As winter approaches the United States and other northern hemisphere countries, it may be time to give a thought to radon. A geologic hazard tied to underground resources, radon is a radioactive gas that may permeate groundwater or natural gas from certain sources at low levels. Radon exposure would be higher during winter because radon can collect in tightly sealed spaces. So now may be a good time to measure the radon level in the living spaces where you spend the majority of your time. High levels, even levels that are tens of times background, are not an immediate hazard. But over the course of a lifetime they add a measurable (that is, statistically significant) amount to the very low risk of contracting lung cancer. If taking steps against radon exposure will give you peace of mind, the start of the shut-in season is a good time for that.
The explosion in natural gas production from tight shales, made possible by widespread use of hydraulic fracturing ("fracking") methods, raises the possibility that radon levels in commercial gas may be rising. There is not enough data in hand to say whether that's true, much less how much of a problem that is, if any. Radon tends to be stripped from gas during processing, and radon disappears in a few weeks by natural radioactive decay. So judging the effect on radon exposure to workers and the public is not simple. But even the worst possibility is not an urgent threat, merely a research question to add to the mix in evaluating the new state of natural gas production.
Background: About Radon