They can travel a few inches through the air but can be stopped by something as thin as a sheet of paper. This means that cells can be protected or shielded from damage by alpha particles by clothing. Even your skin will protect you from damage from alpha particles. However, if alpha particles are inhaled or ingested or get into a cut on the skin, they can cause damage to cells. As alpha particles decay inside the body, the surrounding cells absorb the radiation.
Beta particles contain more energy than alpha particles.
These particles are able to travel several feet through the air, but can be stopped with denser materials such as wood, glass or aluminum foil. Gamma rays are high-energy electromagnetic energy waves and the most penetrating type of radiation. They travel at the speed of light through the air. Cells must be shielded from gamma rays with concrete, lead or steel. Radioactive elements are unstable and spontaneously decay, causing them to emit radiation.