Ionising radiation has enough energy to cause damage to cells which can increase the risk of cancer later in life. However these risks to health are actually low and ionising radiation is widely used in cancer therapy. In general the health effects of ionising radiation are dependent on the dose received. While low doses increase the risk of cancer later in life, very high doses act like a poison and can be fatal.

In the UK, Public Health England has calculated that on average people are exposed to about 2.7 millisieverts ( mSv ) of radiation a year. A millisievert is a measure of radiation dose which accounts for the fact that ionising radiation can affect different parts of the body to differing degrees. The millisievert dose also allows for the different effects of different types of radiation, x rays, gamma rays, neutrons, alpha particles and beta particles.

The 2.7 mSv dose that people in the UK are exposed to comes from a number of sources. Many building materials contain low degrees of natural radioactivity and radon gas seeps from the ground into all buildings, so the largest exposure is to naturally occurring radiation in homes and workplaces. There are also significant contributions from naturally occurring radioactivity in food and from medical exposures.

1. Comparison of doses from sources of exposure