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in buildings for decades, most notably in hospitals. Substantial
research into the presence, abundance, diversity, function, and
transmission of the microorganisms in the BE has taken place
in recent years. This work has revealed common pathogen
exchange pathways and mechanisms that could lend insights
into potential methods to mediate the spread of SARS-2-CoV
through BE mediated pathways.
In December 2019, a novel CoV (SARS-CoV-2) was identified
in Wuhan, a major transport hub of central China. The earliest
COVID-19 cases were linked to a large seafood market in
Wuhan, initially suggesting a direct food source transmission
pathway. Since that time, we have learned that person-
to-person transmission is one of the main mechanisms of
COVID-19 spread.
In the months since the identification of the initial cases,
COVID-19 has spread to 192 countries and territories and there
are approximately 349 187confirmed cases (as of 23 March 2020).
The modes of transmission have been identified as host-to-
human and human-to-human. There is preliminary evidence
that environmentally mediated transmission may be possible;
specifically, that COVID-19 patients could be acquiring the virus
through contact with abiotic (BE) surfaces.
Shared workspaces such as co-work environments, rooms in
homes, cars, bikes, and other elements of the BE may increase
the potential for environmentally mediated pathways of
exposure.
COVID-19 AND THE IMPACT OF THE BE IN
TRANSMISSION
The built environment (BE) is the collection of environments that
humans have constructed, including buildings, cars, roads, public
transport, and other human-built spaces. Since most humans
spend >90% of their daily lives inside the BE, it is essential to
understand the potential transmission dynamics of COVID-19
within the BE ecosystem and the human behaviour, spatial
dynamics and building operational factors that potentially
promote and mitigate the spread and transmission of COVID-19.
BEs serve as potential transmission vectors for the spread of
COVID-19 by forcing close interactions between individuals, by
acting as fomites (objects or materials which are likely to carry
infectious diseases), and through viral exchange and transfer
through the air.
The occupant density in buildings, influenced by
building type and programme, occupancy schedule, and
indoor activity, facilitates the accrual of human-associated
microorganisms. Higher occupant density and increased
indoor activity level typically increases social interaction and
connectivity through direct contact as well as environmentally
mediated contact (fomites).
The original cluster of patients were hospitalised in Wuhan
with respiratory distress (Dec 2019), and approximately ten
days later, the same hospital facility was utilising rt-PCR to
diagnose patients with COVID-19. It is presumed that the
number of infected patients increased because of transmissions
www.hvacronline.co.za
The knowledge of the transmission dynamics of COVID-19 is still
currently developing, especially in the HVAC&R industry.
that occurred within the hospital BE. The increased exposure
risk associated with high occupant density and consistent
contact was demonstrated with the COVID-19 outbreak that
occurred on the Diamond Princess cruise ship in January 2020.
Current estimates of contagiousness of SARS-CoV-2 (known as
the R0), have been estimated from 1.5-3. R0 is defined as the
average number of people who will contract a disease from one
contagious person. For reference, measles has a famously high
R0 of roughly 12-18, and influenza (flu) has an R0 of <2. However,
within the confined spaces of the BE, the R0 of SARS-CoV-2 has
been estimated to be significantly higher (estimates ranging
from 5-14), with ~700 of the 3 711 passengers on board (~19%)
contracting COVID-19 during their two-week quarantine on the
ship. These incidents demonstrate the high transmissibility of
COVID-19 as a result of confined spaces found within the BE.
RACA Journal I May 2020
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