Study shows benefit of regular classroom ventilation

Are they bored or not? A classroom in Zurich. © Keystone / Christian Beutler

A Swiss study has found that poorly ventilated school classrooms record up to six times as many Covid-19 cases compared with those which are regularly aired.

The research by the Swiss Federal Laboratories for Materials Science and Technology (EMPA) analysed data from CO2 sensors in 150 classrooms in canton Graubünden, before checking the results against the regular Covid tests run by the schools.

The correlation is clear: “more students and teaching staff were infected with the corona virus in classrooms with poor air quality than in rooms that are regularly ventilated”, EMPA wrote on ThursdayExternal link. The badly ventilated rooms – 60% of those studied, said canton Graubünden – came out with six times as many cases as the better ventilated ones.

The researchers recommend airing out classrooms more than usual, even when outside temperatures are low; they say three times each hour, for five minutes at a time, is best.

More results from cantons Lucerne and Ticino are currently being analysed before a final publication on the topic will be published at the beginning of next year, EMPA researcher Hossein Gorji told the Keystone-SDA news agency.

Class struggle

Covid numbersExternal link in Switzerland are currently higher than they have been for around a year, with a record high of 12,598 new daily infections recorded yesterday. Much transmission seems to be happening in classrooms; in the week of November 29 to December 5, just under a third of total infections were recorded among those aged 19 and younger. This age group makes up one-fifth of the total population.

As a result, debates around mask-wearing and appropriate measures in schools have been ongoing. On Thursday, the latest cantons to take action were Bern, where school Christmas holidays will begin three days earlier than normal on December 21, and Schwyz, which made masks compulsory for all children from the first year of primary school. Zurich, the country’s biggest region, will implement this latter rule as of next January.