From the point of view of pollution by dangerous substances, Czech air is among the worst in Europe. People in Prague, Brno, Ostrava and Ústí nad Labem protest against the long-term infringement of legal limits and violations of the law. In some parts of Ostrava, up to 60 times higher concentrations of carcinogenic substances in the atmosphere were measured than the World Health Organization's safe limit. Scientific studies also provide further evidence of the fatal impact of polluted air on population health. Yet the problem is solvable, as shown by the experience of the German Poruri.