How clean is air in German cities, really? Air seems to be clean in Germany, for the first time in decades, according to official reports in February 2025 (DW 2025). For the first time in 2024, no air quality measuring station exceeded the annual limit for nitrogen dioxide (NO2) of 40 micrograms per cubic meter of air. EU ozone (O3) thresholds across German cities did not cross the upper limit, while the particulate matter limits in annual averages stayed within acceptable limits since 2018 in most measuring stations. Experts praise these results as the result of targeted air quality improvement measures at multi-scalar level: EU, federal, state, and local communes. Key contributions to clean air in Germany are attributed to technologies such as particle filters, along with measures, for example, speed limits and the electrification of public transport buses etc. The 2025 report testifies to collective action and innovation in environmental policy in Germany.

Yet, how clean is air in German cities, really? A month after the February 2025 report, air quality in Germany is rated as poor due to high levels of particulate matter (PM 2.5), according to the Federal Environment Agency (Umweltbundesamt, UBA 2025). High levels of particulate matter in the air concern not only Germany but much of Central Europe. Particulate matters or fine dust are made of solid particles in the outdoor air that do not immediately settle to the ground but remain in the atmosphere for an extended period of time. Depending on their size, dust particles are classified into different categories. PM 10 refers to particles with an aerodynamic diameter of less than 10 micrometers (µm). The majority of human-made (anthropogenic) fine dust emissions originate from combustion processes (such as motor vehicle traffic and heating systems in built environments) and industrial activities. To a lesser extent, diffuse emissions from commerce and trade, agriculture, fireworks, cigarettes, and barbecues also contribute to dust emissions.

Fine dust emissions are not only due to direct emissions (primary particles), but can also form in the atmosphere from precursor substances such as sulfur dioxide, nitrogen oxides, and ammonia, as secondary particles. The size and chemical composition of dust particles determine their physical and chemical properties. For their impact on health, characteristics such as particle size, geometric shape, and pollutants adhering to the surface are especially important.

Instead of discussing the cleanest and dirtiest air across German cities, we need to look at actual data on site in terms of particular stations if we wish to find out how clean air is in and across German cities. Surprisingly, the air was not the most polluted in big cities like Berlin, Munich, Cologne, Frankfurt or Hamburg but in smaller cities. The question is why. Only contextualized research can tell us why exactly. Among all German cities, air quality recorded between 1 May 2025 and 13 May 2025 demonstrates the top 10 sites where air was the most polluted, containing PM 10 of more than 50 μg/m³: Essen Gladbacker Straße in Nordrhein-Westfalen crossed the upper limits at least 21 times; Bernau Löhmühlenstraße in Brandenburg (17 times); Warstein in Hessen (17 times); Limburg Schiede in Hessen (16 times); Krefeld (Hafen) in Nordrhein-Westfalen (13 times); Ludwigshafen-Mundenheim in Rheinland-Pfalz (13 times); Halle/Paracelsusstraße in Sachsen-Anhalt (13 times); Offenbach Untere Grenzstraße in Hessen (12 times); Brandenburg Neuendorferstraße in Brandenburg (11 times); and Oranienburg Bernauerstraße in Brandenburg (11 times).

Especially in winter, the emission of particulate matters (Feinstaub) is higher because of high energy consumption, with fireplaces heated with wood, and increased road traffic emission. Although precipitation in winter acts like a vacuum cleaner for our air. Rain and snow in winter, therefore, help improve air quality. When water vapor encounters an air mass filled with tiny particles, it condenses on the dirt. Each tiny snowflake and raindrop carries a small particle of dust to the ground, thereby cleaning the air.

Air pollution and breathing troubles are transboundary phenomena. Regionally, agriculture and potential Sahara dust transport, along with contributions from Eastern Europe, can add to the problem. Weather conditions play a major role—limited air circulation and dry, windless conditions have trapped pollutants in the lower atmosphere. The German Weather Service (Deutscher Wetterdienst) predicts improving air quality in the coming days as high-pressure systems weaken, bringing more wind and precipitation to disperse pollutants. Short-term measures to lower particulate matter levels often show limited effectiveness, particularly when pollutants originate from other regions.

Long-term collective efforts, such as emission reductions in industry, transportation, and heating systems, can significantly improve annual particulate matter levels as it showed in Germany in the last two decades. For current updates, the UBA provides real-time air quality data via its app and website, including health tips based on the Air Quality Index. People with pre-existing conditions are advised to avoid outdoor exertion during periods of moderate air quality, and all individuals should take precautions when the air is very poor. Activities like light walking are recommended instead of jogging. This approach minimizes exposure to pollutants while benefiting overall health.