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  1. Article: COVID-19: Reduction of airborne transmission needs paradigm shift in ventilation.

    Melikov, Arsen K

    Building and environment

    2020  Volume 186, Page(s) 107336

    Keywords covid19
    Language English
    Publishing date 2020-10-06
    Publishing country England
    Document type Editorial
    ISSN 0360-1323
    ISSN 0360-1323
    DOI 10.1016/j.buildenv.2020.107336
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: COVID-19

    Melikov, Arsen K.

    Building and Environment

    Reduction of airborne transmission needs paradigm shift in ventilation

    2020  Volume 186, Page(s) 107336

    Keywords Geography, Planning and Development ; Environmental Engineering ; Civil and Structural Engineering ; Building and Construction ; covid19
    Language English
    Publisher Elsevier BV
    Publishing country us
    Document type Article ; Online
    ISSN 0360-1323
    DOI 10.1016/j.buildenv.2020.107336
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: COVID-19

    Melikov, Arsen Krikor

    Melikov , A K 2020 , ' COVID-19: Reduction of airborne transmission needs paradigm shift in ventilation ' , Building and Environment , vol. 186 , 107336 . https://doi.org/10.1016/j.buildenv.2020.107336

    Reduction of airborne transmission needs paradigm shift in ventilation

    2020  

    Abstract: Paradigm shift in ventilation from space focused design to occupant focused design is needed. Ventilation, and indoor environmental systems in general, has to focus on source control, advanced air distribution and providing healthy and comfortable ... ...

    Abstract Paradigm shift in ventilation from space focused design to occupant focused design is needed. Ventilation, and indoor environmental systems in general, has to focus on source control, advanced air distribution and providing healthy and comfortable microenvironment to each occupant when, where and as much as needed. This will be win-win way to go ahead.
    Keywords covid19
    Language English
    Publishing country dk
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Advanced air distribution: improving health and comfort while reducing energy use.

    Melikov, A K

    Indoor air

    2016  Volume 26, Issue 1, Page(s) 112–124

    Abstract: Indoor environment affects the health, comfort, and performance of building occupants. The energy used for heating, cooling, ventilating, and air conditioning of buildings is substantial. Ventilation based on total volume air distribution in spaces is ... ...

    Abstract Indoor environment affects the health, comfort, and performance of building occupants. The energy used for heating, cooling, ventilating, and air conditioning of buildings is substantial. Ventilation based on total volume air distribution in spaces is not always an efficient way to provide high-quality indoor environments at the same time as low-energy consumption. Advanced air distribution, designed to supply clean air where, when, and as much as needed, makes it possible to efficiently achieve thermal comfort, control exposure to contaminants, provide high-quality air for breathing and minimizing the risk of airborne cross-infection while reducing energy use. This study justifies the need for improving the present air distribution design in occupied spaces, and in general the need for a paradigm shift from the design of collective environments to the design of individually controlled environments. The focus is on advanced air distribution in spaces, its guiding principles and its advantages and disadvantages. Examples of advanced air distribution solutions in spaces for different use, such as offices, hospital rooms, vehicle compartments, are presented. The potential of advanced air distribution, and individually controlled macro-environment in general, for achieving shared values, that is, improved health, comfort, and performance, energy saving, reduction of healthcare costs and improved well-being is demonstrated. Performance criteria are defined and further research in the field is outlined.
    MeSH term(s) Air Conditioning/methods ; Air Pollution, Indoor ; Conservation of Energy Resources ; Ventilation/methods
    Language English
    Publishing date 2016-02
    Publishing country England
    Document type Journal Article
    ZDB-ID 1081722-0
    ISSN 1600-0668 ; 0905-6947
    ISSN (online) 1600-0668
    ISSN 0905-6947
    DOI 10.1111/ina.12206
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  6. Article ; Online: Airborne spread of expiratory droplet nuclei between the occupants of indoor environments: A review.

    Ai, Z T / Melikov, A K

    Indoor air

    2018  Volume 28, Issue 4, Page(s) 500–524

    Abstract: This article reviews past studies of airborne transmission between occupants in indoor environments, focusing on the spread of expiratory droplet nuclei from mouth/nose to mouth/nose for non-specific diseases. Special attention is paid to summarizing ... ...

    Abstract This article reviews past studies of airborne transmission between occupants in indoor environments, focusing on the spread of expiratory droplet nuclei from mouth/nose to mouth/nose for non-specific diseases. Special attention is paid to summarizing what is known about the influential factors, the inappropriate simplifications of the thermofluid boundary conditions of thermal manikins, the challenges facing the available experimental techniques, and the limitations of available evaluation methods. Secondary issues are highlighted, and some new ways to improve our understanding of airborne transmission indoors are provided. The characteristics of airborne spread of expiratory droplet nuclei between occupants, which are influenced correlatively by both environmental and personal factors, were widely revealed under steady-state conditions. Owing to the different boundary conditions used, some inconsistent findings on specific influential factors have been published. The available instrumentation was too slow to provide accurate concentration profiles for time-dependent evaluations of events with obvious time characteristics, while computational fluid dynamics (CFD) studies were mainly performed in the framework of inherently steady Reynolds-averaged Navier-Stokes modeling. Future research needs in 3 areas are identified: the importance of the direction of indoor airflow patterns, the dynamics of airborne transmission, and the application of CFD simulations.
    MeSH term(s) Air Microbiology ; Air Movements ; Air Pollution, Indoor/analysis ; Computer Simulation ; Exhalation ; Humans ; Hydrodynamics ; Manikins
    Language English
    Publishing date 2018-05-08
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 1081722-0
    ISSN 1600-0668 ; 0905-6947
    ISSN (online) 1600-0668
    ISSN 0905-6947
    DOI 10.1111/ina.12465
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  7. Article ; Online: Intermittent occupancy combined with ventilation: An efficient strategy for the reduction of airborne transmission indoors.

    Melikov, A K / Ai, Z T / Markov, D G

    The Science of the total environment

    2020  Volume 744, Page(s) 140908

    Abstract: It is important that efficient measures to reduce the airborne transmission of respiratory infectious diseases (including COVID-19) should be formulated as soon as possible to ensure a safe easing of lockdown. Ventilation has been widely recognized as an ...

    Abstract It is important that efficient measures to reduce the airborne transmission of respiratory infectious diseases (including COVID-19) should be formulated as soon as possible to ensure a safe easing of lockdown. Ventilation has been widely recognized as an efficient engineering control measure for airborne transmission. Room ventilation with an increased supply of clean outdoor air could dilute the expiratory airborne aerosols to a lower concentration level. However, sufficient increase is beyond the capacity of most of the existing mechanical ventilation systems that were designed to be energy efficient under non-pandemic conditions. We propose an improved control strategy based on source control, which would be achieved by implementing intermittent breaks in room occupancy, specifically that all occupants should leave the room periodically and the room occupancy time should be reduced as much as possible. Under the assumption of good mixing of clean outdoor supply air with room air, the evolution of the concentration in the room of aerosols exhaled by infected person(s) is predicted. The risk of airborne cross-infection is then evaluated by calculating the time-averaged intake fraction. The effectiveness of the strategy is demonstrated for a case study of a typical classroom. This strategy, together with other control measures such as continuous supply of maximum clean air, distancing, face-to-back layout of workstations and reducing activities that increase aerosol generation (e.g., loudly talking and singing), is applicable in classrooms, offices, meeting rooms, conference rooms, etc.
    MeSH term(s) Air Pollution, Indoor ; Betacoronavirus ; COVID-19 ; Coronavirus Infections ; Humans ; Pandemics ; Pneumonia, Viral ; SARS-CoV-2 ; Ventilation
    Keywords covid19
    Language English
    Publishing date 2020-07-15
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2020.140908
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  8. Article ; Online: Influence of pulmonary ventilation rate and breathing cycle period on the risk of cross-infection.

    Ai, Zhengtao / Hashimoto, Kaho / Melikov, Arsen K

    Indoor air

    2019  Volume 29, Issue 6, Page(s) 993–1004

    Abstract: This study examined the characteristics of the exhaled airflow pattern and breathing cycle period of human subjects and evaluated the influence of pulmonary ventilation rate and breathing cycle period on the risk of cross-infection. Measurements with ... ...

    Abstract This study examined the characteristics of the exhaled airflow pattern and breathing cycle period of human subjects and evaluated the influence of pulmonary ventilation rate and breathing cycle period on the risk of cross-infection. Measurements with five human subjects and a breathing thermal manikin were performed, and the peak exhaled airflow velocity from the mouth and the breathing cycle period were measured. Experiments on cross-infection between two breathing thermal manikins were then conducted in a full-scale test room, in which the pulmonary ventilation rate and breathing cycle period were varied systematically. Both peak flow velocity and breathing cycle length varied considerably between different subjects. The breathing cycle period in a standing posture was 18.9% lower than in a sitting posture. The influence of pulmonary ventilation rate and breathing cycle period extended up to a separation distance of 1.0 m between the two manikins. Increasing the pulmonary ventilation rate of the exposed person greatly increased the risk of cross-infection. Decreasing the breathing cycle period from the widely used "6 second" value led to a considerable increase in the risk of cross-infection. Standing posture resulted in a higher risk of cross-infection than sitting posture.
    MeSH term(s) Adult ; Aged ; Cross Infection/transmission ; Exhalation ; Female ; Humans ; Male ; Manikins ; Middle Aged ; Mouth ; Posture ; Pulmonary Ventilation ; Respiration ; Risk Factors
    Language English
    Publishing date 2019-08-06
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1081722-0
    ISSN 1600-0668 ; 0905-6947
    ISSN (online) 1600-0668
    ISSN 0905-6947
    DOI 10.1111/ina.12589
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  9. Article ; Online: Airborne transmission between room occupants during short-term events: Measurement and evaluation.

    Ai, Zhengtao / Hashimoto, Kaho / Melikov, Arsen K

    Indoor air

    2019  Volume 29, Issue 4, Page(s) 563–576

    Abstract: This study experimentally examines and compares the dynamics and short-term events of airborne cross-infection in a full-scale room ventilated by stratum, mixing and displacement air distributions. Two breathing thermal manikins were employed to simulate ...

    Abstract This study experimentally examines and compares the dynamics and short-term events of airborne cross-infection in a full-scale room ventilated by stratum, mixing and displacement air distributions. Two breathing thermal manikins were employed to simulate a standing infected person and a standing exposed person. Four influential factors were examined, including separation distance between manikins, air change per hour, positioning of the two manikinsand air distribution. Tracer gas technique was used to simulate the exhaled droplet nuclei from the infected person and fast tracer gas concentration meters (FCM41) were used to monitor the concentrations. Real-time and average exposure indices were proposed to evaluate the dynamics of airborne exposure. The time-averaged exposure index depends on the duration of exposure time and can be considerably different during short-term events and under steady-state conditions. The exposure risk during short-term events may not always decrease with increasing separation distance. It changes over time and may not always increase with time. These findings imply that the control measures formulated on the basis of steady-state conditions are not necessarily appropriate for short-term events.
    MeSH term(s) Air Microbiology ; Air Movements ; Air Pollution, Indoor/analysis ; Cross Infection/transmission ; Environmental Monitoring/methods ; Exhalation/physiology ; Humans ; Manikins ; Virus Diseases/transmission
    Keywords covid19
    Language English
    Publishing date 2019-05-08
    Publishing country England
    Document type Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1081722-0
    ISSN 1600-0668 ; 0905-6947
    ISSN (online) 1600-0668
    ISSN 0905-6947
    DOI 10.1111/ina.12557
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

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  10. Article: Intermittent occupancy combined with ventilation: An efficient strategy for the reduction of airborne transmission indoors

    Melikov, A K / Ai, Z T / Markov, D G

    Sci Total Environ

    Abstract: It is important that efficient measures to reduce the airborne transmission of respiratory infectious diseases (including COVID-19) should be formulated as soon as possible to ensure a safe easing of lockdown. Ventilation has been widely recognized as an ...

    Abstract It is important that efficient measures to reduce the airborne transmission of respiratory infectious diseases (including COVID-19) should be formulated as soon as possible to ensure a safe easing of lockdown. Ventilation has been widely recognized as an efficient engineering control measure for airborne transmission. Room ventilation with an increased supply of clean outdoor air could dilute the expiratory airborne aerosols to a lower concentration level. However, sufficient increase is beyond the capacity of most of the existing mechanical ventilation systems that were designed to be energy efficient under non-pandemic conditions. We propose an improved control strategy based on source control, which would be achieved by implementing intermittent breaks in room occupancy, specifically that all occupants should leave the room periodically and the room occupancy time should be reduced as much as possible. Under the assumption of good mixing of clean outdoor supply air with room air, the evolution of the concentration in the room of aerosols exhaled by infected person(s) is predicted. The risk of airborne cross-infection is then evaluated by calculating the time-averaged intake fraction. The effectiveness of the strategy is demonstrated for a case study of a typical classroom. This strategy, together with other control measures such as continuous supply of maximum clean air, distancing, face-to-back layout of workstations and reducing activities that increase aerosol generation (e.g., loudly talking and singing), is applicable in classrooms, offices, meeting rooms, conference rooms, etc.
    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #652784
    Database COVID19

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