Radon can enter the home a number of ways, but the most common is through the foundation. It is important to test for radon every few years to determine the radon level in your home. Since there is no way to detect radon, people are exposed without any knowledge of it, and over time that will cause lung cancer.
Radon is a radioactive gas formed by the natural decay of uranium in soil and rock. Again, there is no odor or taste, so it is easy to be unaware of the presence of radon.