Radon is a radioactive, colourless, odourless and tasteless gas. It is formed as natural deposits of uranium throughout the earth’s crust decay. When radon decay products are inhaled, they can alter the cells in the lungs. These alterations can increase the potential for lung cancer.

The National Cancer Institute in the United Kingdom states that radon is responsible for 10% of lung cancer cases diagnosed each year in the UK. According to the Swedish Radiation Protection Institute, radon constitutes the greatest radiation problem, far outweighing the effects of the Chernobyl accident.

The amount of radon in a building is dependent upon several factors. These factors include geology, pathways into the building, and the ventilation rate. As the concentration of uranium in the underlying soil increases, so does the strength of radon. Radon is transported to buildings more easily through permeable soils. Buildings can also create pressure differentials that will draw in the soil gases. Radon can enter the building through many pathways, such as cracks in the foundation, utility penetrations, sumps and floor drains. The ventilation rate of the building affects the final radon concentration.