Preprint Review Version 2 Preserved in Portico This version is not peer-reviewed

2019 Novel Coronavirus (COVID-19) Outbreak: A Review of the Current Literature and Built Environment (BE) Considerations to Reduce Transmission

Version 1 : Received: 10 March 2020 / Approved: 12 March 2020 / Online: 12 March 2020 (04:18:26 CET)
Version 2 : Received: 18 March 2020 / Approved: 20 March 2020 / Online: 20 March 2020 (05:02:44 CET)
Version 3 : Received: 1 April 2020 / Approved: 2 April 2020 / Online: 2 April 2020 (05:19:41 CEST)

A peer-reviewed article of this Preprint also exists.

Dietz L, Horve PF, Coil DA, Fretz M, Eisen JA, Van Den Wymelenberg K. 2020. 2019 novel coronavirus (COVID-19) pandemic: built environment considerations to reduce transmission. mSystems 5:e00245-20. Dietz L, Horve PF, Coil DA, Fretz M, Eisen JA, Van Den Wymelenberg K. 2020. 2019 novel coronavirus (COVID-19) pandemic: built environment considerations to reduce transmission. mSystems 5:e00245-20.


With the rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that results in coronavirus disease 2019 (COVID-19), corporate entities, federal, state, county and city governments, universities, school districts, places of worship, prisons, health care facilities, assisted living organizations, daycares, homeowners, and other building owners and occupants have an opportunity to reduce the potential for transmission through built environment (BE) mediated pathways. Over the last decade, substantial research into the presence, abundance, diversity, function, and transmission of microbes in the BE has taken place and revealed common pathogen exchange pathways and mechanisms. In this paper, we synthesize this microbiology of the BE research and the known information about SARS-CoV-2 to provide actionable and achievable guidance to BE decision makers, building operators, and all indoor occupants attempting to minimize infectious disease transmission through environmentally mediated pathways. We believe this information is useful to corporate and public administrators and individuals responsible for building operations and environmental services in their decision-making process about the degree and duration of social-distancing measures during viral epidemics and pandemics.


Built Environment (BE); building operations; novel coronavirus; COVID-19; SARS-CoV-2


Biology and Life Sciences, Virology

Comments (6)

Comment 1
Received: 20 March 2020
Commenter: Patrick Horve
Commenter's Conflict of Interests: Author
Comment: All updated information has been added as it has been released in relation to the COVID-19 global pandemic.

We have significantly updated the humidity, lighting, and fomites section. We have also added a new section on specifically the hospital built environment.
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Comment 2
Received: 20 March 2020
The commenter has declared there is no conflict of interests.
Comment: What effect may sunlight be speculated to have SARS COV2 and how may this be effectively used for community benefit?
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Comment 3
Received: 21 March 2020
Commenter: Jeffrey Siegel
The commenter has declared there is no conflict of interests.
Comment: I have two concerns that should be addressed:

1)Filtration is much more complicated than indicated here. Some examples of complications
i)The virus droplets/particles are not usually the size of the virus, but are larger and contain the virus. So the efficiency of the filter at the size of the virus is probably not that relevant.
ii)Virus containing droplets/particles are not a constant size. They shrink or grow depending on the relative humidity of the surrounding air, their composition, and some additional factors.
iii)The test result of a filter (e.g., MERV) is not an indication of in-situ performance. Face velocity, filter loading (amount and composition), filter media type and details (e.g., electret vs. non-electret), and bypass. These are all interacting and often dynamic parameters. See Li and Siegel (2020) Indoor Air for some field tests that show MERV by itself is a very poor predictor of in-situ performance in some applications.
iv)There are a host of other factors that impact filter effectiveness (what are non-filter loss processes, how often does the system run, what is the air flow rate through the filter) that are likely more important than the filter efficiency.
I would suggest that there is no evidence that you can make generalized statements about filter efficiency in most systems in the context of virus removal.

2. I would suggest considerably more caution about tying window opening to ventilation. There are two issues
i) Window opening provides a hole but not a driving force for air flow. If the driving force is small, the window may not provide much ventilation. It is also uncontrolled and so you can have inflow and outflow of the same window simultaneously (or over very short time scales). Of course, I understand that open windows generally provide more ventilation than closed windows, but the amount more is variable. An example of this is Alavy et al. (2019) Building and Environment. The home in that paper was my home and air exchange rates were smaller in the summer when our windows were more likely to be open.

ii)More importantly in the context of infectious disease, the possibility of cross-contamination between different parts of the building or between nearby buildings is much greater with openings and uncontrolled air flows. This was important in some SARS spread.
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Comment 4
Received: 23 March 2020
Commenter: Sherry Hartel
The commenter has declared there is no conflict of interests.
Comment: To start I applaud the intention within this article as I can see so much benefit to our communities from this type of research. How the BE is constructed, in form and in materials chosen, can be instrumental in maintaining healthy environments and inhabitants.

With that said. I’m a bit concerned that the benefit of daylights effect on viruses in general is downplayed in this article. There is a lot of research out there of the benefits, and also why we have minimum daylighting requirements within our codes. I understand little research may be out there in this specific virus on how free sunlight can inhibit it’s growth and kill it, but to spend more time discussing artificial means I feel is not serving the best interest of the general public.

Second, I was hoping for far more discussion on materials for floors, walls and ceilings that can mitigate the transmission of viruses without relying on expensive hvac equipment.
From other sources I’m seeing information suggesting that this virus can survive on metal surfaces for up to 9 days, but not necessarily other surfaces. It also appears to like fabrics. Information on material selections that can reduce the transmission of viruses is important information to get into the hands of designers and I would be very interested in hearing more research on material capabilities to resist viruses.

The humidity discussion was very interesting. Thank you.
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Comment 5
Received: 1 April 2020
Commenter: Kevin G Van Den Wymelenberg
The commenter has declared there is no conflict of interests.
Comment: Wanted to share this related video that generalizes a few of the building operations principles outlined in the preprint.
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Comment 6
Received: 22 May 2020
Commenter: Robert J. O'Neill
The commenter has declared there is no conflict of interests.
Comment: Great paper. I am a retired engineer studying the radiation from the sun - especially RF and UV. The sun is in a solar minimum currently with no sunspots since April 30th (NOAA SWPC).

Your paper lines 376 to 417 have become my environment guideline. We cannot (do not) live outside with the benefit of UVA and UVB. Artificially produced UVC and UVGI is probably the way to go with safety restrictions.

I am able to record daily (sunup to sundown) the RF energy at 20.1 MHz. I have yet to record any large sunspot flares.

Hopefully the sun will be more active in a few months - on it way to the next predicted maximum (in 2025) - with greater UVA and UVB radiation.

A connection between the solar minimum and the activation/rise of Covid-19 virus is possible.
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