I'm sharing my ObservableHQ notebook that gives COVID aerosol risk estimates for schools, work, shopping, and other activities. You can adjust sliders to get counterfactuals/what-ifs for improving ventilation, decreasing time, etc.
https://observablehq.com/@chonghorizons/covid-individual-event-risk-calculator-v0-2
A good risk estimator is very helpful when navigating competing ideas. Some people favor ventilation. Some people better masks. Some, spacing and distancing.
It's based on the decades old Wells-Riley aerosol disease model. A google sheets risk calculator with a ton of documentation was built by Prof Jose Jimenez of Univ Colorado-Boulder. (http://tinyurl.com/covid-estimator a complex google sheets workbook).
It can help you think about doing A or B.
I didn't make any of the modeling equations. I just "reskinned" the google sheet as a menu based system with sliders and radio boxes. But it's more approachable than the google sheet.
Hope this is useful.