Friday, April 3rd, 2015 by Matthew Winslow
Have you ever wondered why radon mitigation in Pennsylvania is so prevalent? Pennsylvania is one of a number of states where many homes have radon levels which exceed 4 pCi/L (4 picocuries per liter of air). A picocurie measures radioactivity. But why does Pennsylvanian have higher than average levels of radon?
The answer lies in the remarkable geology of PA and the Appalachians, a mountain chain that runs from Canada to Alabama, including Maine, New Hampshire, Vermont, Massachusetts, Connecticut, New York, Pennsylvania, Maryland, Virginia, West Virginia, Ohio, Kentucky, Tennessee, New Jersey, North Carolina, South Carolina, Georgia,and Alabama.) The Appalachians are older and were once taller than the Rockies, although the Rockies formed more recently. The Appalachians contain all three kinds of rock formations, including igneous, sedimentary and metamorphic rocks. Uranium, a radioactive substance, is found in rocks, particularly such rocks as light-colored volcanic rocks, granites, dark shales, certain and certain sedimentary and metamorphic rocks derived from these rocks. These rocks and their soils may contain as much as 100 ppm uranium. Layers of these rocks underlie various parts of the United States.
Since the Appalachians include many rocks that are known to contain uranium, and radon gas is the natural by-product of the breakdown of uranium and radium into radon, it is not surprising that radon gas would be found in higher concentrations in the soil in areas near to or part of the Appalachians. Since the Appalachians are also subject to continual wearing down through wind and erosion, those rocks which contain uranium gradually wear down and become part of the soil.
Pennsylvania also contains enormous amounts of shale, such as that found in the Marcellus Shale formation. Shale is also a source of radon gas.
Nearness to mountain ranges is a factor in whether or not outside radon levels are higher in some regions of the United States than others. Other factors, such as home construction, cracks in walls and foundations, weatherproofing, ventilation and any radon reduction or radon mitigation efforts will affect radon levels inside homes and other buildings. There can be great variation in radon levels between neighboring homes or buildings, even if those buildings are side-by-side. Testing inside your home is the only way to know your radon level. Once the level has been determined, if it exceeds 4pCi/L, the EPA recommends undertaking radon mitigation efforts to reduce the level. Many states have programs requiring certification of radon mitigation specialists who can provide testing and radon mitigation services.