A seismologically active geological overthrust zone produces enhanced CO2, H2S, CH4 and Rn exhalation in a village of the Matra mountain. This recently discovered phenomenon results in a radon activity density above 1 kBq/m3 in the air of living rooms of several houses. The rocks are not rich in uranium, the soil exhalation is still intensive, but it varies in space and time, therefore a rather detailed radon mapping of the village in different seasons is reported here, not so much to clarify the geophysical situation but to know the doses affecting the population. Radon insulation is not yet common in this region. Expensive insulation methods seem to work, but more economical ways of satisfying the needs of the population must be found. Radon awareness of the population helps in avoiding panic, and with appropriate life style it enables them to suppress radon concentration in their environment.