Radioactivity and human activity

During them destructions, the radioactive elements emit different radiations: alpha, beta and gamma.
The radiations alpha and beta are particles but the radiations gamma are electromagnetic waves. A paper can stop a radiation alpha, a plate of alumunim for a radiation beta, while a thick concrete wall, a plate of cast iron or gold is necessary for stop one radiation gamma.
The radiations affect the bodies by way external or internal.

A large part of the radioactivity is natural (for example in France, the natural radioactivity is 1.64 millisieverts a year).

But there is also an artificial radioactivity:
In France, the exposure comes mainly from the medical irradiation with 0.8 millisievert, only 0,06 millisievert a year results from fallout from the tries of nuclear weapons and from the leaks of the atomic energy.

But it is not the case everywhere...