E. Ding
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16 records found
1
Journal article
(2026)
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Clarize de Korne, Kim Romijnders, Philomena Bluyssen, Daniel Bonn, Er Ding, Antoine Gaillard, Esmée Janssen, Anne Rittscher-Fogg, Inge Wouters, Patricia Bruijning-Verhagen
During respiratory virus outbreaks, mobile air cleaning devices (MACs) are increasingly considered in schools as a preventive measure. However, evidence on their real-world performance, feasibility, and potential health impact in classroom settings remains limited. This pilot study was conducted to inform the design of a future large-scale trial by providing a comprehensive evaluation of MACs in primary school classrooms, integrating technical performance (including indoor air quality and airborne microbial assessments), user-perceived feasibility, and the suitability of illness-related absenteeism as a potential pragmatic outcome measure for infection rates. A randomized cross-over study was conducted in five Dutch primary schools, involving 45 classrooms equipped with MACs. Each classroom alternated between three-week periods with the devices switched on and off. Indoor air quality was assessed in a subset of classrooms using sensors for CO₂ and particulate matter, while airborne microbial contamination was monitored through air dust sampling and molecular testing. Illness-related absenteeism was evaluated as a potential outcome measure. MACs effectively halved indoor particulate matter levels, confirming their technical performance. This reduction did not translate into a measurable reduction in airborne microbial contamination, although such contamination was successfully detected. Feasibility assessment revealed low acceptability among teachers due to reduced environmental comfort. Absenteeism was identified as a suitable proxy for infectious diseases, with simulations indicating that a future cluster-randomized trial would require 40–70 schools to detect a 20–25% reduction in absenteeism.
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During respiratory virus outbreaks, mobile air cleaning devices (MACs) are increasingly considered in schools as a preventive measure. However, evidence on their real-world performance, feasibility, and potential health impact in classroom settings remains limited. This pilot study was conducted to inform the design of a future large-scale trial by providing a comprehensive evaluation of MACs in primary school classrooms, integrating technical performance (including indoor air quality and airborne microbial assessments), user-perceived feasibility, and the suitability of illness-related absenteeism as a potential pragmatic outcome measure for infection rates. A randomized cross-over study was conducted in five Dutch primary schools, involving 45 classrooms equipped with MACs. Each classroom alternated between three-week periods with the devices switched on and off. Indoor air quality was assessed in a subset of classrooms using sensors for CO₂ and particulate matter, while airborne microbial contamination was monitored through air dust sampling and molecular testing. Illness-related absenteeism was evaluated as a potential outcome measure. MACs effectively halved indoor particulate matter levels, confirming their technical performance. This reduction did not translate into a measurable reduction in airborne microbial contamination, although such contamination was successfully detected. Feasibility assessment revealed low acceptability among teachers due to reduced environmental comfort. Absenteeism was identified as a suitable proxy for infectious diseases, with simulations indicating that a future cluster-randomized trial would require 40–70 schools to detect a 20–25% reduction in absenteeism.
In response to the WHO and UN's call to ensure children's right to breathe "clean"air and the challenges posed by the COVID-19 pandemic on maintaining healthy indoor air quality (IAQ), a holistic research was conducted to explore ventilation and air cleaning strategies to control the spread of infectious respiratory particles (IRPs) in school classrooms. The study follows four key steps: (1) a literature review bridging school ventilation regimes, IRP transmission, and advanced ventilation systems; (2) a field study to evaluate real-world ventilation and thermal conditions during the pandemic; (3) an experimental investigation of performance of mobile air cleaners (MACs) followed by an in-situ validation; and (4) a combined experimental and computational study to assess personalized air cleaners (PACs) as localized exhaust for IRP removal. Findings reveal that most classrooms rely on natural ventilation, often failing to meet IAQ standards, especially when fully occupied. With windows and doors kept open, ventilation rates remained inconsistent, and thermal conditions were unsatisfactory. Hence, more controllable ventilation and air cleaning approaches are needed. MACs, when appropriately selected and positioned, offer effective protection against long-range IRP transmission at room scale, while PACs are effective at mitigating localized, short-range IRP exposure, improving IAQ at an individual level.
...
In response to the WHO and UN's call to ensure children's right to breathe "clean"air and the challenges posed by the COVID-19 pandemic on maintaining healthy indoor air quality (IAQ), a holistic research was conducted to explore ventilation and air cleaning strategies to control the spread of infectious respiratory particles (IRPs) in school classrooms. The study follows four key steps: (1) a literature review bridging school ventilation regimes, IRP transmission, and advanced ventilation systems; (2) a field study to evaluate real-world ventilation and thermal conditions during the pandemic; (3) an experimental investigation of performance of mobile air cleaners (MACs) followed by an in-situ validation; and (4) a combined experimental and computational study to assess personalized air cleaners (PACs) as localized exhaust for IRP removal. Findings reveal that most classrooms rely on natural ventilation, often failing to meet IAQ standards, especially when fully occupied. With windows and doors kept open, ventilation rates remained inconsistent, and thermal conditions were unsatisfactory. Hence, more controllable ventilation and air cleaning approaches are needed. MACs, when appropriately selected and positioned, offer effective protection against long-range IRP transmission at room scale, while PACs are effective at mitigating localized, short-range IRP exposure, improving IAQ at an individual level.
During perception with our senses interactions of different environmental stressors (olfactory, auditory, visual and thermal stimuli) at brain level might occur. To test these cross-modal effects, a three-way factorial design was applied. In total, 60 students across six groups were each exposed to three randomized combinations of different environmental conditions: three sound conditions, three lighting conditions, and two ventilation modes, while sitting in a semi-lab environment. Heart rate and respiration rate were monitored using a smart watch; acceptability and experience were collected through a questionnaire to assess subjects' comfort perception. Results showed no statistical differences between the two ventilation modes and no effect of light type on the physiological indicators. A trend towards an interaction effect was found for sound∗light on the acceptability of odour (p=0.076) and the perceived level of sound (p=0.055). For future studies, it is therefore important to first identify physiological indicators that can be affected by all the independent factors studied.
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During perception with our senses interactions of different environmental stressors (olfactory, auditory, visual and thermal stimuli) at brain level might occur. To test these cross-modal effects, a three-way factorial design was applied. In total, 60 students across six groups were each exposed to three randomized combinations of different environmental conditions: three sound conditions, three lighting conditions, and two ventilation modes, while sitting in a semi-lab environment. Heart rate and respiration rate were monitored using a smart watch; acceptability and experience were collected through a questionnaire to assess subjects' comfort perception. Results showed no statistical differences between the two ventilation modes and no effect of light type on the physiological indicators. A trend towards an interaction effect was found for sound∗light on the acceptability of odour (p=0.076) and the perceived level of sound (p=0.055). For future studies, it is therefore important to first identify physiological indicators that can be affected by all the independent factors studied.
De via de lucht overgedragen infectieuze respiratoire deeltjes (IRDs), ook wel aerosolen genoemd, zijn de primaire route van overdracht voor respiratoire infectieuze ziektes zoals COVID-19 [1]. Klaslokalen hebben een verhoogd risico op besmetting vanwege de lange en hoge bezetting [2]. Deze overdracht kan dichtbij plaatsvinden, maar ook verder weg. Tijdens een door ZonMw gefinancierd veldonderzoek naar de verspreiding van het SARS-CoV-2 virus en de binnenmilieucondities in klaslokalen [3], bleek zowel de ventilatie als de temperatuur onvoldoende te zijn. Scholen hebben behoefte aan beheersbare maar ook betaalbare oplossingen. Mobiele luchtreinigers (MLRs) zijn een mogelijke (betaalbare) oplossing om overdracht van IRDs op lange afstand te verminderen. In opdracht van het Ministerie van Onderwijs Cultuur en Wetenschap werd daarom een vervolgonderzoek gestart met de vraag: zouden mobiele luchtreinigers in een toekomstige pandemie de situatie kunnen verbeteren?
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De via de lucht overgedragen infectieuze respiratoire deeltjes (IRDs), ook wel aerosolen genoemd, zijn de primaire route van overdracht voor respiratoire infectieuze ziektes zoals COVID-19 [1]. Klaslokalen hebben een verhoogd risico op besmetting vanwege de lange en hoge bezetting [2]. Deze overdracht kan dichtbij plaatsvinden, maar ook verder weg. Tijdens een door ZonMw gefinancierd veldonderzoek naar de verspreiding van het SARS-CoV-2 virus en de binnenmilieucondities in klaslokalen [3], bleek zowel de ventilatie als de temperatuur onvoldoende te zijn. Scholen hebben behoefte aan beheersbare maar ook betaalbare oplossingen. Mobiele luchtreinigers (MLRs) zijn een mogelijke (betaalbare) oplossing om overdracht van IRDs op lange afstand te verminderen. In opdracht van het Ministerie van Onderwijs Cultuur en Wetenschap werd daarom een vervolgonderzoek gestart met de vraag: zouden mobiele luchtreinigers in een toekomstige pandemie de situatie kunnen verbeteren?
Healthy air for children
Strategies for ventilation and air cleaning to control infectious respiratory particles in school classrooms
In response to the WHO and UN’s call to ensure children’s right to breathe “clean” air and the challenges posed by the COVID-19 pandemic on maintaining healthy indoor air quality (IAQ), this PhD research explores ventilation and air cleaning strategies to control the spread of infectious respiratory particles (IRPs) in school classrooms.
The study follows four key steps: (1) a literature review bridging school ventilation regimes, IRP transmission, and advanced ventilation systems; (2) a field study to evaluate real-world ventilation and thermal conditions during the pandemic; (3) an experimental investigation of performance of mobile air cleaners (MACs) followed by an in-situ validation; and (4) a combined experimental and computational study to assess personalized air cleaners (PACs) as localized exhaust for IRP removal.
Findings reveal that most classrooms rely on natural ventilation, often failing to meet IAQ standards, especially when fully occupied. With windows and doors open, ventilation rates remained inconsistent, and thermal conditions were unsatisfactory. Hence, more controllable ventilation and air cleaning approaches are needed. MACs, when appropriately selected and positioned, offer effective protection against long-range IRP transmission at room scale, while PACs are effective at mitigating localized, short-range IRP exposure, improving IAQ at an individual level.
This research offers a comprehensive set of solutions for IRP control in classrooms, with actionable insights for a variety of stakeholders. It advocates for a shift from comfort-based to health-centered paradigms. Future research should explore hybrid systems, optimize designs, and validate interventions through real-world infection risk assessments to create healthier, more resilient classrooms. ...
The study follows four key steps: (1) a literature review bridging school ventilation regimes, IRP transmission, and advanced ventilation systems; (2) a field study to evaluate real-world ventilation and thermal conditions during the pandemic; (3) an experimental investigation of performance of mobile air cleaners (MACs) followed by an in-situ validation; and (4) a combined experimental and computational study to assess personalized air cleaners (PACs) as localized exhaust for IRP removal.
Findings reveal that most classrooms rely on natural ventilation, often failing to meet IAQ standards, especially when fully occupied. With windows and doors open, ventilation rates remained inconsistent, and thermal conditions were unsatisfactory. Hence, more controllable ventilation and air cleaning approaches are needed. MACs, when appropriately selected and positioned, offer effective protection against long-range IRP transmission at room scale, while PACs are effective at mitigating localized, short-range IRP exposure, improving IAQ at an individual level.
This research offers a comprehensive set of solutions for IRP control in classrooms, with actionable insights for a variety of stakeholders. It advocates for a shift from comfort-based to health-centered paradigms. Future research should explore hybrid systems, optimize designs, and validate interventions through real-world infection risk assessments to create healthier, more resilient classrooms. ...
In response to the WHO and UN’s call to ensure children’s right to breathe “clean” air and the challenges posed by the COVID-19 pandemic on maintaining healthy indoor air quality (IAQ), this PhD research explores ventilation and air cleaning strategies to control the spread of infectious respiratory particles (IRPs) in school classrooms.
The study follows four key steps: (1) a literature review bridging school ventilation regimes, IRP transmission, and advanced ventilation systems; (2) a field study to evaluate real-world ventilation and thermal conditions during the pandemic; (3) an experimental investigation of performance of mobile air cleaners (MACs) followed by an in-situ validation; and (4) a combined experimental and computational study to assess personalized air cleaners (PACs) as localized exhaust for IRP removal.
Findings reveal that most classrooms rely on natural ventilation, often failing to meet IAQ standards, especially when fully occupied. With windows and doors open, ventilation rates remained inconsistent, and thermal conditions were unsatisfactory. Hence, more controllable ventilation and air cleaning approaches are needed. MACs, when appropriately selected and positioned, offer effective protection against long-range IRP transmission at room scale, while PACs are effective at mitigating localized, short-range IRP exposure, improving IAQ at an individual level.
This research offers a comprehensive set of solutions for IRP control in classrooms, with actionable insights for a variety of stakeholders. It advocates for a shift from comfort-based to health-centered paradigms. Future research should explore hybrid systems, optimize designs, and validate interventions through real-world infection risk assessments to create healthier, more resilient classrooms.
The study follows four key steps: (1) a literature review bridging school ventilation regimes, IRP transmission, and advanced ventilation systems; (2) a field study to evaluate real-world ventilation and thermal conditions during the pandemic; (3) an experimental investigation of performance of mobile air cleaners (MACs) followed by an in-situ validation; and (4) a combined experimental and computational study to assess personalized air cleaners (PACs) as localized exhaust for IRP removal.
Findings reveal that most classrooms rely on natural ventilation, often failing to meet IAQ standards, especially when fully occupied. With windows and doors open, ventilation rates remained inconsistent, and thermal conditions were unsatisfactory. Hence, more controllable ventilation and air cleaning approaches are needed. MACs, when appropriately selected and positioned, offer effective protection against long-range IRP transmission at room scale, while PACs are effective at mitigating localized, short-range IRP exposure, improving IAQ at an individual level.
This research offers a comprehensive set of solutions for IRP control in classrooms, with actionable insights for a variety of stakeholders. It advocates for a shift from comfort-based to health-centered paradigms. Future research should explore hybrid systems, optimize designs, and validate interventions through real-world infection risk assessments to create healthier, more resilient classrooms.
To investigate the feasibility of using mobile air cleaners (MACs) in school classrooms for reducing respiratory aerosols, a test on aerosol removal of seven different types of MACs was conducted in a university classroom, for the optimal condition determined by a prior experimental study. Most of the MACs achieved a good level of clean air delivery rate (CADR) (900-1000 m3/h), and the CADR increased with the number of devices used. Based on the results, three MACs were further selected for conducting an ongoing field study in 45 classrooms at five Dutch primary schools. Each classroom was assigned one type of MAC with two devices, and was monitored for a period of six weeks with three weeks the devices turned on and three weeks off. The assessments of feasibility are based on measurements of indoor air quality, information on absenteeism of the pupils, and interviews with the occupants. The results are yet to be collected to draw further conclusions. However, problems were already encountered during the installation process of the devices which hindered the realization of the pre-determined strategies.
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To investigate the feasibility of using mobile air cleaners (MACs) in school classrooms for reducing respiratory aerosols, a test on aerosol removal of seven different types of MACs was conducted in a university classroom, for the optimal condition determined by a prior experimental study. Most of the MACs achieved a good level of clean air delivery rate (CADR) (900-1000 m3/h), and the CADR increased with the number of devices used. Based on the results, three MACs were further selected for conducting an ongoing field study in 45 classrooms at five Dutch primary schools. Each classroom was assigned one type of MAC with two devices, and was monitored for a period of six weeks with three weeks the devices turned on and three weeks off. The assessments of feasibility are based on measurements of indoor air quality, information on absenteeism of the pupils, and interviews with the occupants. The results are yet to be collected to draw further conclusions. However, problems were already encountered during the installation process of the devices which hindered the realization of the pre-determined strategies.
Journal article
(2024)
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Seyyed Abbas Noorian Najafabadi, Er Ding, Nadine Hobeika, Philomena M. Bluyssen
Indoor air quality (IAQ) is an important aspect of maintaining human health and well-being, particularly since people spend most of their time indoors. Carpets, with their large surface area and dense fibre piles, have the potential to significantly impact IAQ by emitting and absorbing volatile organic compounds (VOC) from building materials and human activities. The cleaning effect of wool carpets regarding the sorption of odours from two sources of pollution: hardboard and sweaty underwear (as a proxy for bio-effluents), was investigated with an untrained panel of subjects assessing the odour intensity and the acceptability. Tests were performed in three different test environments, including a sniffing table, CLIMPAQs, and full-scale test chambers. The outcome showed that wool carpets can potentially clean the air of odours in small-scale environments, where the wool carpet covers the floor and walls of the test environment, and the odour sources are in contact with the wool carpet. However, the results were less conclusive in on scale scenarios where wool carpets only covered the floor. Overall, wool carpets have the potential to ad(b)sorb odorous emissions, but only when these emissions are near the wool carpet, and thus can have the opportunity to be ad(b)sorbed.
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Indoor air quality (IAQ) is an important aspect of maintaining human health and well-being, particularly since people spend most of their time indoors. Carpets, with their large surface area and dense fibre piles, have the potential to significantly impact IAQ by emitting and absorbing volatile organic compounds (VOC) from building materials and human activities. The cleaning effect of wool carpets regarding the sorption of odours from two sources of pollution: hardboard and sweaty underwear (as a proxy for bio-effluents), was investigated with an untrained panel of subjects assessing the odour intensity and the acceptability. Tests were performed in three different test environments, including a sniffing table, CLIMPAQs, and full-scale test chambers. The outcome showed that wool carpets can potentially clean the air of odours in small-scale environments, where the wool carpet covers the floor and walls of the test environment, and the odour sources are in contact with the wool carpet. However, the results were less conclusive in on scale scenarios where wool carpets only covered the floor. Overall, wool carpets have the potential to ad(b)sorb odorous emissions, but only when these emissions are near the wool carpet, and thus can have the opportunity to be ad(b)sorbed.
Using mobile air cleaners in school classrooms for aerosol removal
Which, where and how
Journal article
(2024)
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Er Ding, Arghyanir Giri, Antoine Gaillard, Daniel Bonn, Philomena M. Bluyssen
Mobile air cleaners (MACs) have been proposed as a supplementary solution to combat the spread of respiratory aerosols in school classrooms. To determine which, where and how to use MACs, seven small- and medium-sized MACs were selected and assessed for different settings and configurations by 1) a decay test for determining the clean air delivery rate (CADR), and 2) a perception test with a panel of subjects, together with physical measurements, of noise and air movement. The findings show that to achieve the desired CADR (appr. 1000 m3/h for 30 students per classroom), the key factors are the induced airflow pattern and the location of the MACs. MACs with an upward air supply toward the occupied zone showed much higher CADR (max. 775–1332 m3/h) than those with a horizontal air supply (max. 219–333 m3/h). Moreover, using multiple devices simultaneously was crucial when the room size was increased, and combining mechanical ventilation could improve aerosol removal. Achieving a sufficient CADR would always lead to a noise level above the limit of 35 dB(A), yet sometimes the rating of the panel was more than 50% acceptable. The air velocities mostly fulfilled the requirement (<0.2 m/s), which aligned with the positive panel assessment. Hence, the evaluation by a panel of subjects can help to optimize the use of MACs in a classroom.
...
Mobile air cleaners (MACs) have been proposed as a supplementary solution to combat the spread of respiratory aerosols in school classrooms. To determine which, where and how to use MACs, seven small- and medium-sized MACs were selected and assessed for different settings and configurations by 1) a decay test for determining the clean air delivery rate (CADR), and 2) a perception test with a panel of subjects, together with physical measurements, of noise and air movement. The findings show that to achieve the desired CADR (appr. 1000 m3/h for 30 students per classroom), the key factors are the induced airflow pattern and the location of the MACs. MACs with an upward air supply toward the occupied zone showed much higher CADR (max. 775–1332 m3/h) than those with a horizontal air supply (max. 219–333 m3/h). Moreover, using multiple devices simultaneously was crucial when the room size was increased, and combining mechanical ventilation could improve aerosol removal. Achieving a sufficient CADR would always lead to a noise level above the limit of 35 dB(A), yet sometimes the rating of the panel was more than 50% acceptable. The air velocities mostly fulfilled the requirement (<0.2 m/s), which aligned with the positive panel assessment. Hence, the evaluation by a panel of subjects can help to optimize the use of MACs in a classroom.
SARS‑CoV‑2 incidence in secondary schools
The role of national and school‑initiated COVID‑19 measures
Journal article
(2023)
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Lotte Jonker, Kimberly J. Linde, Annemarijn R. de Boer, Er Ding, D. Zhang, M.L.A. de Hoog, Sander Herfst, Dick Heederik, P.M. Bluyssen, More Authors...
Introduction: Our aim was to gain insight into the effect of COVID-19 measures on SARS-CoV-2 incidence in secondary schools and the association with classroom CO
2 concentration and airborne contamination. Methods: Between October 2020—June 2021, 18 schools weekly reported SARS-CoV-2 incidence and completed surveys on school-initiated COVID-19 measures (e.g. improving hygiene or minimizing contacts). CO
2 was measured in occupied classrooms twice, and SARS-CoV-2 air contamination longitudinally using electrostatic dust collectors (EDC) and analyzed using RT-qPCR. National COVID-19 policy measures varied during pre-lockdown, lockdown and post-lockdown periods. During the entire study, schools were recommended to improve ventilation. SARS-CoV-2 incidence rate ratios (IRR) were estimated by Generalized Estimating Equation (GEE) models. Results: During 18 weeks follow-up (range: 10–22) SARS-CoV-2 school-incidence decreased during national lockdown (adjusted IRR: 0.41, 95%CI: 0.21–0.80) and post-lockdown (IRR: 0.60, 0.39–0.93) compared to pre-lockdown. School-initiated COVID-19 measures had no additional effect. Pre-lockdown, IRRs per 10% increase in time CO
2 exceeded 400, 550 and 800 ppm above outdoor level respectively, were 1.08 (1.00–1.16), 1.10 (1.02–1.19), and 1.08 (0.95–1.22). Post-lockdown, CO
2-concentrations were considerably lower and not associated with SARS-CoV-2 incidence. No SARS-CoV-2 RNA was detected in any of the EDC samples. Conclusion: During a period with low SARS-CoV-2 population immunity and increased attention to ventilation, with CO
2 levels most of the time below acceptable thresholds, only the national policy during and post-lockdown of reduced class-occupancy, stringent quarantine, and contact testing reduced SARS-CoV-2 incidence in Dutch secondary schools. Widespread SARS-CoV-2 air contamination could not be demonstrated in schools under the prevailing conditions during the study.
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Introduction: Our aim was to gain insight into the effect of COVID-19 measures on SARS-CoV-2 incidence in secondary schools and the association with classroom CO 2 concentration and airborne contamination. Methods: Between October 2020—June 2021, 18 schools weekly reported SARS-CoV-2 incidence and completed surveys on school-initiated COVID-19 measures (e.g. improving hygiene or minimizing contacts). CO 2 was measured in occupied classrooms twice, and SARS-CoV-2 air contamination longitudinally using electrostatic dust collectors (EDC) and analyzed using RT-qPCR. National COVID-19 policy measures varied during pre-lockdown, lockdown and post-lockdown periods. During the entire study, schools were recommended to improve ventilation. SARS-CoV-2 incidence rate ratios (IRR) were estimated by Generalized Estimating Equation (GEE) models. Results: During 18 weeks follow-up (range: 10–22) SARS-CoV-2 school-incidence decreased during national lockdown (adjusted IRR: 0.41, 95%CI: 0.21–0.80) and post-lockdown (IRR: 0.60, 0.39–0.93) compared to pre-lockdown. School-initiated COVID-19 measures had no additional effect. Pre-lockdown, IRRs per 10% increase in time CO 2 exceeded 400, 550 and 800 ppm above outdoor level respectively, were 1.08 (1.00–1.16), 1.10 (1.02–1.19), and 1.08 (0.95–1.22). Post-lockdown, CO 2-concentrations were considerably lower and not associated with SARS-CoV-2 incidence. No SARS-CoV-2 RNA was detected in any of the EDC samples. Conclusion: During a period with low SARS-CoV-2 population immunity and increased attention to ventilation, with CO 2 levels most of the time below acceptable thresholds, only the national policy during and post-lockdown of reduced class-occupancy, stringent quarantine, and contact testing reduced SARS-CoV-2 incidence in Dutch secondary schools. Widespread SARS-CoV-2 air contamination could not be demonstrated in schools under the prevailing conditions during the study.
During the COVID-19 pandemic, the importance of ventilation for ensuring occupants’ health was widely stressed, especially for densely occupied places such as schools (Ding et al, 2022). Correspondingly, new protocols of ventilation were implemented in school buildings among many countries and regions. In the Netherlands, school classrooms were first required to keep the windows and doors open, and later after a national lockdown more stringent measures such as reducing student occupancy were introduced. Previous studies have already shown that the ventilation in a large portion of school classrooms did not meet the requirement (National Ventilation Coordination Team, 2020). However, what are the actual effects of the COVID-19 measures on ventilation in school classrooms remains unclear.
This study aims to investigate 1) the ventilation sufficiency, and 2) the ventilation-related effects of temporary pandemic control and prevention measures in school classrooms under the COVID-19 pandemic.
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During the COVID-19 pandemic, the importance of ventilation for ensuring occupants’ health was widely stressed, especially for densely occupied places such as schools (Ding et al, 2022). Correspondingly, new protocols of ventilation were implemented in school buildings among many countries and regions. In the Netherlands, school classrooms were first required to keep the windows and doors open, and later after a national lockdown more stringent measures such as reducing student occupancy were introduced. Previous studies have already shown that the ventilation in a large portion of school classrooms did not meet the requirement (National Ventilation Coordination Team, 2020). However, what are the actual effects of the COVID-19 measures on ventilation in school classrooms remains unclear.
This study aims to investigate 1) the ventilation sufficiency, and 2) the ventilation-related effects of temporary pandemic control and prevention measures in school classrooms under the COVID-19 pandemic.
Ventilation and thermal conditions in secondary schools in the Netherlands
Effects of COVID-19 pandemic control and prevention measures
Journal article
(2023)
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Er Ding, D. Zhang, A.B. Hamida, C. Garcia Sanchez, Lotte Jonker, Annemarijn R. de Boer, Patricia C.J.L. Bruijning, Kimberly J. Linde, Inge M. Wouters, P.M. Bluyssen
During the COVID-19 pandemic, the importance of ventilation was widely stressed and new protocols of ventilation were implemented in school buildings worldwide. In the Netherlands, schools were recommended to keep the windows and doors open, and after a national lockdown more stringent measures such as reduction of occupancy were introduced. In this study, the actual effects of such measures on ventilation and thermal conditions were investigated in 31 classrooms of 11 Dutch secondary schools, by monitoring the indoor and outdoorCO2 concentration and air temperature, both before and after the lockdown. Ventilation rates were calculated using the steady-state method. Pre-lockdown, with an average occupancy of 17 students, in 42% of the classrooms the CO2 concentration exceeded the upper limit of the Dutch national guidelines (800 ppm above outdoors),while 13% had a ventilation rate per person (VRp) lower than the minimum requirement (6 l/s/p). Post lockdown, the indoor CO2 concentration decreased significantly while for ventilation rates significant increase was only found in VRp, mainly caused by the decrease in occupancy (average 10 students). The total ventilation rate per classrooms, mainly induced by opening windows and doors, did not change significantly. Meanwhile, according to the Dutch national guidelines, thermal conditions in the classrooms were not satisfying, both pre and post-lockdown. While opening windows and doors cannot achieve the required indoor environmental quality at all times, reducing occupancy might not be feasible for immediate implementation. Hence, more controllable and flexible ways for improving indoor air quality and thermal comfort in classrooms are needed.
...
During the COVID-19 pandemic, the importance of ventilation was widely stressed and new protocols of ventilation were implemented in school buildings worldwide. In the Netherlands, schools were recommended to keep the windows and doors open, and after a national lockdown more stringent measures such as reduction of occupancy were introduced. In this study, the actual effects of such measures on ventilation and thermal conditions were investigated in 31 classrooms of 11 Dutch secondary schools, by monitoring the indoor and outdoorCO2 concentration and air temperature, both before and after the lockdown. Ventilation rates were calculated using the steady-state method. Pre-lockdown, with an average occupancy of 17 students, in 42% of the classrooms the CO2 concentration exceeded the upper limit of the Dutch national guidelines (800 ppm above outdoors),while 13% had a ventilation rate per person (VRp) lower than the minimum requirement (6 l/s/p). Post lockdown, the indoor CO2 concentration decreased significantly while for ventilation rates significant increase was only found in VRp, mainly caused by the decrease in occupancy (average 10 students). The total ventilation rate per classrooms, mainly induced by opening windows and doors, did not change significantly. Meanwhile, according to the Dutch national guidelines, thermal conditions in the classrooms were not satisfying, both pre and post-lockdown. While opening windows and doors cannot achieve the required indoor environmental quality at all times, reducing occupancy might not be feasible for immediate implementation. Hence, more controllable and flexible ways for improving indoor air quality and thermal comfort in classrooms are needed.
Since the COVID-19 pandemic, the ventilation of school buildings has attracted considerable attention from the general public and researchers. However, guidance to assess the ventilation performance in classrooms, especially during a pandemic, is still lacking. Therefore, aiming to fill this gap, this study conducted a full-scale laboratory study to monitor the CO2 concentrations at 18 locations in a classroom setting under four different ventilation regimes. Additionally, a field study was carried out in two Dutch secondary schools to monitor the CO2 concentrations in the real classrooms with different ventilation regimes. Both the laboratory and field study findings showed that CO2 concentrations varied a lot between different locations in the same room, especially under natural ventilation conditions. The outcome demonstrates the need of monitoring the CO2 concentration at more than one location in a classroom. Moreover, the monitored CO2 concentration patterns for different ventilation regimes were used to determine the most representative location for CO2 monitoring in classrooms. For naturally ventilated classrooms, the location on the wall opposite to windows and the location on the front wall (nearby the teacher) were recommended. For mechanically ventilated classrooms, one measurement location seemed enough because CO2 was well-mixed under this ventilation regime.
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Since the COVID-19 pandemic, the ventilation of school buildings has attracted considerable attention from the general public and researchers. However, guidance to assess the ventilation performance in classrooms, especially during a pandemic, is still lacking. Therefore, aiming to fill this gap, this study conducted a full-scale laboratory study to monitor the CO2 concentrations at 18 locations in a classroom setting under four different ventilation regimes. Additionally, a field study was carried out in two Dutch secondary schools to monitor the CO2 concentrations in the real classrooms with different ventilation regimes. Both the laboratory and field study findings showed that CO2 concentrations varied a lot between different locations in the same room, especially under natural ventilation conditions. The outcome demonstrates the need of monitoring the CO2 concentration at more than one location in a classroom. Moreover, the monitored CO2 concentration patterns for different ventilation regimes were used to determine the most representative location for CO2 monitoring in classrooms. For naturally ventilated classrooms, the location on the wall opposite to windows and the location on the front wall (nearby the teacher) were recommended. For mechanically ventilated classrooms, one measurement location seemed enough because CO2 was well-mixed under this ventilation regime.
To investigate the sufficiency of ventilation during the COVID-19 pandemic for school children, a field study was conducted in 37 classrooms of 11 Dutch secondary schools between October 2020 and June 2021. All the classrooms were visited twice, before and after a three-month national lockdown, when different measures against COVID-19 were taken by the schools. For each visit, both CO2 concentrations and air temperature were measured during school hours, and detailed information on building/classroom characteristics, occupancy, and COVID-19 measures was collected. Results show that before the lockdown, CO2 concentrations in most classrooms exceeded the threshold levels of the Dutch Fresh Schools guidelines. The significantly lower CO2 concentrations measured after the lockdown, however, were mainly due to the decreased occupancy. Moreover, with windows and doors always being opened on purpose, the performance of different ventilation regimes could not be compared, while such behaviour may also lead to thermal discomfort for school children.
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To investigate the sufficiency of ventilation during the COVID-19 pandemic for school children, a field study was conducted in 37 classrooms of 11 Dutch secondary schools between October 2020 and June 2021. All the classrooms were visited twice, before and after a three-month national lockdown, when different measures against COVID-19 were taken by the schools. For each visit, both CO2 concentrations and air temperature were measured during school hours, and detailed information on building/classroom characteristics, occupancy, and COVID-19 measures was collected. Results show that before the lockdown, CO2 concentrations in most classrooms exceeded the threshold levels of the Dutch Fresh Schools guidelines. The significantly lower CO2 concentrations measured after the lockdown, however, were mainly due to the decreased occupancy. Moreover, with windows and doors always being opened on purpose, the performance of different ventilation regimes could not be compared, while such behaviour may also lead to thermal discomfort for school children.
Several recent studies have demonstrated that ventilation plays an important role in the transmission of SARS-CoV-2 (the coronavirus that causes COVID-19) in public buildings, such as schools. However, there are no clear rules on how to assess the ventilation performance in classrooms, especially during a pandemic. Therefore, the main objective of this study was to develop guidance to assess the ventilation performance under different ventilation regimes. A full-scale laboratory study was conducted in the Experience room of the SenseLab, where CO2 concentrations were monitored at 19 locations (18 indoors and one outdoors) simultaneously and recorded every 30 seconds by HOBO® CO2 loggers. The experiment was conducted under four different ventilation regimes: ‘600 m3/h mixing’, ‘open windows’, ‘no ventilation’, and ‘open windows and door’. Each regime lasted 50 minutes, which is approximately the duration of one normal lesson at Dutch secondary schools. Six (three males and three females) healthy subjects were invited to participate in this experiment as CO2 sources. Results showed that CO2 concentrations varied significantly between different measurement locations in the same classroom, especially under natural ventilation conditions. This demonstrates the need of monitoring the CO2 concentration, next to outdoors, at more than one location in a classroom. The finding of this study could contribute to a standardized way of monitoring CO2 concentrations and the assessment of ventilation performance of an occupied space.
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Several recent studies have demonstrated that ventilation plays an important role in the transmission of SARS-CoV-2 (the coronavirus that causes COVID-19) in public buildings, such as schools. However, there are no clear rules on how to assess the ventilation performance in classrooms, especially during a pandemic. Therefore, the main objective of this study was to develop guidance to assess the ventilation performance under different ventilation regimes. A full-scale laboratory study was conducted in the Experience room of the SenseLab, where CO2 concentrations were monitored at 19 locations (18 indoors and one outdoors) simultaneously and recorded every 30 seconds by HOBO® CO2 loggers. The experiment was conducted under four different ventilation regimes: ‘600 m3/h mixing’, ‘open windows’, ‘no ventilation’, and ‘open windows and door’. Each regime lasted 50 minutes, which is approximately the duration of one normal lesson at Dutch secondary schools. Six (three males and three females) healthy subjects were invited to participate in this experiment as CO2 sources. Results showed that CO2 concentrations varied significantly between different measurement locations in the same classroom, especially under natural ventilation conditions. This demonstrates the need of monitoring the CO2 concentration, next to outdoors, at more than one location in a classroom. The finding of this study could contribute to a standardized way of monitoring CO2 concentrations and the assessment of ventilation performance of an occupied space.
Airborne transmission of small respiratory droplets (i.e., aerosols) is one of the dominant transmission routes of pathogens of several contagious respiratory diseases, which mainly takes place between occupants when sharing indoor spaces. The important role of ventilation in airborne infection control has been extensively discussed in previous studies, yet little attention was paid to the situation in school classrooms, where children spend long hours every day. A literature study was conducted to identify the existing ventilation strategies of school classrooms, to assess their adequacy of minimizing infectious aerosols, and to seek further improvement. It is concluded that school classrooms are usually equipped with natural ventilation or mixing mechanical ventilation, which are not fully capable to deal with both long-range and short-range airborne transmissions. In general, the required ventilation designs, including both ventilation rates and air distribution patterns, are still unclear. Current standards and guidelines of ventilation in school classrooms mainly focus on perceived air quality, while the available ventilation in many schools already fail to meet those criteria, leading to poor indoor air quality (IAQ). New ways of ventilation are needed in school classrooms, where the design should be shifted from comfort-based to health-based. Personalized ventilation systems have shown the potential in protecting occupants from aerosols generated within short-range contact and improving local IAQ, which can be used to compensate the existing ventilation regimes. However, more studies are still needed before such new ventilation methods can be applied to children in school classrooms.
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Airborne transmission of small respiratory droplets (i.e., aerosols) is one of the dominant transmission routes of pathogens of several contagious respiratory diseases, which mainly takes place between occupants when sharing indoor spaces. The important role of ventilation in airborne infection control has been extensively discussed in previous studies, yet little attention was paid to the situation in school classrooms, where children spend long hours every day. A literature study was conducted to identify the existing ventilation strategies of school classrooms, to assess their adequacy of minimizing infectious aerosols, and to seek further improvement. It is concluded that school classrooms are usually equipped with natural ventilation or mixing mechanical ventilation, which are not fully capable to deal with both long-range and short-range airborne transmissions. In general, the required ventilation designs, including both ventilation rates and air distribution patterns, are still unclear. Current standards and guidelines of ventilation in school classrooms mainly focus on perceived air quality, while the available ventilation in many schools already fail to meet those criteria, leading to poor indoor air quality (IAQ). New ways of ventilation are needed in school classrooms, where the design should be shifted from comfort-based to health-based. Personalized ventilation systems have shown the potential in protecting occupants from aerosols generated within short-range contact and improving local IAQ, which can be used to compensate the existing ventilation regimes. However, more studies are still needed before such new ventilation methods can be applied to children in school classrooms.
Under current pandemic of COVID-19, children are still spending long hours in school classrooms every day. A literature study is therefore conducted to investigate the current ventilation strategies used in schools and assess their performance of controlling contagious respiratory diseases in the indoor environment, and also to seek for future solutions. Research papers, reports and standards relevant to school ventilation, airborne transmission and complementary air distribution methods are reviewed. It is concluded that schools usually have natural ventilation (NV) or mechanical ventilation (MV), however the overall indoor air quality is not ideal. Both NV and MV can reduce the airborne transmission of respiratory droplets efficiently when designed, operated, and maintained properly, yet schools are in shortage of informative standards and guidance. Personalized ventilation (PV) has a promising potential in protecting occupants from local indoor air contaminants, yet further studies are needed before PV can be applied to children in classrooms.
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Under current pandemic of COVID-19, children are still spending long hours in school classrooms every day. A literature study is therefore conducted to investigate the current ventilation strategies used in schools and assess their performance of controlling contagious respiratory diseases in the indoor environment, and also to seek for future solutions. Research papers, reports and standards relevant to school ventilation, airborne transmission and complementary air distribution methods are reviewed. It is concluded that schools usually have natural ventilation (NV) or mechanical ventilation (MV), however the overall indoor air quality is not ideal. Both NV and MV can reduce the airborne transmission of respiratory droplets efficiently when designed, operated, and maintained properly, yet schools are in shortage of informative standards and guidance. Personalized ventilation (PV) has a promising potential in protecting occupants from local indoor air contaminants, yet further studies are needed before PV can be applied to children in classrooms.