It's your sanctuary from the outside world, but would you know if your home sweet home was making you sick? Dr. Oz welcomes contractor Mike Holmes to reveal the 4 most toxic rooms in your house. Zones 3 and 4 are the basement, home to asbestos, radon and deadly gases that can be emitted by your furnace, and the backyard, where decks built before 2005 can contain pressure-treated, arsenic-infused wood. Learn how to detect potential toxins in your home - and how to eliminate them.
Click here to watch part 1: toxic zones 1 and 2.