‘Danger lurks inside’: German aerosol experts say Covid restrictions should target indoor areas

German aerosol researchers have told the government that Covid-19 spreads almost exclusively indoors through aerosols - and criticised measures that focus on restricting outdoor activity.

'Danger lurks inside': German aerosol experts say Covid restrictions should target indoor areas
People in a Berlin park on April 11th. Aerosol researchers say the virus does not tend to spread outdoors. Photo: DPA

The group, made up of scientists and academics, slammed the constant debates about transmission happening in places like outdoor beer gardens or parks – and said the focus should be on indoor protection, including in the home, offices and schools.

In an open letter, the leaders of the Society for Aerosol Research (GAeF) called on the German government to partially rethink its handling of the pandemic.

They said protection against infection must take place above all where people spend time indoors.

The letter is addressed to Chancellor Angela Merkel, Health Minister Jens Spahn as well as to the state premiers and the health offices of the country’s 16 states.

The central statement of the group is: “The transmission of the SARS-CoV-2 viruses takes place almost without exception indoors.”

Outdoors, the virus is transmitted “extremely rarely” and does not lead to so-called cluster infections or widespread contagion.

The most danger of becoming infected by Covid comes from being indoors with others, the letter states. The risk of cluster infections is highest, for example, in old people’s homes, residential homes, schools, at events, choir rehearsals or during bus journeys.

The researchers warn: “If we want to get a grip on the pandemic, we have to make people aware that danger lurks inside.”


The group said the debate on coronavirus measures does not reflect current scientific knowledge, adding that many people have the “wrong ideas about the contagion potential associated with the virus”.

Measures such as bans on meeting in parks, closing popular routes for walks, or even night-time curfews give the impression that “It’s dangerous outside”.

However, these rules do not prevent “clandestine meetings indoors”, but “only increase the motivation to evade state orders even more”, they argued.

“The ongoing debates about strolling on river promenades, spending time in beer gardens, jogging or cycling have long since proven counterproductive,” the letter continues.

And the constant warning against contact even threatens to reinforce the “pandemic fatigue evident everywhere”, warn the members of the GAeF.

The group is appealing to the federal government, state leaders and ministries to strengthen protective measures indoors.

As few people as possible should meet indoors, they say, particularly because there is a risk of infection not only through direct contact with someone who is infected, but also if an infected person has previously been in the room.

The authors of the letter also mention regular airing or the use of air purifiers in old people’s homes, schools and offices, as well as urging people to wear masks indoors.

Who is the society behind the letter?

The Gesellschaft für Aerosolforschung (GAeF) was founded in 1972 as a non-profit association of pioneers of aerosol research.

It aims to promote scientific aerosol research both nationally and internationally. 

The members of the society include leading national and international researchers as well as many students and PhD students.

The GAeF has about 350 members from 35 countries. The open letter was signed by a handful of leading members of the society, including the president Dr Chrisof Asbach.


Indoor space – (der) Innenraum

Transmission – (die) Übertragung

Danger lurks inside – Drinnen lauert die Gefahr

Pandemic fatigue – (die) Pandemiemüdigkeit

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Member comments

  1. Re the ‘opening’ of Tübingen: if everyone who’s allowed to be there has tested negative, why on earth are they all wearing masks, even outside? When it comes to Covid, it’s always hysteria that wins, not reason . . .

  2. Well, I was at Frankfurt International Airport on Sunday. The inbound passport control booths were working at 1/3 capacity and more than 2 thousand people were crammed in a small place. Before the travel we were asked to have our tests, filled in the forms for trace & track etc. In that room, I have no idea who was behind me, in front of me, next to me at any given point and forget about the 1.5 m distance. There was no place to keep the distance. I haven’t contracted COVID yet but if I get it, it’ll be from the state managed Frankfurt International Airport. I wish they did not take any measures but run normally and told people to wear masks all the time. It would have been more productive and effective against COVID transmission. If anyone wonders how it looked like:

  3. Literally don’t understand why outdoor restaurants, beer gardens, cinemas, and other outdoor venues can’t be reopened now that it’s springtime. What is the problem?

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Germany should prepare for Covid wave in autumn, ministers warn

German health ministers say that tougher Covid restrictions should come back into force if a serious wave emerges in autumn.

Germany should prepare for Covid wave in autumn, ministers warn

Following a video meeting on Monday, the health ministers of Germany’s 16 states said tougher restrictions should be imposed again if they are needed. 

“The corona pandemic is not over yet – we must not be deceived by the current declining incidences,” said Saxony-Anhalt’s health minister Petra Grimm-Benne, of the Social Democrats, who currently chairs the Conference of Health Ministers (GMK).

According to the GMK, new virus variants are expected to appear in autumn and winter. Over the weekend, federal Health Minister Karl Lauterbach (SPD) also warned that the more dangerous Delta variant could return to Germany. “That is why the federal Ministry of Health should draw up a master plan to combat the corona pandemic as soon as possible and coordinate it with the states,” Grimm-Benne said.

Preparations should also include an amendment of the Infection Protection Act, ministers urged. They want to see the states given powers to react to the infection situation in autumn and winter. They called on the government to initiate the legislative process in a timely manner, and get the states actively involved.

The current Infection Protection Act expires on September 23rd this year. Germany has loosened much of its Covid restrictions in the last months, however, face masks are still compulsory on public transport as well as on planes. 

READ ALSO: Do people in Germany still have to wear Covid masks on planes?

The health ministers said that from autumn onwards, it should be possible for states to make masks compulsory indoors if the regional infection situation calls for it. Previously, wearing a Covid mask was obligatory in Germany when shopping and in restaurants and bars when not sitting at a table. 

Furthermore, the so-called 3G rule for accessing some venues and facilities – where people have to present proof of vaccination, recovery, or a negative test – should be implemented again if needed, as well as other infection protection rules, the ministers said. 

Bavaria’s health minister Klaus Holetschek, of the CSU, welcomed the ministers’ unanimous call for a revision of the Infection Protection Act. “The states must be able to take all necessary infection protection measures quickly, effectively, and with legal certainty,” he said.

North Rhine-Westphalia’s health minister Karl-Josef Laumann (CDU) warned that no one should “lull themselves into a false sense of security”.

“We must now prepare for the colder season and use the time to be able to answer important questions about the immunity of the population or the mechanisms of infection chains,” he said.

On Tuesday, Germany reported 86,253 Covid infections within the latest 24 hour period, as well as 215 Covid-related deaths. The 7-day incidence stood at 437.6 infections per 100,000 people. However, experts believe there could be twice as many infections because lots of cases go unreported. 

READ ALSO: Five things to know about the Covid pandemic in Germany right now