Air pollution limits
In new guidelines, the WHO recommends greatly reducing pollutants in the air: Even in low concentrations, they are hazardous to health. In Germany, particulate matter and nitrogen oxide levels in particular are too high.
The World Health Organization (WHO) has published new guidelines on air quality after more than 15 years. They contain recommendations for new guide values for various pollutants. Above all, the pollution with fine dust and nitrogen dioxide (NO2) would have to be reduced significantly… Source Tagesschau
New WHO guidelines (annual mean values)
Particles with an aerodynamic diameter of less than ten micrometers (µm) (PM10) are referred to as fine dust. Particularly small particles with an aerodynamic diameter of less than 2.5 µm (PM2.5) pose an increased risk because they can penetrate deeper into the airways.
