The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2

In the wake of the COVID-19 pandemic, an increased risk of infection by virus-containing aerosols indoors is assumed. Especially in schools, the duration of stay is long and the number of people in the rooms is large, increasing the risk of infection. This problem particularly affects schools withou...

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Autores principales:	Finn F. Duill, Florian Schulz, Aman Jain, Leve Krieger, Berend van Wachem, Frank Beyrau
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	airborne transmission SARS-CoV-2 air purifiers COVID-19 Medicine R
Acceso en línea:	https://doaj.org/article/86ab6c8f78554baebcd968fff05ce467
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spelling	oai:doaj.org-article:86ab6c8f78554baebcd968fff05ce4672021-11-11T16:38:32ZThe Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-210.3390/ijerph1821115231660-46011661-7827https://doaj.org/article/86ab6c8f78554baebcd968fff05ce4672021-11-01T00:00:00Zhttps://www.mdpi.com/1660-4601/18/21/11523https://doaj.org/toc/1661-7827https://doaj.org/toc/1660-4601In the wake of the COVID-19 pandemic, an increased risk of infection by virus-containing aerosols indoors is assumed. Especially in schools, the duration of stay is long and the number of people in the rooms is large, increasing the risk of infection. This problem particularly affects schools without pre-installed ventilation systems that are equipped with filters and/or operate with fresh air. Here, the aerosol concentration is reduced by natural ventilation. In this context, we are investigating the effect of large mobile air purifiers (AP) with HEPA filters on particle concentration and their suitability for classroom use in a primary school in Germany. The three tested APs differ significantly in their air outlet characteristics. Measurements of the number of particles, the particle size distribution, and the CO<sub>2</sub> concentration were carried out in the classroom with students (April/May 2021) and with an aerosol generator without students. In this regard, the use of APs leads to a substantial reduction of aerosol particles in the considered particle size range of 0.178–17.78 µm. At the same time, the three APs are found to have differences in their particle decay rate, noise level, and flow velocity. In addition to the measurements, the effect of various influencing parameters on the potential inhaled particle dose was investigated using a calculation model. The parameters considered include the duration of stay, particle concentration in exhaled air, respiratory flow rate, virus lifetime, ventilation interval, ventilation efficiency, AP volumetric flow, as well as room size. Based on the resulting effect diagrams, significant recommendations can be derived for reducing the risk of infection from virus-laden aerosols. Finally, the measurements were compared to computational fluid dynamics (CFD) modeling, as such tools can aid the optimal placement and configuration of APs and can be used to study the effect of the spread of aerosols from a source in the classroom.Finn F. DuillFlorian SchulzAman JainLeve KriegerBerend van WachemFrank BeyrauMDPI AGarticleairborne transmissionSARS-CoV-2air purifiersCOVID-19MedicineRENInternational Journal of Environmental Research and Public Health, Vol 18, Iss 11523, p 11523 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	airborne transmission SARS-CoV-2 air purifiers COVID-19 Medicine R
spellingShingle	airborne transmission SARS-CoV-2 air purifiers COVID-19 Medicine R Finn F. Duill Florian Schulz Aman Jain Leve Krieger Berend van Wachem Frank Beyrau The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2
description	In the wake of the COVID-19 pandemic, an increased risk of infection by virus-containing aerosols indoors is assumed. Especially in schools, the duration of stay is long and the number of people in the rooms is large, increasing the risk of infection. This problem particularly affects schools without pre-installed ventilation systems that are equipped with filters and/or operate with fresh air. Here, the aerosol concentration is reduced by natural ventilation. In this context, we are investigating the effect of large mobile air purifiers (AP) with HEPA filters on particle concentration and their suitability for classroom use in a primary school in Germany. The three tested APs differ significantly in their air outlet characteristics. Measurements of the number of particles, the particle size distribution, and the CO<sub>2</sub> concentration were carried out in the classroom with students (April/May 2021) and with an aerosol generator without students. In this regard, the use of APs leads to a substantial reduction of aerosol particles in the considered particle size range of 0.178–17.78 µm. At the same time, the three APs are found to have differences in their particle decay rate, noise level, and flow velocity. In addition to the measurements, the effect of various influencing parameters on the potential inhaled particle dose was investigated using a calculation model. The parameters considered include the duration of stay, particle concentration in exhaled air, respiratory flow rate, virus lifetime, ventilation interval, ventilation efficiency, AP volumetric flow, as well as room size. Based on the resulting effect diagrams, significant recommendations can be derived for reducing the risk of infection from virus-laden aerosols. Finally, the measurements were compared to computational fluid dynamics (CFD) modeling, as such tools can aid the optimal placement and configuration of APs and can be used to study the effect of the spread of aerosols from a source in the classroom.
format	article
author	Finn F. Duill Florian Schulz Aman Jain Leve Krieger Berend van Wachem Frank Beyrau
author_facet	Finn F. Duill Florian Schulz Aman Jain Leve Krieger Berend van Wachem Frank Beyrau
author_sort	Finn F. Duill
title	The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2
title_short	The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2
title_full	The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2
title_fullStr	The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2
title_full_unstemmed	The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2
title_sort	impact of large mobile air purifiers on aerosol concentration in classrooms and the reduction of airborne transmission of sars-cov-2
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/86ab6c8f78554baebcd968fff05ce467
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The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2

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