If you’re in an office, cafe, bar or restaurant, look around you. Are the windows or doors wide open? If so, it’s likely because of a very German habit: Lüften or airing out a room.

As The Local reported this week, airing out rooms was recently added to the German government’s advice to tackle coronavirus.

Two more letters are being added to the “AHA” (Abstand halten, Hygiene und Alltagsmaske) formula that Germany advises for keeping distance, good hygiene and wearing so-called everyday masks.

The two extra letters are “C” to stand for the coronavirus tracing app, and “L” to stand for “Lüften” or ventilating a room. It makes the acronym “AHAC” in full.

On Tuesday Chancellor Angela Merkel said ventilation is one of the “cheapest and most effective measures” in the fight against the virus.

“The custom is something of a national obsession, with many Germans habitually opening windows twice a day, even in winter. Often the requirement is included as a legally binding clause in rental agreements, mainly to protect against mould and bad smells,” wrote the Guardian in their report on the new advice and the German pastime of airing out the indoors.

Proving how seriously Germans take airing out rooms there are different methods for ventilating. Stoßlüften literally translates to “shock ventilation” or “impact ventilation”.

For about five minutes at least twice a day (usually in the morning and evening), it involves opening the windows wide and let a ‘shock’ cold air stream in. Then you close the windows and the room is fresh again.

It doesn’t matter what time of year it is – even if it’s winter and it’s freezing outside this will still happen. 

There’s also Querlüften, or cross ventilation, which involves opening all the windows of a house or building and letting the fresh air flow through.

It’s common practice for Germans to turn off all of the heating, and to don a hefty jacket before they let the bitterly cold air in.

They believe regular ventilation of indoors spaces improves the quality of air in a home or workplace and stops mould from forming.

READ ALSO: German word of the day: Stoßlüften

During the pandemic, Lüften has taken on an even more significant role. Experts, including virologist Christian Drosten and the Robert Koch Institute (RKI) for disease control have talked up the importance of frequently airing out indoor spaces.

Scientists say that one of the ways coronavirus can spread is through so-called aerosol droplets in the air – tiny particles that are produced when we breathe, cough, sneeze or speak. Most infections spread indoors, meaning the upcoming colder months are a major concern in many parts of the world, including Germany.

As we reported in August, experts from the Federal Environment Agency (Umweltbundesamt) issued advice to avoid the spread of coronavirus indoors. They said enclosed spaces should be immediately stoßgelüftet (briefly but completely ventilated) after every cough or sneeze.

According to the commission set up by the agency, consistent ventilation can significantly reduce the risk of infection, but they of course added that it cannot eliminate the risk altogether – that’s why distance, washing hands and wearing a mask is also just as important.

The windows of a classroom at a school wide open in Stuttgart. Photo: DPA

READ ALSO: Stoßlüften: The new German guidelines for when someone sneezes indoors

What do people in Germany think about airing out rooms?

It seems that for many Germans, regular ventilation has long since been a Selbstverständlichkeit (a given). 

Despite crisp autumn temperatures, many cafes in the northern Berlin district of Prenzlauer Berg had plenty of open windows or doors to keep the air flowing.

When we questioned one café worker on Oderberger Straße about his attitude to Stoßlüftung, he seemed surprised that we had asked, asserting that it has always been “fundamentally important” for him.

The pandemic has barely changed how often he ventilates his cafe, he told The Local. However, he does “ventilate the space slightly more often” than before.

The cafe owner welcomed the government’s new recommendations, saying they were “a good idea”.

Katie Cantwell, owner of the cafe Cookies and Cream in Prenzlauer Berg, is also supportive of the government advice.

While ventilating her cafe has been easy over the summer months due to the warm weather, she admits that the upcoming colder season will be a “big test” for her business. 

“Usually in the winter, [our windows and doors] are closed because it’s supposed to be cosy and warm,” she said. Their ventilation during the colder months normally comes from the constant flow of people through their front and back doors. 

This winter, however, she is “more willing to stand in the cold if it means that the windows and doors can stay open”.

“The make or break will be whether people feel comfortable in the space or not. I think having ventilated space [this winter] is going to be more important than having a warm, cosy space indoors,” she said.

Kein Durchzug!

There’s a fine line between airing out a room and creating a draught, as anyone who’s experienced the wrath of a German who fear the Durchzug.

And Germany is not the only country where people are worried about this. There’s a similar air draught phenomenon in Spain, for example.

READ ALSO: ‘Durchzug is not harmful’: Red Cross tells Germans to leave their fans on and windows open

As non-Germans at The Local, we’re not 100 percent sure what counts as Durchzug and what is healthy Lüften. I guess we’ll just have to rely on our German friends to keep us right.

With reporting by Rachel Loxton and Eve Bennett