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New study shows: Ventilation reduces airborne transmission

With Corona cases expected to rise towards fall and winter, the World Health Organization (WHO) is encouraging the use of proper ventilation in schools and offices. This urgent need for ventilation in public spaces is further supported by a recently published Italian research project highlighting how effective mechanical ventilation reduces the risk of airborne transmission.

20. March 2023

Fall has made its way back into our daily lives, and with it comes the cold weather and rising concerns about corona infections. The rising concerns stem from previous experience with seasonal variation and epidemic development during the cold fall and winter months. The governments around Europe have therefore prepared for an uncertain and possibly challenging fall and winter season.

While many countries now have a vaccine program ready to protect the most vulnerable part of society, the World Health Organization (WHO) recommends continuously adapting to keep ourselves safe and to take the necessary steps to protect others. One of the highlighted recommendations from WHO to protect people during these seasons is to ventilate crowded public spaces like schools and offices. But why should we focus on the indoor climate in schools when talking about airborne transmission?

The importance of a good indoor climate

Hos Airmaster er bæredygtighed ikke blot miljø, men en del af forretningsstrategien, som også skal karakterisere hele virksomheden. Vi har i en del år fokuseret på at opføre os fornuftigt – bl.a. med hensyn til ressourcer, og i dag er det en del af vores bæredygtige tankegang.


The most essential functions of a school are to provide children with the best conditions for learning and to keep the children safe and healthy. Even though multiple elements affect this aspect, the indoor climate has been scientifically proven to affect children’s ability to learn and overall health. With children spending around 6 hours a day at school, ensuring that the schools have a ventilation system that maintains an ideal learning environment and reduces the risk of airborne transmission of viruses is critical.


It makes a lot of sense for our children and young people to have a good indoor climate. We cannot offer them anything other than the best possible conditions for optimal learning.” – Lasse Mikkelsen, CCO at Airmaster.


A new study shines a light on mechanical ventilation

A recently published Italian publication is now highlighting exactly how much the indoor climate and mechanical ventilation in classrooms mean in reducing the risk of airborne transmission among schoolchildren. The experiment compared corona contagion in more than 10.000 classrooms in the Marche region over five months. Of these classrooms, 316 of them had mechanical ventilation.


The publication shows that the more fresh air supplied into the classrooms, the smaller the risk is of children being infected with airborne viruses, like corona. Additionally, for the classrooms with mechanical ventilation systems that exchanged the used indoor air with fresh air, the risk of being infected with corona fell by 80% compared with those classrooms that only used natural ventilation, meaning ventilation was achieved by opening doors or windows.

Other countries should learn

Good indoor climate
Hos Airmaster er bæredygtighed ikke blot miljø, men en del af forretningsstrategien, som også skal karakterisere hele virksomheden. Vi har i en del år fokuseret på at opføre os fornuftigt – bl.a. med hensyn til ressourcer, og i dag er det en del af vores bæredygtige tankegang.


This experiment has been the first and most comprehensive study about the effect of mechanical ventilation on airborne transmission in classrooms. With the publication of this study, we now have crucial research-based knowledge about the importance of mechanical ventilation in reducing the risk of airborne transmission and the spread of corona at schools.

The problem that Italian schools are facing, where insufficient ventilation does not provide enough fresh air to ensure a healthy learning environment, is not unique. Numerous investigations have shown that many European schools' indoor climate is insufficient and does not meet requirements. This shows that the WHO’s recommendations and the results from the Italian study are of importance and relevance to other countries as well. The new knowledge about mechanical ventilation is a great tool and argument to create better and safer conditions for children’s learning and well-being.

We should share our knowledge and experience in achieving optimal indoor climate. By doing this, we can also support and provide focus to a topic that should be on the political agenda.” – Lasse Mikkelsen, CCO at Airmaster.


Let us help those who cannot help themselves

At Airmaster, we strive to help schools and students achieve the most optimal indoor climate. It is, therefore, important for us to do what we can to put the topic of indoor climate in schools on the agenda and join the debate now. Both because we are experts in school ventilation and indoor climate and because children and students deserve better. Children and students should be able to spend their days in an environment that supports healthy growth and performance. This much we owe them.



​Rabidly escalating COVID-19 cases amid reduced virus surveillance forecasts a challenging autumn and winter in the WHO European Region

Increasing ventilation reduces SARS-CoV-2 airborne transmission in schools: a retrospective cohort study in Italy's Marche region

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