[en] Presented paper is continuation of previous work published on the Conference in Beijing, 1987. During two years observations of changes in radon concentration have been extended to different workings, including sandstone. The radon emission from long drainage boreholes was measured, and the results have been used for the estimation of degasification of boreholes impact. The most essential result is the real possibility to use this phenomenon, that is the changes in radon emission, to forecast outbursts in coal seams and as a means of warning in sandstones