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README.md
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## Applications
### COVID Calculator
### COVID Calculator
A risk assessment tool which simulates the long range airborne spread of the
SARS-CoV-2 virus for space managers.

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# Instructions for use
This is a guide to help you use the calculator tool.
This is a guide to help you use the calculator app.
If you are using the expert version of the tool, you should look at the expert notes.
Please bear in mind that this beta version is for an extensive testing of the functionality of the tool and analyse the results.
At this stage, do not use the results as final output of the workplace risk assessment.
For more information on the Airborne Transmission of SARS-CoV-2, feel free to check out the HSE Seminar: https://cds.cern.ch/record/2743403
## Disclaimer
The risk assessment tool simulates the long range airborne spread SARS-CoV-2 virus in a finite volume, assuming a homogenous mixture, and estimates the risk of COVID-19 infection thereto.
The results DO NOT include short-range airborne exposure (where the physical distance plays a factor) nor the other know modes of transmission of SARS-CoV-2.
Hence, this model implies that proper physical distancing, good hand hygiene and other barrier measures are ensured.
It is based on current scientific data and can be used to measures the effectiveness of different mitigation measures.
The risk assessment tool simulates the long-range airborne spread SARS-CoV-2 virus in a finite volume, assuming a homogenous mixture, and estimates the risk of COVID-19 infection therein.
The results DO NOT include short-range airborne exposure (where the physical distance plays a factor) nor the other known modes of SARS-CoV-2 transmission.
Hence, the output from this model is only valid when the other recommended public health & safety instructions are observed, such as adequate physical distancing, good hand hygiene and other barrier measures.
Note that this model is based on a deterministic approach, i.e., at least one person is infected and shedding viruses into the volume.
Nonetheless, it is also important to understand that the absolute risk of infection is uncertain as it will depend on the probability that someone infected attends the event.
The model is mostly useful to compare the impact and effectiveness of mitigation measures such as ventilation, filtration, exposure time, activity and the size of the room on long-range airborne transmission of COVID-19 in indoor settings.
This application is meant for informative and educational purposes.
The user can be able to adapt different settings and measure the relative impact on the estimated infection probabilities to allow for a targeted decision making and investment.
The user should acknowledge that until the virus is in circulation among the population, the notion of 'zero risk' or a 'completely safe scenario' does not exist.
Each event is unique and the results are as accurate as the inputs.
The app is based on our scientific understanding of infectious diseases transmission, exposure and aerosol science as of November 2020.
The model used is based on scientific publications relating to airborne transmission of infectious diseases, dose-response exposures and aerosol science, as of December 2020 . It can be used to compare the effectiveness of different airborne-related risk mitigation measures.
We do not assume responsibility for any injury or damage to persons or property arising out of or related to any use of this app.
Note that this model applies a deterministic approach, i.e., it is assumed at least one person is infected and shedding viruses into the simulated volume.
Nonetheless, it is also important to understand that the absolute risk of infection is uncertain, as it will depend on the probability that someone infected attends the event.
The model is most useful for comparing the impact and effectiveness of different mitigation measures such as ventilation, filtration, exposure time, physical activity and the size of the room, only considering long-range airborne transmission of COVID-19 in indoor settings.
## Usage
This tool is designed to be informative, allowing the user to adapt different settings and model the relative impact on the estimated infection probabilities.
The objective is to facilitate targeted decision-making and investment through comparisons, rather than a singular determination of absolute risk. While the SARS-CoV-2 virus is in circulation among the population, the notion of 'zero risk' or a 'completely safe scenario' does not exist.
Each event modelled is unique and the results generated therein are only as accurate as the inputs and assumptions.
## How to use this tool
### Simulation Name & Room number
In order to be able to trace the risk assessments that you perform with the calculator, you can give each one a unique name - for example "Office use on Tuesday mornings".
In order to be able to trace back the simulations in your workplace risk assessments, performed with the tool, you can give each one a unique name - for example "Office use on Tuesday mornings".
The simulation name has no bearing on the calculation.
A room number is included, if you do not wish to use a formal room number any reference will do - for example "57/2-004"
### Room Data
Please enter either the room volume (in m3) or both the floor area (m2) and the room height (m).
Please enter either the room volume (in m<sup>3</sup>) or both the floor area (m<sup>2</sup>) and the room height (m).
This information is available via GIS Portal (https://gis.cern.ch/gisportal/).
### Ventilation type
@ -53,37 +49,38 @@ Please bear in mind that any of the two inputs only consider the supply of fresh
#### Natural ventilation
Natural ventilation refers to rooms which have openable windows. There are many possibilities to calculate natural ventilation air flows, for simplification this tool assumes a single-sided natural ventilation scheme which is a conservative appraoch for the purpose of this tool.
Natural ventilation refers to rooms which have openable windows.
There are many possibilities to calculate natural ventilation air flows, for simplification this tool assumes a single-sided natural ventilation scheme which is a conservative approach for the purpose of this tool.
Please enter the number, height and width of the windows (in m).
Please enter the number, height and width and opening distance of the windows (in m).
If there are multiple windows of different sizes, you should take an average.
The window opening distance (in m) is:
* In the case of windows that slide, the length the window is moved open.
* For hinged windows, it is the distance between the fixed frame and the movable glazed part when open.
* For articulated windows, it is the distance between the fixed frame and the movable glazed part when open. Window opening distance example (image of open window and measuring tape):
![Window Opening Distance](static/images/window_opening.png "How to measure window opening distance")
**Notes**: If you are unsure about the opening distance for the window, it is recommended to choose a conservative value (5 cms, 0.05m or 10cms, 0.10m).
If you open the window at different distances throughout the day, choose an average value.
The width of the window is not currently used as an input to the model (height and opening distance is sufficient to calculate the free area), but is included for completeness of the report.
The width of the window is not currently used as an input to the model (height and opening distance is sufficient to calculate the free area).
When using natural ventilation, the circulation of air is simulated as a function of the difference between the temperature inside the room and the outside air temperature. The average outdoor temperature for each hour of the day has been computed for every month of the year based on historical data for Geneva, Switzerland.
It is therefore very important to enter the correct event time and date in the event data section.
It is therefore very important to enter the correct time and date in the event data section.
Finally, you must specify when the windows are open - all the time (always), or for 10 minutes every 2 hours.
#### No ventilation
This option assumes the is neither Mechanical nor Natural ventilation in the simulation.
This option assumes there is neither Mechanical nor Natural ventilation in the simulation.
#### HEPA filtration
A HEPA filter is a high efficiency particulate matter filter, which removes small airborne particles from the air.
They can be very useful for removing viruses from the air in an enclosed space.
They can be very useful for removing particles with viruses from the air in an enclosed space.
The calculator allows you to simulate the installation of a HEPA air filter within the room.
The default air flow rate for the HEPA filter in the model is 250m3/hour.
The recommended airflow rate for the HEPA filter should correspond to a total air exchange rate of 3 - 6 ACH (the higher the better, even beyond 6).
### Event Data
@ -95,25 +92,25 @@ As an example, for a shared office with 4 people, where one person is infected,
#### Activity type
There are three predefined activities in the tool at present.
There are a few predefined activities in the tool at present.
**Office ** = All persons seated, talking occasionally (1/3rd of the time, with normal breathing the other 2/3rds of the time). Everyone (occupants and infected occupants) is treated the same in this model.
**Office ** = All persons seated, talking occasionally (1/3rd of the time, with normal breathing the other 2/3rds of the time). Everyone (exposed and infected occupants) is treated the same in this model.
**Meeting** = All persons seated, conversation of N people is approximately (1/N% of the time talking). Everyone (occupants and infected occupants) is treated the same in this model.
**Meeting** = All persons seated, having a conversation (approximately each occupant is 1/N % of the time talking, where N is the number of occupants). Everyone (exposed and infected occupants) is treated the same in this model.
**Library** = All persons seated, breathing only (no talking!), all the time.
**Library** = All persons seated, breathing only (not talking), all the time.
**Call Centre** = All persons seated, all talking simultaneously, all the time. This is a conservative profile (i.e. will show in increased ``P(i)`` compared to office/meeting) if used for office activity.
**Call Centre** = All persons seated, all talking simultaneously, all the time. This is a conservative profile, i.e. will show an increased ``P(i)`` compared to office/meeting activity. Everyone (exposed and infected occupants) is treated the same in this model.
**Lab** = Based on a typical lab or technical working area, all persons are doing light activity and talking 50% of the time. Everyone (occupants and infected occupants) is treated the same in this model.
**Lab** = Based on a typical lab or technical working area, all persons are doing light activity and talking 50% of the time. Everyone (exposed and infected occupants) is treated the same in this model.
**Workshop** = Based on a mechanical assembly workshop or equipment installation scenario, all persons are doing moderate activity and talking 50% of the time. Everyone (occupants and infected occupants) is treated the same in this model. This model is equally applicable to bicycling, or walking on a gradient, in the LHC tunnels.
**Workshop** = Based on a mechanical assembly workshop or equipment installation scenario, all persons are doing moderate activity and talking 50% of the time. This activity is equally applicable to bicycling, or walking on a gradient, in the LHC tunnels. Everyone (exposed and infected occupants) is treated the same in this model.
**Training** = Based on a typical training course scenario.
One individual (the trainer) is standing and talking, with all other individuals seated and talking quietly (whispering).
In this case it is assumed that the infected person is the trainer, because this is the worst case in terms of viral sheding.
In this case it is assumed that the infected person is the trainer, because this is the worst case in terms of viral shedding.
**Gym** = Included for comparison purposes only, all persons are doing heavy exercise and breathing (no talking). Everyone (occupants and infected occupants) is treated the same in this model.
**Gym** = All persons are doing heavy exercise and breathing (not talking). Everyone (exposed and infected occupants) is treated the same in this model.
### Timings
@ -127,24 +124,27 @@ It is possible to specify a different time for the entry and exit of the infecte
This is included for completeness in all simulations, however it is of particular relevance to those using natural ventilation because of variations in outside air temperature.
If you wish to simulate repetitive events, for example using an office for multiple days in the same month, choose recurrent usage.
Only the month is used by the model to look up outside air temperatures for the Geneva region.
Only the month is used by the model to retrieve the average outdoor air temperatures for the Geneva region.
### Breaks
#### Lunch
You have the option to specify a lunch break.
This will be useful if you plan to simulate a full working day, however you can select 'No' if it is not required for a shorter simulation.
This will be useful if you plan to simulate a typical full working day.
During the lunch break it is assumed that all occupants will leave the simulated space (to go an eat lunch, somewhere else - restaurant or break room).
If you plan to eat lunch in the same area where you have been working, you should select 'No' even if a lunch break will be taken, since the risk of infection is related to the occupation of the simulated space.
It should also be noted that the infection probabilities presented in the report does not take into account any potential exposures during the break times.
### Coffee Breaks
You have the option to choose no coffee breaks, 2 or 4 during the simulated period.
You have the option to choose 0(No breaks), 2 or 4 coffee breaks during the simulated period.
It is assumed that all occupants vacate the space during the break period.
If coffee breaks are taken in-situ, this option should be set to 'No breaks'.
When enabled, the breaks are spread evenly throughout the day - for example if we simulate the period from 9:00 to 18:00, with a lunch break from 13:00 to 14:00, with 2 coffee breaks, one will be scheduled at 11:00 and the second at 16:00.
When enabled, the breaks are spread equally throughout the day - for example if we simulate the period from 9:00 to 18:00, with a lunch break from 13:00 to 14:00 and considering 2 coffee breaks, the tool will schedule the first coffee break around 11:00 and the second around 16:00.
The exact timing of the breaks within the day is not particularly critical to an accurate simulation, so you do not need to be concerned about major differences if you take a coffee break at 10:00 instead of 11:00.
The variation of coffee breaks can be altered in 5 minute increments up to 30 minutes in length.
Note that this doesn't necessarily have to be a coffee break, it can represent any period where the simulated space is vacated.
@ -153,12 +153,14 @@ It should also be noted that the infection probabilities presented in the report
#### Face Masks
At the time of writing, the removal of masks is authorised at workstations provided a physical distance (2m minimum) can be maintained. The model therefore includes the possibility simulate this behaviour.
Alternatively, the continuous wearing of masks can be simulated, i.e. all occupants (infected and non-infected alike) wear masks for the duration of the simulation.
The model allows for a simulation with either a continuous wearing of face masks throughout the duration of the event, or have the removed at all times - i.e. all occupants (infected and exposed alike) wear or not masks for the duration of the simulation.
Please bear in mind the user inputs shall be aligned with the current applicable public health & safety instructions.
Please check what are the applicable rules, before deciding which assumptions are used for the simulation.
If you have selected the Training activity type, this equates to the trainer and all participants either wearing masks throughout the training (Yes), or removing them when seated/standing at their socially distanced positions within the training room (No).
If you have selected the Training activity type, this equates to the trainer and all participants either wearing masks throughout the training (Yes), or removing them when seated/standing at their socially distanced positions within the training room (No).
Please confirm what are the applicable rules, before deciding which assumptions are used for the simulation
For the time being only the Type 1 surgical mask is simulated.
For the time being only the Type 1 surgical and FFP2 masks can be selected.
## Generate Report
@ -168,29 +170,29 @@ When you have entered all the necessary information, please click on the Generat
# Report
The report will open in your web browser.
It contains a summary of all the input data, which will allow the simulation to be repeated if required in future as we improve the calculation.
It contains a summary of all the input data, which will allow the simulation to be repeated if required in the future as we improve the model.
## Results
This part of the report shows the ``P(i)`` or probability of infection.
This part of the report shows the ``P(i)`` or probability of one exposed person getting infected.
It is estimated based on the emission rate of virus into the simulated volume, and the amount which is inhaled by exposed individuals.
This probability is valid for the simulation duration - i.e. if you have simulated one day and plan to work 5 days in these conditions and the infected person emits the same amoung of viruses each day, the cumulative probability of infection is ``(1-(1-P(i))^5)```.
This probability is valid for the simulation duration - i.e. if you have simulated one day and plan to work 5 days in these conditions and the infected person emits the same amount of virus each day, the cumulative probability of infection is ``(1-(1-P(i))^5)```.
If you are using the natural ventilation option, the simulation is only valid for the selected month, because the following or preceding month will have a different average temperature profile.
The ``R0`` for the simulation is calculated based on the probability of infection, multiplied by the number of exposed people.
The ``expected number of new cases`` for the simulation is calculated based on the probability of infection, multiplied by the number of exposed occupants.
### Exposure graph
The graph shows the variation in the concentration of infectious quanta (one quanta is the amount of inhaled viruses which can cause infection with a probability of 63%) within the simulated volume.
The graph shows the variation in the concentration of infectious quanta (one quanta is the amount of inhaled virus that can cause infection in 63% of the exposed occupants) within the simulated volume.
It is determined by:
* The presence of the infected person, who emits airborne viruses in the volume.
* The emission rate is related to the type of activity of the infected person (sitting, light exercise), their level of vocalisation (whispering or talking).
* The accumulation of infectious quanta in the space is driven by ventilation, if applicable (either natural or mechanical, and or HEPA filtration).
* In a mechanical ventilation scenario, the removal rate is constant, based on air flow in and out of the simulated space.
* The emission rate is related to the type of activity of the infected person (sitting, light exercise), their level of vocalisation (breathing, whispering or talking).
* The accumulation of infectious quanta in the volume, which is driven, among other factors, by ventilation (if applicable).
* In a mechanical ventilation scenario, the removal rate is constant, based on fresh airflow supply in and out of the simulated space.
* Under natural ventilation conditions, the effectiveness of ventilation relies upon the hourly temperature difference between the inside and outside air temperature.
* A HEPA filter removes infectious quanta from the air at a constant rate and is modelled in the same way as mechanical ventilation, however air passed through a HEPA filter is recycled not renewed (i.e. it is not fresh air).
* A HEPA filter removes infectious quanta from the air at a constant rate and is modelled in the same way as mechanical ventilation, however air passed through a HEPA filter is recycled (i.e. it is not fresh air).
# Conclusion
This tool provides illustrations for COVID-19 (long range) airborne risk only - see Disclaimer
This tool provides informative comparisons for COVID-19 (long-range) airborne risk only - see Disclaimer
If you have any comments on your experience with the app, or feedback for potential improvements, please share them with the development team at cara-dev@cern.ch.

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<div style="width: 33%; float:left;">
<b>Quick Guide:</b><br>
This tool simulates the long range airborne spread SARS-CoV-2 virus in a finite volume and estimates the risk of COVID-19 infection. It is based on current scientific data and can be used to measures the effectiveness of different mitigation measures.<br>
This tool simulates the long range airborne spread SARS-CoV-2 virus in a finite volume and estimates the risk of COVID-19 infection. It is based on current scientific data and can be used to compare the effectiveness of different mitigation measures.<br>
<b>Ventilation data:</b> <br>
<ul>
<li>Mechanical ventilation = check the rates with a specialist.</li>
@ -220,7 +220,7 @@
</ul>
</ul>
<b>Activity types:</b><br>
The type of activity that includes both the infected and exposed persons:
The type of activity applies to both the infected and exposed persons:
<ul>
<li>Office = Typical office scenario with all persons seated, in conversation (talking 33% of the time, otherwise breathing normally).</li>
<li>Meeting = Typical meeting scenario with all persons seated, in conversation (talking time is shared equally between all persons).</li>
@ -233,9 +233,9 @@
</ul>
<b>Activity breaks:</b><br>
<ul>
<li>If coffee breaks are included, they are spread out evenly throughout the day, in addition to lunch.</li>
<li>If coffee breaks are included, they are spread out evenly throughout the day, in addition to any lunch break (if applicable).</li>
</ul>
Refer to <a href="/calculator/user-guide"> COVID Calculator user-guide </a> for more detailed explanations on how to use this tool. <br>
Refer to <a href="/calculator/user-guide"> COVID Calculator App user guide </a> for more detailed explanations on how to use this tool. <br>
</div>
<button type='submit' id="generate_report">Generate report</button><br><br><br><br>
@ -245,13 +245,12 @@
<div id="DIALOG_welcome" title="Welcome to CARA!" class="dialog">
<p>This software is provided with a disclaimer and code license.<span id="dots"></span><span id="more" style="display: none;">
<br><br><b>Disclaimer:</b><br><br>
<span id="disclaimer">The risk assessment tool simulates the long range airborne spread SARS-CoV-2 virus in a finite volume, assuming a homogenous mixture, and estimates the risk of COVID-19 infection thereto. The results DO NOT include short-range airborne exposure (where the physical distance plays a factor) nor the other know modes of transmission of SARS-CoV-2. Hence, this model implies that proper physical distancing, good hand hygiene and other barrier measures are ensured.<br><br>
It is based on current scientific data and can be used to measures the effectiveness of different mitigation measures.<br><br>
Note that this model is based on a deterministic approach, i.e., at least one person is infected and shedding viruses into the volume. Nonetheless, it is also important to understand that the absolute risk of infection is uncertain as it will depend on the probability that someone infected attends the event. The model is mostly useful to compare the impact and effectiveness of mitigation measures such as ventilation, filtration, exposure time, activity and the size of the room on long-range airborne transmission of COVID-19 in indoor settings.<br><br>
This application is meant for informative and educational purposes. The user can be able to adapt different settings and measure the relative impact on the estimated infection probabilities to allow for a targeted decision making and investment. The user should acknowledge that until the virus is in circulation among the population, the notion of 'zero risk' or a 'completely safe scenario' does not exist. Each event is unique and the results are as accurate as the inputs. The app is based on our scientific understanding of infectious diseases transmission, exposure and aerosol science as of November 2020.<br><br>
<b>We do not assume responsibility for any injury or damage to persons or property arising out of or related to any use of this app.</b></span>
<span id="disclaimer">The risk assessment tool simulates the long-range airborne spread SARS-CoV-2 virus in a finite volume, assuming a homogenous mixture, and estimates the risk of COVID-19 infection therein. The results DO NOT include short-range airborne exposure (where the physical distance plays a factor) nor the other known modes of SARS-CoV-2 transmission. Hence, the output from this model is only valid when the other recommended public health & safety instructions are observed, such as adequate physical distancing, good hand hygiene and other barrier measures.<br><br>
The model used is based on scientific publications relating to airborne transmission of infectious diseases, dose-response exposures and aerosol science, as of December 2020.<br><br>
Note that this model applies a deterministic approach, i.e., it is assumed at least one person is infected and shedding viruses into the simulated volume. Nonetheless, it is also important to understand that the absolute risk of infection is uncertain, as it will depend on the probability that someone infected attends the event. The model is most useful for comparing the impact and effectiveness of different mitigation measures such as ventilation, filtration, exposure time, physical activity and the size of the room, only considering long-range airborne transmission of COVID-19 in indoor settings.<br><br>
This tool is designed to be informative, allowing the user to adapt different settings and model the relative impact on the estimated infection probabilities. The objective is to facilitate targeted decision-making and investment through comparisons, rather than a singular determination of absolute risk. While the SARS-CoV-2 virus is in circulation among the population, the notion of 'zero risk' or a 'completely safe scenario' does not exist. Each event modelled is unique and the results generated therein are only as accurate as the inputs and assumptions.<br><br></span>
<br><br><b>Code License:</b><br><br>
<span id="code_license">THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.</span></p><br>
<span id="code_license">This code is licensed under GPL V3.</span></p><br>
<button onclick="show_disclaimer()" id="myBtn" tabindex="-1">Read more</button><br><br>
</div>

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<br><br><br>
<div style="border: 2px solid black; padding: 15px;">
<p class="image"> <img <img align="middle" src="/calculator/static/images/disclaimer.jpg" width="40" height="40"><b>Disclaimer:</b><br><br></p>
<p class="disclaimer">The risk assessment tool simulates the long range airborne spread SARS-CoV-2 virus in a finite volume, assuming a homogenous mixture, and estimates the risk of COVID-19 infection thereto. The results DO NOT include short-range airborne exposure (where the physical distance plays a factor) nor the other know modes of transmission of SARS-CoV-2. Hence, this model implies that proper physical distancing, good hand hygiene and other barrier measures are ensured.<br><br>
It is based on current scientific data and can be used to measures the effectiveness of different mitigation measures.<br><br>
Note that this model is based on a deterministic approach, i.e., at least one person is infected and shedding viruses into the volume. Nonetheless, it is also important to understand that the absolute risk of infection is uncertain as it will depend on the probability that someone infected attends the event. The model is mostly useful to compare the impact and effectiveness of mitigation measures such as ventilation, filtration, exposure time, activity and the size of the room on long-range airborne transmission of COVID-19 in indoor settings.<br><br>
This application is meant for informative and educational purposes. The user can be able to adapt different settings and measure the relative impact on the estimated infection probabilities to allow for a targeted decision making and investment. The user should acknowledge that until the virus is in circulation among the population, the notion of 'zero risk' or a 'completely safe scenario' does not exist. Each event is unique and the results are as accurate as the inputs. The app is based on our scientific understanding of infectious diseases transmission, exposure and aerosol science as of November 2020.<br><br>
<b>We do not assume responsibility for any injury or damage to persons or property arising out of or related to any use of this app.</b></p>
<p class="discalimer">The risk assessment tool simulates the long-range airborne spread SARS-CoV-2 virus in a finite volume, assuming a homogenous mixture, and estimates the risk of COVID-19 infection therein. The results DO NOT include short-range airborne exposure (where the physical distance plays a factor) nor the other known modes of SARS-CoV-2 transmission. Hence, the output from this model is only valid when the other recommended public health & safety instructions are observed, such as adequate physical distancing, good hand hygiene and other barrier measures.<br><br>
The model used is based on scientific publications relating to airborne transmission of infectious diseases, dose-response exposures and aerosol science, as of December 2020 . It can be used to compare the effectiveness of different airborne-related risk mitigation measures.<br><br>
Note that this model applies a deterministic approach, i.e., it is assumed at least one person is infected and shedding viruses into the simulated volume. Nonetheless, it is also important to understand that the absolute risk of infection is uncertain, as it will depend on the probability that someone infected attends the event. The model is most useful for comparing the impact and effectiveness of different mitigation measures such as ventilation, filtration, exposure time, physical activity and the size of the room, only considering long-range airborne transmission of COVID-19 in indoor settings.<br><br>
This tool is designed to be informative, allowing the user to adapt different settings and model the relative impact on the estimated infection probabilities. The objective is to facilitate targeted decision-making and investment through comparisons, rather than a singular determination of absolute risk. While the SARS-CoV-2 virus is in circulation among the population, the notion of 'zero risk' or a 'completely safe scenario' does not exist. Each event modelled is unique and the results generated therein are only as accurate as the inputs and assumptions.</p>
</div>
</body>
</html>