Physical activity equipment items within the indoor environment showed slight to moderate agreement for reliability (ICC = 0.32–0.68) and slight agreement for validity (ICC = 0.15–0.35). Screen time equipment showed substantial agreement for reliability (ICC = 0.83) and fair for validity (ICC = 0.38). Outdoor items (e.g., backyard size, availability and condition of physical activity equipment, outdoor features) showed substantial agreement for reliability and validity (ICC = 0.84–0.95). ConclusionsThe home audit tool was found to be reliable and valid for many items. This tool could be used in future research to understand the impact of the home environment on young children's physical activity and sedentary behaviour.

Analysis on electricity use and indoor thermal environment for typical air-conditioning residential buildings in Malaysia

In residential buildings, accurate forecast of time-varying electricity demands is important for the estimation and prediction of electricity consumption. Information of the end user's electricity consumption patterns is necessary as it has a significant impact on the load curve in the utility grid. Thus, this study aims to provide detailed information on the electricity use and indoor thermal environment for typical residential buildings. Field measurements were conducted in 19 selected dwellings in Kuala Lumpur, Malaysia to specifically measure the total and the air conditioner (AC) electricity usage along with the indoor thermal environment. There were significant differences in the total electricity consumption among low-, middle-, and high-income dwellings. However, for the AC electricity consumption, the different income groups do not display notable differences. This might be due to the occupant behaviour of using the air conditioner mostly during sleeping hours. The measurement results of all targeted dwellings showed that the daily averages of the total and the AC electricity consumption are 14.5 kWh/day and 3.9 kWh/day, respectively. The daily averages of the AC electricity usage in the living room and the bedroom are 2.7 kWh and 4.4 kWh, respectively. The fraction of the daily peak demand from all targeted dwellings shows that the peak at the nighttime is due to the use of the air conditioner. Moreover, the patterns of hourly indoor thermal environment showed an average of 30.1 °C (living room) and 29.3 °C (bedroom). Generally, the comfort level for the indoor temperature lies between 23 °C and 26 °C, while for relative humidity, the comfortable range is between 40% and 70%. These findings provide preliminary understanding of the detailed characteristics of residential electricity use and indoor environment in Malaysian dwellings and can be used to predict the electricity demand in the future.

Associations between the indoor microbiome, environmental characteristics and respiratory infections in junior high school students of Johor Bahru, Malaysia.

Pathogens are commonly present in the human respiratory tract, but symptoms are varied among individuals. The interactions between pathogens, commensal microorganisms and host immune systems are important in shaping the susceptibility, development and severity of respiratory diseases. Compared to the extensive studies on the human microbiota, few studies reported the association between indoor microbiome exposure and respiratory infections. In this study, 308 students from 21 classrooms were randomly selected to survey the occurrence of respiratory infections in junior high schools of Johor Bahru, Malaysia. Vacuum dust was collected from the floor, chairs and desks of these classrooms, and high-throughput amplicon sequencing (16S rRNA and ITS) and quantitative PCR were conducted to characterize the absolute concentration of the indoor microorganisms. Fifteen bacterial genera in the classes Actinobacteria, Alphaproteobacteria, and Cyanobacteria were protectively associated with respiratory infections (p < 0.01), and these bacteria were mainly derived from the outdoor environment. Previous studies also reported that outdoor environmental bacteria were protectively associated with chronic respiratory diseases, such as asthma, but the genera identified were different between acute and chronic respiratory diseases. Four fungal genera from Ascomycota, including Devriesia, Endocarpon, Sarcinomyces and an unclassified genus from Herpotrichillaceae, were protectively associated with respiratory infections (p < 0.01). House dust mite (HDM) allergens and outdoor NO2 concentration were associated with respiratory infections and infection-related microorganisms. A causal mediation analysis revealed that the health effects of HDM and NO2 were partially or fully mediated by the indoor microorganisms. This is the first study to explore the association between environmental characteristics, microbiome exposure and respiratory infections in a public indoor environment, expanding our understanding of the complex interactions among these factors.

Experimental Study on Thermal Response Characteristics of Indoor Environment with Modular Radiant Cooling System

The radiant cooling system has a substantial energy-saving effect and can be widely applied in different kinds of low-energy buildings. This article reports the experimental study of the design strategy of the radiant cooling system in low-energy buildings from the perspective of thermal response characteristics of an indoor environment. Two types of a modular radiant cooling system, namely, the copper tube radiant cooling (CTRC) and the capillary radiant cooling (CRC) systems, were investigated. The experiments were conducted in two office rooms characterized by low energy consumption. In total, 16 cases (eight for CTRC and eight for CRC) were analyzed, covering supply water temperature with a range of 12–19 °C. The experimental results show that the supply water temperature has a more substantial effect on the temperature distribution of the envelope for CTRC, than that of CRC. The indoor air temperature stratification is acceptable in the active area of the occupant with a modular radiant cooling system. Moreover, the thermal response of the envelope is highly sensitive to the lower supply water temperature (below 16 °C) using CTRC and to the higher supply water temperature (above 15 °C) using CRC. The low supply water temperature (below 15 °C) can improve the thermal stability speed of indoor air to a greater degree using CTRC, than that of CRC. The supply water temperature for CTRC with 15–16 °C, and 18–19 °C for CRC in low-energy buildings can exert an optimal cooling benefit.

Biomonitoring and temporal trends of bisphenols exposure in Japanese school children

The widely used chemical bisphenol A (BPA), applied in various consumer products, has been under scrutiny in the past 20 years due to its widespread detection in humans and potential detrimental effects on human health. Following the implementation of restrictions and phase-out initiatives, BPA has been replaced by other structurally similar bisphenols, which have not yet received the same level of research attention. In this study, we aimed to 1) investigated the internal exposure to seven bisphenols in morning void urine samples (n = 396) from 7-year-old children from Hokkaido, Japan and 2) assess possible time trends in the concentrations of bisphenols between 2012 and 2017. Information on demographic, indoor environment and dietary characteristics of participants were acquired through a self-administered questionnaire. All bisphenols were detected in the study population, with BPA, BPF and BPS showing detection frequencies >50%. Concentrations of bisphenols measured in the Japanese children in our study were generally lower compared to studies worldwide. We found that BPA concentrations decreased significantly over the study time period (average 6.5% per year), whereas BPS rose with 2.8% per year. Levels of BPA and BPF were higher in autumn compared to winter. Higher urinary BPF levels were significantly associated with higher concentrations of the oxidative stress biomarker, 8-hydroxy-2′-deoxyguanosine (8-OHdG). BPA and BPF levels were higher in children from families with lower household income. Bisphenol concentrations were significantly influenced by some other personal (e.g. household income), food intake (e.g. vegetables and cow milk) and indoor housing characteristics (e.g. flooring). This is the first study to report longitudinal time trends of bisphenols in Japan. The presented findings imply that further research on bisphenols is warranted in the future to monitor whether these time trends continue.

Indoor microbiome, environmental characteristics and asthma among junior high school students in Johor Bahru, Malaysia

Indoor microbial diversity and composition are suggested to affect the prevalence and severity of asthma by previous home microbiome studies, but no microbiome-health association study has been conducted in a school environment, especially in tropical countries. In this study, we collected floor dust and environmental characteristics from 21 classrooms, and health data related to asthma symptoms from 309 students, in junior high schools in Johor Bahru, Malaysia. The bacterial and fungal composition was characterized by sequencing 16s rRNA gene and internal transcribed spacer (ITS) region, and the absolute microbial concentration was quantified by qPCR. In total, 326 bacterial and 255 fungal genera were characterized. Five bacterial (Sphingobium, Rhodomicrobium, Shimwellia, Solirubrobacter, Pleurocapsa) and two fungal (Torulaspora and Leptosphaeriaceae) taxa were protective for asthma severity. Two bacterial taxa, Izhakiella and Robinsoniella, were positively associated with asthma severity. Several protective bacterial taxa including Rhodomicrobium, Shimwellia and Sphingobium have been reported as protective microbes in previous studies, whereas other taxa were first time reported. Environmental characteristics, such as age of building, size of textile curtain per room volume, occurrence of cockroaches, concentration of house dust mite allergens transferred from homes by the occupants, were involved in shaping the overall microbial community but not asthma-associated taxa; whereas visible dampness and mold, which did not change the overall microbial community for floor dust, was negatively associated with the concentration of protective bacteria Rhodomicrobium (β = −2.86, p = 0.021) of asthma. The result indicates complex interactions between microbes, environmental characteristics and asthma symptoms. Overall, this is the first indoor microbiome study to characterize the asthma-associated microbes and their environmental determinant in the tropical area, promoting the understanding of microbial exposure and respiratory health in this region.

Hybrid Wireless Fingerprint Indoor Localization Method Based on a Convolutional Neural Network

In the indoor location field, the quality of received-signal-strength-indicator (RSSI) fingerprints plays a key role in the performance of indoor location services. However, changes in an indoor environment may lead to the decline of location accuracy. This paper presents a localization method employing a Hybrid Wireless fingerprint (HW-fingerprint) based on a convolutional neural network (CNN). In the proposed scheme, the Ratio fingerprint was constructed by calculating the ratio of different RSSIs from important contribution access points (APs). The HW-fingerprint combined the Ratio fingerprint and the RSSI to enhance the expression of indoor environment characteristics. Moreover, a CNN architecture was constructed to learn important features from the complex HW-fingerprint for indoor locations. In the experiment, the HW-fingerprint was tested in an actual indoor scene for 15 days. Results showed that the average daily location accuracy of the K-Nearest Neighbor (KNN), Support Vector Machines (SVMs), and CNN was improved by 3.39%, 8.03% and 9.03%, respectively, when using the HW-fingerprint. In addition, the deep-learning method was 4.19% and 16.37% higher than SVM and KNN in average daily location accuracy, respectively.

Assessment of formaldehyde levels in relation to respiratory and allergic symptoms in children from Alba County schools, Romania.

Our study assessed the exposure to formaldehyde of Romanian school children in relation to the classroom indoor environment characteristics and respiratory and allergic symptoms reported in a questionnaire survey, using the data collected in the SINPHONIE (Schools Indoor Pollution and Health: Observatory Network in Europe) project. Measurements of formaldehyde and microclimate parameters were conducted in three classrooms per school, in five schools, together with one outdoor measurement at each school. Questionnaires were used to collect information on classroom characteristics and health effects among children. The indoor formaldehyde levels for a school week varied between 15.5 and 66.2μg/m3, with a median value of 34.8μg/m3. The adjusted odds ratios for allergy-like, asthma-like, and flu-like symptoms were 3.23 (95% CI 1.31-8.00), 2.69 (95% CI 1.04-6.97), and 2.39 (95% CI 1.04-5.50), respectively, when exposed to higher formaldehyde levels (≥ 35μg/m3) during a school week, compared to lower formaldehyde level exposure (< 35μg/m3). Higher levels of indoor formaldehyde were significantly associated with health symptoms in children. The high indoor formaldehyde levels were related to the use of water-resistant paint for ceiling coverings, moisture damage signs, and lower classroom natural ventilation rates.