Free interactive tool reveals the risk of contracting coronavirus indoors

A website built by the University of Cambridge was created to reveal the risk of coronavirus infection in indoor spaces.

The application has several customizable settings that include ventilation level, number of occupants and activity level and mask use.

Anyone can use it to find out the level of risk they are taking in a room of almost any size or type.

For each set of parameters, the website produces a graph that shows the chance of infection in a given period of time, with the default being 9 am to 5 pm.

The site is called Airborne.cam and can be accessed here.

The graph he creates that shows an individual’s risk of infection is calculated by a series of scientific equations described in a new study published in Proceedings of the Royal Society A.

Users can determine room occupancy, type of mask and activity level. Mask configurations include without a mask, surgical masks, N95 masks or covers made of fabric.

The level of activity can also be changed, from sitting / breathing to heavy exercise.

Ventilation can also be changed, with six options, from poorly ventilated to industrial ventilation in hospitals.

The academics also defined the dimensions of the rooms and a period of time that is considered in the equation.

As part of their research, the scientists found that two people talking freely in a poorly ventilated space without a mask pose a greater risk of infection than if one coughs.

This, they say, is because speech leads to the exhalation of small drops called aerosols, which float in a confined space.

Without adequate ventilation, they can remain in the air, increasing the risk of a person inhaling them and subsequently being infected.

However, the cough produces large drops that are much heavier and are likely to fall to the nearest surface and are not suspended in the air.

“Our knowledge of SARS-CoV-2 overhead transmission has evolved at an incredible rate, considering that it has only been a year since the virus was identified,” said Dr. Pedro de Oliveira, the article’s first author.

“There are different ways to approach this problem. In our work, we considered the wide range of respiratory droplets that humans exhale to demonstrate different scenarios of viral transmission through the air – the first being the rapid spread of small infectious droplets over several meters in a matter of a few seconds, which can happen both indoors and outdoors.

‘Next, we show how these small droplets can accumulate in indoor spaces over the long term and how this can be mitigated with adequate ventilation.’

The free online tool shows that in an office of 30 people measuring 100 square meters (1,076 square feet) and three meters (9.8 feet) high, there is a risk that a person will contract the virus from 9 am to 5 pm if a person is infected and no one wears masks is 6.06 percent.

If everyone in the office wears a surgical mask all day and takes an hour break for lunch outdoors, that drops to just 2.13%.

But if three people are working in a medium-sized (18 m² / 193 square feet) dining room with insufficient ventilation and one person is infected, the risk of contracting the virus in eight hours is 48.73 percent.

The calculations are based on the assumption that ‘hands are washed and that individuals are distant from each other – that is, there is no risk of short-range transmission by droplets / aerosol’.

The tool is now being actively used by the University of Cambridge, which has made it a prerequisite for high-risk spaces in the institution, which will allow the team to include mitigating factors such as reduced capacity or increased ventilation.

“The tool can help people use fluid mechanics to make better choices and adapt their day-to-day activities and environment to suppress risk, both for themselves and for others,” said co-author Savvas Gkantonas, who led the development of the app with Dr. de Oliveira.

A similar tool was previously created by researchers from the Atlantic Ocean at MIT.

The tool reveals that the size or type of the room does not matter much – but the types of masks that people who use it and the ventilation system it is equipped with can dramatically increase or decrease risks.

In a standard room with a ceiling height of 8 feet high and each wall measuring about 15 feet in length, 10 fit young men, all wearing surgical masks diligently, could safely sit and chat normally for two hours if the windows were open. closed due to external cold.

But for a family of ten, some of whom are elderly, in a standard dining room where no one wears a mask because they are eating and the windows are closed because it is cold outside – and there are some heated discussions with voices – the tool reveals that the security limit has been reduced to just three minutes.

Its developers say the online site allows people to calculate risk in more nuances than simple, and often vague, guidance for forming “bubbles” or social distance.

The calculations that inform the site were published by authors John Bush and Martin Bazant on the pe-print server medRxiv.