This is where diesel emissions generate air pollution
Air pollution in many parts of Germany is making people sick. In 2023, more than 23,000 people died because of air pollution caused by nitrogen dioxide (NO2) – ten times more than from traffic accidents. Diesel combustion in road traffic is the primary source of NO2 pollution in Germany. People who live or work along busy roads are particularly at risk. This also affects healthcare facilities, schools, kindergartens and nursing homes – places where people with increased vulnerability spend their time. Shockingly, at children's breathing height, around one meter above the ground, air pollution from diesel exhaust is often even higher than at the official measurement height of 1.5 to 4 meters.
We are at a decisive moment in the fight for clean air: The EU has agreed to halve the current NO? limit value from 40 to 20 µg/m³ as an annual average. Starting in 2026, cities must take effective measures as soon as this new limit value is exceeded. This opens the door for targeted and binding reduction of air pollution. However, this requires real-world measurements that show where air pollution is particularly high. This is where our measurement campaign comes in.
In July 2025, we launched our nationwide NO2 measurement initiative “Expose Where Breathing Makes You Sick.” Our campaign reveals locations where air quality is much worse than it should be. This allows us to identify previously unknown pollution hotspots and to require authorities to implement effective measures to protect public health. Thousands of citizens have submitted locations where they suspect particularly high pollution levels.
We selected around 400 measurement sites according to the specifications of the EU Air Quality Directive to ensure that measurements are taken at representative and legally relevant locations. Measurements were conducted in October 2025 and evaluated by the accredited Swiss laboratory Passam AG. The results of the current campaign are available on the German webpage. Measuring NO2 with passive samplers is a well-established method whose accuracy is comparable to the official reference measurement procedure, providing reliable insights into actual air quality.
New limit values to protect environment and health
The newly adopted NO? limit – lowered from 40 to 20 µg/m³ – is still twice as high as the level recommended by the World Health Organization (WHO). The WHO recommends a guideline value of 10 µg/m³ annual average to minimize harmful health effects. Our updated map now shows all exceedances of this WHO guideline measured within the “NO2 Citizen Science” project. Further changes to the new EU Air Quality Directive can be found here.
We launched the “NO2 Citizen Science” project back in 2018 and, through a Europe-wide network and local partners, measured air quality at thousands of sampling points in 19 European countries. The results make one thing clear: harmful nitrogen dioxide from diesel exhaust is a major threat in heavily trafficked urban areas across borders. And that is not all. There are not enough official monitoring stations, and the existing ones are often not located where pollution is highest. Therefore, our measurements – and comparison with official data – formed a crucial part of the project. A summary of these findings can be found in our report.
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© DUH/Erdmann Marc Meunier
Referent Verkehr und Luftreinhaltung