On radioactive air contamination of the prospecting holes and its possible control

One of the main radiation hazard factors for the air in workings is 222Rn presence. Dust aerosols with radon short-lived and long-lived daughter products are a serious hazard for health. The experience has shown that from the point of view of decreasing radon yield, the best is the consequent sinking of workings which provides minimum Rn emission in connection with minimum areas of rock and ore outcrops. The worst results are observed in cases of parallel sinking of workings. In these cases radon yield can be 2.5-3 times higher. The minimum number of faces must be made. The summary Rn yield is shown to increase in direct proportion to the increase of working length