THIS interactive tool lets you check your risk of catching the coronavirus from a loved one at Christmas.

As a second national lockdown ends, Brits will be looking forward to spending five days with their festive bubble over Christmas.

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The Covid-19 Indoor Safety Guideline tool has been produced by experts to help you assess the risk of going to different places such as the office, school and even home for Christmas.

Researchers at the Massachusetts Institutes of Technology used a mathematical equation to work out the risk of catching Covid if one person in a room is infected with the virus.

You can use the tool to find out how long it's safe to stay in a room with someone who has Covid.

The tool lets you select different settings – as well as one to 100 people.

You can chose from a house, a quiet office, a restaurant, a lecture hall, a train, a plane and even church.

The tool then allow you to select how many people will be in the room and for what amount of time.


From December 2 local authorities in England will enter into three tiers.

Tier 3 will have the toughest restrictions with hospitality closed, while in Tier 2 hospitality will be open but you can only sit inside if you live with the person.

In Tier 1 the rule of six applies both indoors and outdoors.

For five days over the Christmas period people will be able to spend time with their loved ones as restrictions are eased.

The interactive tool can help you discover how risky various scenarios could be.

The model states that it would be safe for two people to be in the same room in a house for 14 days and that three people would be safe for seven days – if one person was infected.



It notes that the "two-metre distancing guideline would indicate that up to 55 people would be safe in this room for an indefinite period".

The creators of the tool state: "To mitigate the spread of Covid-19, official public health guidelines have recommended limits on: person-to-person distance, occupancy time, maximum occupancy, or minimum ventilation.

"There is growing scientific evidence for airborne transmission of Covid-19, which occurs when infectious aerosol droplets are exchanged by breathing shared indoor air.

"While public health organisations are beginning to acknowledge airborne transmission, they have yet to provide a safety guideline that incorporates all the relevant variables."

The tool, developed by Kasim Khan, John W. M. Bush, and Martin Z. Bazant works by calculating the maximum allowable exposure time, the occupancy of a room and how long a person is in the presence of an infected person.

The app is based on findings published in a study entitled Beyond Six Feet: A Guideline to Limit Indoor Airborne Transmission of Covid-19.

The paper has not yet been peer-reviewed.

It states that the model "informs the risk of airborne transmission resulting from the inhalation of small, aerosol droplets that remain suspended for extended periods within closed, well-mixed indoor spaces."

The study also highlights different activities such as singing and loud speaking and the effect that this could have on transmission.

Graphs in the study show how the model works.

It details different audio levels such as loud speech to whispers.


It gives estimations of infectiousness and shows areas such as Wuhan and the Diamond Princess ship on the graph in order to show how some scenarios became so infectious.

The authors state: "Above all, our study makes clear the inadequacy of the
Six-Foot Rule in mitigating indoor airborne disease transmission, and offers a rational, physically-informed alternative for managing life in the time of Covid-19.

"If implemented, our safety guideline would impose a limit on the cumulative exposure time in indoor settings, violation of which constitutes an exposure for all of the room’s occupants.

"While our study has allowed for an estimate of the infectiousness of Covid-19, it also indicates how new data characterising indoor spreading events may lead to improved estimates thereof and so to quantitative refinements
of our safety guideline."

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