{"title":"Exposure of children and adolescents to volatile organic compounds in indoor air: Results from the German Environmental Survey 2014–2017 (GerES V)","authors":"Annika Fernandez Lahore , Robert Bethke , Anja Daniels , Konrad Neumann , Stefan Ackermann , Nadine Schechner , Klaus-Reinhardt Brenske , Enrico Rucic , Aline Murawski , Marike Kolossa-Gehring , Wolfram Birmili","doi":"10.1016/j.indenv.2025.100082","DOIUrl":"10.1016/j.indenv.2025.100082","url":null,"abstract":"<div><div>Indoor air concentrations of volatile organic compounds (VOC) were determined in the living environments of German children and adolescents between 2014 and 2017 during the German Environmental Survey (GerES) V. Passive sampling on Tenax TA tubes over 7 days and subsequent thermodesorption/gas chromatographic analysis yielded concentrations of 61 compounds from the groups of alcohols, alkanes, aromatics, carboxylic acid esters, glycol ethers, halogenated hydrocarbons, siloxanes, and terpenes as well as a value for total VOC (TVOC). The most abundant single compounds were decamethylcyclopentasiloxane (D5), limonene, α-pinene, butyl acetate, toluene, and 2-ethylhexanol, with geometric mean concentrations ranging between 12 and 4.5 µg/m³ . The guideline values established by the German Committee on Indoor Guidance Values (AIR) were exceeded in less than 1.3 % of participants when considered as a sum parameter for cyclic dimethylsiloxanes, monocyclic monoterpenes, bicyclic terpenes, C9-C14 alkanes, and xylenes. The concentrations of most compounds were lower in GerES V (2014/17) compared to the previous cycle GerES IV (2003/06). The concentrations of individual compounds showed moderate associations with exposure factors as identified from questionnaire data including the socio-economic status of the household, migration background, smoking status, the presence of wooden furniture, renovations in the test room, the age of the house, outdoor pollution (proximity to road traffic), as well as the age and sex of the participants.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100082"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143591632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ruiji Sun , Stefano Schiavon , Gail Brager , Haiyan Yan , Thomas Parkinson
{"title":"Causal effects estimation: Using natural experiments in observational field studies in building science","authors":"Ruiji Sun , Stefano Schiavon , Gail Brager , Haiyan Yan , Thomas Parkinson","doi":"10.1016/j.indenv.2025.100080","DOIUrl":"10.1016/j.indenv.2025.100080","url":null,"abstract":"<div><div>Correlational analysis, such as linear regression, does not imply causation. This paper introduces and applies a causal inference framework and a specific method, regression discontinuity, to thermal comfort field studies. The method utilizes policy thresholds in China, where the winter district heating policy is based on cities' geographical locations relative to the Huai River. The approximate latitude of the Huai River can be considered as a natural, geographical threshold, where cities near the threshold are quite similar, except for the availability of district heating in cities north of the threshold, creating a situation similar to a randomized experiment. Using the regression discontinuity method, we quantify the causal effects of the experiment treatment (district heating) on the physical indoor environments and subjective responses of building occupants. We found that mean indoor operative temperatures were 4.3 °C higher, and mean thermal sensation votes were 0.6 warmer due to the district heating. In contrast, using conventional correlational analysis, we demonstrate that the correlation between indoor operative temperature and thermal sensation votes does not accurately reflect the causal relationship between the two. We also show that the indoor operative temperature could be either positively or negatively correlated with occupants’ thermal satisfaction. However, we cannot conclude that increasing the indoor operative temperature in these circumstances will necessarily lead to higher or lower thermal satisfaction. This highlights the importance of causal inference methods in thermal comfort field studies and other observational studies in building science, where the regression discontinuity method might apply.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100080"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chai Yoon Um , William W. Delp , Rowan C. Blacklock , Brett C. Singer
{"title":"Demonstration of a novel tracer gas method to investigate indoor air mixing and movement","authors":"Chai Yoon Um , William W. Delp , Rowan C. Blacklock , Brett C. Singer","doi":"10.1016/j.indenv.2025.100081","DOIUrl":"10.1016/j.indenv.2025.100081","url":null,"abstract":"<div><div>This paper reports on equipment and procedures that enable the application of the pulsed tracer method to study air movement, contaminant transport, and mixing in rooms. We use ethanol as a non-toxic tracer and a network of low-cost, fast response (2 s) metal oxide sensors to measure airborne concentrations at high frequency. The method was demonstrated in a 158 m<sup>3</sup> room of the FLEXLAB facility at Lawrence Berkeley National Laboratory, with an overhead HVAC system with controllable supply airflow and temperature. The room was configured as a meeting space with 8 simulated occupants. The sensors were mounted in a 3 × 4 grid in the upper room (0.3 m from the 2.74 m ceiling), in the middle height of the room at 1.1–1.4 m, and at several locations 0.1–0.4 m from the floor. Vaporized ethanol was released in pulses of 20 s. Sensors were cross-calibrated in-situ to provide quantitative information about relative concentrations and exposures. Results show that the method provides quantitative information about air movement patterns and mixing. For example, mixing throughout the room took 3–4 min with high supply airflow at neutral temperature and 7.5–9 min with heated supply air provided at a lower rate. The test can be used to evaluate whether air movement from the occupied zone to the upper room is fast enough to achieve the extremely high air cleaning rates that are possible with upper room germicidal ultraviolet disinfection (GUV) systems under ideal mixing conditions.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100081"},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Corrigendum to “Ventilation characteristics in a hospital where a COVID-19 outbreak occurred in the winter of 2020” [Indoor Environ. 2 (2025) 100065]","authors":"Motoya Hayashi , Sayaka Murata , Koki Kikuta","doi":"10.1016/j.indenv.2025.100076","DOIUrl":"10.1016/j.indenv.2025.100076","url":null,"abstract":"","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100076"},"PeriodicalIF":0.0,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shujie Yan , Jiwei Zou , Chang Shu , Justin Berquist , Vincent Brochu , Marc Veillette , Danlin Hou , Caroline Duchaine , Liang (Grace) Zhou , Zhiqiang (John) Zhai , Liangzhu (Leon) Wang
{"title":"Implementing Bayesian inference on a stochastic CO2-based grey-box model","authors":"Shujie Yan , Jiwei Zou , Chang Shu , Justin Berquist , Vincent Brochu , Marc Veillette , Danlin Hou , Caroline Duchaine , Liang (Grace) Zhou , Zhiqiang (John) Zhai , Liangzhu (Leon) Wang","doi":"10.1016/j.indenv.2025.100079","DOIUrl":"10.1016/j.indenv.2025.100079","url":null,"abstract":"<div><div>The COVID-19 pandemic brought global attention to indoor air quality (IAQ), which increases public’s awareness on monitoring indoor ventilation conditions significantly. Indoor CO<sub>2</sub> monitoring has been widely accepted as an effective way for indicating IAQ conditions, attributed to its close relationships with indoor air change rates. However, real-time estimation of air change rates or CO<sub>2</sub> emission rates from CO<sub>2</sub> measurement data remains challenging due to uncertainties in factors like random air movements, dynamic conditions (e.g., weather and occupancy), and the limitations of deterministic equations. This study addresses these challenges by applying Bayesian inference to a stochastic CO<sub>2</sub>-based grey-box model, enabling the accurate estimation of ventilation and CO<sub>2</sub> emission rates while accounting for uncertainty. The model’s accuracy and robustness were validated through CO<sub>2</sub> tracer gas experiments, employing constant injection and decay methods in a large-scale aerosol chamber. Both prior and posterior predictive checks (PPC) were performed to verify this approach. The approach proposed by this study improves the interpretation of CO<sub>2</sub> monitoring data, thereby facilitating the future real-time IAQ management.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100079"},"PeriodicalIF":0.0,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143219429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Olivier Séguin , Dorra Ghorbal , Gabrielle Denault , Karine Trudeau , Patrick Poulin , Catherine Dea , Stéphane Perron
{"title":"CO2 levels and SARS-CoV-2 transmission in public schools: A retrospective cohort study in Montreal (Canada)","authors":"Olivier Séguin , Dorra Ghorbal , Gabrielle Denault , Karine Trudeau , Patrick Poulin , Catherine Dea , Stéphane Perron","doi":"10.1016/j.indenv.2025.100077","DOIUrl":"10.1016/j.indenv.2025.100077","url":null,"abstract":"<div><div>Scientific evidence suggests that SARS-CoV-2 is transmitted primarily through close contact with susceptible individuals and that the risk of transmission increases during prolonged exposure in confined, inadequately ventilated and densely occupied spaces. In response to concerns related to inadequate ventilation for students and staff, CO<sub>2</sub> concentrations were measured in all of Montreal’s public elementary and high schools during winter of 2020–21. This study aims to evaluate the associations between ventilation system types, mid-class CO<sub>2</sub> concentrations and SARS-CoV-2 transmission amongst Montreal's public school’s attendees during the 2020–2021 school year. Data on building ventilation types, CO<sub>2</sub> measurements and school characteristics such as total enrollment and socioeconomic status (SES), were sourced from Ministry of Education’s administrative data for the 2020–2021 school year. During this pandemic period, the Montreal Public Health Department investigated COVID-19 cases among students and staff in public elementary and high schools, gradually developing a regional database of school cases and outbreaks from intervention files. Negative binomial regression models were employed to examine associations between mid-class CO<sub>2</sub> concentrations and COVID-19 incidence rates for both total cases and those acquired within schools. Regression models were adjusted for school types, neighborhood COVID-19 incidence rates and school SES. The mid-class CO<sub>2</sub> concentration<del>s</del> median was 1050 ppm in the 384 school buildings. CO<sub>2</sub> concentrations were associated with ventilation systems, with schools using natural ventilation exhibiting higher concentrations compared to three other types of mechanical ventilation. No positive association was observed between the incidence rates of school-acquired cases and higher mid-class CO<sub>2</sub> concentrations in both unadjusted and adjusted models.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100077"},"PeriodicalIF":0.0,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stefan Flagner , Thomas Meissner , Steffen Künn , Piet Eichholtz , Nils Kok , Rick Kramer , Wouter van Marken-Lichtenbelt , Cynthia Ly , Guy Plasqui
{"title":"Cognition, economic decision-making, and physiological response to carbon dioxide","authors":"Stefan Flagner , Thomas Meissner , Steffen Künn , Piet Eichholtz , Nils Kok , Rick Kramer , Wouter van Marken-Lichtenbelt , Cynthia Ly , Guy Plasqui","doi":"10.1016/j.indenv.2025.100074","DOIUrl":"10.1016/j.indenv.2025.100074","url":null,"abstract":"<div><div>This study examines the isolated effect of carbon dioxide on cognition, economic decision-making, and the physiological response in healthy adults. The experiment took place in an air-tight respiration chamber controlling the environmental conditions. In a single-blind, within-subject study design, 20 healthy participants were exposed to artificially induced carbon dioxide concentrations of 3,000 ppm and 900 ppm in randomized order, with each exposure lasting for 8 h. A high ventilation rate and an air pollutant filter were used to keep concentrations of volatile organic compounds and fine particles equally low in both conditions. Cognition tests were conducted twice during the 8 h and physiological parameters were measured continuously over the 8 h. No evidence on a robust statistically significant effect of carbon dioxide on either cognitive or physiological outcome variables were found. These findings imply that the human body is able to deal with exposure to indoor carbon dioxide concentration of 3,000 ppm for a limited time without suffering significant cognitive decline, changes in decision-making or showing any physiological response.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100074"},"PeriodicalIF":0.0,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Personal air cleaning by a user-tracking robot equipped with a nanofiber air cleaner in a large work space","authors":"Chengzhong Deng , Zhuolun Niu , Chun Chen","doi":"10.1016/j.indenv.2025.100078","DOIUrl":"10.1016/j.indenv.2025.100078","url":null,"abstract":"<div><div>In large work spaces, such as logistics warehouses, implementing whole-space air cleaning to protect the workers’ health can be costly. To tackle this issue, the present study developed a user-tracking robot equipped with a nanofiber air cleaner to achieve personal air cleaning for a moving worker in a large work space. First, nanofiber air filters with low pressure drop were fabricated using the electrospinning technique. An air cleaner with a deflector for directing the airflow towards the user’s breathing zone and the nanofiber air filters was assembled and then integrated into a user-tracking robot. Experiments were conducted to measure the clean air delivery rate (CADR) of the nanofiber air cleaner, evaluate the accuracy of the user-tracking algorithm, and determine the optimal deflector setup and user-to-robot distance. Field tests were conducted to evaluate the personal air cleaning performance of the proposed method by comparison with a stationary nanofiber air cleaner. The results show that the user-tracking algorithm of the user-tracking robot was accurate, with an average absolute error in the user-to-robot distance of 4 cm. The user-tracking robot with nanofiber air cleaner outperformed the stationary nanofiber air cleaner by reducing the concentration of 0.3–0.4 μm particles in the breathing zone of the user by 16.4 %. Furthermore, compared with commercial panel-type high-efficiency particulate air (HEPA) filters, the use of nanofiber air filters can extend the battery service life, consequently facilitating the practical application of the moving robot.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100078"},"PeriodicalIF":0.0,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143285892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gihyun Song , Kyungcheol Jang , Woobin Song , Wonchul Choi , Simon Song , Hyoungsoo Kim
{"title":"Cyclone negative pressure pump for efficient purification of airborne contaminants","authors":"Gihyun Song , Kyungcheol Jang , Woobin Song , Wonchul Choi , Simon Song , Hyoungsoo Kim","doi":"10.1016/j.indenv.2025.100073","DOIUrl":"10.1016/j.indenv.2025.100073","url":null,"abstract":"<div><div>Maintaining an isolation room with negative pressure is crucial in medical facilities to prevent the spread of airborne infections, especially during the COVID-19 pandemic. However, conventional negative pressure pumps have limitations in gathering suspended particles and controlling the airflow effectively. To resolve this issue, we developed a novel class of negative pressure pump that creates a swirling cyclone flow at the front to efficiently collect pollutants and particles, which was confirmed by a smoke visualization experiment. Based on the prototype pump, we conducted a numerical analysis to evaluate the particle collection performance of the cyclone pump in various scenarios, including patients covered with contaminants, and coughing or breathing. Our results demonstrate that the cyclone pump can purify airborne pollutants by up to 80%, offering superior performance over conventional pumps. We also identified optimal pump placement for effective particle purification. This research provides an innovative solution for improving the efficiency of negative pressure pumps and ventilation systems in medical settings, contributing to better control of airborne infections.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 1","pages":"Article 100073"},"PeriodicalIF":0.0,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}