A few of the highest possible readings have been videotaped in Mallow, County Cork, Ireland. Iowa has the highest possible average radon focus in the United States due to considerable glaciation that ground the granitic rocks from the Canadian Guard and also transferred it as soils comprising the abundant Iowa farmland. Several cities within the state, such as Iowa City, have passed requirements for radon-resistant building and construction in new residences. In a couple of locations, uranium tailings have been made use of for garbage dumps as well as were consequently improved, leading to possible enhanced direct exposure to radon. Numerous homeowner do their very first radon examination after a number of years of occupancy.