Enlarge image

Cyclists in Berlin-Karlshorst: low-quality breathing air

Photo: Jens Kalaene / dpa

The maps appear alarm-red on many weather apps in large parts of Germany at the moment. The ad promises "poor air quality." Especially in the northeast of Germany, the concentration of harmful substances such as particulate matter in the air is worrying these days, as data from the Federal Environment Agency (Uba) also show.

In Berlin or Hamburg, for example, one cubic meter of air contained more than 30 micrograms of particulate matter with a granule size of less than 2.5 micrometers (PM 2.5) on Thursday. In places near the Baltic Sea coast, much higher values were measured. These tiny particles are considered particularly dangerous because they can penetrate through the lung tissue and into blood vessels – with a wide range of medical consequences, such as respiratory and cardiovascular diseases, cancer, but also dementia and possibly some mental illnesses such as depression.

Excessive and persistent air pollution, especially particulate matter, is blamed for hundreds of thousands of premature deaths per year in the European Union – even though the legal limits are mostly met on an annual average.

The World Health Organization advises limiting the concentration to a maximum of five micrograms per cubic meter. However, the EU does not want to reduce the current limit of 25 micrograms to ten micrograms until 2035. And that, too, is likely to be difficult to achieve with the Euro 7 emissions standard, which has recently been increasingly weakened by the EU. Javi López, a member of the European Parliament responsible for the reform of the Ambient Air Quality Directive, spoke of a "pandemic in slow motion".

»Like under a bell«

Parts of Germany are currently experiencing an acute outbreak. Nevertheless, the poor air quality in winter is not exceptional, explains Stefan Feigenspan from the Federal Environment Agency. It was only by luck with the weather that the country had rarely experienced such a constellation in recent years. A number of factors come together:

  • In a stable, rather windless winter weather situation, the air is hardly exchanged. "Like under a bell," the cold air stays close to the ground, according to Feigenspan, where pollutants accumulate.

  • More heating is used in the cold, and wood-burning fireplaces in particular are now considered to be the main cause of the entry of PM 2.5 into the air: In 2021, their emissions exceeded those of road traffic for the first time, whose particulate matter emissions are decreasing in the long term and are now more likely to be caused by abrasion from tires, brakes or road surfaces than from the exhaust, but still dominate with somewhat coarser particles of up to ten micrometers (PM 10).

  • In addition, the exhaust gas purification of passenger cars only works to a limited extent at low temperatures, due to deliberate defeat devices (the so-called thermal window) or simply because the catalytic converters require a flow temperature. Cold starts and short-distance driving in winter significantly increase the load.

  • In the east, there has been an unfavourable weather effect in the past few days: weak, but mainly from the southeast.

"In Poland and the Czech Republic, coal and wood are used for heating even more," explains Stefan Feigenspan. To some extent, therefore, the bad air could be considered imported. In the model of the European Earth observation service Copernicus, it is even possible to assign the origin of pollutants to selected cities at certain times of the day. For example, the Dresden air contained more than 51 micrograms of PM 2.5 at around two o'clock on Wednesday night, of which a good 31 micrograms came from the Czech Republic. In Berlin, too, a high proportion could be traced back to Czech origin on Wednesday, and a little more from Poland this Friday.

It's better not to jog with asthma

But one should not underestimate the home-made problem, says Feigenspan: "We are not free of guilt." Depending on the time of day, the majority of the bad air in Berlin comes from German emitters, and in Hamburg, with also strongly elevated values, there is only a slight influence from the neighbouring countries to the east.

As quickly as the unfavourable weather conditions deteriorated the air we breathed, a fresh wind can also provide relief just as quickly. This Friday, particulate matter levels fell slightly in many places, and from Sunday onwards they should no longer be so worrying according to the Copernicus model. However, the model predicts new peaks for Saturday.

People with pre-existing conditions in particular should avoid outdoor exercise, Feigenspan recommends. Anyone who is prone to asthma, for example, should not go jogging under the current conditions.