Radon enters your home when warm air begins to rise and exits through the roof, creating a vacuum that pulls cooler air from under the foundation. Part of that air is radon, which is an invisible, odorless gas that develops naturally when radioactive particles are deep within the ground. Those particles usually come from decaying matter in soil and rocks.

Radon is present almost everywhere but, like sunlight, the concentration levels and how often you are exposed to it have a large part to play in just how dangerous it is. There are levels of radon that are acceptable inside a house, but above a certain limit, radon becomes a serious radioactive hazard that is a known cause of lung cancer. In fact, radon exposure is the number two leading cause of lung cancer (after smoking).

You can vent radon out of your house sometimes by simply opening a window, but it won’t remove the source, and will likely rise above recommended levels quickly. A professional will be needed to assess your home, and determine the best strategy for radon removal. Active radon sump pumps and soil depressurization systems are often used to forcefully vent the radon from your home.

No level of radon is technically safe, but since it is present everywhere, complete avoidance is impossible. The average radon level in homes across the United States is 1.3 picocuries per liter (pCi/L). The Environmental Protection Agency (EPA) recommends taking preventative measures if your home's radon levels are between 2 and 4 pCi/L or higher.