Researchers at Eindhoven and Delft call for more ventilation in fight against corona

There is strong evidence that the coronavirus also spreads through small airborne droplets (aerosols), the authors state. The consequence: much more attention must be paid to ventilation in combating corona in indoor spaces.

"Since our plea last summer, when we drew attention to this issue in an open letter together with more than 200 scientists, there has only been more evidence of the role of airborne infections," says researcher Philomena Bluyssen of TU Delft's Dapartment of Architecture, one of the 39 authors of the publication in Science. "The World Health Organisation (WHO) and the Centre for Disease Control and Prevention (CDC) in the US have recently revised their position. They now recognize that airborne contamination is a possible route and recommend ventilation in crowded indoor spaces."

"It is difficult to prove exactly what proportion of infections occur through the air, but even if it were a limited percentage, ventilation is a good idea," adds another author, researcher Marcel Loomans of the Department of the Built Environment at Eindhoven University of Technology. "We know from other diseases, such as measles and TB, that they spread through the air. We therefore desire to extend our call for good ventilation beyond the current corona pandemic.

Multidisciplinary

It is striking that the Dutch RIVM is very reluctant on this issue, argue Bluyssen and Loomans. "In other countries they have recognized this problem much earlier and have been working on ventilation options for much longer," says Bluyssen.

"This is pre-eminently a topic that should be addressed in a multidisciplinary manner," says Loomans. "Physicists, virologists, technicians and medics, among others, should work together on this topic, exactly as we have done in our group of 39 scientists. In our opinion, rigidly adhering to the beliefs of your own field is not the way to go."

"Knowledge on basic physics is sometimes lacking among some physicians", observes Bluyssen. "For example, their assumption that particles larger than 5 micrometers fall to the ground within 1.5 m; that is just wrong."

Paradigm Shift

The 39 scientists argue that it is time for a paradigm shift. They draw a parallel with the hygienic situation in the first half of the 19th century, when cities started to improve and organize their water supply and sewage systems en masse. According to the authors, airborne infection risks must standard be taken into account in the design of buildings from now on.

Loomans: "We take it totally for granted that water is supplied clean and free of germs. This should also apply to air. After all, air, just like water and food, is a vital part of life."

Costs

"Ventilation, including filter systems and monitoring, should no longer be seen as something you just add to a building. It has to be cleverly integrated," says Bluyssen. "In new buildings we should integrate hybrid ventilation: Natural ventilation as a basis, and adding mechanical ventilation when and where it is needed. Ventilation is now seen primarily as a cost. But look at what this pandemic is costing us!"

"Improving the ventilation certainly means an investment," Loomans acknowledges. "It might take a bit more energy usage. But this amount is small on the total cost of a building, and it brings a lot of benefits to society as a whole. Apart from this pandemic, poorer air quality in our buildings affects our health. I therefore hope that the attention paid to ventilation, even after Corona, will remain and that we will also include the infection risk component, for example, in our Building Decree."

A group of 39 international scientists published an opinion piece in the journal Science on May 14, entitled: A paradigm shift to combat indoor respiratory infection.

DOI: 10.1126/science.abg2025, https://science.sciencemag.org/content/372/6543/689