Background radiation is all around us. Some of it comes from natural sources and some comes from artificial sources.

Natural sources

Natural sources of background radiation include:

• cosmic rays - radiation that reaches the Earth from space
• rocks and soil - some rocks are radioactive and give off radioactive radon gas
• living things - plants absorb radioactive materials from the soil and these pass up the food chain

For most people, natural sources contribute the most to their background radiation dose.

Artificial sources

There is little we can do about natural background radiation. After all, we cannot stop eating, drinking or breathing to avoid it.

However, human activity has added to background radiation by creating and using artificial sources of radiation. These include medical X-rays, radioactive fallout from nuclear weapons testing and radioactive waste from nuclear power stations.

Artificial sources account for about 15 per cent of the average background radiation dose. Nearly all artificial background radiation comes from medical procedures, such as receiving X-rays for X-ray photographs.