[An investigation on the mortality during a smog situation in western Ruhrgebiet on the 17. January 1979 (author's transl)].

A smog-warning of the first degree was announced on the 19th January 1979 for the first time after the institution of the so called Smog-decree in Northrhine-Westphalia. This warning was calceled after a few hours, already. The mortality in the relevant areas did not increase during this period. The adequacy of the 1st stage of the smog-warning was thus confirmed. This stage signifies a prewarning, which indicates a situation with no expected harmful effects of air-pollution on the population.