I live near Pittsburgh Pa. USA
Whether to worry about radon, depends on your local geography.
In the UK houses in Cornwall [bottom left corner of England] and parts of Scotland lie above granite. Radon can be a problem, because our houses generally have a raised floor with a trapped crawlspace below. It can build up in the crawlspace. So you ventilate the crawlspace. I've come across at least one new housing development where the planning authority insisted on a radon monitoring setup in each house, which could trigger forced ventilation of the crawlspace. I think that was experimental, though.