This estimator is designed to be a simple-to-use tool for experts as well as technical minded persons for understanding the relative risk of contracting COVID-19. As described in the home-page, the focus is kept on aerosols transmission while assuming safe-distancing and personal hygiene measures are being followed.
The Indoors page can be used to estimate risks in different indoor environments. You will need to provide the size of the room you are concerned with. You will also need to get some information about your room’s ventilation from the building’s ventilation engineers. If you have a CO2 sensor, you can also verify the information about the amount of outdoor air supplied to your room using a simple process.
The next important parameter is how many times the event you are estimating risks for will be repeated and how long does each event last. For example, if it is a 50-minute lecture, every weekday, then it lasts 50 minutes and repeats five times every week.
You will need to approximate to the closest kind of activity you expect during this event and also to the closest age group. Based on these inputs, a baseline risk maybe calculated. Next, you may include further, layered safety measures to understand how each step you take reduces risks. Such steps could be increasing ventilation, wearing masks, getting a better filter for the air conditioning system, reducing duration of the event or even moving Outdoors. For estimating risks outdoors, you will need to use the Outdoors page.
For each field on both pages, we have tried to provide simple and helpful explanations as to what the input is about.
You need to keep in mind that the tool is based on best scientific estimate, looked at by multiple experts but knowledge in the field is still evolving. See the original development by Prof. Jimenez for more details. Also, he regularly updates the estimator and if you are of a technical inclination, you can always check-out the latest improvements made on the Google spreadsheet created by him.
The primary goal of this tool is to provide order-of-magnitude estimates related to risks. These estimates may then be used to explore trends and evaluate effectiveness of a combination of measures that may be used to reduce risk.
The output is provided as a probability of getting infected for one person - attending one event or all the repetitions of the event. These are average numbers. While any one repetition maybe have far fewer or far more transmissions, it is expected that over numerous repetitions - say, 1000 - the average will come close to the estimates. For easier comprehension, we follow the example from Prof. Jimenez and compare the risks of catching Covid-19 with the risk of taking your car out for a drive and meting a fatal accident.
To keep abreast of the latest developments related to aerosols transmission of SARS-CoV-2, we advise you to keep track of this excellent compilation of resources prepared by a group of experts, led by Prof. Jimenez.