Radon is an invisible, odorless and tasteless gas that is found naturally in soil and rocks. High levels of radon are found in buildings built on land that contains a lot of radon. If you live or work in one of these areas, you may have an increased chance of getting lung cancer.

The average concentration of radon in the home is 1.25 pCi/L, where pCi/L stands for picocuries (a measure of the amount of radon) per liter of air. Radon levels more than 4 pCi/L are considered unsafe. Although radon gas is thought to cause lung cancer, researchers haven't proved whether there is a link.¹

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.