Indoor Environments最新文献

{"title":"Levels, distribution, sources and children's health risk of PBDEs in household dust from 2010 to 2022 in China","authors":"Xiaotong Zhang ,&nbsp;Wenying Zhang ,&nbsp;Tingting Liu ,&nbsp;Fengjing Song ,&nbsp;Chengyu Chen ,&nbsp;Chao Wang ,&nbsp;Weiyi Zhang ,&nbsp;Xu Han ,&nbsp;Xianliang Wang","doi":"10.1016/j.indenv.2025.100114","DOIUrl":"10.1016/j.indenv.2025.100114","url":null,"abstract":"<div><h3>Background</h3><div>Polybrominated biphenyl ethers (PBDEs) are one of the most common flame retardants in household products. Given their broad-spectrum toxicity, monitoring PBDE levels in indoor environments and assessing their potential health risks are critical for residential health risk management.</div></div><div><h3>Methods</h3><div>Based on published literature data from 2010 to 2022, the concrete raw data regarding the concentration of PBDEs in actual dust samples from true household living conditions in China were collected exhaustively from 26 peer-reviewed papers after screening. Congeners with detection rates exceeding 80 % (BDE-28, −47, −99, −100, −153, −154, −183, −209) were selected for further analysis. Household dust PBDE levels were quantified using the weighted average concentration. Seasonal and regional variations were evaluated using the Mann-Whitney U and Kruskal-Wallis H tests, while Spearman correlation analysis and exploratory factor analysis (EFA) were applied for source apportionment. Health risks to children were assessed based on estimated daily intake (EDI) via ingestion and dermal absorption, using hazard indices (HI) and carcinogenic risk (CR) models.</div></div><div><h3>Results</h3><div>The concentrations of PBDEs in household dust (HD-PBDEs)<span><span>²</span></span> in China ranged from 4.03 ng/g to 37333.58 ng/g, with a weighted average concentration of 3625.43 ng/g. The weighted average concentration was maximum in Zhejiang (27268.66 ng/g) and lowest in Shaanxi (4.03 ng/g). BDE-209 was the predominant congener of HD-PBDEs, ranging from 73.56 % to 99.78 %, followed by BDE-47 (6.84–62.08 %), BDE-99 (1.80–56.77 %), and BDE-153 (0–43.10 %). The weighted average concentrations of ∑₈PBDEs were 1419.97 ng/g in 2006–2009, 5886.15 ng/g in 2010–2014, and 1813.51 ng/g in 2015–2020. HD-PBDE concentration was significantly higher in winter than in spring and fall (<em>P</em> &lt; 0.05). Families residing in rural areas, southern regions, or near e-waste-contaminated areas exhibited higher concentrations of HD-PBDEs (<em>P</em> &lt; 0.05). Two principal components were extracted, accounting for 84.56 % of the total variance. The estimated daily intake of HD-PBDEs for children via ingestion (1.93 × 10¹ ng/kg BW/day) was higher than that via dermal absorption (8.93 ×10⁻¹ ng/kg BW/day). The non-carcinogenic risk of HD-PBDEs (1.01 ×10⁻¹) and the carcinogenic risk of BDE-209 (1.30 ×10⁻⁸) were below the standard criterion.</div></div><div><h3>Conclusions</h3><div>HD-PBDE concentrations in China ranked moderate-to-high globally, with clear regional variations. Both non-carcinogenic and carcinogenic risks of HD-PBDE exposure to Chinese children were acceptable. Future investigations should focus on longitudinal monitoring of PBDE trends in household environments and health impacts on vulnerable subpopulations.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 3","pages":"Article 100114"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exposure risk and source analysis of toxic metal(loid)s in indoor dust of Eastern Nigeria during COVID-19 lockdown","authors":"Chideraa Courage Offor ,&nbsp;John Kanayochukwu Nduka ,&nbsp;Henrietta Ijeoma Kelle","doi":"10.1016/j.indenv.2025.100113","DOIUrl":"10.1016/j.indenv.2025.100113","url":null,"abstract":"<div><div>Outbreak and emergency occasioned by coronavirus virus disease forcefully led to imposition of lockdown in Nigeria; a situation that consequently exposed humans to heavy metal(loid)s laden dust. Hence, this study measured the concentration of heavy metal(loid)s in indoor dust from households of three selected semi-urban areas (Rumuodomaya-Ogale, Ekwulobia and Awka) of Eastern Nigeria. Dust samples (n = 144) were collected from household’s windows and floors using clean brush, filtered, digested by standard method and analyzed for Cd, Co, Ni, Hg, As, Mn, Al, Pb, Cr, Zn, and Fe using Atomic Absorption Spectrometry (Model: Varian AA240, USA). Results show that Fe was dominant when compared to other metals assessed. Whereas the total heavy metal(loid)s concentration (THMC) of the floor dusts was higher than that of window dusts from Ekwulobia, there was no significant difference (p &gt; 0.05) in total heavy metal(loid)s level in window and floor dust of the three semi-urban areas across the months. Awka showed the least THMC in the window (1.17 – 1.52 mg kg⁻¹) and floor (1.08 – 2.35 mg kg⁻¹) dusts in comparison with Ekwulobia (window: 1.23 mg/kg to 9.05 mg kg⁻¹; floor: 1.27 mg kg⁻¹ to 9.22 mg kg⁻¹) and Rumuodomaya-Ogale (window: 1.49 – 2.70 mg kg⁻¹; floor: 1.24 – 2.23 mg kg⁻¹). The cancer and non-cancer risk of exposure to the heavy metal(loid)s dusts was insignificant while most of the heavy metal(loid)s could be related to anthropogenic origin based on the Positive Matrix Factorization and Principal Component Analysis models.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 3","pages":"Article 100113"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144662103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predictability of time-resolved cross-envelope pressures driving natural infiltration in low-rise residential buildings","authors":"Dominic Bledsoe ,&nbsp;Will Clagett ,&nbsp;Misael Soto ,&nbsp;Ellison M. Carter ,&nbsp;Paul W. Francisco ,&nbsp;Tami C. Bond","doi":"10.1016/j.indenv.2025.100106","DOIUrl":"10.1016/j.indenv.2025.100106","url":null,"abstract":"<div><div>Natural infiltration in residential buildings has two major drivers: indoor-outdoor temperature differences (stack effect) and wind effect. While residential infiltration models are long established, their validity has not been evaluated with measurements, and they have rarely been deployed to explain time-resolved indoor-outdoor exchange. Pressure differentials (ΔP) across building envelopes are an intermediate step in modeling; if they cannot be well predicted from the driving forces, then neither can infiltration. We report nearly 16,000 h of environmental and ΔP data, in nine homes, at one-minute resolution that reflects the transient nature of air exchange. Under conditions of low wind (less than 0.25 m/s) and heating (outdoor temperature below indoor), stack pressure is predicted exceptionally well. Biases between observed and predicted values average 0.11 Pa or less across all sites. Biases increase by about a factor of two under cooling conditions, but observations under these conditions were of insufficient length to diagnose the causes. Wind influence on pressure, and hence on infiltration, is not well predicted even with practical, site-based measurements. Airport and site wind speeds, and site wind and envelope pressure, are correlated only modestly, even accounting for wind direction. Simple terrain and shielding classifications cannot reproduce intersite variation. Infiltration models overestimate the influence of wind on pressure even when the most extreme shielding and terrain classes are used in scaling airport data. In addition to evaluating infiltration drivers, this study establishes the difference between time-resolved, cross-envelope pressure differentials at separate points in a single zone (Δ−ΔP) as a building diagnostic.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 3","pages":"Article 100106"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Low-E glass on local skin temperature and thermal sensation in vehicle cabins under cold winter environments","authors":"Hikari Ryuzaki ,&nbsp;Yoshiichi Ozeki ,&nbsp;Akihisa Nomoto ,&nbsp;Reika Miura ,&nbsp;Kan Shindo ,&nbsp;Yasuki Moriya ,&nbsp;Hiromu Hiruma ,&nbsp;Shin-ichi Tanabe","doi":"10.1016/j.indenv.2025.100108","DOIUrl":"10.1016/j.indenv.2025.100108","url":null,"abstract":"<div><div>This study evaluated the effects of Low-E glass on the thermal environment inside a vehicle cabin under winter conditions and its impact on occupants’ thermal physiology and sensation. A human subject experiment was conducted, where participants seated near either Low-E or Normal glass and voted their local and whole-body thermal sensations. Their local skin temperatures and the thermal environment in the vehicle were measured. The plane radiant and equivalent temperatures near Low-E glass were 11.0 °C and 4.5 °C higher, respectively, than near Normal glass. Local skin temperatures decreased less in the Low-E condition compared to the Normal condition. Local thermal sensations were generally warmer in the Low-E condition, particularly for the cheek and hand, even though the impact on whole-body thermal sensation was limited. Females were more sensitive to the improved radiative environment provided by Low-E glass than males. These findings show the effectiveness of Low-E glass in enhancing radiant environment in the vehicle and occupant comfort, which could help improving energy efficiency of vehicles and innovative vehicle designs.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 3","pages":"Article 100108"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144314022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An efficient method for fabricating nanofiber air filters with minimized pressure drop for effective indoor particle removal","authors":"Zhuolun Niu ,&nbsp;Chun Chen","doi":"10.1016/j.indenv.2025.100110","DOIUrl":"10.1016/j.indenv.2025.100110","url":null,"abstract":"<div><div>Electrospun nanofiber air filters can achieve high particle filtration efficiency with lower pressure drop compared with high-efficiency particulate air (HEPA) filters. Therefore, they can potentially be used for effective indoor particle removal. To support practical applications, this study proposed an efficient method for producing electrospun nanofiber air filters that achieve a minimized pressure drop while meeting the target particle filtration efficiency. Specifically, this method decoupled the influence of applied voltage and electrospinning time, enabling the identification of the optimal applied voltage to minimize pressure drop and the calculation of the electrospinning time needed to achieve the target filtration efficiency. Compared with the previous approach, this method eliminated the need to measure structural parameters, thereby significantly simplifying the optimization process. Experimental measurements were conducted to validate the feasibility of the proposed method. The results show that the proposed method can effectively achieve the target particle filtration efficiency with relative errors all less than 1% compared to the target values. Furthermore, the pressure drop of the optimized nanofiber air filters was up to 40.6% lower than that of the randomly selected filters in the verification cases. Finally, the benefits of using the optimized nanofiber air filters for indoor particle removal were numerically assessed. The results show that using the nanofiber air filters optimized by the proposed method in an air cleaner reduced indoor PM_0.3–0.4 of outdoor origin in a typical public housing apartment in Hong Kong by up to 22.7% compared to the randomly selected nanofiber air filters.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 3","pages":"Article 100110"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-reported indoor climate in shared vs. private offices and its effects on headache and respiratory symptoms in Norwegian office workers","authors":"Therese Nitter Moazami ,&nbsp;Tom Sterud","doi":"10.1016/j.indenv.2025.100118","DOIUrl":"10.1016/j.indenv.2025.100118","url":null,"abstract":"<div><div>This two-wave cross-sectional study analyzed data from 7968 Norwegian office workers collected in 2016 and 2019 to investigate associations among self-reported indoor climate, headaches, and respiratory symptoms across six office types. Interaction effects between office type, indoor climate, and health outcomes were assessed, alongside a mediation analysis examining indoor climate as a mediator between office type and health outcomes. Adjusted generalized linear models (GLMs) revealed that shared offices had significantly poorer indoor climate conditions than private offices, with the highest odds reported in flexible spaces (OR = 1.72, 95 % CI: 1.41–2.09) and offices with over 24 occupants (OR = 1.57, 95 % CI: 1.27–1.93). Self-reported poor indoor climate was associated with respiratory symptoms (OR = 2.17, 95 % CI: 1.74–2.27) and headaches (OR = 1.66, 95 % CI: 1.48 – 1.86). No direct association was found between office type and health outcomes; however, mediation analysis demonstrated a significant indirect effect of office type on health outcomes via indoor climate. Interaction analysis further revealed that the association between poor indoor climate and respiratory symptoms was stronger in shared offices compared to cell offices for both respiratory symptoms (OR = 2.32 vs. OR = 1.80) and headaches (OR = 1.69 vs. OR = 1.44). In conclusion, this study demonstrates notable associations between office type, perceived indoor climate, and self-reported health outcomes. While the cross-sectional design limits the ability to determine the direction or underlying mechanisms of these associations, the results emphasize the relevance of both office layout and indoor climate quality in evaluating workplace health.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 3","pages":"Article 100118"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144890534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term impacts of energy retrofits on indoor air quality and climate – Follow-up results of a sample of Finnish apartment buildings","authors":"Virpi Leivo ,&nbsp;Minna Kempe ,&nbsp;Ulla Haverinen-Shaughnessy","doi":"10.1016/j.indenv.2025.100116","DOIUrl":"10.1016/j.indenv.2025.100116","url":null,"abstract":"<div><div>Energy retrofits can have an impact on indoor air quality and climate, particularly on temperature, humidity, and concentrations of air pollutants. Both positive and negative impacts have been identified, usually based on measurements taken quite soon (up to about one year) after the retrofits. We studied the long-term (about seven years) impacts of energy retrofits on indoor thermal conditions, ventilation rates, and CO₂ and radon concentrations during heating season in 13 Finnish apartment buildings (42 apartments) along with the occupants’ self-reported satisfaction with IAQ. High indoor temperatures and low RH were recorded in all the measurements. There were no significant changes in the night-time average CO₂ concentration (less than 700 ppm) and momentary air exchange rates (0.3–0.35 (dm³/s)/ m²) between the measurements. There was a decreasing trend in radon concentration. Seven years after the retrofit, the average radon concentration was 23 % lower than before the retrofit. Concentrations above 100 Bq/m³ were also less frequent after the retrofitting. According to the occupant questionnaire, the respondents were significantly more satisfied with IAQ about one year after the retrofits. About 7 years after the retrofit, they still appeared to be more satisfied with IAQ than before the retrofits.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 3","pages":"Article 100116"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Addressing actual and community expectations on CO2 concentrations within indoor spaces – A reasonably practicable methodology using CO2 concentration to assess ventilation quality to indoor spaces","authors":"Peter McGarry ,&nbsp;Lidia Morawska ,&nbsp;Savinda Arambawatta Lekamge ,&nbsp;Simon Witts","doi":"10.1016/j.indenv.2025.100101","DOIUrl":"10.1016/j.indenv.2025.100101","url":null,"abstract":"<div><div>The ability to quickly assess the performance of a ventilation system to deliver an adequate amount of clean air to the space relative to the number of occupants is important as part of the overall goal of ensuring healthy indoor air. Current debate within the scientific community clearly aims to influence government to legislate a CO₂ concentration as an indoor air quality standard. However, to properly consider this, government will likely demand quantitative data on contemporary indoor CO₂ concentrations and a tested and reasonably practicable method for use by building occupants. Our study addresses this research gap with the aim of testing and documenting how to operationalise CO₂ monitoring for use by occupants as an infection risk reduction tool within mechanically ventilated spaces. The related research objectives were 1) to inform the current scientific debate on an indoor air CO₂ concentration action level for improved ventilation quality and infection risk control, 2) to pilot and document a method for characterising indoor CO₂ concentrations within occupied spaces serviced by heating, ventilation and air conditioning (HVAC) systems and demonstrate it was reasonably practicable in terms of instrument cost and deployment utility, 3) assess the performance of a ventilation systems to deliver an adequate amount of clean air to indoor spaces relative to the number of space occupants, and 4) to action improvements in ventilation quality where identified. The method was informed by a literature review of various standards that described optimal number, location, and layout of sensors, resulting in demonstration of deployment of CO₂ sensors. Sensors were deployed within 1439 teaching and office spaces across 78 mechanically ventilated buildings. In 1025 (72 %) rooms, CO₂ concentration was &lt; 800 ppm, in 267 (18 %) between 800 ppm and 1000 ppm, and in 147 (10 %) &gt; 1000 ppm, during room occupancy.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 3","pages":"Article 100101"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144314023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Air changes per hour in residential buildings and health outcomes: a scoping review","authors":"Lisbeth Mølgaard Laustsen ,&nbsp;Marie Bergmann ,&nbsp;Torben Sigsgaard ,&nbsp;Steffen Petersen ,&nbsp;Charlotte Gabel","doi":"10.1016/j.indenv.2025.100102","DOIUrl":"10.1016/j.indenv.2025.100102","url":null,"abstract":"<div><h3>Background</h3><div>Ventilation is a key parameter for indoor air quality and thereby preventing adverse health symptoms. However, health-based recommendations on air changes per hour (ACH) in residential buildings is not thoroughly substantiated by evidence, and an extensive overview of the quality and findings of studies on ACH in residential buildings and health outcomes is lacking.</div></div><div><h3>Methods</h3><div>We searched PubMed, Web of Science, and Scopus up to March 13, 2025, and conducted chain search of existing reviews to include observational and interventional studies. Pairs of reviewers independently assessed study quality using Joanna Briggs Institute’s critical appraisal tools. Findings were categorized into symptom groups and visualized using locally weighted scatterplot smoothing.</div></div><div><h3>Results</h3><div>After screening 10,737 articles, 18 studies were included: six cross-sectional, seven case-control, and five quasi-experimental or interventional studies. The study quality varied considerably with frequent limitations due to non-responses and lack of follow-up, insufficient length of the exposure assessment period, and inadequate strategies to deal with confounding. The study findings were mixed but indicated fewer adverse health outcomes when the ACH level was higher for six out of seven symptom groups (asthma, dermal, mucosal, infections, respiratory, and general symptoms), especially at lower mean ACH levels.</div></div><div><h3>Conclusion</h3><div>Our review expands and updates the insights obtained from previous narrative reviews, identifying several additional studies. Beside biases and residual confounding, the mixed results might be due to different levels of indoor- and outdoor-originated pollutants. Future studies could benefit from focusing on elderly populations and multi-family housing and provide findings for several ventilation metrics.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 2","pages":"Article 100102"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Building age is a determining factor of indoor CO2 levels in a University setting","authors":"Leigh Ann Broadway ,&nbsp;Hannah Aycock ,&nbsp;Andrew Broadway ,&nbsp;Ty Russell ,&nbsp;Ana Endsley ,&nbsp;Buddy Harley ,&nbsp;Alex Colmorgan ,&nbsp;Tyler Drafts ,&nbsp;David Estey ,&nbsp;Tom Syfert","doi":"10.1016/j.indenv.2025.100100","DOIUrl":"10.1016/j.indenv.2025.100100","url":null,"abstract":"<div><div>Literature on CO₂ levels in classrooms routinely focus on CO₂ exposure in primary education settings, but comparatively little attention has been given to higher education settings such as colleges. Due to concerns about the relationship between COVID-19 and CO₂, the University of South Carolina’s (USC) Environmental Health and Safety Department (EHS) monitored indoor air quality for 26 buildings and 198 classrooms from the Fall of 2021 to the Spring of 2022 in general purpose university classrooms. 30 Onset HOBO data loggers were used to monitor these classrooms. Average CO₂ levels varied greatly between buildings built after 1981 and before 1955, from 126 ppm over 24 hours to 179 ppm over the 9 am to 5 pm timeframe. There were lesser differences between buildings built between 1956 and 1980 and before 1955, showing CO₂ levels from 23 ppm over 24 hours to 30 ppm over the 9 am to 5 pm timeframe. The parts per million differences were statistically significant over the 24-hour period and the 9 am to 5 pm period. Class occupancy greatly affected CO₂ levels in tested classrooms, with statistically significant differences from 187 ppm to 192 ppm in buildings built after 1981 and those built before 1955 and between 1956 and 1980 when the classroom was at least 50 % occupied. However, these levels dropped to only a 5 ppm difference for buildings build before 1955 and between 1956 and 1980 and were not statistically significant. The rate of CO₂ decrease was slower in buildings built after 1981 with a decrease of 65.4 ppm per hour compared to a decrease of 77.9 ppm per hour in buildings built before 1955. The results were comparable based on the age of the HVAC systems in the buildings, showing total HVAC systems installed after 2000 were 79–113 ppm higher average CO₂ than total HVAC systems installed before 2000 during a 24-hour timeframe and a 9am-5pm timeframe. While none of the classrooms had CO₂ levels that exceeded federal limits for CO₂ exposure, there is a scarcity of data and guidelines of CO₂ levels within a collegiate setting. The data provides information on changes in CO₂ levels related to classroom occupancy and differences in CO₂ levels based on building age.</div></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"2 2","pages":"Article 100100"},"PeriodicalIF":0.0,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144131136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}