There is a lot of debate on what is worse for radon, winter or summer. There are people who argue that radon is more of a threat in the winter because your home is sealed up tight. You don’t want the heater’s air to leak out of the home. So you tighten up the home and seal up all the doors. People say that the radon then can leak into the home and linger there for the homeowner to be exposed to. Tests have been done on the radon levels in an area in the winter vs summer. Surprisingly enough, radon has shown to be ranging from 3 to 10 times higher in the summer months than in the wintertime. That is pretty wild. You do seal up the home in the summer if you have AC though. You don’t want to lose cooling the same way you lose heating. To show the drastic increase from winter to summer, there was a test that demonstrated a home increase by a ton. The scientists measured one meter below the surface to see the amounts of radon. The tests revealed that the home that had 300 picocuries per liter in the winter and it changed to about 3,000 picocuries per liter in the summer. That is quite a jump and a scary one at that. You want to be worried if the radon levels get above 4. That house must have been really suffering from radon gas. Don’t think you are totally safe in the winter and not safe in the summer. Radon is not picky on who it chooses and how long it stays.