“Up to twelve times less risk of contamination in the classroom if there is an air purifier” | Coronavirus what you need to know

Blocking gives the concrete example of a class with 25 students. If an infected student were to infect the other 24 students in a class without an air purifier via the air, it would only infect two if the class was equipped with a filter. The engineer bases this calculation on an internationally recognized formula that determines the risk of infection.

Additional data is needed to estimate the risk of contamination with and without air purifiers even more accurately, Blocken emphasizes. The project will therefore run until the end of December of this year. A total of 100 schools participate: 47 in Flanders, 3 in Wallonia and 50 in the Netherlands. A total of 1,000 classrooms are monitored: 500 received a filter, 500 did not.

However, children can also become infected in places other than the classroom, says Blocken. “Of course they also go for hobbies, are at home, … That is why it is important to include as many classes as possible in the study. This way we can be sure that we find a significant correlation between the risk of contamination and the presence of air filters.”

The air purifiers used in the study reduce the concentration of aerosols by 90 to 95 percent. The air is completely cleaned six times an hour. “The filter also removes a lot of fine dust from the air, which benefits the general health of the children and teachers,” says the engineer.

According to calculations by Blocken’s team, it would cost 120 million euros to equip all classrooms throughout Flanders with an air purifier. “That is the same amount as the cost of three weeks of PCR testing for the government, said corona commissioner Pedro Facon,” says Blocken. “So it would be ‘peanuts’.”