As an oncology nurse , Wright was aware of the risks of radon and its presence in the Black Hills . An invisible threat , the naturally occurring gas with no color , taste or smell is the second leading cause of lung cancer in the United States , and about 21,000 deaths are associated with it each year .
Formed when radioactive metals break down in rocks , soil and groundwater , radon can enter buildings through foundations , sinks , showers and toilets . It can be found in water or air , the latter being the most worrisome in terms of cancer risk .
The Wrights ’ house had a radon level around 80 picocuries per liter . The average indoor reading in the U . S . is 1.3 pCi / L , and the EPA says levels exceeding 4 pCi / L are unsafe .
Sixty percent of homes tested in South Dakota have elevated radon levels , which is the highest rate in the nation , according to the American Lung Association .
The state also has the highest average reading of radon levels across the nation , according to a 2022 report from the association . According to the EPA , the average indoor reading in South Dakota is 9.8 picocuries per liter — over twice the recommended safety level .
The Wrights hired a radon mitigation expert to install piping and a fan in their home to better circulate the air . Now , their radon levels are “ basically zero ,” Wright said .
“ You just have to be aware of where you ’ re at ,” Wright said . “ If you lived in a big city , you should be aware of smog . I think it ’ s just environmental awareness and knowing the environment you ’ re in here in South Dakota .”
Why is South Dakota so high ?
Bob Burns , owner of Earthorizons Inc . in the Black Hills , has been working in radon mitigation for decades . He said it ’ s more likely than not that homes have high levels of radon , and although the EPA safety threshold is 4 pCi / L , he considers any reading above the average outdoor level of 0.4 pCi / L to be elevated .
“ I would guess every house in South Dakota has an elevated radon level ,” Burns said .
Radon risk in the state is particularly elevated in the Black Hills , where a ridge around the Black Hills is rich with minerals including some uranium deposits in the Edgemont and Elkhorn Creek areas . Rapid City sits on both sides of the ridge , which is known as the Dakota Hogback .