Super Simplified Model for Aerosol Relative Risk Transmission (SSMARRT)
Developed by: Sigma Expert Solutions, LLC
Analysis Date and Time: 2020-11-22 21:24:24.436781
Requestor:
DISCLAIMER:
These results are provided for informational purposes only and provide insight
on the level of risk that business and social activities may pose due to
aerosol spread of the SARS-CoV-2 virus. The information provided in no way
implies a guarantee of safety from spread of infection. See information below
to understand the assumptions used. For a more detailed assessment, or
additional information, contact info@sigmaexpertsolutions.com
--How to Read the Results--
The results are provided in a tabular format based on user inputs of
Potentially Infected People: 1
Floor area of: 900 square feet
Duration of the Gathering: 120 minutes
The results show how external Air Changes per Hour (ACH) and various acitivities
affect infection risk. Note that 0.18 ACH is the normally accepted minimum
standard for most ventilation systems and 3 ACH is for a high flow rate
laboratory or hospital system.
The least risky scenario is where there is the highest air exchange rate during
quiet conversation with a mask. All other scenarios are compared against this
standard. Therefore the higher the number, the higher the risk in your scenario.
0.00 ACH 0.18 ACH 1.00 ACH 3.00 ACH
Singing with no mask 35.5X 31.6X 20.3X 10.0X
Loud Conversation no mask 17.9X 15.9X 10.2X 5.0X
Wind Instrument with bell cover 14.3X 12.8X 8.1X 4.0X
Loud Conversation with mask 7.2X 6.4X 4.1X 2.0X
Quiet Conversation no mask 7.2X 6.4X 4.1X 2.0X
Quiet Conversation with mask 3.6X 3.2X 2.0X 1.0X
ASSUMPTIONS:
This calculation was performed with much of the information assumed and only
uses the minimum of user inputs to show how the effectiveness of mitigation
strategies. This does not capture the complexity of most situations but provides
valuable insight. The critical assumptions made of relevance include:
--Assumptions about the space--
1. The air within the defined space volume is evenly mixed.
2. Ventilation air exchange rates are uniform over the space - aka, no dead spots.
3. There are nine foot ceilings in the space.
--Assumptions about infection spread--
1. Aerosol spread of viroid particles is the only means of tranmission
2. The same infectious dose is applicable to all people.
3. Every person in the space has the same breathing rate.
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