[en] The increased lead concentrations in the atmosphere are to be attributed particularly to the combustion of gasoline containing organic lead components as antiknock additives. Furthermore, the operation of smelters and coal burning electric power plants can be important as pollutant sources. Since each natural lead deposit has a characteristic isotopic composition the knowledge of this composition can make it possible to differentiate between the various sources of emission. The isotopes ²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb are continuously created as the end-products of radioactive decay of uranium and thorium. In contrast to that the isotope ²⁰⁴Pb is not known to have been formed by any radioactive decay process. The present-day lead isotope ratios are, therefore, a function of the parent uranium-thorium abundances and the age of the systems. In order to identify the lead emitted by coal burning electric power plants the isotopic composition of lead in various West German pit coals was determined by mass spectrometry. The procedure is described, and the results are given and discussed. (author)