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Study suggests transparent screens, open windows in classrooms

Copyright © 2020 Albuquerque Journal

Open classroom windows and put up transparent barriers in front of students’ desks.

Those are key mitigation findings in a new study on how particles travel through the air in an air-conditioned classroom.

According to the Centers for Disease Control and Prevention, the novel coronavirus spreads from person to person mainly through close contact, with infections primarily occurring through exposure to respiratory droplets. Airborne transmission is possible, too, according to the CDC.

Over the summer, Khaled Talaat, a Ph.D. candidate in nuclear engineering at the University of New Mexico and one of the authors of the study, and other researchers used simulations to analyze the classroom environment. They found that open windows increase the amount of particles that leave the classroom by about 40%.

“Opening windows while the air conditioning is running is key,” he said.

A UNM news release on the latest research said a significant number of particles can pass between students even at a distance of 7.8 feet because of airflow.

And the research also found that barriers – like commonly used plexiglass – were effective in front of desks. While a Plexiglas screen doesn’t directly stop the particles, it does direct the airflow away from a child, Talaat said.

“In our particular model, we noticed a very significant reduction in the amount of particles that get transmitted between individuals separated by 2.4 meters,” he said.

Talaat said that with screens the transmission of particles was reduced up to 92%. The percentage can be affected by where a person is in the classroom and where the air conditioner vent is located.

The study, which was published Tuesday, comes as the state battles a record-breaking surge in coronavirus cases. On Friday, officials announced 797 new cases.

But the state Public Education Department said schools that have already opened with a mix of in-person and online learning can stay open to give families consistency.

Since schools began operating under this model in early September, there have been 427 cases in 231 schools – 279 staff members and 148 students as of Friday, according to PED.

Among the requirements the state is imposing on schools in order to open is that they have adequate personal protective equipment, space out students in a class and meet air filtration and ventilation guidelines. According to PED documents, schools have to use the most effective filters that are compatible with their systems.

Talaat said another key finding is that where kids are in the room matters. For example, if students are in rows of three, then the middle desk should be empty.

Researchers also stress that a student shouldn’t be seated near the air conditioning vent “because the particles concentrate near the air conditioning outlet,” Talaat said.

Still, he said air conditioners move the air, moving particles out of the room along with it, while filtering incoming air.

“In the absence of air conditioning, the particles that you exhale will accumulate in the room. There’s nothing that removes the particles,” he said.

Talaat told the Journal that heaters ventilate in a similar way to air conditioners, and his findings should be roughly transferable to a classroom with a heater on.

He said taking research-backed steps such as these has the potential for major impacts on a bigger scale.

“You actually have actual life savings from these probabilities,” he said.

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