Human: I've heard that I should be concerned about radon gas. What is it? Assistant: 
Radon is a radioactive gas that can seep into homes from the ground. It can accumulate in basements and other areas with poor ventilation, which makes it dangerous to inhale. If you have a home with a basement, you should test for radon levels before you move in. You can also install an air purifier or fan to help reduce radon levels.