There's just the one, and it's 222Rn, or radon-222.
There might be a trace of some of the other isotopes around if there has been a nuclear accident or the like, but it is unlikely that they could be detected unless the accident was huge, had just occurred and you were testing right on top of it.
It is an isotope that occurs in nature, and is not manmade. Isotopes, by the way, are atoms that have the same number of protons, but different number of neutrons. The atomic number is the same, but...