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CLASSROOM AEROSOL RISK CALCULATOR: Duke researchers have developed a new online calculator that teachers and students can use to “estimate the risk of airborne transmission of the #COVID19 virus in classrooms”. This is huge. 
https://nicholas.duke.edu/news/online-tool-calculates-risk-classroom-transmission-airborne-covid-19
2) Though initially developed for use on college campuses, the calculator can also be used by K-12 schools to inform their decisions on school re-openings and assess the effectiveness of different control measures in various settings like classrooms, cafeterias and gymnasiums.
3) “The idea was to make it as easy as possible for non-scientists to assess the probable risk of COVID transmission from microscopic airborne aerosols containing the virus, which is a newly discovered route of infection”
4) This is not an infectious disease dynamics model, but rather a model that predicts airborne virion concentrations within a classroom, taking into account exhalation of virion-containing aerosols by infected individuals and the loss of these particles. …http://covid-exposure-modeler-data-devils.cloud.duke.edu
5) To calculate a risk of infection, users enter information about the physical characteristics of the room to be used – such as its height and floor, the number of students, and duration of each in-person class session or school activity – into the calculator’s webpage.
6) One also has to know a room’s ventilation rate, which can be calculated. There is even a link to a page that explains how community infection rates – a required field – can be derived from current information on COVID case counts in the user’s area.
7) Based on the entered information, the model calculates the probable concentration of airborne virions, or aerosol particles, that have been exhaled into the room by someone infected with COVID...
8) as well as the probable concentration, or dose, of these virions inhaled by uninfected people in the room, even if they are using protective masks and practicing social distancing.
9) The actual risk of infection from aerosols may be higher than calculated if social distancing, mask use and hygiene protocols are not strictly adhered to in a classroom.
10) Good time to remind people how to improve ventilation in schools and offices: see video below. https://twitter.com/drericding/status/1289099932100710400?s=21 https://twitter.com/DrEricDing/status/1289099932100710400
