The skin can be bombarded by alpha or beta rays, either because of the radioactivity in the atmosphere (tritium, carbon-14), or by accident if one touches a surface contaminated by radioactivity. Only Beta rays of sufficient energy, like strontium-90 will reach the deepest part of the skin (the subcutis). Less powerful beta rays like carbon-14 will just reach the dermis. Beta rays of tritium (energetically weak) and alpha because they are quickly stopped (fifty microns) do not pass through the epidermis. The contact with a radioactive source, especially alpha, can lead to burns. The wearing of a protection suit and gloves stops all or mostt of these rays.