Are we all exposed to radon?

A set of articles first outlines that radon exposure is the second reason for lung cancer after tobacco, and outlines the recent commitment of French public authorities with respect to the problem of radon exposure in dwellings. The Swiss example is evoked. This policy implies actions of detection, diagnosis and control. Techniques to reduce radon in dwellings are briefly indicated. An expert in radiation protection who belongs to the IRSN and who launched the first radon measurement campaign in dwellings answer three questions on this issue