The Indian government has stressed upon maintaining Do gaz ki doori (a distance of six feet or nearly 2 metres) from each other to contain the spread of the novel coronavirus that causes COVID-19.
This is largely based on the assumption that large droplets do not travel further than 2 meters while coughing or sneezing. But in a recent systematic review, eight of the 10 studies showed droplets travel more than 2 meters (~6 feet), in some cases up to 8 meters (~26 feet).
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There is overwhelming evidence that indoor airborne transmission is associated with relatively small, micron-scale aerosol droplets that play a dominant role in the spread of COVID-19, researchers from the Massachusetts Institute of Technology (MIT) said in a new study.
The research, published in the journal PNAS (Proceedings of the National Academy of Sciences), said that in large and poorly-ventilated spaces, masks are more important than physical or social distancing to reduce the risk of transmission.
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The researchers have developed an open-access mobile app and website that uses a theoretical model to calculate safe exposure times and occupancy levels for indoor spaces.?
Users can choose room specifications, ventilation and filtration rates, face-mask usage, respiratory activities, and risk tolerance to get an estimate of how long it would take, under those circumstances, for one new person to catch the virus if an infected person enters the space.
The calculations used a strictly quantitative approach based on inferences made from various mass-spreading events, the report said. And rather than giving a simple yes or no answer about whether a given setting or activity is safe, the model provides a guide as to just how long a person could safely expect to engage in a particular activity indoors,
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The guideline is based on well-mixed air within a given space, and obviously, the risk would be higher if someone is positioned directly within a focused jet of particles emitted by a sneeze, the researchers said.
Martin Z. Bazant, the professor who co-developed the guideline, said that the app already has about half a million users after they made it available in October. Their feedback helped researchers refine the model to account for the higher spreading rates of the new emerging variants, which has helped influence some decisions about reopening of businesses. The app can also predict how much ventilation is needed to reach a particular level of safety.
And in addition to recommending guidelines for specific spaces, the new tools found that while improved ventilation systems and face mask use make a big difference, air filtration systems have a relatively smaller effect on disease spread.
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