Dispersion of sneeze droplets in a meat facility indoor environment - Without partitions

Abstract

Spreading patterns of the coronavirus disease (COVID-19) showed that infected and asymptotic carriers both played critical role in escalating transmission of virus leading to global pandemic. Indoor environments of restaurants, classrooms, hospitals, offices, large assemblies, and industrial installations are susceptible to virus outbreak. Industrial facilities such as fabrication rooms of meat processing plants, which are laden with moisture and fat in indoor air are the most sensitive spaces. Fabrication room workers standing next to each other are exposed to the risk of long-range viral droplets transmission within the facility. An asymptomatic carrier may transmit the virus unintentionally to fellow workers through sporadic sneezing leading to community spread. A novel Computational Fluid Dynamics (CFD) model of a fabrication room with typical interior (stationary objects) was prepared and investigated. Study was conducted to identify indoor airflow patterns, droplets spreading patterns, leading droplets removal mechanism, locations causing maximum spread of droplets, and infection index for workers along with stationary objects in reference to seven sneeze locations covering the entire room. The role of condensers, exhaust fans and leakage of indoor air through large and small openings to other rooms was investigated. This comprehensive study presents flow scenarios in the facility and helps identify locations that are potentially at lower or higher risk for exposure to COVID-19. The results presented in this study are suitable for future engineering analyses aimed at redesigning public spaces and common areas to minimize the spread of aerosols and droplets that may contain pathogens.

Full text

Environmental Research 236 (2023) 116603
Available online 16 July 2023
0013-9351/© 2023 Elsevier Inc. All rights reserved.
Dispersion of sneeze droplets in a meat facility indoor environment –
Without partitions
Sunil Kumar
a
, Mark Klassen
b
, David Klassen
c
, Robert Hardin
a
, Maria D. King
a
,
*
a
Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA
b
Canada Beef, Mississauga, ON, L5N 5R1, Canada
c
Department of Mechanical Engineering, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
ARTICLE INFO
Handling Editor: Jose L Domingo
Keywords:
COVID-19
Sneeze droplets dispersion
Computational uid dynamics (CFD)
Indoor environment
Meat processing plant
Infection index
ABSTRACT
Spreading patterns of the coronavirus disease (COVID-19) showed that infected and asymptotic carriers both
played critical role in escalating transmission of virus leading to global pandemic. Indoor environments of res-
taurants, classrooms, hospitals, ofces, large assemblies, and industrial installations are susceptible to virus
outbreak. Industrial facilities such as fabrication rooms of meat processing plants, which are laden with moisture
and fat in indoor air are the most sensitive spaces. Fabrication room workers standing next to each other are
exposed to the risk of long-range viral droplets transmission within the facility. An asymptomatic carrier may
transmit the virus unintentionally to fellow workers through sporadic sneezing leading to community spread. A
novel Computational Fluid Dynamics (CFD) model of a fabrication room with typical interior (stationary objects)
was prepared and investigated. Study was conducted to identify indoor airow patterns, droplets spreading
patterns, leading droplets removal mechanism, locations causing maximum spread of droplets, and infection
index for workers along with stationary objects in reference to seven sneeze locations covering the entire room.
The role of condensers, exhaust fans and leakage of indoor air through large and small openings to other rooms
was investigated. This comprehensive study presents ow scenarios in the facility and helps identify locations
that are potentially at lower or higher risk for exposure to COVID-19. The results presented in this study are
suitable for future engineering analyses aimed at redesigning public spaces and common areas to minimize the
spread of aerosols and droplets that may contain pathogens.
1. Introduction
The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-
2) also known as the causative agent of the COVID-19 pandemic,
infected more than 645 million people, and already caused more than
6.6 million cumulative deaths across the globe as of December 11, 2022
(NCDC, 2022), since its emergence in December 2019. The spread of
virus is caused by the infected as well as asymptomatic person without
symptoms. The micron size droplets generated during coughs, sneezes,
talks, and even breaths are emitted in the environment. Among respi-
ratory events the sneeze is considered most violent, ejecting large
numbers of saliva droplets of various sizes (Han et al., 2013), which can
travel considerably long distances (Bourouiba, 2020) and feasibly de-
posit on closest surfaces (Asadi et al., 2020). The presence of contami-
nated droplets was observed on different surfaces. The probable survival
of SARS-CoV-2 on various surfaces varies from few hours to days.
COVID-19 virus can stay 4–5 days on paper, 4–9 days on plastics, up to 5
days on metals, up to 4 h on copper, 2–3 days on steel, up to 4 days on
glass, up to 8 h on latex gloves, and 4–5 days on wood (Wiktorczyk--
kapischke et al., 2021). A healthy person may get infected by touching
these surfaces (secondary mode of transmission) accidently.
Studies have shown that the fate of the droplets primarily depends on
their initial size (Wells, 1933; Xie et al., 2007). Large size droplets
(>100
μ
m) fall under the effect of gravity, while small droplets (<100
μ
m) are easily affected by the surrounding airow and can travel longer
distance under the effect of airow. The aerosolized droplets may keep
oating for a long time and eventually evaporate into aerosol or droplet
nuclei referred to as airborne transmission. Study by (Wells, 1933)
showed that 100
μ
m droplets would settle on ground within 2 m, and up
to 6 m, if sneeze jet velocity is 50 m/s (Xie et al., 2007). Exceptionally
long traveled distance up to 8 m before losing its momentum has also
been reported (Bourouiba, 2020), which is greatly affected by wind
* Corresponding author.
E-mail addresses: ksunil86.in@gmail.com (S. Kumar), mdking@tamu.edu (M.D. King).
Contents lists available at ScienceDirect
Environmental Research
journal homepage: www.elsevier.com/locate/envres
https://doi.org/10.1016/j.envres.2023.116603
Received 20 December 2022; Received in revised form 26 June 2023; Accepted 7 July 2023

1
*Corresponding Author.
E-mail address: mdking@tamu.edu (Maria D. King), ksunil86.in@gmail.com (Sunil Kumar)
Dispersion of sneeze droplets in a meat facility indoor
environment – without partitions
Sunil Kumar1, Mark Klassen3, David Klassen2, Robert Hardin1 and Maria D. King1*
1Department of Biological and Agricultural Engineering, Texas A&M University, College
Station, Texas 77843, USA
2Department of Mechanical Engineering, University of Calgary, Calgary Alberta T2N 1N4,
Canada
3Canada Beef, Mississauga, ON L5N 5R1, Canada

2
Abstract
Spreading patterns of Coronavirus disease (COVID-19) showed that infected and
asymptotic carriers both played critical role in escalating transmission of virus leading to global
pandemic. Indoor environments of restaurants, classrooms, hospitals, offices, large assemblies,
and industrial installations are susceptible to virus outbreak. Industrial facilities such as fabrication
rooms of meat processing plants, which are laden with moisture and fat in indoor air are the most
sensitive spaces. Fabrication room workers standing next to each other are exposed to the risk of
long-range viral droplets transmission within the facility. An asymptomatic carrier may transmit
the virus unintentionally to fellow workers through sporadic sneezing leading to community
spread. A novel Computational Fluid Dynamics (CFD) model of a fabrication room with typical
interior (stationary objects) was prepared and investigated. Study was conducted to identify indoor
airflow patterns, droplets spreading patterns, leading droplets removal mechanism, locations
causing maximum spread of droplets, and infection index for workers along with stationary objects
in reference to seven sneeze locations covering the entire room. Role of condensers, exhaust fans
and leakage of indoor air through large and small openings to other room was investigated.
Comprehensive study presents flow scenarios in the facility and helps identify locations that are
potentially at lower or higher risk for exposure to COVID-19. The results presented in this study
are suitable for future engineering analyses aimed at redesigning public spaces and common areas
to minimize the spread of aerosols and droplets that may contain pathogens.
Keywords: COVID-19, Sneeze droplets dispersion, Computational Fluid Dynamics (CFD),
Indoor environment, Meat processing plant, Infection index
1. Introduction
The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) also known as
COVID-19 infected more than 645 million people, which already caused more than 6.6 million
cumulative deaths across the globe as of December 11, 2022 (NCDC, 2022), since its emergence
in December 2019. Spread of virus is caused by the infected as well as asymptomatic person
without symptoms. The micron size droplets generated during coughs, sneezes, talks, and even
breathes are emitted in the environment. Among respiratory events sneeze is considered most
violent, ejecting large number of saliva droplets of various size (Han et al., 2013), which can travel
considerably a long distance (Bourouiba, 2020) and feasibly deposit on closest surfaces (Asadi et
al., 2020). The presence of contaminated droplets was observed on different surfaces. The probable
duration of SARS-CoV-2 on various surfaces varies from few hours to days. COVID-19 virus can
stay 4-5 days on paper, 4-9 days on plastics, up to 5 days on metals, up to 4 hours on copper, 2-3
days on steel, up to 4 days on glass, up to 8 hours on latex gloves, and 4-5 days on wood
(Wiktorczyk-kapischke et al., 2021). A healthy person may get infected by touching these surfaces
(secondary mode of transmission) accidentally.
Studies have shown that fate of the droplets primarily depends on their initial size (Wells, 1933;
Xie et al., 2007). Large size droplets (> 100 µm) fall under the effect of gravity, while small

3
droplets (< 100 µm) are easily affected by the surrounding airflow and can travel longer distance
under the effect of air flow. The aerosolized droplets may keep floating a long time and eventually
evaporate into aerosol or droplet nuclei referred to as airborne transmission. Study by (Wells,
1933) showed that 100 µm droplets would settle on ground within 2 m, and up to 6 m, if sneeze
jet velocity is 50 m/s (Xie et al., 2007). Exceptionally long traveled distance up to 8 m before
losing its momentum has also been reported (Bourouiba, 2020), which is greatly affected by wind
localized air flow for indoor environments and wind speed for outdoors (Dbouk and Drikakis,
2020; Li et al., 2020).
One of the main reason for accelerated spread of infection is interpersonal transmission of
contaminated droplets, which may carry viral RNA via air route primarily (Asadi et al., 2020;
Jayaweera et al., 2020; Tellier et al., 2019) and on the concentration of pollutants. The role of
pollutants in the air on public health was investigated by many researchers. A comprehensive
review study performed by (Domingo et al., 2020) assessed relationship between air pollutants
concentration on airborne transmission of SARS-CoV-2 among the patients infected by
coronavirus. Chronically exposed patients to certain air pollutants (e.g., sulfur oxides, nitrogen
oxides, carbon monoxide and dioxide, particulate matter (PM), ozone and volatile organic
compounds) might have severe and lethal form of COVID-19, with complicated/delayed recovery.
A review on effect of air pollutants on the transmission and severity of the respiratory viral
infection presented by (Domingo and Rovira, 2020) further notes that decrease in deaths during
the quarantine periods is a result of huge decrease in air pollution. This shows clear evidence that
high concentration of pollutants in the local environment adversely affects the human respiratory
system.
Apart from the outdoor environment, the indoor environment of buildings is crucial for
controlling the spread of respiratory infection. (Passos et al., 2021) showed that small size droplets
facilitate diseases including COVID-19 transmission through aerosolization. The swab sample
from air exhaust grill also tested positive testifying that indoor airflow transported the droplets on
vents (Ong et al., 2020). Experimental and numerical study by Zhou et al. (Zhou and Ji, 2021)
shows that vortices generated in the room affect the transport of aerosols in fever clinic room.
Study finds that the spread of droplets is sensitive to position of patient. (Kumar and King, 2022)
performed a comprehensive study to show that location of diffuser is critical for achieving early
decontamination of hospital room. Placing the exhaust on the wall behind the patient and diffuser
on the roof helps achieve early decontamination. Additionally, installation of a low flow air curtain
further accelerates the decontamination even when small size droplets are uniformly diluted and
offers maximum comfort. A review on strategies to reduce the indoor airborne transmission and
improve the air quality was presented by (Nair et al., 2022). Study recommends using negative
pressure mix ventilation in hospital isolation rooms. Large size indoor environments of Hospital
areas (Grimalt et al., 2022), coach buses (Luo et al., 2022), slaughter facilities (Beck et al., 2019),
and industrial installations are susceptible to virus outbreak. Presence of moisture and fat in the air
like fabrication room of a meat facility further increases the possibility of virus transmission in the
presence of an infected (symptomatic or asymptomatic) person. Therefore, a careful analysis to

4
understand the routes of micron size droplets transmission under the effect of indoor air flow
pattern is critically important.
In present study, an actual size fabrication room (with a capacity of 116 workers) of a meat
facility was investigated for dispersion of sneeze droplets generated from seven different locations.
CFD analysis helps understand the flow patterns developed in the fabrication room in presence of
stationary objects. Role of large size vortices is evaluated to develop correlating effects in
reference to dispersion of droplets. The characteristics dispersion pattern provides crucial
information to identify areas with risk of high and low exposure in the facility, where use of
protective equipment would be especially helpful. Droplets removal mechanisms such as
evaporation, deposition, and escape was investigated to understand the impact airborne droplets.
The detailed infection index for all the workers including stationary objects provide critical
information for the safety of workers The study leads to characterization of indoor environment
and is extremely helpful for safety teams, civil, and specially Heating, ventilation, and air
conditioning (HVAC) engineers. Based on the study, appropriate decontamination strategy can be
developed.
2. Methods
Sneeze is a critical mechanism in which large pressure variation
within a small period creates a fast flow in the upper respiratory tract,
which breaks the saliva and mucus into small sized droplets that gets
sprayed from the mouth cavity. Sneeze ejecta is considered as mixture
of droplets and aerosols in transient manner. Study by (Busco et al.,
2020; Gupta et al., 2009) show that pressure response is key time
varying parameter to understand the spraying of micron size droplets.
For simulations, it was considered that asymptotic worker expels a
downward jet with a typical flow rate at an angle of 27.5° (figure 1).
2.1. Geometrical design of fabrication room
The photograph of the interior of the fabrication room considered
for study is shown in figure 2a. Typically, fabrication room consists
of central conveyer belts, fabrication tables, electric motor housings,
and evaporators to circulate the cold air. Schematic diagram of the top
and isometric view of the fabrication room including typical internals and workers standing on
both sides of the table is shown in figures 2b and 2c. The workers are wearing protective apparels
therefore appear like a cylinder mannequin as shown in figure 2c. The workers are standing in
columns A to H (numbered over green circular pellets) as shown in figure 2b. The side and front
views of the facility indicating pillars, mezzanine, condensers, and belts is shown in figure 2d.
Figure 1: Schematic
diagram sneezer. The
arrow indicates the
reference inclination of
the sneeze jet from the
horizontal.

5
(a) (b)
(c)

6
(d)
Figure 2. (a) Inside photograph (b) Top view (c) isometric view, and (d) side and front views of
fabrication room
Dimensions of the fabrication room along with zoomed view of an area over the belt 3 are
shown in the figure 2c. Fresh air from the front end enters the facility. Indoor air is circulated
mainly by the two evaporators at left and right side. The exhaust at roof, large exhaust and small
exhaust allows removal of ventilated air. Critical geometrical details of the internals of fabrication
room were considered for CFD modeling. Seven different sneeze locations selected to investigate
droplets dispersion are highlighted by yellow circles and corresponding worker location
identification numbers (figure 2b). Table 1 shows worker location number and assigned sneeze
number used for this study.
Table 1: Worker location identification number and assigned sneeze number
Location
Sneeze
number
Location
Sneeze
number
Location
Sneeze
number
Location
Sneeze
number
64
Sneeze_S1
1
Sneeze_S2
42
Sneeze_S3
90
Sneeze_S4
21
Sneeze_S5
11
Sneeze_S6
51
Sneeze_S7
3. Numerical method
Eulerian-Lagrangian approach is used to simulate respiratory event of sneeze. Dynamics of a
single droplet coming from the sneeze acts on a sub-grid scale. Droplets interact with the resolved
Eulerian macro-scales by exchanging mass, energy, and momentum. The droplets are simulated
as discrete phase while air is simulated as continuous phase.

7
The continuous phase moist air is modeled as compressible homogeneous mixture of dry air
and water vapor by solving the conservation equations for scalar variables representing mass
fractions of species. The water vapor and air are assumed to share same temperature, velocity, and
pressure forming the homogeneous mixture. Interaction between droplets and moist air is achieved
by interphase mass, momentum, and energy exchange. Reynolds number used for peak sneeze
velocity is 20000 (Busco et al., 2020).
The Lagrangian phase has two critical components namely “Droplet tracking” and “Droplet
evaporation”. Tracking is performed by integrating the force balance which is equated using inertia
with forces acting on the droplet. Stochastic tracking is performed using Random Walk model and
Random Eddy lifetime for each airborne droplet. Evaporation of the droplets is governed by the
diffusive flux of the droplet vapor in the air. Presence of non-volatile components such as mineral
salts lower the saturated pressure of water, which affect the droplets evaporation rate. The vapor
pressure of saturated and pure water is used to calculate activity coefficient, while Reynolds and
Schmidt numbers are employed to calculate mass transfer coefficient. Droplets temperature
variation is governed by thermal balance including sensible and latent heat. Droplets distortion
and breakup is accounted by Taylor Analogy Breakup (TAB) model (O’Rourke and Amsden,
1987).
Additional details of numerical method along with equations adopted for present study can be
found in previous publication of (Kumar and King, 2022) and (“ANSYS Fluent User Guide,” n.d.,
“Fluent Theory Guide,” n.d.).
3.1. Model assumptions
For simulations following assumptions were made:
1. The fresh clean unidirectional air enters the fabrication room from front end of facility.
2. All the workers wearing protective apparels appear as cylindrical mannequins.
3. Internal objects of significant importance to airflow are modeled with simplification.
4. Workers marked in figure 2b sneeze away from conveyor belt in downward direction.
5. Workers are considered stationary for the duration of simulation.
3.2. Boundary conditions
For CFD simulations, all the walls including stationary objects were considered adiabatic. No
slip boundary condition was imposed on all the surfaces including workers. The temperature and
velocity boundary conditions are shown in table 2.
Table 2. Details of velocity and temperature boundary conditions
Zone
Boundary condition
Temperature (°C)
Velocity (m/s) / Flow rate (kg/s)
Asymptomatic Sneezer
Constant Temperature (34 °C)
No slip (   )
Walls, floor, roof, belts,
tables, electric housings
Adiabatic (
 
 
  )
No slip (   )

8
Imaginary wall air inlet
10 °C
    
Evaporator inlet flow rate
--
4.42 (kg/s)
Evaporator outlet flow
rate
2 °C
    
Roof exhaust
--
2.15 (kg/s)
Large exhaust
--
0.53 (kg/s)
Small exhaust
--
0.0589 (kg/s)
4. Mesh independency test and CFD simulation setup
Details of the mesh independency test and simulation setup are presented below:
4.1. Mesh independency test
Dimensions of the fabrication room are shown in figure 2c. The isometric meshed view of
fabrication room, mesh over workers and flow obstructions (e.g., conveyer belts, tables, electric
housings, pillars, partitions, and inclined belts) and a zoomed view of an area over the belt 3 are
shown in figure 3a. Meshing was performed using polyhedral cells. A grid independency study
was performed for the fabrication room. For the domain 3.65, 4.36, and 6.05 million cells were
created. The mesh independency graph in figure 3b shows variation of velocity along the height
of the fabrication room. The velocity for the mesh 4.36 million cell behaves similarly to the 6.05
million cells and will have similar effects on droplets movement. Therefore 4.3 million cells were
used for further simulations.
(a)

9
(b)
Figure 3. Fabrication room (a) Meshed isometric view (b) velocity variation along the height
4.2. Details of simulation setup
The pressure-based solver, with realizable k-ε, and scalable wall function is used for
simulations. SIMPLE approach was used for pressure-velocity coupling. The second-order upwind
scheme was used for density, momentum, turbulent kinetic energy, turbulent dissipation rate, and
energy. The pressure was discretized using second order. For developing airflow in the facility,
initially steady state simulations were performed, which were later used for transient simulations.
The transient simulations were performed for 240 seconds (4 minutes), allowing sufficient time
for droplets to spread and dilute in room. Temperature and velocity data for the air inlet/outlet in
facility is shown in table 2. The average humidity value of 68.5% was used for the simulations.
In present study, single sneeze at a time from designated sneezer shown in figure 2b and table
1 was considered for investigation. Sneeze droplets originate from 2.25 cm2 opening area and vary
in size from 1 – 1000 µm, which is based on the experimental study by Han et al. (Han et al.,
2013). For injecting droplets, Rosin-Rammler diameter distribution approach was adopted with
mean diameter of 90 µm and spreading parameter of 1.99. Real sneeze is characterized by mixture
of water droplets entrained in the warm humid air from lungs in the direction as shown in table 3.
Sneeze droplets were injected for a period of 0.2381 s (Busco et al., 2020) with cumulative mass
of 6.3 mg. Each droplet constitutes 93.5% water and 6.5% salt in terms of mass fraction. The cough
and sneeze show similar pressure responses with different intensities (Busco et al., 2020; Gupta et
al., 2009).
Table 3. Direction of sneeze for asymptomatic sneezers
Asymptomatic sneezer
X (radian)
Y (radian)
Z (radian)
Sneeze_S1
-1
-1
-0.48
Sneeze_S2
-1
1
-0.48
Sneeze_S3
1
1
-0.48
Sneeze_S4
-1
1
-0.48

10
Sneeze_S5
1
-1
-0.48
Sneeze_S6
-1
-1
-0.48
Sneeze_S7
1
-1
-0.48
Implemented sneeze velocity profile based on previously published research by (Kumar
and King, 2022) and obtained using following equation-
󰇛󰇜󰇡
󰇢󰇛󰇜󰇡
󰇢󰇛󰇛  󰇜󰇜󰇛󰇜󰇡󰇛󰇜
󰇢 (m/s) (1)
where the coefficients values are,
a1 = 12.7124, a2 = -36.8307, b1 = 5.7364, b2 = 4.9688, c1 = 0.0360, c2 = 0.0373, and d = 0.0244.
During exhalation, droplets and turbulent cloud were considered to have same velocity. Sneeze
droplets and air both at 38 °C come out of the mouth cavity since the beginning of expiratory event.
The droplets stop at 0.2381 s, while lung air continued to exhale up to 0.55 s. The droplet tracking
accuracy of 10-5 was applied.
5. Validation of the evaporation model
Before performing CFD simulations an exhaustive droplet evaporation model validation was
performed using experimental literature data. In first validation evaporation of motionless droplet
of size 1050 µm, initial temperature 25 °C in a dry environment of 9 °C was simulated based on
experimental study of Ranz and Marshall (RANZ, W.E., Marshall, 1952). In second case, height
and diameter variation due to evaporation of freely droplets of size 110 µm, 115 µm and 170 µm
in humid environment (68% – 70%) was validate against experimental study by (Hamey, 1982;
Spillman, 1984). The CFD model demonstrated good agreement for both validation studies.
Additional details and graphs can be found in previous publication by (Kumar and King, 2022).
6. Results and discussion
The results obtained from CFD study are discussed in following sections.
6.1. Airflow velocity development and streamlines
Fabrication room consists of conveyer belts, tables, electric motor housing, extension tables
and workers which are obstructions for airflow. Fresh air of 10 °C at 0.0135 m/s (equivalent to
4650 CFM) enter the fabrication room from front end of the fabrication room. The indoor air is
cooled and circulated by the two evaporators on left and right (figure 2). These evaporators blow
cold air of 2 °C at 15000 CFM with the help of four air outlet fans on each as shown in figure 2c.
The roof exhaust, large and small exhaust allow the air to leave the fabrication room. Interactions
of the air streams with walls, stationary surfaces and with each other develop a flow pattern as
shown in figure 6.
Figure 6a shows top, 6b shows isometric, 6c shows front and 6d shows side view of the airflow
pattern in fabrication room. Overall flow pattern shows that entire facility can be divided into four
zones, with two small zones upstream and downstream of the evaporators. The airflow from
evaporator gets deflected towards the left and right walls, where a secondary deflection of airflow

11
takes place. After secondary deflection, major portion moves along the wall in downward direction
and divides in two portions namely towards the front end and back wall of the facility (figure 6a,
6b and 6d).
(a) (Video figure 6a) (b) (Video figure 6b)
(c) (d)
Figure 6: Airflow streamlines (a) top view, (b) isometric view, (c) front view, and (d) side view
in fabrication room
Isometric and side view show that deflected air interacts with the incoming air (from font
end of facility) in the left zone before left evaporator and creates large size circulation (figure 6b)
of high activity. While area after both evaporator shows relatively less air activity. The gap
between mezzanines behaves like a duct and allow development of long-range streamlines near
the roof (figure 6d). A comprehensive airflow distribution in the fabrication room can be identified
through videos for figures 6a and 6b, for understanding the droplets dispersion patterns discussed
in following sections. The vortices developed in planes of columns A to H (figure 2b) is shown in
figure 7.

12
(a) (Sneeze 2 and 6) (b) (Sneeze 5)
(c) (d) (Sneeze 3 and 7)
(e) (Sneeze 1) (f)
(g) (Sneeze 4) (h)
Figure 7: Airflow streamlines in planes of (a) column A (left-most according to figure 2b), (b)
column B, (c) column C, and (d) column D, (e) column E, (f) column F, (g) column G, and (h)
column H, in fabrication room
The overhead mezzanine areas in columns A, B, F, G and H are denoted as red rectangles.
Large size vortices develop in fabrication room can circulate, and transport contaminants including
droplets from one location to another. These vortices significantly increase the risk resuspension
of contaminants and transmission of airborne viral droplets. The seven different sneeze locations
considered for this study are shown by yellow star and corresponding location identification
number.
The air velocity vectors in fabrication room were presented in the supplementary figure S1.
The velocity vectors help to understand the long- and short-range transmission leading to overall
dispersion of droplets.
6.2. Droplets dispersion in fabrication room
Droplets dispersion in such complex facilities depend on airflow pattern and location of
the sneeze. Therefore, 7 distinct locations (characterizing entire fabrication room) were selected
to release sneeze by an asymptomatic worker, which was discussed in following sections-
Mezzanine
Mezzanine
Mezzanine
Mezzanine
Mezzanine
1
11
21
42
51
64
90

13
6.2.1. Asymptotic sneezer in column “E” at location 64 (Sneeze_S1)
In this case, it was considered that asymptotic worker is standing in column “E” at location
64 as shown in figure 2b. The worker sneezes downward directing droplets toward the floor of the
fabrication room, as shown in figure 8a at 0.5 s. The sneeze droplets ejected in the indoor
environment are subjected to deposition, escape, and evaporation processes. Deposition and escape
processes completely remove the droplets from indoor environment, while evaporation processes
decrease the mass of droplets making them susceptible to become airborne, which is true for all
other sneeze locations also.
A complete sequence of droplets cloud dispersion from location 64 (past the evaporators)
can be seen in the Sneeze_S1 video. Following the initial momentum, large size droplets (> 500
µm) almost immediately deposit on floor as can be seen for a duration of 0-3 s in the video.
Simultaneously, medium (100-500 µm) and small size droplets (< 100 µm) lose their momentum
during flight and change their directions following the airflow streamlines. The availability of
mezzanine gap over the workers provides enough space to develop a large vortex capable of
transferring droplets in the fabrication room. Upward rising droplets cloud (figure 8b) is influenced
by combined airflow effect of both evaporators and attempt to pull the droplets towards left, right
and back side wall following the streamlines (figures 6a, and 6b). However, figure 8c shows that
majority of the droplets are pulled towards the right wall, since location 64 is positioned
geometrically towards the right side of fabrication room. The droplets reaching the gap between
mezzanines are pushed by long range streamlines towards the vortices past the evaporators near
the back wall of facility (figure 8d). Droplets distribution shown in figures 8e, 8f, and 8g for front,
side, and top view show that droplets start diffusing towards the front end after filling the back
side space of the facility.
(a) (b)

14
(c) (d)
(e) (f)
(g)
Figure 8: Sneeze droplets dispersion
for asymptomatic worker at location
64 (a) 0.5 s, (b) 15 s, (c) 115 s, (d) 155
s, (e) front, (f) side, and (g) top view at
240 s.
Droplets dispersion video for this
location is available at following link
Sneeze_S1.

15
6.2.2. Asymptotic worker in column “A” at location 1 (Sneeze_S2)
For this case, the asymptomatic worker is standing in column “A” at location 1 (figure 2b).
A complete sequence of droplets dispersion from location 1 can be seen in the video of Sneeze_S2
and supplementary figure S2. The worker sneezes downward directing droplets towards the floor
(figure S2a). Large size droplets tend to deposit while medium and small size droplets tend to
become airborne after losing their mass via evaporation. During their flight, loss of momentum
causes change of direction, and droplets typically start to follow the streamlines. As shown in
figures 6a, 6b, S1b and S1c, the air after secondary deflection from walls, moves toward the front
end of fabrication room (videos of figures 6a and 6b). Air velocity remains high around 1.8 m/s
near the floor and relatively low near the mezzanine roof (figure S1). This effect is observable
from figure S2b at 35 s, where large size droplets are pushed backward to become airborne along
with small size droplets. These diffusing droplets are trapped in the lower left quadrant of indoor
airflow distribution (figures 6a and S2c) and acts as a source. The air circulation further stirs these
droplets of different sizes locally. The upward rising air at the center of fabrication room (figures
6d, and S2c) trap these droplets in gap between two mezzanines and starts spreading in cleaner
zones (figure S2d). Droplets distribution shown in figures S2e, S2f, and S2g for front, side, and
top view show that the left section, specifically lower left quadrant of the fabrication room (figure
6a and S2d) remains highly contaminated posing a greater risk for workers.
6.2.3. Asymptotic worker in column “D” at location 42 (Sneeze_S3)
For this case, the asymptomatic worker is standing in column “D” at location 42 (figure 2b).
The worker sneezes downward towards the floor, as shown in figure S3a at 0.5 s. Droplets cloud
dispersion can be seen from video of Sneeze_S3 and figure S3 in supplementary. In this case, after
losing initial momentum and mass, droplets are pushed towards the front end of the fabrication
room (figure S3b). This flow reversal towards the front end at the center of the facility is caused
by the interacting cold air from both evaporators (figure S1). The relatively hot air (10 °C) entering
from the front end of facility interact with the cold air (2 °C) and generates large air circulation
zone. Circulation of air over the column “D” at location 42 (figures 6, 7d and S1) diffuses and stir
the droplets. Long range air streamlines (figure 7d) are able of transport the droplets to distant
locations within 115 s (figure S3c). The streamlines deflection towards the width of fabrication
room further diffuse droplets (figure S3d). Distribution of droplets at 240 s from the front, side,
and top view (figures S3e, S3f, and S3g) shows that sneeze released from location 42 distributed
uniformly after initial concentration in right side of facility.
6.2.4. Asymptotic sneezer in column “G” at location 90 (Sneeze_S4)
For this case, the asymptomatic worker is standing in column “G” (almost below the evaporator
on right) at location 90 (figure 2b). The worker sneezes towards the floor, as shown in figure S4a
at 0.5 s. Droplets cloud dispersion can be seen from video of Sneeze_S4 and figure S4 in
supplementary. Videos of figure 6a and 6b show that air from surrounding and after second
deflection from right wall move towards the inlet of evaporator, as a result droplets could is

16
strongly affected. The airborne droplets are strongly pulled by right evaporator (figure S4b),
resulting in early escape of majority droplets (figures S4c, and S4d). Figures S4e, S4f, and S4g for
front, side, and top views respectively at 240 s show that fabrication room is almost
decontaminated, therefore least risk of spreading infection.
6.2.5. Asymptotic sneezer in column “B” at location 21 (Sneeze_S5)
In this case, the asymptomatic worker is standing in column “B” (nearest to the evaporator
on left) at location 21 (figure 2b). The worker sneezes towards the floor, as shown in figure S5a
at 0.5 s. Droplets cloud dispersion can be seen from video of Sneeze_S5 and figure S5 in
supplementary. In reference to this location, airflow primarily takes place towards the left and back
wall due to the bulk airflow from evaporator. Vortex created over the worker (figure 7b) is capable
of transferring droplets from cloud along the length of facility. On the other hand, majority of the
droplets cross over the inclined conveyer belt 1 and move towards the left wall, because of
localized flow along width of facility (figure S5b and 6b). Secondary deflection of airflow by wall
further divides these droplets in two groups in proportion of airflow distribution (figure S5c).
The vortex near back wall of facility (figure 7b) traps considerable number of droplets in
back potion (figure 12c) in form of a cluster. While, droplets shifted towards front end of facility,
start diffusing like the sneeze location 1 (figures S5c, S5d and S2c, S2d). Figures S5e, S5f, and
S5g for front, side, and top views respectively at 240 s show that fabrication room is almost
decontaminated, therefore least risk of spreading infection. droplets primarily accumulate over the
inclined conveyer belts 1-3 and diffuse towards the right wall with time, thereby posing risk to the
workers standing in column “H” as well.
6.2.6. Asymptotic sneezer in column “A” at location 11 (Sneeze_S6)
In this case, the asymptomatic worker is standing in column “A” at location 21 (figure 2b
and 7a). The worker sneezes towards the floor as shown in figure S6a at 0.5 s. Droplets cloud
dispersion can be seen from video of Sneeze_S6 and figure S6 in supplementary. Location 11 was
chosen to examine the behavior of droplets dispersion when the indoor air does not have possibility
to escape from any nearby exhaust and sneezer is in a corner of fabrication room. After initial
deposition, the airborne droplets rise towards the mezzanine roof. The forward movement of
droplets cloud is partially opposed by local airflow as a result only few airborne droplets are pushed
backwards while majority are move towards the first quadrant of facility (figure 6a, 6b and S6b,
S6c). The droplets trapped in the first quadrant start dispersing like sneeze took place at location
1 (figure S6c and S2c). Figures S6e, S6f, and S6g for front, side, and top view at 240 s show that
droplets tend to diffuse in fabrication room and corner works as droplets source.
6.2.7. Asymptotic sneezer in column “D” at location 51 (Sneeze_S7)
In this case, the asymptomatic worker is standing in column “D” at location 51 (figure 2b
and 7d). The worker sneezes towards the floor as shown in figure S7a at 0.5 s. Droplets cloud
dispersion can be seen from video of Sneeze_S7 and figure S7 in supplementary. Location 51

17
helps to examine, if recirculation of air can transport the sneeze droplets toward the front end of
fabrication room. After losing momentum, the airborne droplets cloud is captured by local vortex
over the worker (figure 7d), which starts pushing the droplets towards the center of facility (figure
S7b). During this transfer, droplets are further exposed to opposing direction high airflow from the
evaporators. Consequently, droplets quickly scatter in the back part of fabrication room (figure
S7c and S7d) past the evaporators. Distribution of droplets in figures S7e, S7f, and S7g for front,
side, and top view shows that droplets slowly diffuse towards the front end to dilute in indoor air
of entire facility.
Overall, it can be observed that droplets released by the workers standing around the
inclined belts 1 and 2 will primarily spread in left section of fabrication room. On the contrary,
droplets released by workers standing around inclined belts 3 and 4 will spread in the right section
of the fabrication room.
6.3. Factors affecting the removal of droplets from indoor environment
The sneeze droplets are subjected to escape, evaporation, and deposition depending on
droplets size. Loss of droplets mass is governed by initial droplet (38 °C) and surrounding air
temperature difference. Large size droplets deposit under the influence of gravity. While small and
medium size droplets deposit due to their momentum towards surfaces and walls. Loss of droplets
due to escape is primarily dependent on streamlines, which terminate at exhaust. These processes
lead to overall sneeze mass depletion from fabrication room indoor environment. The fraction of
deposited, evaporated, escaped and airborne mass can be calculated as-
Deposited mass (%) =󰇡
 󰇢   (2)
Evaporated mass (%) = 󰇡
 󰇢   (3)
Escaped mass (%) = 󰇡
 󰇢  (4)
Airborne mass (%) = 󰇡
 󰇢   (5)
Transient mass loss balance in fabrication room after sneeze by worker at location 1 in column
“A” is shown in figure 9a. It was observed that around 50% of mass is depleted within the first 30
s. Evaporation is found to be leading process for sneeze mass depletion (due to high droplet and
room temperature difference) followed by deposition and escape. Since location 1 for sneeze_S2
is close to evaporator on the left, substantial droplets escape during rise of cloud initially. Later
the dispersion of droplets, away from the evaporators, causes droplets to deposit more on different
stationary surfaces including workers thereby increasing the overall deposition contribution.
Similar depletion patterns were observed for other sneeze locations in the fabrication room.

18
(a) (b)
(c) (d)
(e)

19
Figure 9: Percentage of (a) mass balance for Sneeze_S2, (b) evaporated mass, (c) deposited mass
and (d) escaped mass (e) airborne droplets number in fabrication room for different sneeze
locations
A comparison of evaporated, deposited, and escaped mass percentages for all sneeze locations,
is shown in figure 9b, 9c and 9d, respectively. Any droplet remaining airborne for a long time loses
its mass mainly by evaporation. Figure 9b and 9d show that droplets originated by asymptomatic
sneezer (Sneeze_S1) at location 64 in column “E” will mainly vanishes by evaporation process,
with least contribution from the escape process. Similar effect can be seen for asymptomatic
sneezer in column “D” (Sneeze_S7) at location 51 (figure 9b, 9d). However, due to decreased
deposition process after 180 s (figure 9c) large number of droplets remains airborne as seen in
figure S7 and 9e. These airborne droplets quickly start dispersing towards front end in the indoor
environment.
The sensitivity of sneeze location can be distinctly seen for Sneeze_S4 at location 90 in column
“G”. The worker stands almost below the evaporator on right side of fabrication room.
Recirculating indoor air quickly pushes the upward rising sneeze droplets cloud towards the
evaporator. As a result, 60% of the droplets mass escapes (figure 9d). Strong airflow activity in
the surrounding of sneezer causes escalated droplets deposition (figure 9c). Because droplets cloud
spend least time after generation, therefore, evaporative loss is least for location 90 (figure 9b). As
a result, droplets disappear from the indoor environment of fabrication room quickly.
The overall effect of different droplets removal processes on the fate of airborne droplets can
be seen in figure 9e, which closely represents the effect of processes on airborne droplets for
Sneeze_S7 after 240 s.
6.4. Relative presence of airborne droplets for different sneeze locations
Relative presence of airborne droplets at different time instants corresponding to different
sneeze locations is shown in figure 10. They can be regarded independently contributing to
contamination of the indoor environment. It can be observed that droplets generated from location
90 (sneeze_S4) nearly vanish within 95 s compared to all others. A comparison of percentage
airborne droplets variation at 240 s shows that fabrication room has approximately same
percentage of airborne droplets when released from locations 1 (sneeze_S2), 42 (sneeze_S3), 21
(sneeze_S5), 64 (sneeze_S1), and 11 (sneeze_S6). However, when sneeze takes place from
location 51 (sneeze_S7), the fabrication room is exhibiting the highest number of airborne droplets.
Therefore, location 51 would be highly contaminating for indoor environments of fabrication room
type.

20
Figure 10: Airborne sneeze droplets distribution for Sneezes 1 through 7 in fabrication room
6.5. Effect of sneeze location on infection index
Long-range transport of the droplets with the help of indoor airflow pattern causes deposition
of droplets over the workers and stationary objects in the entire fabrication room. Depending on
the location of sneeze, the workers and stationary objects are uniquely contaminated. Therefore, a
healthy worker can directly or indirectly (by touching the solid surfaces) get infected. An infection
index can be defined as the ratio of deposited mass on individual worker and surface(s) to total
deposited mass.
󰇛󰇜󰇛󰇜
 
The location of workers in the fabrication room is marked from 1 to 116 and name of stationary
objects are shown in the figure 2b and 2c.
The infection index corresponding to different sneezes for all the workers in the fabrication
room is shown in figure 11. A qualitative analysis for the “Sneeze_S1”, surrounding workers at
locations 60-67 and 80-84 get highly infected. Interestingly, neighboring worker 63 instead of
sneezer at location 64 gets severely infected. For the “Sneeze_S2” shows that worker 1 (sneezer),
2, 15-18 and 42-43 get most of infectious droplet’s deposition. For the “Sneeze_S3”, workers 42
(sneezer), 55, 58, 61, and 88 get most of infectious droplet’s deposition. For the “Sneeze_S4”,
workers 90, 91 (sneezer), 92, 93 in the column “G” and nearby workers 73-76 also get infected.
For the “Sneeze_S5”, workers standing on both side in the beginning of inclined belt 1 get severely
infected. Sneezer at location 21 himself get highly infected. For “Sneeze_S6”, workers 1-11, 15-

21
18 and 31-32 in the column “A” and “B” get highly infected following the droplets dispersion
patterns. For the “Sneeze_S7”, workers 50-54, 61-70, and 38-40 including sneezer at location 51
get infected. All these infection index patterns strongly associate with indoor airflow (figure 6-7)
and droplets dispersion (figure 8, S2-S7) patterns observed in previous sections.

22
Figure 11: Infection index for the workers in fabrication room corresponding to different sneeze
locations

23
Infection index for all the stationary indoor objects including walls of the fabrication room
is shown in the figure 12. A qualitative analysis shows that due to the direction of sneeze, the floor
of the fabrication room in all the sneezes becomes highly infected. Under the effect of airflow
patterns infection index for floor can vary from 22% to 72%. Similarly, increased infection index
can be observed for left and right-side evaporators depending on the relative distance of
asymptomatic sneezer from either. A qualitative analysis for the “Sneeze_S4” clearly demonstrates
that escape is the predominant process of droplets removal through evaporator on right. As a result,
stationary objects in the fabrication room get least infected, when sneeze is released from location
90 compared to all others. The infection indexes shown in figure 12 are found in close association
with airflow and droplets dispersion patterns.

24

25
Figure 12: Infection index for stationary objects present in the fabrication room corresponding to
different sneeze locations
7. Conclusion
The indoor airflow pattern of all residential and commercial buildings depends on several
factors including size of facility, stationary objects, location of diffuser and exhaust, number of
occupants, ventilation rate, and location of evaporators (for commercial facilities). All the facilities
with large occupants are highly vulnerable to the spread of airborne infections. Specifically, the
fabrication rooms of meat facilities are highly susceptible to virus outbreak as indoor air is laden
with moisture and fat particles. The airflow streamlines are capable of transporting contaminants
and viral respiratory droplets generated by asymptomatic sneezer from remote locations. In this
study, dispersion of sneeze droplets in fabrication room corresponding to selected sneeze locations
is presented. The following conclusions can be drawn from the present study-

26
• The location of evaporators, exhausts, and stationary objects play critical role in the
development of unique airflow pattern. The reflected airflow from left and right walls each
divide in two directions near the floor (figure 6).
• The complex airflow pattern primarily divides the whole fabrication room into four
quadrants. Large size airflow vortices developed in the indoor environment consequently
trap and spread the contaminated droplets.
• Respiratory droplets cloud strongly associate and follow the airflow pattern developed in
the fabrication room.
• Location of the asymptomatic sneezer critically affects the droplets spreading behavior,
which affects the decontamination processes. Sneeze_S4, by the asymptomatic sneezer at
location 90 in column “G” is an excellent example.
• Evaporation remains the prevalent decontamination process followed by deposition and
escape. Extended time spent by droplets cloud in air results in highest contribution to
evaporation process.
• Sneeze_S7 by asymptomatic sneezer at location 51 in column “D” is found highly
contaminating as droplets remain airborne for more than 240 s. While Sneeze_S4 by the
asymptomatic sneezer at location 90 in column “G” supports early decontamination.
• The infection index for the workers as well as stationary objects is strongly correlated with
the droplet’s dispersion pattern. Floor becomes highly infected for each sneeze location.
Sneeze_S1 by asymptomatic sneezer at location 64 in column “E” causes neighboring
worker 63 to have highest infection index.
Results presented in this study are comprehensive and represent the entire fabrication room. It
can be used to effectively model and mitigate the transmission of infectious diseases in large indoor
environments. This study offers insight into designing appropriate decontamination measures.
Future studies including investigating the effects of partitions on droplets dispersion in
fabrication room.
Acknowledgement
This work is a part of the NSF-CBET 2034048 award and the USDA National Institute of
Food and Agriculture, Hatch project TEX09746. We thank the Texas A&M University High
Performance Research Computing group (https://hprc.tamu.edu) for providing the computing
resources.
References
ANSYS Fluent User Guide [WWW Document], n.d. URL
http://www.pmt.usp.br/academic/martoran/notasmodelosgrad/ANSYS Fluent Users
Guide.pdf
Asadi, S., Bouvier, N., Wexler, A.S., Ristenpart, W.D., 2020. The coronavirus pandemic and
aerosols: Does COVID-19 transmit via expiratory particles? Aerosol Sci. Technol.

27
https://doi.org/10.1080/02786826.2020.1749229
Beck, S.H., Castillo, A., Kinney, K.A., Zuniga, A., Mohammad, Z., Lacey, R.E., King, M.D.,
2019. Monitoring of Pathogenic Bioaerosols in Beef Slaughter Facilities Based on Air
Sampling and Airflow Modeling. Appl. Eng. Agric. 35, 1015–1036.
https://doi.org/10.13031/AEA.13553
Bourouiba, L., 2020. Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential
Implications for Reducing Transmission of COVID-19. JAMA 323, 1837–1838.
https://doi.org/10.1001/JAMA.2020.4756
Busco, G., Yang, S.R., Seo, J., Hassan, Y.A., 2020. Sneezing and asymptomatic virus
transmission. Phys. Fluids 32, 1–18. https://doi.org/10.1063/5.0019090
Dbouk, T., Drikakis, D., 2020. On coughing and airborne droplet transmission to humans. Phys.
Fluids 32, 053310. https://doi.org/10.1063/5.0011960
Domingo, J.L., Marquès, M., Rovira, J., 2020. Influence of airborne transmission of SARS-CoV-
2 on COVID-19 pandemic. A review. Environ. Res. 188, 17–20.
https://doi.org/10.1016/j.envres.2020.109861
Domingo, J.L., Rovira, J., 2020. Effects of air pollutants on the transmission and severity of
respiratory viral infections. Environ. Res. 187, 109650.
https://doi.org/10.1016/j.envres.2020.109650
Fluent Theory Guide [WWW Document], n.d. URL
https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/flu_th
/flu_th.html
Grimalt, J.O., Vílchez, H., Fraile-Ribot, P.A., Marco, E., Campins, A., Orfila, J., van Drooge,
B.L., Fanjul, F., 2022. Spread of SARS-CoV-2 in hospital areas. Environ. Res. 204.
https://doi.org/10.1016/j.envres.2021.112074
Gupta, J.K., Lin, C.H., Chen, Q., 2009. Flow dynamics and characterization of a cough. Indoor
Air 19, 517–525. https://doi.org/10.1111/j.1600-0668.2009.00619.x
Hamey, P.Y., 1982. The evaporation of airborne droplets.
Han, Z.Y., Weng, W.G., Huang, Q.Y., 2013. Characterizations of particle size distribution of the
droplets exhaled by sneeze. J. R. Soc. Interface 10, 20130560.
https://doi.org/10.1098/rsif.2013.0560
Jayaweera, M., Perera, H., Gunawardana, B., Manatunge, J., 2020. Transmission of COVID-19
virus by droplets and aerosols: A critical review on the unresolved dichotomy. Environ.
Res. https://doi.org/10.1016/j.envres.2020.109819
Kumar, S., King, M.D., 2022. Numerical investigation on indoor environment decontamination
after sneezing. Environ. Res. 213. https://doi.org/10.1016/J.ENVRES.2022.113665
Li, H., Leong, F.Y., Xu, G., Ge, Z., Kang, C.W., Lim, K.H., 2020. Dispersion of evaporating
cough droplets in tropical outdoor environment. Phys. Fluids 32, 113301.
https://doi.org/10.1063/5.0026360

28
Luo, Q., Ou, C., Hang, J., Luo, Z., Yang, H., Yang, X., Zhang, X., Li, Y., Fan, X., 2022. Role of
pathogen-laden expiratory droplet dispersion and natural ventilation explaining a COVID-
19 outbreak in a coach bus. Build. Environ. 220.
https://doi.org/10.1016/j.buildenv.2022.109160
Nair, A.N., Anand, P., George, A., Mondal, N., 2022. A review of strategies and their
effectiveness in reducing indoor airborne transmission and improving indoor air quality.
Environ. Res. 213. https://doi.org/10.1016/j.envres.2022.113579
NCDC, 2022. Coronavirus disease (COVID-2019) situation reports [WWW Document]. World
Heal. Organ. URL https://www.who.int/emergencies/diseases/novel-coronavirus-
2019/situation-reports/
O’Rourke, P.J., Amsden, A.A., 1987. The tab method for numerical calculation of spray droplet
breakup. SAE Tech. Pap. https://doi.org/10.4271/872089
Ong, S.W.X., Tan, Y.K., Chia, P.Y., Lee, T.H., Ng, O.T., Wong, M.S.Y., Marimuthu, K., 2020.
Air, Surface Environmental, and Personal Protective Equipment Contamination by Severe
Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) from a Symptomatic Patient.
JAMA - J. Am. Med. Assoc. https://doi.org/10.1001/jama.2020.3227
Passos, R.G., Silveira, M.B., Abrahão, J.S., 2021. Exploratory assessment of the occurrence of
SARS-CoV-2 in aerosols in hospital facilities and public spaces of a metropolitan center in
Brazil. Environ. Res. 195. https://doi.org/10.1016/j.envres.2021.110808
RANZ, W.E., Marshall, W.R., 1952. Evaporation from drops 1. Chem. Eng. Prog.
https://doi.org/Chem. Eng. Prog. 48(3), 141–146 (1952)
Spillman, J.J., 1984. Evaporation from freely falling droplets. Aeronaut. J. 88, 181–185.
https://doi.org/10.1017/S0001924000020479
Tellier, R., Li, Y., Cowling, B.J., Tang, J.W., 2019. Recognition of aerosol transmission of
infectious agents: a commentary. BMC Infect. Dis. 2019 191 19, 1–9.
https://doi.org/10.1186/S12879-019-3707-Y
Wells, W.F., 1933. ON AIR-BORNE INFECTION.* STUDY II. DROPLETS AND DROPLET
NUCLEI. under the title, "Viability of Bacteria in. t Stokes’ Math. Phys. Pap. 1, 60.
Wiktorczyk-kapischke, N., Grudlewska-buda, K., Wa, E., Kwieci, J., Radtke, L., Gospodarek-
komkowska, E., Skowron, K., 2021. Science of the Total Environment SARS-CoV-2 in the
environment — Non-droplet spreading routes. Sci. Total Environ. 770, 145260.
Xie, X., Li, Y., Chwang, A.T.Y., Ho, P.L., Seto, W.H., 2007. How far droplets can move in
indoor environments - revisiting the Wells evaporation- falling curve. Indoor Air 17, 211–
225. https://doi.org/10.1111/J.1600-0668.2007.00469.X
Zhou, Y., Ji, S., 2021. Experimental and numerical study on the transport of droplet aerosols
generated by occupants in a fever clinic. Build. Environ. 187, 107402.
https://doi.org/10.1016/j.buildenv.2020.107402

*Corresponding Author.
E-mail address: mdking@tamu.edu (Maria D. King), ksunil86.in@gmail.com (Sunil Kumar)
Dispersion of sneeze droplets in a meat facility indoor
1
environment – without partitions
2
3
Sunil Kumar1, Mark Klassen3, David Klassen2, Robert Hardin1 and Maria D. King1*
4
1Department of Biological and Agricultural Engineering, Texas A&M University, College
5
Station, Texas 77843, USA
6
7
2Department of Mechanical Engineering, University of Calgary, Calgary Alberta T2N 1N4,
8
Canada
9
10
3Canada Beef, Mississauga, ON L5N 5R1, Canada
11
12
13
14
15
16
17

2
Supplementary Information
18
19
The supplementary information associated with research work is presented below.
20
21
Supplementary S1: Air velocity vector in the fabrication room
22
The air velocity vectors in the fabrication room are shown in figure S1 with zoomed crucial
23
locations for reverse flow. As discussed for figure 6, after the secondary deflection from the wall
24
(figure S1a), the evaporator air starts moving towards the front end of fabrication room, shown
25
from right and left zoomed corner views in figures S1b and S1c respectively.
26
27
Figure S1: Velocity vectors in the fabrication room with zoomed views of separate locations
28
29
In addition, zoomed view of the center location (figure S1d) shows flow reversal of air towards
30
the front end of fabrication room due to outgoing air rushing towards each other from both
31
evaporators. These flow reversals determine the faith of airborne droplets dispersion in the
32
presence of large size vortices.
33
34
Supplementary S2: Asymptotic worker in column “A” at location 1 (Sneeze_S2)
35
Dispersion of sneeze doplets in fabrication room at different time instants for correspondng
36
location 1 is shown in figure S2.
37

3
38
(a) (b)
39
40
(c) (d)
41
42
(e) (f)
43

4
44
(g)
45
46
Supplementary S3: Asymptotic worker in column “D” at location 42 (Sneeze_S3)
47
Dispersion of sneeze doplets in fabrication room at different time instants for correspondng
48
location 42 is shown in figure S3.
49
50
(a) (b)
51
Figure S2: Sneeze droplets dispersion
for asymptomatic worker at location 1
at (a) 0.5 s, (b) 35 s, (c) 115 s, (d) 155
s, (e) front, (f) side, and (g) top view
at 240 s.
Droplets dispersion video for this
location is available at following link
Sneeze_S2.

5
52
(c) (d)
53
54
(e) (f)
55
56
(g)
57
58
59
Figure S3: Sneeze droplets
dispersion for asymptomatic worker
at location 42 (a) 0.5 s, (b) 35 s, (c)
115 s, (d) 155 s, (e) front, (f) side, and
(g) top view at 240 s.
Droplets dispersion video for this
location is available at following link
Sneeze_S3.

6
Supplementary S4: Asymptotic sneezer in column “G” at location 90 (Sneeze_S4)
60
Dispersion of sneeze doplets in fabrication room at different time instants for correspondng
61
location 90 is shown in figure S4.
62
63
(a) (b)
64
65
(c) (d)
66
67
(e) (f)
68

7
69
(g)
70
71
Supplementary S5: Asymptotic sneezer in column “B” at location 21 (Sneeze_S5)
72
Dispersion of sneeze doplets in fabrication room at different time instants for correspondng
73
location 21 is shown in figure S5.
74
75
(a) (b)
76
Figure S4: Sneeze droplets dispersion
for asymptomatic worker at location
90 (a) 0.5 s, (b) 15 s, (c) 55 s, (d) 75
s, (e) front, (f) side, and (g) top view
at 145 s.
Droplets dispersion video for this
location is available at following link
Sneeze_S4.

8
77
(c) (d)
78
79
(e) (f)
80
81
82
(g)
83
84
Figure S5: Sneeze droplets dispersion
for asymptomatic worker at location
21 (a) 0.5 s, (b) 15 s, (c) 115 s, (d) 155
s, (e) front, (f) side, and (g) top view at
240 s.
Droplets dispersion video for this
location is available at following link
Sneeze_S5.

9
Supplementary S6: Asymptotic sneezer in column “A” at location 11 (Sneeze_S6)
85
Dispersion of sneeze doplets in fabrication room at different time instants for correspondng
86
location 11 is shown in figure S6.
87
88
(a) (b)
89
90
(c) (d)
91
92
(e) (f)
93

10
94
(g)
95
96
Supplementary S7: Asymptotic sneezer in column “D” at location 51 (Sneeze_S7)
97
Dispersion of sneeze doplets in fabrication room at different time instants for correspondng
98
location 51 is shown in figure S7.
99
100
101
(a) (b)
102
Figure S6: Sneeze droplets dispersion
for asymptomatic worker at location
11 (a) 0.5 s, (b) 35 s, (c) 115 s, (d) 155
s, (e) front, (f) side, and (g) top view at
240 s.
Droplets dispersion video for this
location is available at following link
Sneeze_S6.

11
103
(c) (d)
104
105
(e) (f)
106
107
108
(g)
109
110
Figure S7: Sneeze droplets dispersion
for asymptomatic worker at location
51 (a) 0.5 s, (b) 35 s, (c) 115 s, (d) 155
s, (e) front, (f) side, and (g) top view at
215 s.
Droplets dispersion video for this
location is available at following link
Sneeze_S7.