This app predicts when you will contract COVID-19; conditions apply

The guidelines developed by MIT researchers suggests a limit for exposure time, based on the number of people, the size of the place, the kind of activities, whether masks are worn and ventilation.

The guideline, that appeared recently in journal PNAS, mainly stressed the specific time a person can spend in a given setting where a COVID-positive person might be present.

Their analysis is based on the fact that in enclosed spaces, tiny airborne pathogen-carrying droplets, spread by people — while talking, coughing, sneezing, singing or eating — will float in the air for a long time and mix well throughout the space. They say that such airborne transmission plays a major role in the spread of COVID-19.

Bush said that the study was initially motivated early last year over concerns about social distancing and maintaining "6-feet" distance. According to him, this doesn't adequately address airborne transmission indoors.

The research was initially based on the transmissibility of the original strain of COVID-19 virus from epidemiological data on early spread. Subsequently, the researchers have added a transmissibility parameter for higher spreading rate of the new variants like the UK strain, which has been estimated to be 60 percent more transmissible than the original.

On their mobile application and website, users can enter specific details about a situation and receive an estimate of how long it would take for them to catch the virus if an infected person enters the space. They have to enter details like the size of the space, number of people there, type of ventilation, activity, if they are wearing masks and the transmissibility parameter for the predominant strain in the area at the time.

Since the launch of the app in October the project has got about 5 lakh users.

Bazant said that ventilation systems and the use of face masks can dramatically affect the safety levels.