Air pollutants at a glance
![Smog in an urban area - Trier](https://www.umweltbundesamt.de/sites/default/files/styles/800w400h/public/medien/370/bilder/trier_dunst_1.jpg?itok=sy8XQ97a)
Source: Axel Eggert / Umweltbundesamt
The composition of the air is affected by humans. Many components of the air are, above a certain concentration, a threat to humans and animals and affect plants, water bodies, soils and even buildings and materials.