THIS TYPE OF RADIATION IS ALL BAD! Electromagnetic waves of extremely short wavelength (Cosmic Rays, Radon, X-rays, Gamma rays, Radioactive Fallout) and accelerated atomic particles (such as electrons, protons, neutrons, and alpha particles) deposit enough localized energy in an absorbing medium to dislodge electrons from atoms with which they interact and to disrupt chemical bonds. As ionizing radiation penetrates living cells, it collides randomly with atoms and molecules in its path, giving rise to ions, free radicals, and other molecular alterations that may injure the cell. Any molecule in the cell can be altered by radiation, but DNA is the most critical biological target. Ionizing radiation is measured with a Geiger Counter in millisievert (mSv).