2. LOJ Feb 2004 Radioactivity 3 Background radiation

3. LOJ Feb 2004 'Mr. Average UK‘ – Background dose

4. LOJ Feb 2004 Background radiation There are radioactive substances all around us, including in the ground, in the air, in building materials and in food. Radiation also reaches us from space. The radiation from all these sources is called background radiation.

5. LOJ Feb 2004 Background Radiation Most of the background radiation dose we receive in the UK is from natural sources (about half is inhaled as radon gas). About 15% of our annual dose comes from human activities such as X-rays in hospital or at the dentist or emissions from nuclear establishments.

6. LOJ Feb 2004 Your Background Radiation Dose The radiation dose you get in a year depends on: –where you live (the rock type in your locality), –your state of health (whether you require treatment or investigation in hospital that involves ionizing radiation ), –your diet (salt substitutes contain potassium rather than sodium and the percentage of potassium that naturally occurs in the radioactive form is higher than that of sodium), –your occupation (do you work in an environment that exposes you to nuclear radiation?)

7. LOJ Feb 2004 Experiments You need to count the background radiation before you perform an experiment. The background count can then be deducted from the count in your experiment.