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TO USE:Input your own values into any of the blue-highlighted boxes. These default example parameters are currently set to model "going to Costco in San Francisco on April 17, 2020."
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global parameterswhat's this?how this number was calculatedsuggested parameter calculations
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p_i =0.002The probability that any given person outside is infected.Through the suggested calculation format over on the right.calculate p_i:
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p_hu_vs =0.5The probability that your hands remain uninfected given that you touch a surface contaminated with virus.A highly approximate Fermi estimate.region population:881549
2019 est: https://www.census.gov/quickfacts/sanfranciscocountycalifornia
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p_w =0.000001A catch-all term for wildcard fluctuations (fluid dynamics glitches, etc.) that were beyond the scope of this model.A highly approximate Fermi estimate.
region number of active cases:
1137
April 18, 2020. https://missionlocal.org/2020/04/18-daily-figures-on-sf-coronavirus-cases-confirmed-cases/
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confirmed-to-latent multiplier:
10
approximate, based on estimation of under-testing
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latent-to-asymptomatic multiplier:
0.18
source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7078829/
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situation-specific parametersp_i=0.232%
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calculate N_s at a store:
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surface-based:N_s =150The number of surfaces you touch while outside.Through the suggested calculation format over on the right.
num items you buy:
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N_p_s =0.9The average number of people that also touched the surfaces you're touching, in the time since those surfaces were last sanitized.Through the suggested calculation format over on the right.N_s=150
you have to touch each item at least twice to purchase it. plus, there are a fixed number of touches upon entering the store: doors, shopping cart, etc.
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calculate N_p_s at a store:
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warm-body-based:
r =6The distance, in feet, that you're standing away from the breathing person.Recommended social distancing amount. Change to match your scenario.
store foot traffic since the last sanitization:
3600
open for 9hr, average 400 people per hour maybe (rough approximation)
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N_b =8The average number of breath events per person you encountered. So, times they breathed or coughed on you during your interaction with them.Change to match your scenario. 960 breaths an hour is the suggested rate on the right.
fraction of items in the store that the average patron probably touched:
0.00025
fermi estimate based on the size of the average costco
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N_p_b =100The number of people that breathed on you.Change to match your scenario. This seems like approximately how many people you would pass on a Costco trip.N_p_s=0.9
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projectiness =0.5A scale factor describing the number of viral particles emitted (projected) by the breathing person, relative to a cough. Set = 1 for a cough, 0.5 for normal breathing, 0.3 for t-shirt masks, and 0.1 for surgical masks.
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calculate N_b:
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human breaths per hour:
960
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hours you hung out:
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Infection Risk:13.500%Final SYGO estimator probability that you have coronavirus after this venture outside.N_b=240
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do not modify numbers below this row, they are calculation infrastructure
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surface component:
0.865
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breathing component:
1.00
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airborne component:
0.00
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radius z score:9.00
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probability that N_v is below T_c:
1.00
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