Before revision: Because a portion of the ash from a coal power plant is discharged through the smokestack, the radioactive contamination released during the regular operation of coal power plants is, in fact, higher than that of nuclear power plants.
After revision: Due to the fact that part of the ash of a coal power plant escapes through the smokestack, the radioactive contamination released by coal power plants in regular operation is actually higher than that of nuclear power plants.