Radon test kits are available for purchase. The good news is that, if you do have radon present but at low levels, the situation can be very easily remedied by just ventilating the basement. This pulls out the emission and can reverse the detectable emission of radon. It's based on geology and the natural composition of the bedrock and soil. It is not related to anything man-made.
Pollution is a man-made problem.
We do believe, although again it's been hard to prove, that pollution puts people at risk for lung cancer and other cancers. While the data is a little bit harder to document, in my opinion, there is no reason not to believe that car exhaust and other chemicals are not carcinogenic. It's actually very effective. We know that the more you smoke, or have smoked, directly correlates with the incidence of lung cancer. So if you smoked two packs per day for 20 years and then stopped, that's much better than two packs per day for 40 years.