Radiation Exposure

You are exposed to ionizing radiation every day from natural and human-made sources.

Natural radiation comes from the soil, which contains a number of radioactive elements such as uranium, radium, and thorium. High-energy radiation also reaches Earth from far in outer space.

Human-made radiation is the greatest source of exposure today, primarily in medical imaging and procedures. In fact, medical uses of radiation account for 98% of exposure to artificial radiation. In contrast, nuclear power plants account for less than 1% of exposure.

Is radiation harmful?

Like many tools, radiation brings humanity a number of significant benefits. Cancer treatment, pest control, smoke detection, medical sterilization, space travel, clean energy— these are ways that nuclear science and technology improve our lives.

Handled correctly, radiation is a safe and powerful tool.

Using radiation safely

How much radiation you receive depends on three things:

• Time
• Distance
• Shielding

Time

The amount of radiation exposure you receive increases the longer you are near the source. Radiation workers are exposed to radiation every day, so they wear dosimeters—devices that measure the amount of radiation a worker receives as they work. Very few people who do not work with radioactivity spend enough time near a powerful source.

Distance

Distance can be used to reduce exposure. The farther away you are from a radiation source, the less your exposure. In fact, doubling the distance from a source of radiation decreases the exposure rate to 1/4 the original exposure rate.

Shielding

Shielding is the placement of a material that reduces radiation between the radiation source and you, like the lead apron a radiologist places over your body.

Different kinds of radiation require different absorbers

Radiation safety often involves shielding--placing a radiation absorbing material near the radiation source.

α ALPHA – can be stopped after traveling through about 1.2 inches of air, about 0.008 inches of water, or a piece of paper. Your skin provides adequate shielding because alpha particles can’t penetrate it. Alpha particles can be very harmful if inhaled or ingested, though.

β BETA – – Beta particles are more penetrating than alpha particles. They travel farther in air than alpha particles, but can be stopped by a layer of clothing or by a layer of a metal.

γ GAMMA: Thick, dense materials are necessary to shield from gamma rays. The higher the energy of the gamma ray, the thicker the shield must be. X-rays also require thicker shielding. This is why x-ray technicians often give patients receiving x-rays a lead apron to cover other parts of their body.

The Nuclear Regulatory Commission regulates commercial nuclear power plants and other uses of nuclear materials, such as in nuclear medicine, through licensing, inspection and enforcement of its requirements.

Learn about the effects of radiation

Learn more about radiation