About 85% of radiation comes from natural sources. The main source is radon gas, which poses a risk to your health.
Overview
The radiation that people are most commonly exposed to in the UK comes from a natural source called radon. Radiation can affect people’s health.
Radiation is energy moving through space. Sunshine is one of the most familiar forms of radiation, but it also comes from other natural and some man-made sources. The most familiar and the largest source of man-made radiation is medical X-rays, although people often think of radiation from nuclear power stations.
Radio waves are the lowest energy and least harmful type of radiation. Higher energy level sources include cosmic radiation that passes through the atmosphere from outer space. We are also exposed to radiation from certain rock types, radon gas and radioactive material in our food and drink.
Exposure to radiation can damage your body and increase the risk of cancer. The higher and longer the dose of radiation you are exposed to, the greater the risk.
The average individual radiation dose in the UK is 2.6mSv (milli-Sieverts) per year. Most of this is from natural (2.2mSv per year) and medical (0.36mSv per year) sources of radiation .
About 84 per cent of the average individual radiation dose comes from natural sources, mostly from inhaling radon gas. Your body also emits radiation from radioactive potassium (potassium-40) present naturally in bones and soft tissues.
Radon gas comes from small particles of uranium that occur naturally in all rocks and soils. The wind disposes radon gas in the open air, but it can get into houses, offices or schools where it can build up.
Radon exposure varies across the country. Some of the highest levels have been found in the South West of England, but levels well above average have been found in some other parts of England and Wales (Figure 1). However, even in these areas most homes have low levels.
Radon gas enters the body when we breathe it in. Radon accounts for about 5% (2,000) of lung cancer deaths each year. The risk of harm is much greater to smokers than to non-smokers.
The average level of radon in homes is 20 bequerels per cubic metre (1 bequerel = 1 disintegration per second of radon atoms), but levels shouldn’t exceed 200Bq/m3. Good ventilation in houses can stop radon gas building up. New homes in high-risk areas must meet building regulations designed to protect against radon build-up.
Medical procedures contribute most to your man-made radiation dose (the amount of radiation that you are exposed to), mainly through x-rays. Exposure to radiation at work and fallout from nuclear weapons testing contributes 0.4% of your yearly background dose.
Radioactive discharges from nuclear sites account for about less than 1% per year of the average dose.
Radioactive materials discharged to the environment are carefully controlled. We are responsible for authorising discharges from all nuclear licensed sites and making sure people are not exposed to a dose of more than 1 mSv per year.
We calculate doses by measuring radioactivity in the food and environment of a sample group of people who are at greatest risk of exposure, called the critical group. Other people are generally exposed to less radiation than the critical group.
Sellafield nuclear fuel processing site in Cumbria is a major source of controlled radioactive discharges. Discharges from Sellafield enter the atmosphere and the Irish Sea. Falling discharges from Sellafield since the 1980s have lowered the radiation dose (Figure 2). The increase in dose between 2001 and 2006 is due to the critical group eating more fish and seafood.
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