As schools reopen around the world, scientists have analysed exactly how the particles that spread COVID-19 do so through actual classrooms.
The research has once again highlighted the importance of good ventilation in containing the virus. It has also shown where are the safest places to sit.
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Scientists said that glass shields could be an important tool in preventing the spread of coronavirus in classroom settings.
Lead author Khaled Talaat, of the University of New Mexico, said: “In our model, the back corners are the safest spots.”
The researchers said that students at higher risk of complications from COVID-19 could be seated where they are least exposed to it.
One of the main ways the virus spreads is when aerosol particles are released during exhalation, talking, coughing, or sneezing.
The researchers found that opening windows increases the fraction of particles that exit the system by nearly 40%, while also reducing aerosol transmission between people within.
“Nearly 70% of exhaled 1-micron particles exit the system when windows are open," said one of the authors.
“And air conditioning removes up to 50% of particles released during exhalation and talking, but the rest get deposited onto surfaces within the room and may reenter the air.”
Particles are transmitted in significant quantities (up to 1% of exhaled particles) between students – even at 7.8 feet of separation distance because of air flow.
The researchers found that glass droplet screens placed in front of desks significantly reduced the transmission of 1-micron particles from one student to another, according to Talaat.
“Screens don't stop 1-micron particles directly, but they affect the local air flow field near the source, which changes the particle trajectories,” he said.
“Their effectiveness depends on the position of the source with respect to the air conditioning diffusers.
“The aerosol distribution within the room isn't uniform, because of air conditioning and source location.
“Student position within the room affects the likelihood of transmitting particles to others and of receiving particles.”
The researchers also stressed the importance of sanitising hands, even without contact with other people's belongings.
Talaat said: “Particles can be transmitted from one student to other students' desks or clothes etcetera, even when keeping separated by a distance of eight feet.”
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