Which European cities have the worst air quality? This interactive graphic shows where the concentration of nitrogen dioxide is the highest.
After more than 150 years, Germany's last black coal mine will close in the Ruhr region, posing a gigantic geological and environmental challenge to the former industrial heartland.
Industry wants to curb nitrogen oxide emissions from diesel engines using modern catalytic converter technology. One possibility is the admixture of AdBlue, which contains urea. But how exactly does it work?
For decades, plastic straws have been essential props for cocktail makers, smoothie lovers and fast food addicts. But that may be starting to change.