Indoor Environments最新文献

{"title":"What sizes of droplets contribute to long-range airborne transmission?","authors":"Pan Cheng ,&nbsp;Wei Jia ,&nbsp;Li Liu ,&nbsp;Hui-Ling Yen ,&nbsp;Yuguo Li","doi":"10.1016/j.indenv.2024.100045","DOIUrl":"10.1016/j.indenv.2024.100045","url":null,"abstract":"<div><p>The size range of respiratory droplets contributing to long-range airborne transmission of infections determines the targeted intervention methods. However, the exact size range remains unknown, and the influencing parameters are also undetermined. Here, we investigated the size-resolved transport and fate of respiratory droplets in four reported venues of COVID-19 outbreaks. We utilised a transient number balance model, a set of expired droplet size distributions, existing formulas for size-resolved settling rates and filtration efficiencies, and a deposition model from the International Commission on Radiological Protection. This enabled us to obtain the size-resolved concentrations of exhaled droplets in indoor air, the size-resolved number of droplet nuclei in the inhaled air, and the number of droplets deposited throughout the respiratory tract. The newly defined airborne transmission size range of expired droplets depends on the effective dilution flow rate of the infection venue under consideration. Three criteria were proposed for determining the sizes of droplets involved in long-range airborne transmission. The airborne transmission droplets typically featured an initial diameter of 0.1–4–6 µm, with an hourly volume generation rate of 0.38–0.42 nL/h per index case in the four venues. This newly estimated volume of airborne transmission droplets provides an essential input into the viral load method for estimating the infectious quanta generation rate.</p></div><div><h3>Practical significance</h3><p>Our size-resolved estimation reveals that only a tiny fraction of expired infectious droplets within an airborne transmission size range survives after the removal effects of ventilation, settling, deactivation, and filtration, as well as the transient dilution effect. These droplets remain in indoor air, potentially contributing to long-range airborne transmission. The airborne transmission size range depends on the size-dependent dilution capacity of a room.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 4","pages":"Article 100045"},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000420/pdfft?md5=95ce39aa153ba140e10698beac00b665&pid=1-s2.0-S2950362024000420-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163535","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":"Measured PM2.5 indoors and outdoors related to smoking prevalence by Zip code using 14,400 low-cost monitors in California, Washington, and Oregon","authors":"Lance Wallace","doi":"10.1016/j.indenv.2024.100043","DOIUrl":"10.1016/j.indenv.2024.100043","url":null,"abstract":"<div><p>Low-cost monitors have made possible for the first time measurements of long-term (months to years) potential indoor exposures to fine particles. Indoor and outdoor measurements made over nearly 5 years (2017–2021) by the largest network of low-cost monitors in the United States (PurpleAir) are compared to the prevalence of adult smokers in 1650 Zip codes within the three West Coast states of California, Oregon, and Washington. The results show that mean potential indoor exposures above the 75th percentile of adult smoking prevalence are more than 50 % higher than those below the 25th percentile. Mean outdoor concentrations are also elevated, but by a smaller amount (∼ 20 %). Both comparisons are significant at the <em>p</em> &lt; 0.001 level. The elevation of PM_2.5 concentrations with increasing smoking prevalence is evidence of environmental disparities in income, education, and other socioeconomic indices. The relatively stronger effect on indoor rather than outdoor PM_2.5 exposures highlights the importance of including indoor measurements when possible in environmental justice studies.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 4","pages":"Article 100043"},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000407/pdfft?md5=20d6ee336e59b8811f007fc8564f3105&pid=1-s2.0-S2950362024000407-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128283","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":"Effectiveness of triethylene glycol disinfection on airborne MS2 bacteriophage under diverse building operational parameters","authors":"Zuraimi Sultan ,&nbsp;Irvan Luhung ,&nbsp;Ngu War Aung ,&nbsp;Akira Uchida ,&nbsp;Arulmani Natarajan ,&nbsp;Santhi Puramadathil ,&nbsp;Jiayu Li ,&nbsp;Stephan Schuster ,&nbsp;Stefano Schiavon","doi":"10.1016/j.indenv.2024.100042","DOIUrl":"10.1016/j.indenv.2024.100042","url":null,"abstract":"<div><p>Research on triethylene glycol (TEG) use to disinfect airborne microorganisms have been conducted in non-realistic chamber settings. This study assesses how air temperature, humidity, HVAC settings, and filtration impact TEG's effectiveness in deactivating a common SARS-CoV-2 substitute, MS2 bacteriophage, in a simulated non-occupied office-sized chamber. The chamber was served by a dedicated HVAC system operating at 22.0, 23.5 and 25.0 °C, at 40, 55 and 70 % relative humidity, at 0, 3 and 6 air change per hour (ACH) recirculation, at 0.8, 2.5 and 5.0 ACH outdoor ventilation and at no, MERV8 and MERV14 filtration status. Airborne MS2 log₁₀ reductions in the presence of TEG increased linearly over time and we noted a higher MS2 inactivation rate with higher TEG concentration. The estimated TEG concentration needed for a one-log inactivation of the MS2 within an hour was 0.44 mg/m³. The efficacy of TEG declined with the increase in temperature from 22.0 to 25.0 °C, peaked at 55 % RH, increased with higher recirculation rates but decreased with increasing ventilation rates and higher efficiency filters. The results of our study suggest that the optimum environmental and building conditions for TEG performance is at 22.0 or 23.5 °C air temperature, 55 % relative humidity, 0.8 ACH ventilation rate and 6 ACH recirculation rate. By conducting experiments in simulated office conditions, this study closes significant knowledge gaps in TEG performance application.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 3","pages":"Article 100042"},"PeriodicalIF":0.0,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000390/pdfft?md5=6ba4e271f9c464ea1bf9f1fe44b32cfc&pid=1-s2.0-S2950362024000390-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141998131","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":"Optimal operations of gaspers for minimizing the exposure risks of airborne disease transmission in an economy-class aircraft cabin","authors":"Yiding Zhou ,&nbsp;Yunge Hou ,&nbsp;Chun Chen ,&nbsp;Ruoyu You","doi":"10.1016/j.indenv.2024.100041","DOIUrl":"10.1016/j.indenv.2024.100041","url":null,"abstract":"<div><p>Overhead gaspers with adjustable open ratios and flow directions can alter the airflow pattern in aircraft cabins and consequently influence airborne infectious diseases transmission. To achieve the optimal operations of gaspers for minimizing the passengers’ exposure risks, this study developed a Bayesian optimization method based on computational fluid dynamics (CFD). A seven-row, single-aisle, fully occupied, economy-class aircraft cabin was used for the numerical investigation. Two air distribution systems, i.e., a mixing ventilation system and a personalized displacement ventilation system, were considered. First, the open ratios of all the gaspers were optimized by the CFD-based Bayesian optimization method. The optimal operations of gaspers were determined with only 20 trials calculated by CFD using the Bayesian optimization. With the optimal open ratios of all the gaspers, the number of relatively high-risk passengers (exposure index over 0.95) was effectively reduced by at least 55% and 86% under the mixing ventilation and the personalized displacement ventilation, respectively, when compared with the results with all the gaspers turned off. Next, the optimal open ratios and flow directions of the gaspers near the index passenger were also determined by the proposed method. With the optimized operations of gaspers, the number of relatively high-risk passengers was effectively reduced by at least 50% and 67% under the mixing ventilation and the personalized displacement ventilation, respectively.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 3","pages":"Article 100041"},"PeriodicalIF":0.0,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000389/pdfft?md5=a7c8b850b9f5bbc0a3213d5c45d0bf6f&pid=1-s2.0-S2950362024000389-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142089409","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":"A novel method for establishing typical daily profile of PM concentrations in underground railway stations","authors":"Valisoa M. Rakotonirinjanahary ,&nbsp;Suzanne Crumeyrolle ,&nbsp;Mateusz Bogdan ,&nbsp;Benjamin Hanoune","doi":"10.1016/j.indenv.2024.100040","DOIUrl":"10.1016/j.indenv.2024.100040","url":null,"abstract":"<div><p>The air quality in underground railway stations (URS) poses a significant public health concern due to extremely high concentrations of particulate matter: PM₁₀ and PM_2.5. Indeed, PM sources are strong and numerous, such as train braking and tunnel effect and URS are often confined spaces with low air change rates. Despite multiple PM measurements within URS, the variability of those concentrations from stations to stations is still poorly understood. We present here a methodology for establishing a daily profile of particle mass concentrations, based on a 5-year long measurement series in a Parisian URS. This approach incorporates an extensive data cleaning process based on the identification of URS operation periods and physically inconsistent or mathematically aberrant data, together with a linear regression model. This methodology delivers three usable outcomes: a typical profile for weekdays, a typical profile for weekends, and a PM concentration Daily Amplitude Coefficient (DAC) for the considered period. The DAC is a daily metric of the pollution levels, that enables the analysis of temporal trends and facilitates the comparison with other data with other acquisition frequency. The methodology developed here in a specific URS for PM₁₀ measurements can be easily applied to different particle size fractions or to other measured parameters exhibiting a daily profile. Weekdays PM₁₀ concentrations exhibit two distinct peaks corresponding to morning and evening rush hours, with an average daytime concentration of 193 µg/m³. These peaks are delayed by ∼1 hour compared to the train traffic. Weekends show consistently lower PM levels with no observable peaks, averaging 157 µg/m³ during the day. Our analysis reveals the long-term temporal evolution of PM concentration within the URS, highlighting seasonal patterns with higher PM₁₀ concentrations observed in summer (up to 400 µg/m³) and lower values in winter (down to 250 µg/m³). This indoor seasonal evolution is not correlated with the outdoor temporal evolution, showing higher concentrations during the winter. Furthermore, our results show that the optimal period (DAC∼1) for conducting experiments to obtain reliable profiles is during the spring months (April, May, June).</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 3","pages":"Article 100040"},"PeriodicalIF":0.0,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000377/pdfft?md5=e497d09b29ce3c6b365b441b04684ac4&pid=1-s2.0-S2950362024000377-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141978850","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":"Exploring how social housing residents interact with building openings in a hot-humid climate","authors":"Solange Maria Leder ,&nbsp;Andreia Cardoso de Oliveira ,&nbsp;Celina Pinto Leão ,&nbsp;Erivaldo Lopes de Souza","doi":"10.1016/j.indenv.2024.100038","DOIUrl":"10.1016/j.indenv.2024.100038","url":null,"abstract":"<div><p>In a hot-humid climate, natural ventilation is the most recommended strategy for obtaining thermal comfort indoors. The residents' behavior in opening windows and doors to promote natural ventilation is crucial for predicting thermal comfort, especially for low-income housing where energy costs can exceed household budgets. This study identifies residents’ behavior in social housing in northeast Brazil (a hot-humid climate), focusing on actions to regulate thermal comfort with natural ventilation. The methodology comprehends field research, surveys, data processing, and analysis. Interviews with 375 individuals across two social housing complexes reveal the significant role of security and cultural factors in window control behavior. The results highlight the considerable role of security and cultural factors in shaping occupant behavior concerning window control. The residents indicated that they are stimulated to open the windows and doors right after they wake up and close them at bedtime or when leaving the house. Occupancy is a significant driving factor, but the sleep period (unconscious state) plays a crucial role in determining the closure of openings, even to housing units with a 2.0 m high wall on the plot land limits and security bars on windows. This study contributes to the understanding of the complex interplay between security, cultural factors, and thermal comfort regulation, proposing valuable insights for design and policy interventions aimed at improving living conditions in similar contexts.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 3","pages":"Article 100038"},"PeriodicalIF":0.0,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000353/pdfft?md5=a9a35b7ee0171c5c01c8c31c09a23999&pid=1-s2.0-S2950362024000353-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141998065","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":"Should we use ceiling fans indoors to reduce the risk of transmission of infectious aerosols?","authors":"Jiayu Li ,&nbsp;Sultan Zuraimi ,&nbsp;Stefano Schiavon","doi":"10.1016/j.indenv.2024.100039","DOIUrl":"10.1016/j.indenv.2024.100039","url":null,"abstract":"<div><p>The effects of ceiling fans on the transmission of infectious aerosols remain poorly understood, leading to conflicting recommendations. We conducted repeated experiments in a well-controlled chamber with a typical mixing ventilation system at three different ventilation rates with and without ceiling fans. We evaluated airborne infection risks for short- and long-range transmission routes based on size-resolved tracer particles measured at various locations. We found that the mixing ventilation without fans only effectively diluted the airborne particle concentration for the long-range route but not for the short-range. By using ceiling fans to enhance air mixing, tracer particles were distributed more homogeneously throughout the room, leading to up to 77 % reduction in short-range particle exposure while a slight increase of less than 14 % in long-range exposure. Based on the dilution-based Wells-Riley model, the changes in particle concentration translated to a maximum 47 % reduction in short-range infection risk and a marginal 4 % increase for long-range transmission. Based on the dilution factors obtained from the experiments, we developed a decision-making tool that uses the ventilation rate, the number of individuals at short- and long-range, and the disease's transmissibility to decide whether the use of ceiling fans is beneficial. Deploying ceiling fans always reduces the concentration of particles in the short range and, assuming a relationship between particles and pathogens, this directly translates to a diminished short-range risk. Based on the modeling of the overall risk, the benefits of fans are highest when the room is ventilated according to code, when masking measures are in place, and when the pathogen is not highly contagious.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 3","pages":"Article 100039"},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000365/pdfft?md5=bf9a0f847e5d5f1512747b400bbe2081&pid=1-s2.0-S2950362024000365-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984844","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":"An original device to assess the respiratory impact of indoor air VOCs mixture using an in vitro approach","authors":"Plaisance Hervé ,&nbsp;Costarramone Nathalie ,&nbsp;Dalliès Gaëlle ,&nbsp;Al Zallouha Margueritta ,&nbsp;Achard Sophie ,&nbsp;Desauziers Valérie","doi":"10.1016/j.indenv.2024.100037","DOIUrl":"10.1016/j.indenv.2024.100037","url":null,"abstract":"<div><p>Exposure to indoor air pollution, particularly volatile organic compounds (VOCs), has been recognized as a risk factor in the development of respiratory and allergic diseases. VOCs are mainly emitted continuously at low concentrations from construction furniture and decoration products. Measurement campaigns carried out in new dwellings in France have shown that aldehydes predominate with a tendency to decrease formaldehyde concentrations and to increase those in hexanal. As the main route of VOCs exposure is inhalation, this project assessed the impact of a mixture of 17 VOCs representative of indoor air (in quality and quantity) on respiratory health using an <em>in vitro</em> approach. This original work was based on the set-up of an experimental device, combining a gas generation and dilution bench and exposure to the air-liquid interface (ALI) adapted to the reconstructed human airway epithelium model. The VOC mixture was enriched with formaldehyde or hexanal in different proportions (from 20 to 240 µg.m⁻³) to study the biological impact of these aldehydes after repeated exposures of airway epithelium. After examination of the stability of the VOC concentrations in generated mixtures and the found of the optimal operating conditions for the dynamic gas generating system, the gaseous mixtures were distributed to the epithelium using the ALI exposure system providing direct contact between the epithelium and the tested mixtures. Our device lead to reproduce real conditions of human exposure. The results showed that the inflammatory response, assessed by the production of four cytokines, varied according to the nature of the aldehyde present in the VOC mixture (formaldehyde or hexanal), its concentration, and the duration and number of exposures applied. The most original and innovative results concern those obtained with hexanal, pollutant under-researched. Our results showed that this aldehyde could pose risks to respiratory health.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 3","pages":"Article 100037"},"PeriodicalIF":0.0,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000341/pdfft?md5=5846045cceadf95ad5474ce49fda613a&pid=1-s2.0-S2950362024000341-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141960395","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":"Investigation of the effects of indoor air stability on the airborne transmission of droplets from violent respiratory events","authors":"Xiaorui Deng ,&nbsp;Guangcai Gong ,&nbsp;Xudong Yang","doi":"10.1016/j.indenv.2024.100036","DOIUrl":"10.1016/j.indenv.2024.100036","url":null,"abstract":"<div><p>Indoor air stability is a condition under which the indoor temperature gradients can affect the trajectories of constant breathing flows. However, it remains unclear how indoor air stability affects the airborne contaminants from violent respiratory events such as coughing. Here, we report a study of the dispersion of airborne droplets from coughing under different indoor air stability conditions. The distributions of droplets from coughing processes under stable and unstable conditions were compared. The results revealed that the stable conditions confined the coughed droplets to the breathing zone of the droplet host, whereas the unstable conditions intensified the dispersion of droplets and reduced their local concentration. The dimensionless vertical distance of the droplet cloud under the stable condition was 4 times longer than that of the unstable condition at t = 15 s. In addition, we observed that high ventilation rate caused an intense mixing of the indoor air, thus weakening the effect of indoor air stability on the propagation of droplet cloud. Personal exposure of the stable condition was 6.5 times larger than that of the unstable condition at a ventilation rate of 2.1 ACH, while it decreased to lower than half of that of the unstable condition at 7.1 ACH and 12.3 ACH. Personal exposure to the indoor environment should be assessed by simultaneously considering the indoor air stability conditions and ventilation rates. This study has provided insights into the transmission of cough droplets in indoor environments and has practical significance for preventing the spread of contagious diseases.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 3","pages":"Article 100036"},"PeriodicalIF":0.0,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S295036202400033X/pdfft?md5=8782352f7efc1ca8524f53c4ead836fe&pid=1-s2.0-S295036202400033X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141841247","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":"Coupled indoor air quality and dynamic thermal modelling to assess the potential impacts of standalone HEPA filter units in classrooms","authors":"Henry C. Burridge ,&nbsp;Sen Liu ,&nbsp;Sara Mohamed ,&nbsp;Samuel G.A. Wood ,&nbsp;Cath J. Noakes","doi":"10.1016/j.indenv.2024.100034","DOIUrl":"10.1016/j.indenv.2024.100034","url":null,"abstract":"<div><p>The quality of the classroom environment, including ventilation, air quality and thermal conditions, has an important impact on children’s health and academic achievement. The use of portable HEPA filter air cleaners is widely suggested as a strategy to mitigate exposure to particulate matter and airborne viruses. However, there is a need to quantify the relative benefits of such devices including the impacts on energy use. We present a simple coupled dynamic thermal and air quality model and apply it to naturally ventilated classrooms, representative of modern and Victorian era construction. We consider the addition of HEPA filters with, and without, reduced opening of windows, and explore concentrations of carbon dioxide (CO₂), particulate matter PM_2.5, airborne viral RNA, classroom temperature and energy use. Results indicate the addition of HEPA filters was predicted to reduce PM_2.5 by 40–60 % and viral RNA by 30–50 % depending on the classroom design and window opening behaviour. The energy cost of running HEPA filters is likely to be only 1 %–2 % of the classroom heating costs. In scenarios when HEPA filters were on and window opening was reduced (to account for the additional clean air delivery rate of the filters), the heating cost was predicted to be reduced by as much as − 13 %, and these maximum reductions grew to − 46 % in wintertime simulations. In these scenarios the HEPA filters result in a notable reduction in PM_2.5 and viral RNA, but the CO₂ concentration is significantly higher. The model provides a mechanism for exploring the relative impact of ventilation and air cleaning strategies on both exposures and energy costs, enabling an understanding of where trade-offs lie.</p></div>","PeriodicalId":100665,"journal":{"name":"Indoor Environments","volume":"1 3","pages":"Article 100034"},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950362024000316/pdfft?md5=ad59075dadac850e89effc24b0780f2c&pid=1-s2.0-S2950362024000316-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141950730","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}