Asbestos, mold and radon: three hazardous substances you never want to find in your home. While all three can be removed and remediated by trained professionals, radon is different, because you can’t see, smell or taste it. That doesn't mean radon is harmless. If left untreated, it can be hazardous to your family’s health. In fact, it’s the second leading cause of lung cancer in the United States.